var ctx = null;
var canvas = null;

var player = null;

var now = 0;
var last = 0;
var ts = 0;

var camera_offset = 2;

const sprite_scale = 2;

var spritesheet = null;

const sprites = {
	player:     { x: 0,   y: 0,  w: 16, h: 16 },
	rock:       { x: 0,   y: 32, w: 16, h: 16 },
	hard_rock:  { x: 96,  y: 32, w: 16, h: 16 },
	sky:        { x: 112, y: 16, w: 16, h: 16 },
	background: { x: 112, y: 32, w: 16, h: 16 },
	grass:      { x: 128, y: 0,  w: 16, h: 16 },
	diamond:    { x: 112, y: 0,  w: 16, h: 16 },
	food_icon:  { x: 128, y: 16,  w: 16, h: 16 },
	food:       { x: 128, y: 32,  w: 16, h: 16 },
}

const animations = {
	player_dig_right: {
		frames: [	
			{ x: 0,  y: 0, w: 16, h: 16 },
			{ x: 16, y: 0, w: 16, h: 16 },
			{ x: 32, y: 0, w: 16, h: 16 },
			{ x: 48, y: 0, w: 16, h: 16 },
			{ x: 64, y: 0, w: 16, h: 16 },
			{ x: 80, y: 0, w: 16, h: 16 },
			{ x: 96, y: 0, w: 16, h: 16 },
			{ x: 0,  y: 0, w: 16, h: 16 },
		],
		speed: 15,
		loop: false
	},
	player_dig_left: {
		frames: [	
			{ x: 0,  y: 16, w: 16, h: 16 },
			{ x: 16, y: 16, w: 16, h: 16 },
			{ x: 32, y: 16, w: 16, h: 16 },
			{ x: 48, y: 16, w: 16, h: 16 },
			{ x: 64, y: 16, w: 16, h: 16 },
			{ x: 80, y: 16, w: 16, h: 16 },
			{ x: 96, y: 16, w: 16, h: 16 },
			{ x: 0,  y: 16, w: 16, h: 16 },
		],
		speed: 15,
		loop: false
	},
	player_hurt_left: {
		frames: [	
			{ x: 144, y: 32, w: 16, h: 16 },
			{ x: 144, y: 32, w: 16, h: 16 },
		],
		speed: 5,
		loop: false
	},
	player_hurt_right: {
		frames: [	
			{ x: 144, y: 16, w: 16, h: 16 },
			{ x: 144, y: 16, w: 16, h: 16 },
		],
		speed: 5,
		loop: false
	},
	tile_decay: {
		frames: [
			{ x: 0,  y: 32, w: 16, h: 16 },
			{ x: 16, y: 32, w: 16, h: 16 },
			{ x: 32, y: 32, w: 16, h: 16 },
			{ x: 48, y: 32, w: 16, h: 16 },
			{ x: 64, y: 32, w: 16, h: 16 },
			{ x: 80, y: 32, w: 16, h: 16 },
		],
		speed: 20,
		loop: false
	},
	fire: {
		frames: [
			{ x: 144, y: 0, w: 16, h: 16 },
			{ x: 160, y: 0, w: 16, h: 16 },
			{ x: 176, y: 0, w: 16, h: 16 },
		],
		speed: 10,
		loop: true
	}
}

const spawn_rates = {
	diamond: 10
}

var characters = {};

var animated_tiles = [];
var objs = [];

var map = null;
var map_width = 0;
var map_height = 0;
var map_value = 0;
const map_bottom_size = 6;
const map_grid_size = 16;

var collected = 0;
var gem_count = 0;

var score = 0;
var level = 0;
var food = 100;
const hunger = 1;

var name_buffer = "";

var win = null;
var next_level_timer = 0;

var state = "menu";

function random_int(min, max) {
	return Math.floor(Math.random() * (max - min)) + min;
}

function random_chance(chance) {
	if (chance > 100) {
		chance = 100;
	}

	return random_int(0, 100) < chance;
}

function remove_from_array(arr, value) {
	var idx = arr.indexOf(value);
	if (idx !== -1) {
		arr.splice(idx, 1);
	}
}

function turn() {
	objs.forEach(function(value) {
		if (value.turn) {
			value.turn();
		}
	});

	for (let i = 0; i < level; i++) {
		let x = random_int(1, map_width  - 1);
		let y = random_int(1, map_height - 1);

		if (map[x][y] == 0 && obj_at(x, y) == null) {
			objs.push(new Fire(x, y));
		}
	}
}

function obj_at(x, y) {
	for (let i = 0; i < objs.length; i++) {
		if (objs[i].go.x == x && objs[i].go.y == y) {
			return objs[i];
		}
	}

	return null;
}

function apply_gravity(obj) {
	while (map[obj.go.x][obj.go.y + 1] == 0) {
		let other_obj = false;

		for (let i = 0; i < objs.length; i++) {
			let value = objs[i];
			if (obj.go.x == value.go.x && obj.go.y + 1 == value.go.y) {
				other_obj = true;
				break;
			}
		}

		if (other_obj) {
			break;
		}

		obj.go.y += 1;
	}
}

function GameObject(sprite) {
	this.x = 0;
	this.y = 0;

	this.rect = sprite;

	this.animation = null;
	this.current_frame = 0;
	this.timer = 0;

	this.draw = function() {
		ctx.drawImage(spritesheet, this.rect.x, this.rect.y, this.rect.w,
			this.rect.h, this.x * map_grid_size * sprite_scale, (this.y + camera_offset) * map_grid_size * sprite_scale,
			this.rect.w * sprite_scale, this.rect.h * sprite_scale);
	}

	this.update = function() {
		if (this.animation != null) {
			this.timer += ts * this.animation.speed;

			if (this.timer >= 1.0) {
				this.current_frame++;
				this.timer = 0;

				if (this.current_frame >= this.animation.frames.length) {
					if (this.animation.loop) {
						this.current_frame = 0;
					} else {
						this.animation = null;
					}
				}

				if (this.animation != null) {
					this.rect = this.animation.frames[this.current_frame];
				}
			}
		}
	}

	this.animate = function(animation) {
		this.animation = animation;
		this.current_frame = 0;
	}
}

function DecayTile() {
	this.go = new GameObject(sprites.rock);
	this.go.animate(animations.tile_decay);
	this.go.type = "fire";

	this.update = function() {
		this.go.update();

		if (this.go.animation == null) {
			map[this.go.x][this.go.y] = 0;
			remove_from_array(animated_tiles, this);
		}
	}
}

function Fire(px, py) {
	this.go = new GameObject(animations.fire.frames[0]);
	this.go.animate(animations.fire);

	this.go.x = px;
	this.go.y = py;

	this.timer = 0;
	this.spawned = false;

	this.update = function() {
		this.go.update();

		if (this.go.x == player.go.x && this.go.y == player.go.y) {
			food -= 10;
			if (player.face == "left") {
				player.go.animate(animations.player_hurt_left);
			} else {
				player.go.animate(animations.player_hurt_right);
			}
			remove_from_array(objs, this);
		}

		if (!this.spawned && this.timer > 3) {
			for (let x = this.go.x - 1; x < this.go.x + 2; x++) {
				for (let y = this.go.y - 1; y < this.go.y + 2; y++) {
					if (random_chance(40) && (x != this.go.x || y != this.go.y) && map[x][y] == 0 && obj_at(x, y) == null) {
						objs.push(new Fire(x, y));
						this.timer = 0;
						this.spawned = true;
					}
				}
			}

			this.timer = 0;
		} else if (this.spawned && this.timer > random_int(0, 4)) {
			remove_from_array(objs, this);
		}

		apply_gravity(this);
	}

	this.draw = function() {
		this.go.draw();
	}

	this.turn = function() {
		this.timer++;
	}
}

function Gem(x, y, sprite, is_food) {
	this.go = new GameObject(sprite);

	this.go.x = x;
	this.go.y = y;

	this.value = random_int(10, 25);

	this.update = function() {
		this.go.update();

		if (this.go.x == player.go.x && this.go.y == player.go.y) {
			if (!is_food) {
				score += this.value;
				collected++;
			} else {
				food += this.value;
			}

			remove_from_array(objs, this);
		}

		apply_gravity(this);
	}

	this.draw = function() {
		this.go.draw();
	}
}

function destroy_tile(x, y) {
	if (map[x][y] != 0) {
		map[x][y] = 200;

		let obj = new DecayTile();
		obj.go.x = x;
		obj.go.y = y;
		obj.go.animate(animations.tile_decay);

		animated_tiles[animated_tiles.length + 1] = obj;
	}
}

function Player() {
	this.go = new GameObject(sprites.player);

	this.go.x = 11;

	this.next_move_x = null;
	this.next_move_y = null;

	this.face = "right";

	this.draw = function() {
		this.go.draw();
	}

	this.update = function() {
		this.go.update();

		while (map[this.go.x][this.go.y + 1] == 0) {
			this.go.y += 1;

			if (this.go.y > 10) {
				camera_offset -= 1;
			}
		}

		if (this.go.animation == null) {
			if (this.next_move_x != null) {
				this.go.x += this.next_move_x;
				this.next_move_x = null;
			}

			if (this.next_move_y != null) {
				this.go.y += this.next_move_y;

				if (this.go.y > 10) {
					camera_offset -= 1;
				}
				this.next_move_y = null;
			}
		}

		if (food <= 0) {
			win = false;
		}

		if (collected == gem_count) {
			win = true;
		}

		if (this.go.y == map_height - 1) {
			win = true;
		}
	}

	this.update_movement = function(key) {
		if (this.go.animation == null) {
			if (key == 37) {
				this.next_move_x = -1;
				this.go.rect = animations.player_dig_left.frames[0];
				this.face = "left";

				let tile = map[this.go.x + this.next_move_x][this.go.y];

				if (tile == 1) {
					destroy_tile(this.go.x + this.next_move_x, this.go.y);
					this.go.animate(animations.player_dig_left);
					food -= hunger;
				} else if (tile == 2) {
					this.next_move_x = null;
				}

				turn();
			} else if (key == 39) {
				this.next_move_x = 1;
				this.go.rect = animations.player_dig_right.frames[0];
				this.face = "right";

				let tile = map[this.go.x + this.next_move_x][this.go.y];

				if (tile == 1) {
					destroy_tile(this.go.x + this.next_move_x, this.go.y);
					this.go.animate(animations.player_dig_right);
					food -= hunger;
				} else if (tile == 2) {
					this.next_move_x = null;
				}

				turn();
			} else if (key == 40) {
				if (this.face == "right") {
					this.go.rect = animations.player_dig_right.frames[0];
					this.next_move_x = 1;
				} else {
					this.go.rect = animations.player_dig_left.frames[0];
					this.next_move_x = -1;
				}

				this.next_move_y = 1;

				if (map[this.go.x + this.next_move_x][this.go.y + this.next_move_y] == 1 ||
					map[this.go.x + this.next_move_x][this.go.y] == 1) {
					if (this.face == "right") {
						this.go.animate(animations.player_dig_right);
						food -= hunger;
					} else {
						this.go.animate(animations.player_dig_left);
						food -= hunger;
					}

					if (map[this.go.x + this.next_move_x][this.go.y + this.next_move_y] == 2) {
						this.next_move_y = null;
					}

					destroy_tile(this.go.x + this.next_move_x, this.go.y);
					destroy_tile(this.go.x + this.next_move_x, this.go.y + this.next_move_y);
				} else {
					this.next_move_x = null;
					this.next_move_y = null;
				}

				turn();
			}
		}
	}
}

function draw_text(start_x, start_y, text) {
	let x = start_x;
	let y = start_y;

	for (let i = 0; i < text.length; i++) {
		let c = text.charAt(i);

		let rect = characters[c];

		if (rect) {
			ctx.drawImage(spritesheet, rect.x, rect.y, rect.w,
				rect.h, x, y,
				rect.w * sprite_scale, rect.h * sprite_scale);
		}
		
		x += 16 * sprite_scale;
	}
}

function on_init() {
	window.addEventListener("keydown", on_key_down)

	canvas = document.createElement("canvas");
	canvas.width = 800;
	canvas.height = 600;

	ctx = canvas.getContext("2d");
	ctx.imageSmoothingEnabled= false

	document.body.insertBefore(canvas, document.body.childNodes[0]);
	let interval = setInterval(on_update, 20);

	spritesheet = new Image();
	spritesheet.src = "res/sprites.png"

	now = performance.now();
	last = performance.now();

	let char_order = " !\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~";
	let cx = 0;
	let cy = 0;
	for (let i = 0; i < char_order.length; i++) {
		let c = char_order.charAt(i);

		characters[c] = { x: cx, y: cy + 48, w: 16, h: 16 };

		cx += 16;

		if (cx > 240) {
			cx = 0;
			cy += 16;
		}
	}

	init_game(true);
}

function init_game(restart) {
	if (restart) {
		score = -100;
		level = 0;
		food = 100;
	}

	score += 100;

	level++;

	win = null;

	collected = 0;

	map = null;
	next_level_timer = 0;

	animated_tiles.length = 0;
	objs.length = 0;

	camera_offset = 2;

	player = new Player();

	map_width  = Math.round((canvas.width / (sprites.rock.w * sprite_scale)));
	map_height = Math.round((canvas.height / (sprites.rock.h * sprite_scale))) * 2;

	map = new Array(map_width);
	for (let i = 0; i < map_width; i++) {
		map[i] = new Array(map_height);
	}

	for (let y = 0; y < map_height; y++) {
		for (let x = 0; x < map_width; x++) {
			if (random_chance(1)) {
				map[x][y] = 0;
			} else {
				map[x][y] = 1;
			}
		}
	}

	/* Spawn gems */
	gem_count = random_int(10, 20);
	for (let i = 0; i < gem_count; i++) {
		let x = random_int(1, map_width  - 1);
		let y = random_int(1, map_height - 1);

		map[x][y] = 0;

		objs.push(new Gem(x, y, sprites.diamond, false));
	}

	/* Spawn fire */
	let fire_count = random_int(5, 15);
	for (let i = 0; i < fire_count; i++) {
		let x = random_int(1, map_width  - 1);
		let y = random_int(1, map_height - 1);

		map[x][y] = 0;

		objs.push(new Fire(x, y));
	}

	/* Spawn food */
	let food_count = random_int(2, 10);
	for (let i = 0; i < food_count; i++) {
		let x = random_int(1, map_width  - 1);
		let y = random_int(1, map_height - 1);

		map[x][y] = 0;

		let obj = new Gem(x, y, sprites.food, true);
		obj.value = random_int(10, 15);
		objs.push(obj);
	}

	for (let y = 0; y < map_height; y++) {
		map[0][y] = 2;
	}

	for (let y = 0; y < map_height; y++) {
		map[map_width - 1][y] = 2;
	}

	for (let x = 0; x < map_width; x++) {
		for (let y = map_height; y < map_height + map_bottom_size; y++) {
			map[x][y] = 2;
		}
	}

	map[10][0] = 0;
	map[11][0] = 0;
	map[12][0] = 0;
	map[13][0] = 0;
}

function on_update() {
	if (state == "game") {
		if (win == null) {
			player.update();

			animated_tiles.forEach(function(value) {
				value.update();
			});

			objs.forEach(function(value) {
				value.update();
			});
		}

		ctx.clearRect(0, 0, canvas.width, canvas.height);

		/* Draw the sky */
		for (let y = 0; y < 2; y++) {
			for (let x = 0; x < map_width; x++) {
				let rect = sprites.sky;

				ctx.drawImage(spritesheet, rect.x, rect.y, rect.w, rect.h,
					x * map_grid_size * sprite_scale, (y + camera_offset - 2) * map_grid_size * sprite_scale, rect.w * sprite_scale, rect.h * sprite_scale);
			}
		}

		/* Draw the grass */
		for (let x = 0; x < map_width; x++) {
			let y = 1;
			let rect = sprites.grass;

			if (map[x][0] != 0) {
				ctx.drawImage(spritesheet, rect.x, rect.y, rect.w, rect.h,
					x * map_grid_size * sprite_scale, (y + camera_offset - 2) * map_grid_size * sprite_scale, rect.w * sprite_scale, rect.h * sprite_scale);
				}
		}

		/* Draw the background */
		for (let y = 2; y < map_height + 2; y++) {
			for (let x = 0; x < map_width; x++) {
				let rect = sprites.background;

				ctx.drawImage(spritesheet, rect.x, rect.y, rect.w, rect.h,
					x * map_grid_size * sprite_scale, (y + camera_offset - 2) * map_grid_size * sprite_scale, rect.w * sprite_scale, rect.h * sprite_scale);
			}
		}

		/* Draw the map */
		for (let y = 0; y < map_height + map_bottom_size; y++) {
			for (let x = 0; x < map_width; x++) {
				let rect = null;

				if (map[x][y] == 1) {
					rect = sprites.rock;
				} else if (map[x][y] == 2) {
					rect = sprites.hard_rock;
				}

				if (rect != null) {
					ctx.drawImage(spritesheet, rect.x, rect.y, rect.w, rect.h,
						x * map_grid_size * sprite_scale, (y + camera_offset) * map_grid_size * sprite_scale, rect.w * sprite_scale, rect.h * sprite_scale);
				}
			}
		}

		animated_tiles.forEach(function(value) {
			value.go.draw();
		});

		objs.forEach(function(value) {
			value.go.draw();
		});

		player.draw();

		let score_text = `Score: ${score}`;
		let level_text = `Level: ${level}`;
		draw_text(canvas.width - score_text.length * 16 * sprite_scale, 0, score_text);
		draw_text(canvas.width - level_text.length * 16 * sprite_scale, 16 * sprite_scale, level_text);

		let food_text = `${Math.round(food)}%`;
		let r = sprites.food_icon;
		ctx.drawImage(spritesheet, r.x, r.y, r.w, r.h,
			0, 0, r.w * sprite_scale, r.h * sprite_scale);
		draw_text(16 * sprite_scale, 0, food_text);

		if (win != null) {
			let win_text = "Game Over!";

			if (win) {
				win_text = "Level Up!";
			}

			draw_text((canvas.width / 2) - ((win_text.length * 16 * sprite_scale) / 2),
				(canvas.height / 2) - ((16 * sprite_scale) / 2), win_text);

			next_level_timer += ts;

			if (win && next_level_timer >= 3) {
				init_game(true);
			}
		}

		now = performance.now();
		ts = (now - last) / 1000;
		last = now;
	} else if (state == "menu") {
		ctx.clearRect(0, 0, canvas.width, canvas.height);

		let text = "[S]tart";
		draw_text((canvas.width / 2) - ((text.length * 16 * sprite_scale) / 2),
			((canvas.height / 2) - ((16 * sprite_scale) / 2)) - 16 * sprite_scale, text);
		text = "MINI MINER";
		draw_text((canvas.width / 2) - ((text.length * 16 * sprite_scale) / 2),
			(canvas.height / 2) - ((16 * sprite_scale) / 2) - 16 * 3 * sprite_scale, text);
	}
}

function on_key_down(e) {
	e.preventDefault();

	if (e.keyCode == 75) { /* K */
		food = 0;
	}

	if (e.keyCode == 80) { /* K */
		score += 10;
	}

	if (state == "menu") {
		if (e.keyCode == 83) { /* S */
			state = "game";
			init_game(true);
		}
	} else if (state == "game") {	
		if (win == null) {
			player.update_movement(e.keyCode);
		}
	}
}