// SquareShooter - an abstract Asteroids-like game in HTML5
// 2010-09-28 Felix Pleșoianu <felixp7@yahoo.com>
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

var SquareShooter = {
	Vector2D: function (x, y) {
		this.x = x;
		this.y = y;
		
		this.incr = function (vector) {
			this.x += vector.x;
			this.y += vector.y;
		}
		
		this.decr = function (vector) {
			this.x -= vector.x;
			this.y -= vector.y;
		}
		
		this.copy = function (vector) {
			this.x = vector.x;
			this.y = vector.y;
		}
	},

	Bubble2D: function (radius) {
		this.position = new SquareShooter.Vector2D(0, 0);
		this.radius = radius;
		this.speed = new SquareShooter.Vector2D(0, 0);
		
		this.update = function () {
			this.position.incr(this.speed);
		}
		
		this.wrap_around = function () {
			var pos = this.position;
			if (pos.x < 0) pos.x = 1;
			if (pos.y < 0) pos.y = 1;
			if (pos.x > 1) pos.x = 0;
			if (pos.y > 1) pos.y = 0;
		}

		this.is_out = function () {
			var pos = this.position;
			return pos.x < 0 || pos.y < 0 || pos.x > 1 || pos.y > 1;
		}
		
		this.collides_with = function (bubble) {
			var a = Math.abs(this.position.x - bubble.position.x);
			var b = Math.abs(this.position.y - bubble.position.y);
			var distance = Math.sqrt(a * a + b * b);
			return distance < (this.radius + bubble.radius);
		}
	},

	WorldModel: function () {
		this.tick = 0.1; // Assume 10 FPS by default.
		this.bubbles = [];
		this.explosions = [];
		this.powerups = [];
		this.bullet = null;
		this.ship = null;
		this.ax = this.ay = this.dvx = this.dvy = 0;
		this.move_timer = this.death_timer = this.finish_timer = 0;
		this.ship_shield_timer = this.bullet_shield_timer = 0;
		this.freeze_timer = 0;
		this.level = this.game_score = this.level_score = 0;
		this.high_score = this.max_level = 0;
		this.lives = 0;
		
		var powerup_types = ["shield", "bullet", "freeze"];
		
		this.init_level = function (level) {
			this.level = level;
			this.level_score = 0;
			if (level > this.max_level) this.max_level = level;
			if (this.ship == null)
				this.ship = new SquareShooter.Bubble2D(1 / 25);
			this.ship.position =
				new SquareShooter.Vector2D(0.5, 0.5);
			this.ship.speed =
				new SquareShooter.Vector2D(0, 0);
			this.bullet = null;
			this.ax = this.ay = this.dvx = this.dvy = 0;
			this.move_timer = this.death_timer = 0;
			this.finish_timer = 0;
			this.ship_shield_timer = 6;
			this.bullet_shield_timer = 0;
			this.freeze_timer = 0;
			
			this.bubbles.length = 0;
			this.explosions.length = 0;
			this.powerups.length = 0;
			for (var i = 0; i < level; i++) {
				this.bubbles[i] = this.make_bubble("big");
			}
		};
		
		this.make_bubble = function (type) {
			if (type == "big") {
				var size = 0.1;
				var speed = 1 * this.tick;
			} else if (type == "medium") {
				var size = 0.075;
				var speed = 2 * this.tick;
			} else if (type == "small") {
				var size = 0.05;
				var speed = 3 * this.tick;
			}
			
			var new_bubble =
				new SquareShooter.Bubble2D(size);
			new_bubble.position =
				new SquareShooter.Vector2D(
					this.random_position(),
					this.random_position());
			new_bubble.speed =
				new SquareShooter.Vector2D(
					this.random_speed(speed),
					this.random_speed(speed));
			new_bubble.type = type;
			return new_bubble;
		};

		this.random_position = function() {
			return (Math.random() - 0.5) * 3 + 0.5;
		};
		
		this.random_speed = function (magnitude) {
			return (Math.random() * magnitude * 2 - magnitude)
				* this.tick;
		};
		
		this.update = function () {
			this.handle_collisions();
			
			if (this.explosions.length > 0) {
				if (this.explosions[0].radius > 0.5)
					this.explosions.shift();
			}
			for (var i = 0; i < this.explosions.length; i++) {
				this.explosions[i].radius += this.tick;
			}
			
			if (this.powerups.length > 0) {
				if (this.powerups[0].age > 9)
					this.powerups.shift();
			}
			for (var i = 0; i < this.powerups.length; i++) {
				this.powerups[i].age += this.tick;
			}
			if (this.ship_shield_timer > 0)
				this.ship_shield_timer -= this.tick;
			if (this.bullet_shield_timer > 0)
				this.bullet_shield_timer -= this.tick;
			if (this.freeze_timer > 0)
				this.freeze_timer -= this.tick;
			
			if (this.bubbles.length == 0) {
				if (this.finish_timer > 0) {
					this.finish_timer -= this.tick;
				} else {
					this.game_score += this.level_score;
					this.level_score = 0;
					this.level++;
					this.lives++;
					this.init_level(this.level);
					return;
				}
			} else if (this.freeze_timer <= 0) {
				for (var i = 0; i < this.bubbles.length; i++) {
					var bubble = this.bubbles[i];
					bubble.update();
					bubble.wrap_around();
				}
			}

			if (this.bullet != null) {
				this.bullet.update();
				if (this.bullet.is_out()) {
					this.bullet = null;
				}
			}

			if (this.ship == null) {
				if (this.death_timer > 0) {
					this.death_timer -= this.tick;
				} else if (this.lives > 0) {
					this.init_level(this.level);
				} else {
					this.level = 0; // Game over
				}
				return;
			}
			
			this.handle_acceleration();
			
			this.ship.speed.x *= 0.99;
			this.ship.speed.y *= 0.99;
			this.ship.update();
			this.ship.wrap_around();
			
			this.shoot();
		};
		
		this.handle_collisions = function () {
			for (var i = 0; i < this.bubbles.length; i++) {
				var b = this.bubbles[i];
				if (this.bullet != null
					&& b.collides_with(this.bullet)) {

					this.bubbles.splice(i, 1);
					if (this.bullet_shield_timer <= 0)
						this.bullet = null;
					this.spawn_bubbles(b);
					this.spawn_explosion(b);
					this.mark_score(b);
					if (this.bubbles.length == 0) {
						this.finish_timer = 3;
					}
					break;
				} else if (this.ship != null
					&& b.collides_with(this.ship)
					&& this.ship_shield_timer <= 0) {

					this.spawn_explosion(this.ship);
					this.ship = null;
					this.lives--;
					this.death_timer = 3;
					break;
				}
			}

			if (this.ship == null) return;
			for (var i = 0; i < this.powerups.length; ) {
				var p = this.powerups[i];
				if (p.collides_with(this.ship)) {
					this.apply_powerup(p);
					this.powerups.splice(i, 1);
				} else {
					i++;
				}
			}
		};
		
		this.handle_acceleration = function () {
			if (this.ax != 0 || this.ay != 0) {
				this.move_timer += this.tick;
				var t = this.move_timer;
				var dvx = this.ax * t * t / 2;
				var dvy = this.ay * t * t / 2;
				this.ship.speed.x += (dvx - this.dvx);
				this.ship.speed.y += (dvy - this.dvy);
				this.dvx = dvx;
				this.dvy = dvy;
			} else {
				this.move_timer = this.dvx = this.dvy = 0;
			}
		};
		
		this.spawn_bubbles = function (parent) {
			if (parent.type == "small") {
				if (Math.random() < 0.25)
					this.spawn_powerup(parent);
			} else {
				if (parent.type == "big") {
					var new_type = "medium";
				} else if (parent.type == "medium") {
					var new_type = "small";
				}
				var b = this.make_bubble(new_type);
				b.position.copy(parent.position);
				this.bubbles.push(b);
				b = this.make_bubble(new_type);
				b.position.copy(parent.position);
				this.bubbles.push(b);
			}
		};
		
		this.spawn_explosion = function (bubble) {
			var explosion = new SquareShooter.Bubble2D(0);
			explosion.position.copy(bubble.position);
			this.explosions.push(explosion);
		};
		
		this.spawn_powerup = function (bubble) {
			var powerup = new SquareShooter.Bubble2D(0.03);
			powerup.position.copy(bubble.position);
			powerup.type = powerup_types[
				Math.floor(Math.random() * 3)];
			powerup.age = 0;
			this.powerups.push(powerup);
		};
		
		this.shoot = function () {
			if (this.bullet != null || this.ship == null)
				return;
			if (this.ax != 0 && this.ax != 0) {
				var b = new SquareShooter.Bubble2D(0.01);
				b.position.copy(this.ship.position);
				b.speed.x = this.ax * this.tick * 1.5;
				b.speed.y = this.ay * this.tick * 1.5;
				// Help out the poor sods who click on their
				// own ship and get stuck with a non-moving
				// bullet. (2009-11-14)
				var aax = Math.abs(this.ax);
				var aay = Math.abs(this.ay);
				if (aax < 0.08 && aay < 0.08) {
					b.speed.x *= (0.08 - aax) * 1000;
					b.speed.y *= (0.08 - aay) * 1000;
				}
				this.bullet = b;
			}
		};
		
		this.mark_score = function(bubble) {
			if (bubble.type == "small") {
				this.level_score += 5;
			} else if (bubble.type == "medium") {
				this.level_score += 2;
			} else if (bubble.type == "big") {
				this.level_score += 1;
			}
			if (this.game_score+this.level_score > this.high_score)
				this.high_score =
					this.game_score + this.level_score;
		};
		
		this.apply_powerup = function (powerup) {
			switch (powerup.type) {
				case "shield":
					this.ship_shield_timer += 6;
					break;
				case "bullet":
					this.bullet_shield_timer += 6;
					break;
				case "freeze":
					this.freeze_timer += 6;
					break;
				default:
					throw "Bad powerup type";
			}
			this.game_score += this.level * 10;
			if (this.game_score+this.level_score > this.high_score)
				this.high_score =
					this.game_score + this.level_score;
		};
	},
	
	Renderer: function (model, canvas, width, height) {
		this.model = model;

		this.canvas = canvas;
		this.context = canvas.getContext("2d");
		this.width = width || canvas.width;
		this.height = height || canvas.height;
		this.zoom = Math.min(this.width, this.height);
		
		this.title_size = this.height * 0.1;
		this.text_size = this.height * 0.05;
		this.game_paused = false;
		
		var bubble_colors = ["#ffffcc", "#ffccff", "#ccffff",
			"#ffdddd", "#ddffdd", "#ddddff"];
		
		this.render = function () {
			var ctx = this.context;
			var m = this.model;
			
			ctx.fillStyle = "black";
			ctx.fillRect(0, 0, this.width, this.height);

			if (m.ship != null) this.render_ship();
			if (m.bullet != null) this.render_bullet();
			
			for (var i = 0; i < m.bubbles.length; i++) {
				var bubble = m.bubbles[i];
				if (!bubble.color) {
					bubble.color = bubble_colors[
						Math.floor(Math.random() * 6)];
				}
				this.circle(
					bubble.position.x,
					bubble.position.y,
					bubble.radius,
					bubble.color);
			}
			
			for (var i = 0; i < m.explosions.length; i++) {
				var explosion = m.explosions[i];
				this.circle(
					explosion.position.x,
					explosion.position.y,
					explosion.radius,
					"#ff0000");
			}
			
			for (var i = 0; i < m.powerups.length; i++) {
				this.render_powerup(m.powerups[i]);
			}
			
			if (ctx.fillText) this.render_hud();
		};
		
		this.render_ship = function () {
			var ship = this.model.ship;
			var pos = ship.position;
			this.disc(
				pos.x, pos.y, ship.radius, "#cccccc");
			this.circle(
				pos.x, pos.y, ship.radius * 0.5, "#000000");
			if (this.model.ship_shield_timer > 0) {
				this.square(
					pos.x, pos.y, ship.radius, "#cccccc");
			}
		};
		
		this.render_bullet = function () {
			var bullet = this.model.bullet;
			this.disc(
				bullet.position.x,
				bullet.position.y,
				bullet.radius,
				"#ff0000");
			if (this.model.bullet_shield_timer > 0) {
				this.square(
					bullet.position.x,
					bullet.position.y,
					bullet.radius,
					"#ff0000");
			}
		};
		
		this.render_powerup = function (powerup) {
			var pos = powerup.position;
			this.square(pos.x, pos.y, powerup.radius, "#ffffff");
			switch (powerup.type) {
				case "shield":
					this.circle(
						pos.x,
						pos.y,
						powerup.radius,
						"#ffffff");
					break;
				case "bullet":
					this.circle(
						pos.x,
						pos.y,
						powerup.radius * 0.3,
						"#ffffff");
					break;
				case "freeze":
					this.square(
						pos.x,
						pos.y,
						powerup.radius * 0.5,
						"#ffffff");
					this.square(
						pos.x,
						pos.y,
						powerup.radius * 0.25,
						"#ffffff");
					break;
				default:
					throw "Bad power-up type: "
						+ powerup.type;
			}
		};
		
		this.circle = function (x, y, radius, color) {
			var ctx = this.context;
			var z = this.zoom;

			ctx.strokeStyle = color;
			ctx.beginPath();
			ctx.arc(x * z, y * z, radius * z, 0, Math.PI*2, true);
			ctx.stroke();
		};
		
		this.disc = function (x, y, radius, color) {
			var ctx = this.context;
			var z = this.zoom;

			ctx.fillStyle = color;
			ctx.beginPath();
			ctx.arc(x * z, y * z, radius * z, 0, Math.PI*2, true);
			ctx.fill();
		};
		
		this.square = function (x, y, radius, color) {
			var ctx = this.context;
			var z = this.zoom;

			ctx.strokeStyle = color;
			var diameter = radius * 2 * z;
			ctx.strokeRect(
				(x - radius) * z, (y - radius) * z,
				diameter, diameter);
		}
		
		this.render_hud = function () {
			var ctx = this.context;
			var w = this.width;
			var h = this.height;
			var m = this.model;

			ctx.fillStyle = "#00ff00";
			if (m.level > 0) {
				ctx.font = this.text_size
					+ "px monospace bold";

				ctx.textAlign = "left";
				ctx.textBaseline = "top";
				ctx.fillText("(P)ause", 0, 0);
				ctx.textAlign = "right";
				ctx.fillText("Score: "
					+ (m.game_score	+ m.level_score),
					w, 0);
				ctx.textBaseline = "bottom";
				ctx.textAlign = "left";
				ctx.fillText(
					"Level " + m.level, 0, h);
				ctx.fillText(
					"Lives: " + m.lives,
					0, h - this.text_size);
					
				if (m.death_timer > 0 && m.lives == 0) {
					ctx.textAlign = "center";		
					ctx.font = this.title_size
						+ "px monospace bold";
					ctx.textBaseline = "bottom";
					ctx.fillText("GAME", w * 0.5, h * 0.5);
					ctx.textBaseline = "top";
					ctx.fillText("OVER", w * 0.5, h * 0.5);
				}

				if (!this.game_paused)
					ctx.fillStyle = "#009900";
				ctx.textAlign = "right";
				ctx.fillText("(Q)uit", w, h);
			} else {
				ctx.textAlign = "center";
					
				ctx.font = this.title_size
					+ "px monospace bold";
				ctx.textBaseline = "bottom";
				ctx.fillText("SQUARE", w * 0.5, h * 0.5);
				ctx.textBaseline = "top";
				ctx.fillText("SHOOTER", w * 0.5, h * 0.5);

				ctx.textBaseline = "middle";
				ctx.font = this.text_size
					+ "px monospace bold";
				ctx.fillText("Click to (p)lay",
					w * 0.5, h * 0.25);
				ctx.textBaseline = "bottom";
				ctx.fillText("High score: " + m.high_score,
					w * 0.5, h * 0.75);
				ctx.textBaseline = "top";
				ctx.fillText("Max level: " + m.max_level,
					w * 0.5, h * 0.75);
			}
		}
	},
	
	Game: function (canvas, width, height) {
		if (canvas.style.position != "absolute")
			canvas.style.position = "relative";
		this.model = new SquareShooter.WorldModel();
		this.renderer = new SquareShooter.Renderer(
			this.model, canvas, width, height);

		this.renderer.render();
		this.fps = 20;
		this.model.tick = 1 / 20;

		var r = this.renderer;
		var m = this.model;
		var g = this;
		var loop = null;

		this.clickPause = function (x, y) {
			if (x < r.width * 0.15 && y < r.height * 0.05) {
				this.togglePause();
				return true;
			} else {
				return false;
			}
		};

		this.clickQuit = function (x, y) {
			if (x > r.width * 0.9 && y > r.height * 0.95) {
				if (loop != null) {
					return;
				}
				this.model.level = 0;
				this.renderer.render_hud();
				return true;
			} else {
				return false;
			}
		};
		
		canvas.onclick = function (event) {
			if (m.level > 0) {
				var x = event.layerX || event.offsetX;
				var y = event.layerY || event.offsetY;
				if (g.clickPause(x, y)) return;
				if (g.clickQuit(x, y)) return;
			} else {
				g.start();
			}
		};

		canvas.onmousedown = function (event) {
			if (m.ship == null) return;
			var x = event.layerX || event.offsetX;
			var y = event.layerY || event.offsetY;
			m.ax = x / r.width - m.ship.position.x;
			m.ay = y / r.height - m.ship.position.y;
			m.ax *= 2;
			m.ay *= 2;
		};
		canvas.onmouseup = function (event) {
			m.ax = m.ay = 0;
		};
		
		document.addEventListener("keypress", function (event) {
			var key = String.fromCharCode(
				event.charCode || event.keyCode);
			switch (key) {
				case "q":
				case "Q":
					m.level = 0; break;
				case "p":
				case "P":
					if (m.level > 0)
						g.togglePause();
					else
						g.start();
			}
		}, false);
		
		this.loop = function () {
			this.model.update();
			this.renderer.render();
			if (this.model.level == 0) {
				clearInterval(loop);
				loop = null;
			}
		};
		
		this.start = function () {
			this.model.game_score = 0;
			this.model.lives = 1;
			this.model.init_level(1);
			loop = setInterval(
				function () { g.loop(); }, 1000/this.fps);
		};
		
		this.togglePause = function () {
			if (loop != null) {
				clearInterval(loop);
				loop = null;
			} else {
				loop = setInterval(
					function () {g.loop();},
					1000/this.fps);
			}
			r.game_paused = (loop == null);
			if (r.game_paused) r.render();
		};
	}
}