fix file naming

.gitignore

@@ -1,4 +1,5 @@
 /__pycache__/
 /static/
 /venv/
+/media/
 /pythagoras.tar.xz

LICENSE

@@ -0,0 +1,673 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The GNU General Public License is a free, copyleft license for
+software and other kinds of works.
+
+  The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
+the GNU General Public License is intended to guarantee your freedom to
+share and change all versions of a program--to make sure it remains free
+software for all its users.  We, the Free Software Foundation, use the
+GNU General Public License for most of our software; it applies also to
+any other work released this way by its authors.  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+them if you wish), that you receive source code or can get it if you
+want it, that you can change the software or use pieces of it in new
+free programs, and that you know you can do these things.
+
+  To protect your rights, we need to prevent others from denying you
+these rights or asking you to surrender the rights.  Therefore, you have
+certain responsibilities if you distribute copies of the software, or if
+you modify it: responsibilities to respect the freedom of others.
+
+  For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must pass on to the recipients the same
+freedoms that you received.  You must make sure that they, too, receive
+or can get the source code.  And you must show them these terms so they
+know their rights.
+
+  Developers that use the GNU GPL protect your rights with two steps:
+(1) assert copyright on the software, and (2) offer you this License
+giving you legal permission to copy, distribute and/or modify it.
+
+  For the developers' and authors' protection, the GPL clearly explains
+that there is no warranty for this free software.  For both users' and
+authors' sake, the GPL requires that modified versions be marked as
+changed, so that their problems will not be attributed erroneously to
+authors of previous versions.
+
+  Some devices are designed to deny users access to install or run
+modified versions of the software inside them, although the manufacturer
+can do so.  This is fundamentally incompatible with the aim of
+protecting users' freedom to change the software.  The systematic
+pattern of such abuse occurs in the area of products for individuals to
+use, which is precisely where it is most unacceptable.  Therefore, we
+have designed this version of the GPL to prohibit the practice for those
+products.  If such problems arise substantially in other domains, we
+stand ready to extend this provision to those domains in future versions
+of the GPL, as needed to protect the freedom of users.
+
+  Finally, every program is threatened constantly by software patents.
+States should not allow patents to restrict development and use of
+software on general-purpose computers, but in those that do, we wish to
+avoid the special danger that patents applied to a free program could
+make it effectively proprietary.  To prevent this, the GPL assures that
+patents cannot be used to render the program non-free.
+
+  The precise terms and conditions for copying, distribution and
+modification follow.
+
+                       TERMS AND CONDITIONS
+
+  0. Definitions.
+
+  "This License" refers to version 3 of the GNU General Public License.
+
+  "Copyright" also means copyright-like laws that apply to other kinds of
+works, such as semiconductor masks.
+
+  "The Program" refers to any copyrightable work licensed under this
+License.  Each licensee is addressed as "you".  "Licensees" and
+"recipients" may be individuals or organizations.
+
+  To "modify" a work means to copy from or adapt all or part of the work
+in a fashion requiring copyright permission, other than the making of an
+exact copy.  The resulting work is called a "modified version" of the
+earlier work or a work "based on" the earlier work.
+
+  A "covered work" means either the unmodified Program or a work based
+on the Program.
+
+  To "propagate" a work means to do anything with it that, without
+permission, would make you directly or secondarily liable for
+infringement under applicable copyright law, except executing it on a
+computer or modifying a private copy.  Propagation includes copying,
+distribution (with or without modification), making available to the
+public, and in some countries other activities as well.
+
+  To "convey" a work means any kind of propagation that enables other
+parties to make or receive copies.  Mere interaction with a user through
+a computer network, with no transfer of a copy, is not conveying.
+
+  An interactive user interface displays "Appropriate Legal Notices"
+to the extent that it includes a convenient and prominently visible
+feature that (1) displays an appropriate copyright notice, and (2)
+tells the user that there is no warranty for the work (except to the
+extent that warranties are provided), that licensees may convey the
+work under this License, and how to view a copy of this License.  If
+the interface presents a list of user commands or options, such as a
+menu, a prominent item in the list meets this criterion.
+
+  1. Source Code.
+
+  The "source code" for a work means the preferred form of the work
+for making modifications to it.  "Object code" means any non-source
+form of a work.
+
+  A "Standard Interface" means an interface that either is an official
+standard defined by a recognized standards body, or, in the case of
+interfaces specified for a particular programming language, one that
+is widely used among developers working in that language.
+
+  The "System Libraries" of an executable work include anything, other
+than the work as a whole, that (a) is included in the normal form of
+packaging a Major Component, but which is not part of that Major
+Component, and (b) serves only to enable use of the work with that
+Major Component, or to implement a Standard Interface for which an
+implementation is available to the public in source code form.  A
+"Major Component", in this context, means a major essential component
+(kernel, window system, and so on) of the specific operating system
+(if any) on which the executable work runs, or a compiler used to
+produce the work, or an object code interpreter used to run it.
+
+  The "Corresponding Source" for a work in object code form means all
+the source code needed to generate, install, and (for an executable
+work) run the object code and to modify the work, including scripts to
+control those activities.  However, it does not include the work's
+System Libraries, or general-purpose tools or generally available free
+programs which are used unmodified in performing those activities but
+which are not part of the work.  For example, Corresponding Source
+includes interface definition files associated with source files for
+the work, and the source code for shared libraries and dynamically
+linked subprograms that the work is specifically designed to require,
+such as by intimate data communication or control flow between those
+subprograms and other parts of the work.
+
+  The Corresponding Source need not include anything that users
+can regenerate automatically from other parts of the Corresponding
+Source.
+
+  The Corresponding Source for a work in source code form is that
+same work.
+
+  2. Basic Permissions.
+
+  All rights granted under this License are granted for the term of
+copyright on the Program, and are irrevocable provided the stated
+conditions are met.  This License explicitly affirms your unlimited
+permission to run the unmodified Program.  The output from running a
+covered work is covered by this License only if the output, given its
+content, constitutes a covered work.  This License acknowledges your
+rights of fair use or other equivalent, as provided by copyright law.
+
+  You may make, run and propagate covered works that you do not
+convey, without conditions so long as your license otherwise remains
+in force.  You may convey covered works to others for the sole purpose
+of having them make modifications exclusively for you, or provide you
+with facilities for running those works, provided that you comply with
+the terms of this License in conveying all material for which you do
+not control copyright.  Those thus making or running the covered works
+for you must do so exclusively on your behalf, under your direction
+and control, on terms that prohibit them from making any copies of
+your copyrighted material outside their relationship with you.
+
+  Conveying under any other circumstances is permitted solely under
+the conditions stated below.  Sublicensing is not allowed; section 10
+makes it unnecessary.
+
+  3. Protecting Users' Legal Rights From Anti-Circumvention Law.
+
+  No covered work shall be deemed part of an effective technological
+measure under any applicable law fulfilling obligations under article
+11 of the WIPO copyright treaty adopted on 20 December 1996, or
+similar laws prohibiting or restricting circumvention of such
+measures.
+
+  When you convey a covered work, you waive any legal power to forbid
+circumvention of technological measures to the extent such circumvention
+is effected by exercising rights under this License with respect to
+the covered work, and you disclaim any intention to limit operation or
+modification of the work as a means of enforcing, against the work's
+users, your or third parties' legal rights to forbid circumvention of
+technological measures.
+
+  4. Conveying Verbatim Copies.
+
+  You may convey verbatim copies of the Program's source code as you
+receive it, in any medium, provided that you conspicuously and
+appropriately publish on each copy an appropriate copyright notice;
+keep intact all notices stating that this License and any
+non-permissive terms added in accord with section 7 apply to the code;
+keep intact all notices of the absence of any warranty; and give all
+recipients a copy of this License along with the Program.
+
+  You may charge any price or no price for each copy that you convey,
+and you may offer support or warranty protection for a fee.
+
+  5. Conveying Modified Source Versions.
+
+  You may convey a work based on the Program, or the modifications to
+produce it from the Program, in the form of source code under the
+terms of section 4, provided that you also meet all of these conditions:
+
+    a) The work must carry prominent notices stating that you modified
+    it, and giving a relevant date.
+
+    b) The work must carry prominent notices stating that it is
+    released under this License and any conditions added under section
+    7.  This requirement modifies the requirement in section 4 to
+    "keep intact all notices".
+
+    c) You must license the entire work, as a whole, under this
+    License to anyone who comes into possession of a copy.  This
+    License will therefore apply, along with any applicable section 7
+    additional terms, to the whole of the work, and all its parts,
+    regardless of how they are packaged.  This License gives no
+    permission to license the work in any other way, but it does not
+    invalidate such permission if you have separately received it.
+
+    d) If the work has interactive user interfaces, each must display
+    Appropriate Legal Notices; however, if the Program has interactive
+    interfaces that do not display Appropriate Legal Notices, your
+    work need not make them do so.
+
+  A compilation of a covered work with other separate and independent
+works, which are not by their nature extensions of the covered work,
+and which are not combined with it such as to form a larger program,
+in or on a volume of a storage or distribution medium, is called an
+"aggregate" if the compilation and its resulting copyright are not
+used to limit the access or legal rights of the compilation's users
+beyond what the individual works permit.  Inclusion of a covered work
+in an aggregate does not cause this License to apply to the other
+parts of the aggregate.
+
+  6. Conveying Non-Source Forms.
+
+  You may convey a covered work in object code form under the terms
+of sections 4 and 5, provided that you also convey the
+machine-readable Corresponding Source under the terms of this License,
+in one of these ways:
+
+    a) Convey the object code in, or embodied in, a physical product
+    (including a physical distribution medium), accompanied by the
+    Corresponding Source fixed on a durable physical medium
+    customarily used for software interchange.
+
+    b) Convey the object code in, or embodied in, a physical product
+    (including a physical distribution medium), accompanied by a
+    written offer, valid for at least three years and valid for as
+    long as you offer spare parts or customer support for that product
+    model, to give anyone who possesses the object code either (1) a
+    copy of the Corresponding Source for all the software in the
+    product that is covered by this License, on a durable physical
+    medium customarily used for software interchange, for a price no
+    more than your reasonable cost of physically performing this
+    conveying of source, or (2) access to copy the
+    Corresponding Source from a network server at no charge.
+
+    c) Convey individual copies of the object code with a copy of the
+    written offer to provide the Corresponding Source.  This
+    alternative is allowed only occasionally and noncommercially, and
+    only if you received the object code with such an offer, in accord
+    with subsection 6b.
+
+    d) Convey the object code by offering access from a designated
+    place (gratis or for a charge), and offer equivalent access to the
+    Corresponding Source in the same way through the same place at no
+    further charge.  You need not require recipients to copy the
+    Corresponding Source along with the object code.  If the place to
+    copy the object code is a network server, the Corresponding Source
+    may be on a different server (operated by you or a third party)
+    that supports equivalent copying facilities, provided you maintain
+    clear directions next to the object code saying where to find the
+    Corresponding Source.  Regardless of what server hosts the
+    Corresponding Source, you remain obligated to ensure that it is
+    available for as long as needed to satisfy these requirements.
+
+    e) Convey the object code using peer-to-peer transmission, provided
+    you inform other peers where the object code and Corresponding
+    Source of the work are being offered to the general public at no
+    charge under subsection 6d.
+
+  A separable portion of the object code, whose source code is excluded
+from the Corresponding Source as a System Library, need not be
+included in conveying the object code work.
+
+  A "User Product" is either (1) a "consumer product", which means any
+tangible personal property which is normally used for personal, family,
+or household purposes, or (2) anything designed or sold for incorporation
+into a dwelling.  In determining whether a product is a consumer product,
+doubtful cases shall be resolved in favor of coverage.  For a particular
+product received by a particular user, "normally used" refers to a
+typical or common use of that class of product, regardless of the status
+of the particular user or of the way in which the particular user
+actually uses, or expects or is expected to use, the product.  A product
+is a consumer product regardless of whether the product has substantial
+commercial, industrial or non-consumer uses, unless such uses represent
+the only significant mode of use of the product.
+
+  "Installation Information" for a User Product means any methods,
+procedures, authorization keys, or other information required to install
+and execute modified versions of a covered work in that User Product from
+a modified version of its Corresponding Source.  The information must
+suffice to ensure that the continued functioning of the modified object
+code is in no case prevented or interfered with solely because
+modification has been made.
+
+  If you convey an object code work under this section in, or with, or
+specifically for use in, a User Product, and the conveying occurs as
+part of a transaction in which the right of possession and use of the
+User Product is transferred to the recipient in perpetuity or for a
+fixed term (regardless of how the transaction is characterized), the
+Corresponding Source conveyed under this section must be accompanied
+by the Installation Information.  But this requirement does not apply
+if neither you nor any third party retains the ability to install
+modified object code on the User Product (for example, the work has
+been installed in ROM).
+
+  The requirement to provide Installation Information does not include a
+requirement to continue to provide support service, warranty, or updates
+for a work that has been modified or installed by the recipient, or for
+the User Product in which it has been modified or installed.  Access to a
+network may be denied when the modification itself materially and
+adversely affects the operation of the network or violates the rules and
+protocols for communication across the network.
+
+  Corresponding Source conveyed, and Installation Information provided,
+in accord with this section must be in a format that is publicly
+documented (and with an implementation available to the public in
+source code form), and must require no special password or key for
+unpacking, reading or copying.
+
+  7. Additional Terms.
+
+  "Additional permissions" are terms that supplement the terms of this
+License by making exceptions from one or more of its conditions.
+Additional permissions that are applicable to the entire Program shall
+be treated as though they were included in this License, to the extent
+that they are valid under applicable law.  If additional permissions
+apply only to part of the Program, that part may be used separately
+under those permissions, but the entire Program remains governed by
+this License without regard to the additional permissions.
+
+  When you convey a copy of a covered work, you may at your option
+remove any additional permissions from that copy, or from any part of
+it.  (Additional permissions may be written to require their own
+removal in certain cases when you modify the work.)  You may place
+additional permissions on material, added by you to a covered work,
+for which you have or can give appropriate copyright permission.
+
+  Notwithstanding any other provision of this License, for material you
+add to a covered work, you may (if authorized by the copyright holders of
+that material) supplement the terms of this License with terms:
+
+    a) Disclaiming warranty or limiting liability differently from the
+    terms of sections 15 and 16 of this License; or
+
+    b) Requiring preservation of specified reasonable legal notices or
+    author attributions in that material or in the Appropriate Legal
+    Notices displayed by works containing it; or
+
+    c) Prohibiting misrepresentation of the origin of that material, or
+    requiring that modified versions of such material be marked in
+    reasonable ways as different from the original version; or
+
+    d) Limiting the use for publicity purposes of names of licensors or
+    authors of the material; or
+
+    e) Declining to grant rights under trademark law for use of some
+    trade names, trademarks, or service marks; or
+
+    f) Requiring indemnification of licensors and authors of that
+    material by anyone who conveys the material (or modified versions of
+    it) with contractual assumptions of liability to the recipient, for
+    any liability that these contractual assumptions directly impose on
+    those licensors and authors.
+
+  All other non-permissive additional terms are considered "further
+restrictions" within the meaning of section 10.  If the Program as you
+received it, or any part of it, contains a notice stating that it is
+governed by this License along with a term that is a further
+restriction, you may remove that term.  If a license document contains
+a further restriction but permits relicensing or conveying under this
+License, you may add to a covered work material governed by the terms
+of that license document, provided that the further restriction does
+not survive such relicensing or conveying.
+
+  If you add terms to a covered work in accord with this section, you
+must place, in the relevant source files, a statement of the
+additional terms that apply to those files, or a notice indicating
+where to find the applicable terms.
+
+  Additional terms, permissive or non-permissive, may be stated in the
+form of a separately written license, or stated as exceptions;
+the above requirements apply either way.
+
+  8. Termination.
+
+  You may not propagate or modify a covered work except as expressly
+provided under this License.  Any attempt otherwise to propagate or
+modify it is void, and will automatically terminate your rights under
+this License (including any patent licenses granted under the third
+paragraph of section 11).
+
+  However, if you cease all violation of this License, then your
+license from a particular copyright holder is reinstated (a)
+provisionally, unless and until the copyright holder explicitly and
+finally terminates your license, and (b) permanently, if the copyright
+holder fails to notify you of the violation by some reasonable means
+prior to 60 days after the cessation.
+
+  Moreover, your license from a particular copyright holder is
+reinstated permanently if the copyright holder notifies you of the
+violation by some reasonable means, this is the first time you have
+received notice of violation of this License (for any work) from that
+copyright holder, and you cure the violation prior to 30 days after
+your receipt of the notice.
+
+  Termination of your rights under this section does not terminate the
+licenses of parties who have received copies or rights from you under
+this License.  If your rights have been terminated and not permanently
+reinstated, you do not qualify to receive new licenses for the same
+material under section 10.
+
+  9. Acceptance Not Required for Having Copies.
+
+  You are not required to accept this License in order to receive or
+run a copy of the Program.  Ancillary propagation of a covered work
+occurring solely as a consequence of using peer-to-peer transmission
+to receive a copy likewise does not require acceptance.  However,
+nothing other than this License grants you permission to propagate or
+modify any covered work.  These actions infringe copyright if you do
+not accept this License.  Therefore, by modifying or propagating a
+covered work, you indicate your acceptance of this License to do so.
+
+  10. Automatic Licensing of Downstream Recipients.
+
+  Each time you convey a covered work, the recipient automatically
+receives a license from the original licensors, to run, modify and
+propagate that work, subject to this License.  You are not responsible
+for enforcing compliance by third parties with this License.
+
+  An "entity transaction" is a transaction transferring control of an
+organization, or substantially all assets of one, or subdividing an
+organization, or merging organizations.  If propagation of a covered
+work results from an entity transaction, each party to that
+transaction who receives a copy of the work also receives whatever
+licenses to the work the party's predecessor in interest had or could
+give under the previous paragraph, plus a right to possession of the
+Corresponding Source of the work from the predecessor in interest, if
+the predecessor has it or can get it with reasonable efforts.
+
+  You may not impose any further restrictions on the exercise of the
+rights granted or affirmed under this License.  For example, you may
+not impose a license fee, royalty, or other charge for exercise of
+rights granted under this License, and you may not initiate litigation
+(including a cross-claim or counterclaim in a lawsuit) alleging that
+any patent claim is infringed by making, using, selling, offering for
+sale, or importing the Program or any portion of it.
+
+  11. Patents.
+
+  A "contributor" is a copyright holder who authorizes use under this
+License of the Program or a work on which the Program is based.  The
+work thus licensed is called the contributor's "contributor version".
+
+  A contributor's "essential patent claims" are all patent claims
+owned or controlled by the contributor, whether already acquired or
+hereafter acquired, that would be infringed by some manner, permitted
+by this License, of making, using, or selling its contributor version,
+but do not include claims that would be infringed only as a
+consequence of further modification of the contributor version.  For
+purposes of this definition, "control" includes the right to grant
+patent sublicenses in a manner consistent with the requirements of
+this License.
+
+  Each contributor grants you a non-exclusive, worldwide, royalty-free
+patent license under the contributor's essential patent claims, to
+make, use, sell, offer for sale, import and otherwise run, modify and
+propagate the contents of its contributor version.
+
+  In the following three paragraphs, a "patent license" is any express
+agreement or commitment, however denominated, not to enforce a patent
+(such as an express permission to practice a patent or covenant not to
+sue for patent infringement).  To "grant" such a patent license to a
+party means to make such an agreement or commitment not to enforce a
+patent against the party.
+
+  If you convey a covered work, knowingly relying on a patent license,
+and the Corresponding Source of the work is not available for anyone
+to copy, free of charge and under the terms of this License, through a
+publicly available network server or other readily accessible means,
+then you must either (1) cause the Corresponding Source to be so
+available, or (2) arrange to deprive yourself of the benefit of the
+patent license for this particular work, or (3) arrange, in a manner
+consistent with the requirements of this License, to extend the patent
+license to downstream recipients.  "Knowingly relying" means you have
+actual knowledge that, but for the patent license, your conveying the
+covered work in a country, or your recipient's use of the covered work
+in a country, would infringe one or more identifiable patents in that
+country that you have reason to believe are valid.
+
+  If, pursuant to or in connection with a single transaction or
+arrangement, you convey, or propagate by procuring conveyance of, a
+covered work, and grant a patent license to some of the parties
+receiving the covered work authorizing them to use, propagate, modify
+or convey a specific copy of the covered work, then the patent license
+you grant is automatically extended to all recipients of the covered
+work and works based on it.
+
+  A patent license is "discriminatory" if it does not include within
+the scope of its coverage, prohibits the exercise of, or is
+conditioned on the non-exercise of one or more of the rights that are
+specifically granted under this License.  You may not convey a covered
+work if you are a party to an arrangement with a third party that is
+in the business of distributing software, under which you make payment
+to the third party based on the extent of your activity of conveying
+the work, and under which the third party grants, to any of the
+parties who would receive the covered work from you, a discriminatory
+patent license (a) in connection with copies of the covered work
+conveyed by you (or copies made from those copies), or (b) primarily
+for and in connection with specific products or compilations that
+contain the covered work, unless you entered into that arrangement,
+or that patent license was granted, prior to 28 March 2007.
+
+  Nothing in this License shall be construed as excluding or limiting
+any implied license or other defenses to infringement that may
+otherwise be available to you under applicable patent law.
+
+  12. No Surrender of Others' Freedom.
+
+  If conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot convey a
+covered work so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you may
+not convey it at all.  For example, if you agree to terms that obligate you
+to collect a royalty for further conveying from those to whom you convey
+the Program, the only way you could satisfy both those terms and this
+License would be to refrain entirely from conveying the Program.
+
+  13. Use with the GNU Affero General Public License.
+
+  Notwithstanding any other provision of this License, you have
+permission to link or combine any covered work with a work licensed
+under version 3 of the GNU Affero General Public License into a single
+combined work, and to convey the resulting work.  The terms of this
+License will continue to apply to the part which is the covered work,
+but the special requirements of the GNU Affero General Public License,
+section 13, concerning interaction through a network will apply to the
+combination as such.
+
+  14. Revised Versions of this License.
+
+  The Free Software Foundation may publish revised and/or new versions of
+the GNU General Public License from time to time.  Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+  Each version is given a distinguishing version number.  If the
+Program specifies that a certain numbered version of the GNU General
+Public License "or any later version" applies to it, you have the
+option of following the terms and conditions either of that numbered
+version or of any later version published by the Free Software
+Foundation.  If the Program does not specify a version number of the
+GNU General Public License, you may choose any version ever published
+by the Free Software Foundation.
+
+  If the Program specifies that a proxy can decide which future
+versions of the GNU General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.
+
+  Later license versions may give you additional or different
+permissions.  However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
+later version.
+
+  15. Disclaimer of Warranty.
+
+  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read

Makefile

@@ -2,6 +2,7 @@
 default: run
 
 include client/make.mk
+include libretranslate/make.mk
 
 .PHONY: run
 run: $(CLIENT_TARGETS) venv
@@ -13,8 +14,11 @@ build: $(CLIENT_TARGETS)
 .PHONY: pack
 pack: pythagoras.tar.xz
 
+.PHONY: test
+test: client_test
+
 .PHONY: clean
-clean: client_clean
+clean: client_clean libretranslate_clean
 	rm -rf __pycache__
 	rm -rf venv
 	rm -f pythagoras.tar.xz

README.md

@@ -1,77 +1,218 @@
 # Pythagoras
 
-Local-run server which acts as a proxy between the moderation server, presentation client and subtitle scripts. This is a single-purpose ugly implementation with its sole purpose being the Richard Stallman lecture at TUL.
+**Pythagoras** is a local-run server that acts as a proxy between the moderation server, presentation client, and subtitle scripts. This implementation is specifically designed for the Richard Stallman lecture at TUL.
+
+## Table of Contents
+
+- [Dependencies](#dependencies)
+- [Installation](#installation)
+- [Running the App](#running-the-app)
+  - [Running Translation Server](#running-translation-server)
+  - [Cleaning Up](#cleaning-up)
+  - [Packing for Production](#packing-for-production)
+- [Usage](#usage)
+  - [Subtitles](#subtitles)
+  - [Commands](#commands)
+  - [Media](#media)
+
+## Dependencies
+
+- `pyenv`
+- `python-virtualenv`
+- `bun`
 
 ## Installation
 
-Clone the repository: 
+1. Clone the repository:
 
-`git clone git@gordon.zumepro.cz:zumepro/pythagoras.git`
+   ```bash
+   git clone git@gordon.zumepro.cz:zumepro/pythagoras.git
+   ```
 
-Install the dependencies:
+2. Install the dependencies:
 
-`sudo pacman -S python-virtualenv`
+   ```bash
+   sudo pacman -S python-virtualenv
+   ```
 
-## Running the app
+## Running the App
 
-Simply execute the **run** recipe in the Makefile to start the server:
+To start the server, simply execute the **run** recipe in the Makefile:
 
-`make run`
+```bash
+make run
+```
 
-Note that run is also the default recipe. So `make` works too.
+Note: `run` is the default recipe, so you can also just use:
 
-The run recipe should take care of everything for you... enjoy!
+```bash
+make
+```
 
-## Cleaning up the mess
+The run recipe will take care of everything for you. Enjoy!
 
-If you wish to go back to a clean slate just run:
+### Running Translation Server
 
-`make clean`
+To start the translation server for subtitle translation, run:
 
-## Packing for production
+```bash
+make libretranslate
+```
 
-To make an archive `pythagoras.tar.xz` in project root simply run:
+You can keep it running through multiple `make run` commands. The Makefile will pre-install everything if needed.
 
-`make pack`
+### Cleaning Up
+
+If you wish to return to a clean slate, just run:
+
+```bash
+make clean
+```
+
+### Packing for Production
+
+To create an archive named `pythagoras.tar.xz` in the project root, simply run:
+
+```bash
+make pack
+```
 
 ## Usage
 
-To connect to the WebSocket for receiving subtitles and messages, simply use the `/ws` endpoint, for example like this:
+To connect to the WebSocket for receiving subtitles, messages, and commands, use the `/ws` endpoint. For example:
 
-`
+```bash
 websocat ws://localhost:8000/ws
-`
+```
 
-To push new subtitles onto the server, use the `/subtitles` endpoint, for example like this:
+### Subtitles
 
-`
-curl -X POST http://localhost:8000/subtitles -H "Content-Type: text/plain" -d 'I love pushing subtitles to servers!'
-`
+Here is a list of all subtitle types:
 
-To control the server using commands, use the `/control` endpoint, for example like this:
+- `subtitle_en_submit_sentence`
+- `subtitle_cs_submit_sentence`
+- `subtitle_en_update_current`
 
-- Poll the peehaitchpea server for the latest message to display:
+To push new subtitles onto the server, use the `/subtitles/` endpoints. There are currently two different endpoints, each producing a different response type. When translation is enabled, each sentence submission yields two WebSocket messages, one in English and one in Czech. Here are some examples:
 
-`
+#### Update Current Subtitle
+
+To update the current sentence as it comes, use:
+
+```bash
+curl -X POST http://localhost:8000/subtitles/update_current -H "Content-Type: text/plain" -d 'I love pushing '
+```
+
+#### Submit Finished Sentence
+
+To submit the next finished sentence, use:
+
+```bash
+curl -X POST http://localhost:8000/subtitles/submit_sentence -H "Content-Type: text/plain" -d 'I love pushing sentences to servers!'
+```
+
+### Commands
+
+Here is a list of all available commands:
+
+- `getselectedmessage`
+- `setlibretranslate`
+- `setautopolling`
+- `autopollingrate`
+- `playvideo`
+- `seekvideo`
+- `setscreen_main`
+- `setscreen_video`
+- `setscreen_idle`
+
+To control the server using commands, use the `/control` endpoint. Here are some examples:
+
+#### Get Selected Message
+
+Poll the server for the latest message to display:
+
+```bash
 curl -X POST http://localhost:8000/control -H "Content-Type: application/json" -d '{"command": "getselectedmessage"}'
-`
+```
 
-- Change the state of auto-polling:
+#### Set LibreTranslate State
 
-`
+Change the state of the LibreTranslate translation module (active or deactivated):
+
+```bash
+curl -X POST http://localhost:8000/control -H "Content-Type: application/json" -d '{"command": "setlibretranslate", "state": false}'
+```
+
+#### Set Auto-Polling State
+
+Change the state of auto-polling:
+
+```bash
 curl -X POST http://localhost:8000/control -H "Content-Type: application/json" -d '{"command": "setautopolling", "state": false}'
-`
+```
 
-`
-curl -X POST http://localhost:8000/control -H "Content-Type: application/json" -d '{"command": "setautopolling", "state": true}'
-`
+#### Set Polling Rate
 
-- Set the polling rate to a value (in seconds):
+Set the polling rate to a value (in seconds):
 
-`
+```bash
 curl -X POST http://localhost:8000/control -H "Content-Type: application/json" -d '{"command": "autopollingrate", "rate": 10}'
-` 
+```
 
-## TODO
+#### Play Video
 
-- Create a command for playing a video (the TED talk RMS likes to play at the beginning of his lecture)
+Tell the client to play a video, defined by the `filename` parameter. It has optional parameters `subtitles` (which should point to a subtitle file and defaults to `null`) and `secondsfromstart` (which indicates the timestamp at which the video should start, defaulting to `0`):
+
+```bash
+curl -X POST http://localhost:8000/control -H "Content-Type: application/json" -d '{"command": "playvideo", "filename": "stallman.webm"}'
+```
+
+To include subtitles and specify a start time:
+
+```bash
+curl -X POST http://localhost:8000/control -H "Content-Type: application/json" -d '{"command": "playvideo", "filename": "stallman.webm", "subtitles": "stallman.vtt", "secondsfromstart": 69}'
+```
+
+#### Seek Video
+
+Seek the currently played video to a specific timestamp (in seconds):
+
+```bash
+curl -X POST http://localhost:8000/control -H "Content-Type: application/json" -d '{"command": "seekvideo", "timestamp": 420}'
+```
+
+#### Set Screen to Main View
+
+Set the screen of the client to the main view (subtitles and messages):
+
+```bash
+curl -X POST http://localhost:8000/control -H "Content-Type: application/json" -d '{"command": "setscreen_main"}'
+```
+
+#### Set Screen to Video Playback
+
+Set the screen of the client to the video playback view:
+
+```bash
+curl -X POST http://localhost:8000/control -H "Content-Type: application/json" -d '{"command": "setscreen_video"}'
+```
+
+#### Set Screen to Idle
+
+Set the screen of the client to the idle screen (this is the default screen after startup of the app):
+
+```bash
+curl -X POST http://localhost:8000/control -H "Content-Type: application/json" -d '{"command": "setscreen_idle"}'
+```
+
+### Media
+
+You can also request media from Pythagoras using the `/media/` endpoint, which will yield a standard HTTP FileResponse. Here’s an example:
+
+```bash
+curl -X GET http://localhost:8000/media/stallman.webm
+```
+
+## License
+
+This project is licensed under the GNU General Public License v3.0 - see the [LICENSE](LICENSE) file for details.

assets/zmp_logo.svg

@@ -0,0 +1 @@
+<svg height="50mm" viewBox="0 0 50 50.000001" width="50mm" xmlns="http://www.w3.org/2000/svg"><g fill-rule="evenodd" transform="matrix(-.63629813 0 0 -.63629813 66.59034128483 91.64520371211)"><path d="m-11.759578-96.806604v-3.098032q-2.223016-.189194-3.500067-1.418944-1.253402-1.2534-1.3007-3.28723h2.128418q0 1.15881.685824 1.89193.709473.73312 1.986525.89867v-6.19607l-.638526-.18919q-1.773682-.54393-2.743295-1.82098-.945964-1.27705-.945964-3.00344 0-1.89192 1.158805-3.12168 1.182455-1.22975 3.16898-1.41894v-3.12168h1.418946v3.09803q1.9628749.18919 3.1453299 1.41894 1.182455 1.22976 1.2061041 3.16898h-2.128419q0-1.1115-.5912275-1.79733-.5675783-.70947-1.6317875-.87501v5.86497l.9459637.30744q1.7263842.54393 2.6723482 1.84463.945964 1.3007.945964 3.05073 0 1.93923-1.2534023 3.21628-1.2297532 1.27705-3.3108736 1.489894v3.098032zm-2.199367-16.412476q0 1.06421.567579 1.84463.567578.78042 1.631788 1.11151v-5.41564q-1.040561.16554-1.631788.80406-.567579.63853-.567579 1.65544zm3.618313 11.39887q1.1588056-.1892 1.7973312-.89867.6385257-.70947.6385257-1.84463 0-1.04056-.5675784-1.79733-.5439293-.78042-1.5844895-1.11151l-.283789-.0946z" fill="#fff" transform="matrix(-1.0225486 0 0 -.97794862 24.554623 -1.612364)"/><path d="m-59.312695-104.31899q-.273111.60084-.710088 1.11065-.436977.4916-1.001405.87395-.546222.36415-1.219894.58264-.673673.20028-1.438383.20028-.782917 0-1.584041-.21849-.801125-.2367-1.547627-.54622-.910369-.36415-1.747908-.69188-.819332-.32774-1.602249-.32774-.910368 0-1.511212.45519-.600843.43698-1.074235 1.20169l-1.857152-1.32914q.273111-.60085.710088-1.09244.436977-.50981.983198-.87396.564429-.38235 1.238101-.58263.673673-.21849 1.438383-.21849.892161 0 1.80253.29131.910368.29132 1.747908.63726.782917.32774 1.529419.60085.746502.2549 1.401968.2549.892161 0 1.511212-.43698.61905-.45518 1.074235-1.21989z" fill="#9aff00" transform="scale(-1)"/><path d="m100.26473 100.06705v-3.596477l-7.441251 7.192957 7.441251 7.19295v-3.59647l-3.720626-3.59648z" fill="#fff"/></g></svg>

client/index.html

@@ -4,9 +4,10 @@
         <meta charset="UTF-8">
         <meta name="viewport" content="width=device-width, initial-scale=1">
         <title></title>
-        <link href="css/style.css" rel="stylesheet">
+        <link href="style.css" rel="stylesheet">
     </head>
     <body>
-    
+        <button id="run">Run</button>
+        <script src="script.js"></script>
     </body>
 </html>

client/make.mk

@@ -1,18 +1,38 @@
 CLIENT_PAGES := index.html
 CLIENT_STYLES := style.css
 CLIENT_SCRIPTS := script.js
+CLIENT_ASSETS := fm_logo.svg zmp_logo.svg tul_logo.svg qr_ask.svg
 CLIENT_TARGETS := $(CLIENT_PAGES:%=static/%) \
 				  $(CLIENT_STYLES:%=static/%) \
-				  $(CLIENT_SCRIPTS:%=static/%)
+				  $(CLIENT_SCRIPTS:%=static/%) \
+				  $(CLIENT_ASSETS:%=static/%)
 
 .PHONY: client_clean
 client_clean:
 	rm -rf static
 	rm -rf client/node_modules
 
+.PHONY: client_test
+client_test:
+	bun test client
+
 client/node_modules:
 	cd client && bun install
 
+# specific files
+static/script.js: \
+	client/script.ts \
+	client/ws.ts \
+	client/pythagoras_client.ts \
+	client/tools.ts \
+	client/presentationmgr.ts \
+	client/settings.ts \
+	client/scrolling_textbox.ts \
+	client/node_modules
+	@mkdir -p $(@D)
+	bun build $< --minify --outfile $@
+
+# generic pages
 static/%.html: client/%.html client/node_modules
 	@mkdir -p $(@D)
 	cat $< | \
@@ -24,10 +44,17 @@ static/%.html: client/%.html client/node_modules
 		--remove-comments \
 		--remove-redundant-attributes > $@
 
+# generic styles
 static/%.css: client/%.scss client/node_modules
 	@mkdir -p $(@D)
 	bun run --cwd client sass $(notdir $<) --style compressed > $@
 
+# generic svgs
+static/%.svg: assets/%.svg
+	@mkdir -p $(@D)
+	ln -f $< $@
+
+# generic scripts
 static/%.js: client/%.ts client/node_modules
 	@mkdir -p $(@D)
 	bun build $< --minify --outfile $@

client/presentationmgr.ts

@@ -0,0 +1,296 @@
+import {
+	PythagorasIncomingMessageType, type PythagorasClient, type PythagorasIncomingMessage
+} from "./pythagoras_client";
+import { ScrollingTextBox } from "./scrolling_textbox";
+import { dict, IDLE_LOGOS, QUESTION_LINK, QUESTION_QR } from "./settings";
+import { AsyncRunner, el, sleep, wait_for_dom_refresh } from "./tools";
+
+interface PresentationScreen {
+	prepare(): Promise<void>;
+	start(): Promise<void>;
+	end(): Promise<void>;
+	serve(trigger: PythagorasIncomingMessage): Promise<void>;
+	dom: HTMLDivElement;
+}
+
+export class PresentationManager {
+	private screen: PresentationScreen;
+	private dom_root: HTMLDivElement;
+
+	public constructor() {
+		this.dom_root = el.div([]);
+
+		this.screen = new BlankScreen();
+	}
+
+	private async update_dom_screen(): Promise<void> {
+		await this.screen.prepare();
+		this.dom_root.innerHTML = "";
+		this.dom_root.appendChild(this.screen.dom);
+		await wait_for_dom_refresh();
+	}
+
+	public async serve(ws_client: PythagorasClient): Promise<void> {
+		while (true) {
+			const received = await ws_client.recv();
+			if (received.type == PythagorasIncomingMessageType.SetScreen) {
+				await this.screen.end();
+				this.set_screen(received.screen);
+				await this.update_dom_screen();
+				await this.screen.start();
+				continue;
+			}
+			await this.screen.serve(received);
+		}
+	}
+
+	private set_screen(screen: "idle" | "video" | "main"): void {
+		switch (screen) {
+			case "idle":
+				this.screen = new IdleScreen();
+				break;
+			case "video":
+				this.screen = new VideoScreen();
+				break;
+			case "main":
+				this.screen = new MainScreen();
+				break;
+			default:
+				throw new Error("unknown screen id");
+		}
+	}
+
+	public get dom(): HTMLDivElement {
+		return this.dom_root;
+	}
+}
+
+class MainScreen implements PresentationScreen {
+	private dom_root: HTMLDivElement;
+	private subs_english: AsyncRunner<ScrollingTextBox>;
+	private subs_czech: AsyncRunner<ScrollingTextBox>;
+	private dom_question: HTMLDivElement;
+	private dom_question_link: HTMLDivElement;
+	private question_insert: HTMLParagraphElement;
+
+	public constructor() {
+		const subs_en = new ScrollingTextBox();
+		const subs_cz = new ScrollingTextBox();
+		this.subs_english = new AsyncRunner(subs_en);
+		this.subs_czech = new AsyncRunner(subs_cz);
+		this.question_insert = el.p("Otázka");
+		this.dom_question_link = el.div([el.h1(QUESTION_LINK)], ["link"]);
+		this.dom_question = el.div([this.dom_question_link, this.question_insert], ["question"]);
+		this.dom_root = el.div([
+			this.dom_question,
+			el.div([
+				el.div([subs_en.dom], ["lang"]),
+				el.div([subs_cz.dom], ["lang"]),
+			], ["subtitles"]),
+			el.div([
+				el.p("Jedná se o automaticky generovaný přepis. Omluvte, prosíme, případné chyby.", ["disclaimer"]),
+			]),
+		], ["main"]);
+	}
+
+	public async prepare(): Promise<void> {
+		//this.dom_question_link.append(await el.img(QUESTION_QR, ["qr"]));
+	}
+
+	public async start(): Promise<void> {
+		await wait_for_dom_refresh();
+		this.dom_root.style.opacity = "1";
+		await sleep(500);
+	}
+
+	public async end(): Promise<void> {
+		this.dom_root.style.opacity = "0";
+		await sleep(500);
+	}
+
+	private async show_question(text: string): Promise<void> {
+		this.question_insert.innerText = text;
+		this.question_insert.style.opacity = "1";
+		await sleep(500);
+	}
+
+	private async hide_question(): Promise<void> {
+		this.question_insert.style.opacity = "0";
+		await sleep(500);
+	}
+
+	public async serve(trigger: PythagorasIncomingMessage): Promise<void> {
+		switch (trigger.type) {
+			case PythagorasIncomingMessageType.SubEnUpdateCur:
+				this.subs_english.run((target: ScrollingTextBox) => {
+					return target.update_current(trigger.text)
+				});
+				break;
+			case PythagorasIncomingMessageType.SubEnSubmit:
+				this.subs_english.run((target: ScrollingTextBox) => {
+					return target.finish_current(trigger.text);
+				});
+				break;
+			case PythagorasIncomingMessageType.SubCzSubmit:
+				this.subs_czech.run((target: ScrollingTextBox) => {
+					return target.add_line(trigger.text);
+				});
+				break;
+			case PythagorasIncomingMessageType.SelectedMessage:
+				if (trigger.message === null) { this.hide_question(); }
+				else { this.show_question(trigger.message); }
+				break;
+		}
+	}
+
+	public get dom(): HTMLDivElement {
+		return this.dom_root;
+	}
+}
+
+class VideoScreen implements PresentationScreen {
+	private dom_root: HTMLDivElement;
+	private dom_video: HTMLVideoElement;
+
+	private src: string | null;
+	private subtitles: string | null;
+
+	public constructor() {
+		this.src = null;
+		this.subtitles = null;
+		this.dom_video = document.createElement("video");
+		this.dom_root = el.div([this.dom_video], ["video"]);
+	}
+
+	public async prepare(): Promise<void> {
+		this.dom_root.innerHTML = "";
+		if (this.src !== null) {
+			this.dom_video = await el.video(
+				this.src, this.subtitles === null ? "" : this.subtitles
+			);
+			this.dom_video.volume = 0;
+			this.dom_root.appendChild(this.dom_video);
+		}
+	}
+
+	public async start(): Promise<void> {
+		this.dom_video.style.opacity = "1";
+		for (let i = 0; i <= 100; ++i) {
+			this.dom_video.volume = i / 100;
+			await sleep(10);
+		}
+	}
+
+	public async end(): Promise<void> {
+		this.dom_video.style.opacity = "0";
+		for (let i = 100; i >= 0; --i) {
+			this.dom_video.volume = i / 100;
+			await sleep(10);
+		}
+	}
+
+	public async serve(trigger: PythagorasIncomingMessage): Promise<void> {
+		switch (trigger.type) {
+			case PythagorasIncomingMessageType.PlayVideo:
+				await this.play_video(
+					trigger.filename, trigger.subtitles, trigger.seconds_from_start
+				);
+				break;
+			case PythagorasIncomingMessageType.SeekVideo:
+				this.seek_video(trigger.timestamp);
+				break;
+		}
+	}
+
+	private async play_video(
+		video_url: string, subtitles_url: string | null, seconds_from_start: number
+	): Promise<void> {
+		this.dom_video = await el.video(video_url, subtitles_url);
+		this.dom_video.currentTime = seconds_from_start;
+		this.dom_root.innerHTML = "";
+		this.dom_root.appendChild(this.dom_video);
+		await wait_for_dom_refresh();
+		await this.start();
+	}
+
+	private seek_video(seconds_from_start: number): void {
+		this.dom_video.currentTime = seconds_from_start;
+	}
+
+	public get dom(): HTMLDivElement {
+		return this.dom_root;
+	}
+}
+
+class IdleScreen implements PresentationScreen {
+	private dom_root: HTMLDivElement;
+	private dom_title: HTMLHeadingElement;
+	private dom_subtitle: HTMLHeadingElement;
+	private dom_logos: HTMLDivElement[];
+
+	public constructor() {
+		this.dom_title = el.h1(dict.IDLE_TITLE)
+		this.dom_subtitle = el.h2(dict.IDLE_STARTING);
+		this.dom_logos = [];
+		this.dom_root = el.div([this.dom_title, this.dom_subtitle], ["idle"]);
+	}
+
+	public async prepare(): Promise<void> {
+		for (const logo of IDLE_LOGOS) {
+			this.dom_logos.push(el.div([await el.img(logo)], ["logo"]));
+		}
+		const logos = el.div([...this.dom_logos], ["logos"]);
+		this.dom_root.appendChild(logos);
+	}
+
+	public async start(): Promise<void> {
+		await wait_for_dom_refresh();
+		this.dom_title.style.transform = "translateY(0)";
+		this.dom_title.style.opacity = "1";
+		await sleep(250);
+		this.dom_subtitle.style.opacity = "1";
+		await sleep(250);
+		for (const logo of this.dom_logos) {
+			logo.style.transform = "translateY(0)";
+			logo.style.opacity = "1";
+			await sleep(250);
+		}
+		await sleep(250);
+	}
+
+	public async end(): Promise<void> {
+		for (const logo of this.dom_logos) {
+			logo.style.transform = "translateY(100%)";
+			logo.style.opacity = "0";
+			await sleep(250);
+		}
+		this.dom_subtitle.style.opacity = "0";
+		await sleep(250);
+		this.dom_title.style.transform = "translateY(-100%)";
+		this.dom_title.style.opacity = "0";
+		await sleep(500);
+	}
+
+	public async serve(trigger: PythagorasIncomingMessage): Promise<void> {}
+
+	public get dom(): HTMLDivElement {
+		return this.dom_root;
+	}
+}
+
+class BlankScreen implements PresentationScreen {
+	private dom_root: HTMLDivElement;
+
+	public constructor() {
+		this.dom_root = el.div([]);
+	}
+
+	public async prepare() {}
+	public async start() {}
+	public async end() {}
+	public async serve(_: PythagorasIncomingMessage) {}
+
+	public get dom(): HTMLDivElement {
+		return this.dom_root;
+	}
+}

client/pythagoras_client.ts

@@ -0,0 +1,126 @@
+import { sleep, uint_bytes_to_num, utf8_decode, utf8_encode } from "./tools";
+import { WSClient } from "./ws";
+
+export enum PythagorasIncomingMessageType {
+
+	// subtitles
+	SubEnUpdateCur = "subtitle_en_update_current",
+	SubEnSubmit = "subtitle_en_submit_sentence",
+	SubCzSubmit = "subtitle_cs_submit_sentence",
+
+	// mode management
+	SetScreen = "setscreen",
+
+	// video
+	PlayVideo = "playvideo",
+	SeekVideo = "seekvideo",
+
+	// message
+	SelectedMessage = "selectedmessage",
+};
+
+export type PythagorasIncomingMessage = (
+
+{
+	type: (
+		PythagorasIncomingMessageType.SubEnUpdateCur |
+		PythagorasIncomingMessageType.SubEnSubmit |
+		PythagorasIncomingMessageType.SubCzSubmit
+	),
+	text: string,
+} |
+
+{
+	type: PythagorasIncomingMessageType.SelectedMessage,
+	message: string | null,
+} |
+
+{
+	type: PythagorasIncomingMessageType.SetScreen,
+	screen: "main" | "video" | "idle",
+} |
+
+{
+	type: PythagorasIncomingMessageType.PlayVideo,
+	filename: string,
+	subtitles: string,
+	seconds_from_start: number,
+} |
+
+{
+	type: PythagorasIncomingMessageType.SeekVideo,
+	timestamp: number,
+}
+
+);
+
+export class PythagorasClient {
+	private sock: WSClient | null;
+	private addr: string;
+
+	private buf: Uint8Array;
+
+	public constructor(addr: string) {
+		this.sock = null;
+		this.addr = addr;
+		this.buf = new Uint8Array(0);
+	}
+
+	private async reconnect(): Promise<void> {
+		this.sock = new WSClient(this.addr);
+		await this.sock.wait_for_connection();
+	}
+
+	/**
+	 * Force receive from the underlying `WSClient`.
+	 * This will try to receive (or reconnect) up to `PythagorasClient.max_recv_retry` times.
+	 */
+	private async recv_inner(): Promise<Blob> {
+		if (this.sock === null) { await this.reconnect(); }
+		while (true) {
+			const received = await this.sock!.receive();
+			if (received !== null) { return received; }
+			await sleep(500);
+			await this.reconnect();
+		}
+	}
+
+	/**
+	 * Force receive from the underlying `WSClient` and convert the result to bytes (if the result
+	 * is not bytes already).
+	 */
+	private async recv_inner_bytes(): Promise<Uint8Array> {
+		const received = await this.recv_inner();
+		if (received.bytes !== undefined) { return await received.bytes(); }
+		const text = await received.text();
+		return utf8_encode(text);
+	}
+
+	/**
+	 * Receive `target` bytes from the underlying stream (or leftovers from previous reads).
+	*/
+	private async recv_length(target: number): Promise<Uint8Array> {
+		if (target == 0) { return new Uint8Array(0); }
+		while (this.buf.length < target) {
+			const received = await this.recv_inner_bytes();
+			const merged = new Uint8Array(this.buf.length + received.length);
+			merged.set(this.buf);
+			merged.set(received, this.buf.length);
+			this.buf = merged;
+		}
+		const total = this.buf;
+		this.buf = new Uint8Array(total.length - target);
+		this.buf.set(total.slice(target));
+		return total.slice(0, target);
+	}
+
+	public async recv(): Promise<PythagorasIncomingMessage> {
+		while (true) {
+			const payload = await this.recv_inner();
+			const text = payload.bytes === undefined ?
+				(await payload.text()).slice(4) : (utf8_decode((await payload.bytes()).slice(4)));
+			const parsed = JSON.parse(text);
+			return parsed;
+		}
+	}
+}

client/script.ts

@@ -0,0 +1,14 @@
+import { PresentationManager } from "./presentationmgr";
+import { PythagorasClient } from "./pythagoras_client";
+
+async function main(): Promise<void> {
+	const ws_client = new PythagorasClient("/ws");
+	document.body.innerHTML = "";
+	const presentation_manager = new PresentationManager();
+	document.body.appendChild(presentation_manager.dom);
+	await presentation_manager.serve(ws_client);
+}
+
+(<HTMLButtonElement>document.querySelector("#run")).onclick = () => {
+	main();
+}

client/scrolling_textbox.ts

@@ -0,0 +1,284 @@
+import { el, sleep, wait_for_dom_refresh } from "./tools";
+
+class Word {
+	private dom_root: HTMLParagraphElement;
+
+	private inner: string;
+	private is_visible: boolean;
+
+	private static ANIMATION_DURATION: number = 20;
+
+	public constructor(inner: string, initially_visible: boolean = false) {
+		this.inner = inner;
+		this.is_visible = initially_visible;
+		this.dom_root = el.p(this.inner, ["word"]);
+
+		if (!this.is_visible) {
+			this.dom_root.style.opacity = "0";
+			this.dom_root.style.transform = "scale(0)";
+		}
+	}
+
+	public set text(new_value: string) {
+		this.inner = new_value;
+		this.dom_root.innerText = this.inner;
+	}
+
+	public get text(): string {
+		return this.inner;
+	}
+
+	public async show(): Promise<void> {
+		if (this.is_visible) { return; }
+		this.dom_root.style.opacity = "1";
+		this.dom_root.style.transform = "scale(100%)";
+		this.is_visible = true;
+		await sleep(Word.ANIMATION_DURATION);
+	}
+
+	public get visible(): boolean {
+		return this.is_visible;
+	}
+
+	public get dom(): HTMLDivElement {
+		return this.dom_root;
+	}
+}
+
+class Paragraph {
+	private dom_root: HTMLDivElement;
+	private words: Word[];
+
+	private height: number;
+	private height_current: boolean;
+	private visible: boolean;
+	private vertical_position: number;
+
+	private static SUBTLE_COLOR: string = "gray";
+	private static ACTIVE_COLOR: string = "white";
+	private static WORD_ANIM_POST_WAIT: number = 180;
+
+	public constructor(initial_text: string | null) {
+		this.dom_root = el.div([], ["paragraph"]);
+		this.set_color(Paragraph.ACTIVE_COLOR);
+		this.words = [];
+		this.visible = true;
+		this.height = 0;
+		this.height_current = true;
+		this.vertical_position = 0;
+		this.set_initial_text(initial_text);
+	}
+
+	private set_initial_text(text: string | null): void {
+		if (text === null) { return; }
+		this.visible = false;
+		this.height_current = false;
+		this.dom_root.style.opacity = "0";
+		const initial_words = text.split(" ");
+		for (const word of initial_words) {
+			const cur_word = new Word(word, true);
+			this.words.push(cur_word);
+			this.dom_root.appendChild(cur_word.dom);
+		}
+	}
+
+	private set_color(new_color: string): void {
+		this.dom_root.style.color = new_color;
+	}
+
+	private trim_words(target_length: number): void {
+		if (this.words.length == 0 || target_length < 0) { return; }
+		if (this.words.length != target_length) { this.invalidate_height(); }
+		for (let i = this.words.length - 1; i >= target_length; --i) {
+			const current_pop = this.words.pop();
+			if (current_pop === undefined) { continue; }
+			this.dom_root.removeChild(current_pop.dom);
+		}
+	}
+
+	private invalidate_height(): void {
+		this.height_current = false;
+	}
+
+	public set_text(new_text: string): void {
+		const new_words = new_text.split(" ");
+		if (new_words.length < this.words.length) { this.trim_words(new_words.length); }
+		for (let i = 0; i < new_words.length; ++i) {
+			const new_word = new_words[i];
+			if (this.words.length <= i) {
+				const cur_word = new Word(new_word);
+				this.words.push(cur_word);
+				this.dom_root.appendChild(cur_word.dom);
+				this.invalidate_height();
+				continue;
+			}
+			if (this.words[i].text != new_word) {
+				this.words[i].text = new_word;
+				this.invalidate_height();
+			}
+		}
+	}
+
+	public async animate(): Promise<void> {
+		for (const word of this.words) {
+			await word.show();
+		}
+		await sleep(Paragraph.WORD_ANIM_POST_WAIT);
+	}
+
+	private calculate_height(): void {
+		this.height = this.dom_root.getBoundingClientRect().height;
+	}
+
+	public get real_height(): number {
+		if (!this.height_current) {
+			this.calculate_height();
+			this.height_current = true;
+		}
+		return this.height;
+	}
+
+	public subtleize(): Promise<void> {
+		this.set_color(Paragraph.SUBTLE_COLOR);
+		return sleep(500);
+	}
+
+	public async show(): Promise<void> {
+		if (this.visible) { return; }
+		this.dom_root.style.opacity = "1";
+		return sleep(500);
+	}
+
+	public set translate_y(value: number) {
+		this.vertical_position = value;
+		this.dom_root.style.transform = `translateY(${value}px)`;
+	}
+
+	public get translate_y(): number {
+		return this.vertical_position;
+	}
+
+	public get dom(): HTMLDivElement {
+		return this.dom_root;
+	}
+}
+
+export class ScrollingTextBox {
+	private dom_root: HTMLDivElement;
+
+	private paragraphs: Paragraph[];
+
+	private static MAX_HEIGHT: number = 650;
+	private static CENTER_HEIGHT: number = 350;
+	private static VERTICAL_MARGIN: number = 10;
+
+	public constructor() {
+		this.dom_root = el.div([], ["scrolling-textbox"]);
+		this.paragraphs = [];
+	}
+
+	private add_paragraph(initial_text: string | null): void {
+		const new_paragraph = new Paragraph(initial_text);
+		new_paragraph.translate_y = ScrollingTextBox.CENTER_HEIGHT;
+		this.paragraphs.push(new_paragraph);
+		this.dom_root.appendChild(new_paragraph.dom);
+	}
+
+	private add_paragraph_bottom(initial_text: string): void {
+		if (this.paragraphs.length == 0) {
+			this.add_paragraph(initial_text);
+			return;
+		}
+		const most_bottom = this.paragraphs[this.paragraphs.length - 1];
+		const offset = most_bottom.translate_y + most_bottom.real_height;
+		const new_paragraph = new Paragraph(initial_text);
+		new_paragraph.translate_y = offset;
+		this.paragraphs.push(new_paragraph);
+		this.dom_root.appendChild(new_paragraph.dom);
+	}
+
+	/**
+	 * Remove all paragraphs up to (not including) a certain index.
+	*/
+	private trim_to(exclusive_end: number): void {
+		const spliced = this.paragraphs.splice(0, exclusive_end);
+		for (const item of spliced) {
+			this.dom_root.removeChild(item.dom);
+		}
+	}
+
+	/**
+	 * Run scroll animation on the first element and then pop it off of the DOM.
+	 */
+	private async scroll_trim(offset: number): Promise<void> {
+		const to_trim = this.paragraphs.shift();
+		if (to_trim === undefined) { return; }
+		to_trim.translate_y = offset;
+		await sleep(500);
+		this.dom_root.removeChild(to_trim.dom);
+	}
+
+	/**
+	 * Update elements DOM scrolls and wait for animations to complete.
+	 *
+	 * Note that this will remove any paragraphs that aren't visible anymore.
+	*/
+	private async update_scroll(): Promise<void> {
+		if (this.paragraphs.length == 0) { return; }
+		const last = this.paragraphs[this.paragraphs.length - 1];
+		let offset = Math.min(
+			ScrollingTextBox.MAX_HEIGHT - last.real_height, ScrollingTextBox.CENTER_HEIGHT
+		);
+		last.translate_y = offset;
+		if (this.paragraphs.length == 1) { return; }
+		for (let i = this.paragraphs.length - 2; i >= 0; --i) {
+			offset -= ScrollingTextBox.VERTICAL_MARGIN;
+			const cur = this.paragraphs[i];
+			if (offset <= 0) {
+				this.trim_to(i);
+				this.scroll_trim(offset - cur.real_height);
+				break;
+			}
+			offset -= cur.real_height;
+			cur.translate_y = offset;
+		}
+		await sleep(500);
+	}
+
+	public async update_current(text: string): Promise<void> {
+		if (this.paragraphs.length == 0) {
+			this.add_paragraph(null);
+			this.update_scroll();
+		}
+		const current = this.paragraphs[this.paragraphs.length - 1];
+		current.set_text(text);
+		await wait_for_dom_refresh();
+		await Promise.all([this.update_scroll(), current.animate()]);
+	}
+
+	public async finish_current(text: string): Promise<void> {
+		if (this.paragraphs.length == 0) {
+			this.add_paragraph(text);
+		}
+		const current = this.paragraphs[this.paragraphs.length - 1];
+		current.set_text(text);
+		this.add_paragraph(null);
+		await Promise.all([this.update_scroll(), current.subtleize(), current.animate()]);
+	}
+
+	public async add_line(text: string): Promise<void> {
+		if (this.paragraphs.length != 0) {
+			this.paragraphs[this.paragraphs.length - 1].subtleize();
+		}
+		this.add_paragraph_bottom(text);
+		await wait_for_dom_refresh();
+		await Promise.all([
+			this.update_scroll(),
+			this.paragraphs[this.paragraphs.length - 1].show(),
+		]);
+	}
+
+	public get dom(): HTMLDivElement {
+		return this.dom_root;
+	}
+}

client/settings.ts

@@ -0,0 +1,15 @@
+export namespace dict {
+	export const IDLE_TITLE: string = "Richard Stallman na Technické univerzitě v Liberci";
+	export const IDLE_STARTING: string = "Přednáška o soukromí a svobodě v digitální době";
+}
+
+export const IDLE_LOGOS: string[] = [
+	"files/tul_logo.svg",
+	"files/fm_logo.svg",
+	"files/zmp_logo.svg",
+];
+
+export const QUESTION_QR: string = "files/qr_ask.svg";
+export const QUESTION_LINK: string = "https://ask.libre-liberec.cz";
+
+export const DELAY_WORDS: number = 1;

client/style.scss

@@ -0,0 +1,178 @@
+@use "sass:color";
+
+#run {
+  width: 100%;
+  height: 100vh;
+  background-color: transparent;
+  border: none;
+}
+
+body {
+  font-family: Arial;
+  background-color: black;
+  color: white;
+  margin: 0;
+  overflow-x: hidden;
+  overflow-y: hidden;
+}
+
+.idle {
+  display: flex;
+  flex-direction: column;
+  width: 100%;
+  height: 100vh;
+  justify-content: center;
+  align-items: center;
+
+  h1 {
+    transition: .5s ease transform, .5s ease opacity;
+    font-size: 3em;
+    opacity: 0;
+    transform: translateY(-100%);
+  }
+
+  h2 {
+    transition: .5s ease opacity;
+    color: color.scale(white, $lightness: -25%);
+    margin: 0;
+    opacity: 0;
+    font-weight: normal;
+  }
+
+  .logos {
+    display: flex;
+    margin-top: 15em;
+    justify-content: center;
+    align-items: center;
+
+    .logo {
+      display: flex;
+      align-items: center;
+      transition: .5s ease-out transform, .5s ease-out opacity;
+      height: 7em;
+      transform: translateY(100%);
+      opacity: 0;
+      margin: 0 2em;
+
+      img {
+        max-height: 100%;
+        max-width: 25em;
+      }
+    }
+  }
+}
+
+.video {
+  display: block;
+
+  video {
+    transition: 1s linear opacity;
+    width: 100vw;
+    height: 100vh;
+    object-fit: contain;
+    opacity: 0;
+  }
+}
+
+.main {
+  transition: .5s ease opacity;
+  opacity: 0;
+
+  .disclaimer {
+    color: color.adjust(white, $lightness: -40%);
+    position: absolute;
+    bottom: 0;
+    left: 50%;
+    transform: translateX(-50%);
+    font-size: 1.5em;
+  }
+}
+
+.question {
+  display: flex;
+  flex-direction: column;
+  width: 100%;
+  align-items: center;
+  margin-bottom: 5em;
+
+  p {
+    transition: .5s ease opacity;
+    font-size: 2em;
+    opacity: 0;
+  }
+
+  .link {
+    display: flex;
+    align-items: center;
+    height: fit-content;
+    margin-top: 1em;
+    margin-bottom: 2em;
+
+    .qr {
+      display: block;
+      margin-left: 2em;
+      width: 7em;
+      height: 7em;
+    }
+  }
+}
+
+.subtitles {
+  display: flex;
+  width: 90%;
+  justify-content: space-between;
+  margin: 0 auto;
+
+  .lang {
+    display: block;
+    width: 100%;
+    margin: 0 2em;
+    overflow: hidden;
+  }
+}
+
+.scrolling-textbox {
+  $line-height: 2rem;
+
+  display: flex;
+  position: relative;
+  flex-direction: column;
+  padding-top: $line-height;
+  box-sizing: border-box;
+  overflow-x: hidden;
+  -ms-overflow-style: none;
+  scrollbar-width: none;
+  width: 100%;
+  height: 650px;
+
+  .paragraph {
+    transition: .5s ease color, .5s ease transform, .5s ease opacity;
+    position: absolute;
+    display: flex;
+    font-size: $line-height;
+    flex-wrap: wrap;
+    margin: 0;
+    top: 0;
+    transform: translateY(0);
+    height: fit-content;
+    width: 100%;
+    max-width: 100%;
+
+    .word {
+      transition: .2s ease opacity, .2s ease transform;
+      margin: 0;
+      margin-right: .5ch;
+    }
+  }
+
+  .previous {
+    position: absolute;
+    transition: .5s ease transform, .5s ease opacity;
+    color: grey;
+    transform: translateY(-100%);
+  }
+}
+
+.scrolling-textbox::-webkit-scrollbar {
+  display: none;
+}

client/tools.test.ts

@@ -0,0 +1,31 @@
+import { expect, test } from "bun:test";
+import { uint_bytes_to_num, utf8_decode, utf8_encode } from "./tools";
+
+test("parse_uint - 0xFF", () => {
+	expect(uint_bytes_to_num(new Uint8Array([0x0, 0x0, 0x0, 0xFF]))).toBe(0xFF);
+});
+
+test("parse_uint - 0xFF00", () => {
+	expect(uint_bytes_to_num(new Uint8Array([0x0, 0x0, 0xFF, 0x0]))).toBe(0xFF00);
+});
+
+test("parse_uint - 0xFF0000", () => {
+	expect(uint_bytes_to_num(new Uint8Array([0x0, 0xFF, 0x0, 0x0]))).toBe(0xFF0000);
+});
+
+test("parse_uint - 0xFF000000", () => {
+	expect(uint_bytes_to_num(new Uint8Array([0xFF, 0x0, 0x0, 0x0]))).toBe(0xFF000000);
+});
+
+test("decode_utf8 - \"test\"", () => {
+	expect(utf8_decode(new Uint8Array([0x74, 0x65, 0x73, 0x74]))).toBe("test");
+});
+
+test("encode_utf8 - \"test\"", () => {
+	expect(utf8_encode("test")).toMatchObject(new Uint8Array([0x74, 0x65, 0x73, 0x74]));
+});
+
+test("encode_decode_utf8 - \"Hello, world!\"", () => {
+	const text = "Hello, world!";
+	expect(utf8_decode(utf8_encode(text))).toBe(text);
+});

client/tools.ts

@@ -0,0 +1,139 @@
+/**
+ * Convert big-endian u32 to native JavaScript number.
+ */
+export function uint_bytes_to_num(value: Uint8Array): number {
+	if (value.length != 4) { throw new Error("can't convert non 4-byte integer"); }
+	const data_view = new DataView(value.buffer);
+	return data_view.getUint32(0, false);
+}
+
+export function utf8_encode(value: string): Uint8Array {
+	const encoder = new TextEncoder();
+	let res: Uint8Array = new Uint8Array(0);
+	for (const ch of value) {
+		const cur = encoder.encode(ch)[0];
+		const prev = res;
+		res = new Uint8Array(prev.length + 1);
+		res.set(prev, 0);
+		res.set([cur], prev.length);
+	}
+	return res;
+}
+
+export function utf8_decode(value: Uint8Array): string {
+	const decoder = new TextDecoder("utf-8");
+	return decoder.decode(value);
+}
+
+export async function sleep(millis: number): Promise<void> {
+	await new Promise<void>((resolver) => {
+		setTimeout(resolver, millis);
+	});
+}
+
+export function wait_for_dom_refresh(): Promise<void> {
+	return new Promise<void>((resolver) => {
+		requestAnimationFrame(() => {
+			requestAnimationFrame(() => {
+				resolver();
+			});
+		});
+	});
+}
+
+/**
+ * Provides a locking abstraction around any ref-passed object to provide inner mutability that can
+ * automatically release on promise resolution. This provides "atomic transactions" on the inner
+ * type.
+ *
+ * This allows you to not await the transaction result, but offload the waiting to the next call
+ * to run. So other tasks can normally run when the transaction is executing. And if the inner
+ * type is needed again... the run call will wait for the (possibly) running transaction to
+ * finish first.
+ */
+export class AsyncRunner<T> {
+	private inner: T;
+	private lock: Promise<void>;
+
+	public constructor(inner: T) {
+		this.inner = inner;
+		this.lock = Promise.resolve();
+	}
+
+	public async run(transaction: (target: T) => Promise<void>): Promise<void> {
+		await this.lock;
+		this.lock = new Promise((resolver) => {
+			transaction(this.inner).then(() => { resolver() });
+		});
+	}
+}
+
+export namespace el {
+	function add_classes(target: HTMLElement, classes?: string[]): void {
+		if (classes === undefined) { return; }
+		for (const cls of classes) {
+			target.classList.add(cls);
+		}
+	}
+
+	export function div(children: HTMLElement[], classes?: string[]): HTMLDivElement {
+		const el = document.createElement("div");
+		add_classes(el, classes);
+		el.append(...children);
+		return el;
+	}
+
+	export function h1(text: string, classes?: string[]): HTMLHeadingElement {
+		const el = document.createElement("h1");
+		el.innerText = text;
+		add_classes(el, classes);
+		return el;
+	}
+
+	export function h2(text: string, classes?: string[]): HTMLHeadingElement {
+		const el = document.createElement("h2");
+		el.innerText = text;
+		add_classes(el, classes);
+		return el;
+	}
+
+	export function p(text: string, classes?: string[]): HTMLParagraphElement {
+		const el = document.createElement("p");
+		el.innerText = text;
+		add_classes(el, classes);
+		return el;
+	}
+
+	export async function img(src: string, classes?: string[]): Promise<HTMLImageElement> {
+		const el = new Image();
+		el.src = src;
+		el.draggable = false;
+		add_classes(el, classes);
+		await new Promise<void>((resolver) => {
+			el.addEventListener("load", () => { resolver(); });
+		});
+		return el;
+	}
+
+	export async function video(
+		src: string,
+		subtitles_url: string | null,
+		classes?: string[],
+	): Promise<HTMLVideoElement> {
+		const blob = await (await fetch(src)).blob();
+		const el = document.createElement("video");
+		el.autoplay = true;
+		const source = document.createElement("source");
+		source.src = URL.createObjectURL(blob);
+		el.appendChild(source);
+		if (subtitles_url !== null) {
+			const subs = document.createElement("track");
+			subs.src = subtitles_url;
+			subs.kind = "subtitles";
+			subs.default = true;
+			el.appendChild(subs);
+		}
+		add_classes(el, classes);
+		return el;
+	}
+}

client/ws.ts

@@ -0,0 +1,76 @@
+export class WSClient {
+	private is_connected: boolean;
+	private is_closed: boolean;
+	private sock: WebSocket;
+
+	private messages_received: Blob[];
+
+	// callbacks
+	private callbacks_connected: (() => void)[];
+	private callbacks_receive: ((data: Blob | null) => void)[];
+
+	public constructor(addr: string) {
+		this.is_connected = false;
+		this.is_closed = false;
+		this.messages_received = [];
+		this.callbacks_connected = [];
+		this.callbacks_receive = [];
+
+		this.sock = new WebSocket(addr);
+		this.sock.binaryType = "blob";
+		this.sock.addEventListener("open", (_) => {
+			this.is_connected = true;
+			for (const callback of this.callbacks_connected) { callback(); }
+			this.callbacks_connected = [];
+		});
+		this.sock.addEventListener("message", (e) => {
+			const callback = this.callbacks_receive.shift();
+			if (callback === undefined) { this.messages_received.push(e.data); return; }
+			callback(e.data);
+		});
+		this.sock.addEventListener("error", (_) => { this.end(); });
+		this.sock.addEventListener("close", (_) => { this.end(); });
+	}
+
+	public async wait_for_connection(): Promise<void> {
+		if (this.is_closed) { throw new Error("connetion was already closed"); }
+		if (this.is_connected) { return; }
+		await new Promise<void>((resolver) => {
+			this.callbacks_connected.push(resolver);
+		});
+	}
+
+	private end(): void {
+		this.is_connected = false;
+		this.is_closed = true;
+		for (const callback of this.callbacks_connected) { callback(); }
+		this.callbacks_connected = [];
+		for (const callback of this.callbacks_receive) { callback(null); }
+		this.callbacks_receive = [];
+	}
+
+	/**
+	 * @returns `true` if the send call was placed successfully, `false` if the client is not
+	 * active anymore
+	 */
+	public send(message: string | ArrayBufferLike | Blob | ArrayBufferView): boolean {
+		if (!this.is_connected) { return false; }
+		this.sock.send(message);
+		return true;
+	}
+
+	/**
+	 * Waits for a new incoming message or connection close.
+	 *
+	 * @returns a `Blob` if there was an incoming message, `null` if the connection closed before
+	 * a message could be received
+	*/
+	public receive(): Promise<Blob | null> {
+		const queued = this.messages_received.shift();
+		if (queued !== undefined) { return Promise.resolve(queued); }
+		if (this.is_closed) { return Promise.resolve(null); }
+		return new Promise<Blob | null>((resolver) => {
+			this.callbacks_receive.push(resolver);
+		});
+	}
+}

libretranslate/.gitignore

@@ -0,0 +1,2 @@
+/venv/
+/db/

libretranslate/make.mk

@@ -0,0 +1,17 @@
+LIBRETRANSLATE_PYTHON_VERSION = 3.10.12
+
+.PHONY: libretranslate
+libretranslate: libretranslate/venv
+	cd libretranslate && . venv/bin/activate && libretranslate --port 5000 --load-only en,cs
+
+.PHONY: libretranslate_clean
+libretranslate_clean:
+	rm -rf libretranslate/venv
+	rm -rf libretranslate/db
+
+libretranslate/venv:
+	pyenv install -s $(LIBRETRANSLATE_PYTHON_VERSION)
+	cd libretranslate && \
+		PYENV_VERSION=$(LIBRETRANSLATE_PYTHON_VERSION) pyenv exec python -m venv venv
+	cd libretranslate && . venv/bin/activate && \
+		pip install --upgrade pip && pip install -r requirements.txt

libretranslate/requirements.txt

@@ -0,0 +1,3 @@
+libretranslate
+torch==2.2.0
+

main.py

@@ -1,5 +1,20 @@
-from fastapi import FastAPI, Request, WebSocket, WebSocketDisconnect, BackgroundTasks
-from fastapi.responses import HTMLResponse, JSONResponse
+# This file is part of Pythagoras.
+#
+# Pythagoras is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Pythagoras is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Pythagoras. If not, see <https://www.gnu.org/licenses/>.
+
+from fastapi import FastAPI, File, Request, WebSocket, WebSocketDisconnect, BackgroundTasks, HTTPException
+from fastapi.responses import JSONResponse, FileResponse
 import logging
 import uvicorn
 from typing import Dict, List, Any
@@ -7,10 +22,14 @@ from dataclasses import dataclass
 import json
 import httpx
 import asyncio
+import struct
+import os
+from pathlib import Path
+from asyncio import Lock
 
 # Some useful variables
-PEEHAITCHPEA_ENDPOINT = "http://localhost:9000/api.php?cmd=getselectedmessage"
-PYTHAGORAS_PORT = 9000
+PEEHAITCHPEA_ENDPOINT = "http://peehaitchpea.libre-liberec.cz/api.php?cmd=getselectedmessage"
+PYTHAGORAS_PORT = 8000
 
 # Configure logging
 logging.basicConfig(
@@ -23,39 +42,119 @@ logger = logging.getLogger("pythagoras")
 app = FastAPI(title="Pythagoras", description="A proxy service handling HTTP and WebSocket connections")
 app.state.auto_polling = False
 app.state.polling_rate = 5
+app.state.enable_libretranslate = True
+app.state.client_state = "idle"
+app.state.latest_message = None
+
+# Define the media directory
+MEDIA_DIR = Path("./media")
+
+# Create the media directory if it doesn't exist
+os.makedirs(MEDIA_DIR, exist_ok=True)
 
 # Store for connected websocket clients
+
+class WSConnection:
+    inner: WebSocket
+    lock: Lock
+
+    def __init__(self, sock: WebSocket):
+        self.inner = sock
+        self.lock = Lock()
+
+    async def accept(self):
+        async with self.lock:
+            await self.inner.accept()
+
+    async def send_bytes(self, data: bytes):
+        async with self.lock:
+            await self.inner.send_bytes(data)
+
+    async def send_text(self, data: str):
+        async with self.lock:
+            await self.inner.send_text(data)
+
 class ConnectionManager:
     def __init__(self):
-        self.active_connections: List[WebSocket] = []
+        self.active_connections: List[WSConnection] = []
     
-    async def connect(self, websocket: WebSocket):
+    async def connect(self, websocket: WSConnection):
         await websocket.accept()
         self.active_connections.append(websocket)
+        await setscreen_single(websocket, app.state.client_state)    # Send the latest client state to any new client
+        await self.singlecast_binary({"type": "selectedmessage", "message": app.state.latest_message}, websocket) # Broadcast latest message to all clients
         logger.info(f"WebSocket client connected. Total connections: {len(self.active_connections)}")
     
-    def disconnect(self, websocket: WebSocket):
+    def disconnect(self, websocket: WSConnection):
         self.active_connections.remove(websocket)
         logger.info(f"WebSocket client disconnected. Total connections: {len(self.active_connections)}")
+
+    def json_to_binary(self, json_str: str):
+        json_bytes = json_str.encode('utf-8')
+        json_length = len(json_bytes)
+        
+        # 4-byte unsigned integer (uint32)
+        length_bytes = struct.pack('!I', json_length)
+        if len(length_bytes) != 4:
+            raise Exception("invalid packed length")
+        
+        return length_bytes + json_bytes
+
     
     async def broadcast(self, message: str):
         for connection in self.active_connections:
             await connection.send_text(message)
+    
+    async def broadcast_binary(self, data_dict: dict):
+        """
+        Broadcasts a message to all connections as binary data.
+        """
+        if not self.active_connections:
+            return
+        
+        json_str = json.dumps(data_dict)
+        message_bytes = self.json_to_binary(json_str) 
+        
+        for connection in self.active_connections:
+            try:
+                await connection.send_bytes(message_bytes)
+                logger.debug(f"Sent binary message ({len(message_bytes)} bytes) to a client")
+            except Exception as e:
+                logger.error(f"Failed to send binary message: {str(e)}")
+
+    async def singlecast_binary(self, data_dict: dict, ws: WSConnection):
+        """
+        I love code duplication
+        """
+        
+        json_str = json.dumps(data_dict)
+        message_bytes = self.json_to_binary(json_str) 
+        
+        try:
+            await ws.send_bytes(message_bytes)
+            logger.debug(f"Sent binary message ({len(message_bytes)} bytes) to a client")
+        except Exception as e:
+            logger.error(f"Failed to send binary message: {str(e)}")
 
 manager = ConnectionManager()
 
-# Static files
-def read_file(filepath: str) -> str:
-    with open(filepath, "r", encoding="utf-8") as f:
-        return f.read()
-
-@dataclass
-class StaticFiles:
-    index_html: str = read_file("static/index.html")
-
 @app.get("/presentation/")
 async def presentation_index(_: Request):
-    return HTMLResponse(status_code=200, content=StaticFiles.index_html)
+    return FileResponse(status_code=200, path="static/index.html", media_type="text/html")
+
+@app.get("/presentation/script.js")
+async def presentation_script(_: Request):
+    return FileResponse(
+        status_code=200, path="static/script.js", media_type="text/javascript"
+    )
+
+@app.get("/presentation/style.css")
+async def presentation_style(_: Request):
+    return FileResponse(status_code=200, path="static/style.css", media_type="text/css")
+
+@app.get("/presentation/files/{file_path:path}")
+async def presentation_file(file_path: str):
+    return FileResponse(status_code=200, path=f"static/{file_path}")
 
 # Endpoints
 @app.post("/control")
@@ -67,6 +166,7 @@ async def control_endpoint(request: Request):
         
         if data['command'] == "getselectedmessage":
             message = await fetch_selected_message()
+            message = None if message == "" else message
             await process_selected_message(message)
             logger.info(f"Received new selected message initiated from control: {message}")
 
@@ -75,11 +175,49 @@ async def control_endpoint(request: Request):
             app.state.auto_polling = new_state 
             logger.info(f"Polling command issued, changing auto-polling to {new_state}")
         
+        elif data['command'] == "setlibretranslate" and 'state' in data:
+            new_state = data['state']
+            app.state.auto_polling = new_state 
+            logger.info(f"LibreTranslate command issued, changing state to {new_state}")
+
         elif data['command'] == "autopollingrate" and 'rate' in data:
             new_rate = data['rate']
             app.state.polling_rate = new_rate
             logger.info(f"Auto-polling rate change requested: {new_rate} seconds")
 
+        elif data['command'] == "playvideo" and 'filename' in data:
+            filename = data['filename']
+            subtitles = None
+            seconds_from_start = 0
+            if 'subtitles' in data:
+                subtitles = data['subtitles']
+            if 'secondsfromstart' in data:
+                seconds_from_start = data['secondsfromstart']
+            await playvideo(filename, subtitles, seconds_from_start)
+            logger.info(f"Video playback requested: {filename} with subtitles {subtitles} starting {seconds_from_start} seconds from start.")
+
+        elif data['command'] == "seekvideo" and 'timestamp' in data:
+            timestamp = data['timestamp']
+            await seekvideo(timestamp)
+            logger.info(f"Seeking of the currently playing video requested to {timestamp} seconds")
+
+
+
+        elif data['command'] == "setscreen_main":
+            await setscreen("main")
+            app.state.client_state = "main"
+            logger.info(f"Setting the client screen to main view.")
+
+        elif data['command'] == "setscreen_video":
+            await setscreen("video")
+            app.state.client_state = "video"
+            logger.info(f"Setting the client screen to video playback.")
+
+        elif data['command'] == "setscreen_idle":
+            await setscreen("idle")
+            app.state.client_state = "idle"
+            logger.info(f"Setting the client screen to idle.")
+
         
         return JSONResponse(
             status_code=200,
@@ -92,52 +230,138 @@ async def control_endpoint(request: Request):
             content={"status": "error", "message": f"Failed to process request."}
         )
 
-@app.post("/subtitles")
-async def subtitles_endpoint(request: Request):
-    """Endpoint for subtitle data."""
-    try:
-        text_content = await request.body()
-        subtitle_text = text_content.decode("utf-8")
-        logger.info(f"Received subtitle text: {subtitle_text}")
-        
-        if manager.active_connections:
-            await manager.broadcast(json.dumps({"type": "subtitle", "text": subtitle_text}))
-        
-        return JSONResponse(
-            status_code=200,
-            content={"status": "success", "message": "Subtitle text received"}
-        )
-    except Exception as e:
-        logger.error(f"Error processing subtitle data: {str(e)}")
-        return JSONResponse(
-            status_code=400,
-            content={"status": "error", "message": f"Failed to process request."}
-        )
+@app.post("/subtitles/update_current")
+async def subtitles_update_current_endpoint(request: Request):
+    """Endpoint for subtitle data - updating the current sentence as it comes."""
+    return await process_subtitles(request, "update_current")
+
+@app.post("/subtitles/submit_sentence")
+async def subtitles_submit_sentence_endpoint(request: Request):
+    """Endpoint for subtitle data - submitting the final version of a sentence."""
+    return await process_subtitles(request, "submit_sentence")
 
 @app.websocket("/ws")
 async def websocket_endpoint(websocket: WebSocket):
     """WebSocket endpoint for real-time communication."""
-    await manager.connect(websocket)
+    conn = WSConnection(websocket)
+    await manager.connect(conn)
     try:
         while True:
             data = await websocket.receive_text()
             logger.info(f"Received message from WebSocket: {data}")
     except WebSocketDisconnect:
-        manager.disconnect(websocket)
+        manager.disconnect(conn)
     except Exception as e:
         logger.error(f"WebSocket error: {str(e)}")
-        manager.disconnect(websocket)
+        manager.disconnect(conn)
+
+@app.get("/media/{file_path:path}")
+async def get_media(file_path: str):
+    """
+    Serve media files from the media directory.
+    """
+    full_path = MEDIA_DIR / file_path
+    absolute_path = full_path.resolve()
+    
+    # Security check: Make sure the path is within the media directory
+    if not str(absolute_path).startswith(str(MEDIA_DIR.resolve())):
+        logger.warning(f"Attempted directory traversal: {file_path}")
+        raise HTTPException(status_code=403, detail="Access denied")
+    
+    # Check if the file exists
+    if not absolute_path.is_file():
+        logger.warning(f"File not found: {absolute_path}")
+        raise HTTPException(status_code=404, detail="File not found")
+    
+    logger.info(f"Serving media file: {file_path}")
+    
+    return FileResponse(path=absolute_path, filename=absolute_path.name)
 
 
 
 # Functions
+async def process_subtitles(request: Request, sub_type: str):
+    try:
+        text_content = await request.body()
+        en_subtitle_text = text_content.decode("utf-8")
+        logger.info(f"Received subtitle text: {en_subtitle_text}, request type: {sub_type}")
+        
+        if manager.active_connections:
+            await manager.broadcast_binary({"type": f"subtitle_en_{sub_type}", "text": en_subtitle_text})
+
+            if app.state.enable_libretranslate and sub_type == "submit_sentence":
+                cs_subtitle_text = await translate_to_cs_libre(en_subtitle_text)
+                await manager.broadcast_binary({"type": f"subtitle_cs_{sub_type}", "text": cs_subtitle_text})
+       
+        return JSONResponse(
+            status_code=200,
+            content={"status": "success", "message": "Subtitle text received"}
+        )
+    except Exception as e:
+        logger.error(f"Error processing {sub_type} subtitle data: {str(e)}")
+        return JSONResponse(
+            status_code=400,
+            content={"status": "error", "message": f"Failed to process request."}
+        )
+
+async def translate_to_cs_libre(text: str):
+    """
+    Translates the provided text from English to Czech using LibreTranslate.
+    """
+    if not text:
+        return text
+    
+    try:
+        url = "http://localhost:5000/translate"
+        
+        payload = {
+            "q": text,
+            "source": "en",
+            "target": "cs",
+            "format": "text"
+        }
+        
+        timeout = httpx.Timeout(10.0)
+        
+        async with httpx.AsyncClient(timeout=timeout) as client:
+            response = await client.post(url, json=payload)
+            
+            if response.status_code == 200:
+                result = response.json()
+                translated_text = result.get("translatedText", text)
+                logger.info(f"Successfully translated text to Czech")
+                return translated_text
+            else:
+                logger.error(f"Translation API error: {response.status_code}, {response.text}")
+                return text
+                
+    except Exception as e:
+        logger.error(f"Translation error: {str(e)}")
+        return text
+
+async def setscreen_single(ws: WSConnection, screen: str):
+    return await manager.singlecast_binary({"type": "setscreen", "screen": screen}, ws)
+
+async def setscreen(screen: str):
+    return await manager.broadcast_binary({"type": "setscreen", "screen": screen})
+
+async def playvideo(filename: str, subtitles: str | None, seconds_from_start: int):
+    return await manager.broadcast_binary({"type": "playvideo", "filename": filename, "subtitles": subtitles, "seconds_from_start": seconds_from_start})
+
+async def seekvideo(timestamp: int):
+    return await manager.broadcast_binary({"type": "seekvideo", "timestamp": timestamp})
+
+    
+
+
 async def fetch_selected_message():
     """
     Fetches a selected message from the specified endpoint.
     Returns the message as a string or None if no message is available.
     """
+    auth = httpx.BasicAuth(username="stallman", password="gnu")
     try:
-        async with httpx.AsyncClient() as client:
+        async with httpx.AsyncClient(auth=auth) as client:
             response = await client.get(PEEHAITCHPEA_ENDPOINT)
             if response.status_code == 200:
                 message = response.text.strip()
@@ -153,13 +377,14 @@ async def fetch_selected_message():
         logger.error(f"Error fetching selected message: {str(e)}")
         return None
 
-async def process_selected_message(message: str):
+async def process_selected_message(message: str | None):
     """
-    Processes the selected message.
+    Processes the selected message and saves it to cache.
     """
     logger.info(f"Processing message: {message}")
+    app.state.latest_message = message
     if manager.active_connections:
-        await manager.broadcast(json.dumps({"type": "selectedmessage", "message": message}))
+        await manager.broadcast_binary({"type": "selectedmessage", "message": message})
 
 async def periodic_message_check():
     """Periodically checks for new messages."""