import { MAX_NAME_LENGTH } from "$/common/protocol.ts";
import { InputManager } from "$/client/input_manager.ts";
import { canvas, draw_rect, draw_text, measure_text } from "$/client/renderer/mod.ts";
import { default_server, HandshakeError, server_address, ServerAddress } from "$/client/handshake.ts";
import { default_player_name } from "$/client/network.ts";
import { GuiScreen } from "./gui_screen.ts";
import { CreditsScreen } from "./credits_screen.ts";
import { Button, EditBox, TEXT_HEIGHT, TEXT_SCALE, TextInput } from "./widgets.ts";

const LAST_SERVER_KEY = "bworld:last_server";
const LAST_NAME_KEY = "bworld:last_name";

const WIDTH = 440;
const ROW_HEIGHT = 48;
const LABEL_GAP = 28;
const GAP = 20;
const TITLE_SCALE = 8;

// connects to a server and joins it. it reports progress through status, and throws with a message
// for the player when it fails
export type JoinServer = (address: ServerAddress, name: string, status: (text: string) => void) => Promise<void>;

// the first thing players see, like minecraft's title and multiplayer screens rolled into one:
// a name, a server, and a button to join it
export class TitleScreen extends GuiScreen {
	#join_server: JoinServer;

	name = new EditBox(
		WIDTH,
		ROW_HEIGHT,
		new TextInput(initial_name(), MAX_NAME_LENGTH, (char) => /^[A-Za-z0-9_]$/.test(char)),
		"Random name",
	);
	server = new EditBox(WIDTH, ROW_HEIGHT, new TextInput(initial_server(), 256, (char) => char !== " "), "host:port");
	join_button = new Button("Join server", WIDTH, ROW_HEIGHT, () => this.#join());
	credits_button = new Button("Credits", WIDTH, ROW_HEIGHT, () => this.#open_credits());
	// open over the title screen, it gets the input while it's there
	#credits: CreditsScreen | undefined;

	status = "";
	status_is_error = false;
	#joining = false;

	constructor(join_server: JoinServer, message?: string) {
		super();
		this.#join_server = join_server;
		this.name.focused = this.name.value === "";
		this.server.focused = !this.name.focused;
		if (message) {
			this.#show_error(message);
		}
	}

	on_tick(delta: number): void {
		this.#layout();
		if (this.#credits) {
			if (InputManager.is_key_pressed("Escape")) {
				this.#close_credits();
			} else {
				this.#credits.on_tick(delta);
			}
			return;
		}

		const fields = [this.name, this.server];
		for (const field of fields) {
			if (field.handle_input()) {
				for (const other of fields) other.focused = other === field;
			}
		}
		if (InputManager.is_key_pressed("Tab")) {
			const next = this.name.focused ? this.server : this.name;
			for (const field of fields) field.focused = field === next;
		}
		if (InputManager.is_key_pressed("Enter")) {
			this.#join();
		}
		this.join_button.handle_input();
		this.credits_button.handle_input();
	}

	on_render(): void {
		const title = "bworld";
		const title_width = measure_text(title, TITLE_SCALE);
		draw_text(
			title,
			(canvas.width - title_width) / 2,
			this.name.y - LABEL_GAP - 40 - TEXT_HEIGHT * TITLE_SCALE,
			TITLE_SCALE,
		);

		this.#label("Name", this.name);
		this.#label("Server", this.server);
		this.name.render();
		this.server.render();
		this.join_button.render();
		this.credits_button.render();

		if (this.status) {
			const width = measure_text(this.status, TEXT_SCALE);
			const x = (canvas.width - width) / 2;
			const y = this.credits_button.y + ROW_HEIGHT + GAP;
			draw_rect(x - 8, y - 4, width + 16, TEXT_HEIGHT * TEXT_SCALE + 8, [0, 0, 0, 0.5]);
			draw_text(this.status, x, y, TEXT_SCALE, this.status_is_error ? [1, 0.45, 0.45, 1] : [1, 1, 1, 1]);
		}
		this.#credits?.on_render();
	}

	on_close(): void {
		this.#close_credits();
	}

	#open_credits() {
		this.#credits ??= new CreditsScreen(() => this.#close_credits());
	}

	#close_credits() {
		this.#credits?.on_close();
		this.#credits = undefined;
	}

	#layout() {
		const x = (canvas.width - WIDTH) / 2;
		const total = 2 * (LABEL_GAP + ROW_HEIGHT + GAP) + 2 * ROW_HEIGHT + GAP;
		let y = (canvas.height - total) / 2 + 40;
		for (const field of [this.name, this.server]) {
			field.x = x;
			field.y = y + LABEL_GAP;
			y += LABEL_GAP + ROW_HEIGHT + GAP;
		}
		this.join_button.x = x;
		this.join_button.y = y;
		this.credits_button.x = x;
		this.credits_button.y = y + ROW_HEIGHT + GAP;
	}

	#label(text: string, field: EditBox) {
		draw_text(text, field.x, field.y - LABEL_GAP, TEXT_SCALE, [0.15, 0.15, 0.2, 1]);
	}

	async #join() {
		if (this.#joining) {
			return;
		}

		let address: ServerAddress;
		try {
			address = server_address(this.server.value);
		} catch (e) {
			this.#show_error((e as HandshakeError).message);
			return;
		}
		remember(LAST_SERVER_KEY, this.server.value.trim());
		remember(LAST_NAME_KEY, this.name.value);

		this.#set_joining(true);
		this.status = `Connecting to ${address.base.host}...`;
		this.status_is_error = false;
		try {
			await this.#join_server(address, this.name.value, (text) => this.status = text);
		} catch (e) {
			this.#show_error(e instanceof Error ? e.message : String(e));
			this.#set_joining(false);
		}
	}

	#set_joining(joining: boolean) {
		this.#joining = joining;
		this.name.active = this.server.active = this.join_button.active = !joining;
	}

	#show_error(message: string) {
		this.status = message;
		this.status_is_error = true;
	}
}

// what was typed last time, unless the page was opened with ?server= or ?name=
function initial_server() {
	const page = new URL(location.href);
	return page.searchParams.has("server") ? default_server(page) : recall(LAST_SERVER_KEY) ?? default_server(page);
}

function initial_name() {
	const page = new URL(location.href);
	return page.searchParams.has("name") ? default_player_name() : recall(LAST_NAME_KEY) ?? "";
}

function recall(key: string): string | undefined {
	try {
		return localStorage.getItem(key) ?? undefined;
	} catch {
		return undefined;
	}
}

function remember(key: string, value: string) {
	try {
		localStorage.setItem(key, value);
	} catch {
		// private windows and blocked storage just start empty next time
	}
}

// a server's mods can't be unloaded, so going back to the title screen starts the page over. without ?server=
// or ?name=, so the fields show what was used last
export function back_to_title() {
	location.href = location.pathname;
}