import { ClientLevel } from "./level/client_level.ts";
import type { BlockHitResult } from "./level/client_level.ts";
import { LocalPlayer } from "./entity/local_player.ts";
import { RemotePlayer } from "./entity/remote_player.ts";
import { Camera } from "./camera.ts";
import { Options } from "./options.ts";
import { MultiPlayerGameMode } from "./game_mode.ts";
import { ClientPacketListener } from "./packet_listener.ts";
import { GameRenderer } from "./rendering/game_renderer.ts";
import { ChatComponent } from "./gui/chat_component.ts";
import { GuiInventoryScreen, GuiScreen } from "./gui/gui_screen.ts";
import { GuiPlayerInventory } from "./gui/gui_player_inventory.ts";
import { GuiChat } from "./gui/gui_chat.ts";
import { InputManager } from "./input_manager.ts";
import { Connection } from "./network.ts";
import { canvas, resize_canvas } from "./renderer/mod.ts";
import { show_fatal_error } from "./fatal.ts";
import { TICK_DELTA } from "$/common/constants.ts";

// after a long stall (a hidden tab, a debugger) the game skips ahead instead of running every missed tick at once
const MAX_TICKS_PER_FRAME = 10;

// the game client, like minecraft's Minecraft class: owns the level, the player, the screens and the renderer.
// the game runs in fixed ticks (TICKS_PER_SECOND), input and drawing happen every frame
export class Client {
	connection: Connection;
	options = new Options();
	level: ClientLevel;
	player: LocalPlayer;
	camera = new Camera();
	game_mode: MultiPlayerGameMode;
	packet_listener: ClientPacketListener;
	game_renderer = new GameRenderer();
	chat = new ChatComponent();

	// open screens, the last one is on top and gets the input
	screens: GuiScreen[] = [];
	// what the player is looking at, updated every frame
	hit_result: BlockHitResult | undefined;
	debugging = false;

	// seconds of game time not ticked yet
	#pending_time = 0;
	// whether the attack button is held on a block, breaking it advances every tick
	#attacking = false;
	#stopped = false;

	constructor(connection: Connection) {
		this.connection = connection;

		self.addEventListener("resize", resize_canvas);
		resize_canvas();
		canvas.addEventListener("contextmenu", (event) => event.preventDefault());

		this.level = new ClientLevel(connection.seed);
		for (const [x, y, z, id, state] of connection.initial_changes) {
			this.level.record_change(x, y, z, id, state);
		}

		const spawn = connection.spawn;
		this.player = new LocalPlayer(this, connection.id, connection.name);
		this.player.set_position(spawn.x, spawn.y, spawn.z);
		this.player.yaw = spawn.yaw;
		this.player.pitch = spawn.pitch;
		this.player.inventories.hotbar_selected = connection.selected_slot;
		this.level.add_entity(this.player);
		for (const info of connection.initial_players) {
			this.level.add_entity(new RemotePlayer(this.level, info));
		}

		this.game_mode = new MultiPlayerGameMode(this);
		this.packet_listener = new ClientPacketListener(this);
	}

	get screen(): GuiScreen | undefined {
		return this.screens.at(-1);
	}

	push_screen(screen: GuiScreen) {
		this.screens.push(screen);
	}

	pop_screen() {
		this.screens.pop()?.on_close();
	}

	// one frame: input, as many ticks as are due, then drawing between the last tick and the next
	run_frame(delta: number) {
		this.screen?.on_tick(delta);
		this.#handle_keybinds();

		this.#pending_time += delta;
		let ticks = 0;
		while (this.#pending_time >= TICK_DELTA && ticks < MAX_TICKS_PER_FRAME) {
			this.tick();
			if (this.#stopped) {
				return;
			}
			this.#pending_time -= TICK_DELTA;
			ticks += 1;
		}
		if (ticks === MAX_TICKS_PER_FRAME) {
			this.#pending_time = Math.min(this.#pending_time, TICK_DELTA);
		}

		this.game_renderer.render(this, this.#pending_time / TICK_DELTA);
	}

	// one step of the game: what the server sent, breaking, chunk loading, then every entity
	tick() {
		this.packet_listener.handle_packets();
		if (this.connection.closed) {
			show_fatal_error("Lost connection to the server");
			this.#stopped = true;
			return;
		}

		if (this.#attacking && this.hit_result) {
			this.game_mode.continue_destroy_block(this.hit_result);
		}

		this.level.update_loaded_chunks(this.player.x, this.player.z, this.options.render_distance);
		this.level.tick();
	}

	#handle_keybinds() {
		const options = this.options;
		const player = this.player;

		if (InputManager.is_key_pressed(options.key_inventory)) {
			if (!this.screen) {
				this.push_screen(new GuiPlayerInventory(player.inventories, (m) => this.connection.send(m)));
			} else if (this.screen instanceof GuiInventoryScreen) {
				this.pop_screen();
			}
		}
		if (InputManager.is_key_pressed(options.key_chat) && !this.screen) {
			this.push_screen(new GuiChat(this));
		}
		if (InputManager.is_key_pressed("Escape")) {
			this.pop_screen();
		}
		if (InputManager.is_key_pressed(options.key_debug)) {
			this.debugging = !this.debugging;
		}
		if (InputManager.is_key_pressed(options.key_fullscreen)) {
			InputManager.toggle_fullscreen();
		}

		if (InputManager.is_mouse_grabbed()) {
			const mouse = InputManager.get_mouse_delta();
			player.turn(mouse.x, mouse.y);
		}
		InputManager.set_mouse_grabbed(!this.screen);

		this.hit_result = this.level.pick(player.x, player.y + player.eye_height, player.z, player.yaw, player.pitch);
		this.#handle_block_interaction();

		if (!this.screen) {
			this.#handle_hotbar();
		}
	}

	// clicks happen right away, holding to break advances in tick()
	#handle_block_interaction() {
		const hit = this.hit_result;
		const attacking = !this.screen && InputManager.is_mouse_down(0);
		this.#attacking = attacking;

		if (!attacking || !hit) {
			this.game_mode.stop_destroy_block();
		}
		if (this.screen) {
			return;
		}

		if (hit) {
			if (InputManager.is_mouse_pressed(0)) {
				this.game_mode.start_destroy_block(hit);
			}
			if (!attacking && InputManager.is_mouse_pressed(2)) {
				this.game_mode.use_item_on(hit);
			}
		} else if (InputManager.is_mouse_pressed(2)) {
			this.game_mode.use_item();
		}
	}

	#handle_hotbar() {
		const inventories = this.player.inventories;
		const previous = inventories.hotbar_selected;

		const scroll = InputManager.get_wheel_delta();
		if (scroll > 0) {
			inventories.hotbar_selected = Math.min(8, inventories.hotbar_selected + 1);
		} else if (scroll < 0) {
			inventories.hotbar_selected = Math.max(0, inventories.hotbar_selected - 1);
		}

		const pressed = this.options.key_hotbar.findIndex((key) => InputManager.is_key_pressed(key));
		if (pressed !== -1) {
			inventories.hotbar_selected = pressed;
		}

		if (inventories.hotbar_selected !== previous) {
			this.connection.send({ type: "select_slot", slot: inventories.hotbar_selected });
		}
	}
}