class ElementBuilder {
	constructor(tag) {
		let parts = tag.split(/(\.|#)/);

		if(parts.length % 2 == 0) {
			throw new Error("invalid element builder tag string");
		}

		this.element = document.createElement(parts[0]);

		parts = parts.slice(1);

		for(let i = 0; i < parts.length; i += 2) {
			let type = parts[i];
			let value = parts[i + 1];

			switch(type) {
				case ".":
					this.element.classList.add(value);
					break;

				case "#":
					this.element.id = value;
					break;
			}
		}
	}

	// Need more stuff? Just implement it here.

	id(id) {
		this.element.id = id;
		return this;
	}

	class(clazz) {
		for(const subclass of clazz.split(" ").filter(x => x !== "")) {
			this.element.classList.add(subclass);
		}

		return this;
	}

	text(text) {
		this.element.innerText = text;
		return this;
	}

	html(html) {
		this.element.innerHTML = html;
		return this;
	}

	on_click(handler) {
		this.element.onclick = handler;
		return this;
	}

	on_input(handler) {
		this.element.oninput = handler;
		return this;
	}

	for(fr) {
		this.element.htmlFor = fr;
		return this;
	}

	src(src) {
		this.element.src = src;
		return this;
	}

	target(target) {
		this.element.target = target;
		return this;
	}

	href(href) {
		this.element.href = href;
		return this;
	}

	download(download) {
		this.element.download = download;
		return this;
	}

	type(type) {
		this.element.type = type;
		return this;
	}

	value(value) {
		this.element.value = value;
		return this;
	}

	checked(checked) {
		this.element.checked = checked;
		return this;
	}

	placeholder(placeholder) {
		this.element.placeholder = placeholder;
		return this;
	}

	append(element) {
		if(element instanceof ElementBuilder) {
			element = element.finish();
		}

		this.element.appendChild(element);
		return this;
	}

	append_all(elements) {
		for(const element of elements) {
			this.element.appendChild(element);
		}

		return this;
	}

	style(name, value) {
		this.element.style[name] = value;
		return this;
	}

	if(cond, handler) {
		if(cond) handler(this);
		return this;
	}

	finish() {
		return this.element;
	}
}

class ButtonListBuilder {
	constructor(list) {
		this.list = list;
		this.display_handler = null;
		this.onclick_handler = null;
		this.modify_handler = null;
	}

	should_be_pressed(handler) {
		this.display_handler = handler;
		return this;
	}

	on_click(handler) {
		this.onclick_handler = handler;
		return this;
	}

	modify(handler) {
		this.modify_handler = handler;
		return this;
	}

	finish() {
		let buttons = this.list.map((key) => new ElementBuilder("button")
			.if(this.modify_handler !== null, (b) => this.modify_handler(b, key))
			.if(this.display_handler(key), (b) => b.class("accent"))
			.finish()
		);

		for(let i = 0; i < buttons.length; i++) {
			buttons[i].onclick = () => {
				if(this.onclick_handler !== null) this.onclick_handler(this.list[i]);

				for(let j = 0; j < buttons.length; j++) {
					buttons[j].classList.remove("accent");

					if(this.display_handler(this.list[j])) {
						buttons[j].classList.add("accent");
					}
				}
			};
		}

		return buttons;
	}
}

class TextInputBuilder {
	constructor(result, key) {
		this.result = result;
		this.key = key;
		this.text = "";
	}

	placeholder(placeholder) {
		this.text = placeholder;
		return this;
	}

	finish() {
		return new ElementBuilder("input")
			.type("text")
			.placeholder(this.text)
			.value(this.result[this.key])
			.on_input((e) => this.result[this.key] = e.target.value)
			.finish();
	}
}

class BinaryInputBuilder {
	constructor(result, key) {
		this.result = result;
		this.key = key;
		this.text = "";
		this.update_handler = null;
	}

	label(label) {
		this.text = label;
		return this;
	}

	on_update(handler) {
		this.update_handler = handler;
		return this;
	}

	finish() {
		let input = new ElementBuilder("input#" + this.key)
			.type("checkbox")
			.checked(this.result[this.key])
			.if(this.update_handler !== null, b => b.on_click(e => {
				console.log(e.target.checked);
				this.result[this.key] = e.target.checked;
				this.update_handler(e.target.checked);
			}))
			.finish();

		let bundle = new ElementBuilder("div.horizontal-list")
			.append(input)
			.append(new ElementBuilder("label")
				.for(this.key)
				.text(this.text))
			.finish();

		if(this.update_handler !== null) {
			this.update_handler(this.result[this.key]);
		}

		return bundle;
	}
}

async function delay_ms(ms) {
	await new Promise((r) => setTimeout(r, ms));
}