const BIASES = {
	0xc8ff50: 1,
	0x46aafa: 0.5,
	0xff0000: 0.75,
	0x0000ff: 0.4,
};

function validXY(x, y) {
	if (x < 0 || x >= 3200) return false;
	if (y < 0 || y >= 1600) return false;
	return true;
}

function getRGBA(data, i, out) {
	for (let j = i * 4; j < i * 4 + 4; j++) {
		out[j - i*4] = data[j];
	}
	return out;
}

function setRGBA(data, i, input) {
	for (let j = i * 4; j < i * 4 + 4; j++) {
		data[j] = input[j - i * 4];
	}
}

function isLand(data) {
	if (data[0] == 255 && data[1] == 255 && data[2] == 255 && data[3] == 255) return false;
	return true;
}

function Game(baseMap) {
	this.img = new Image();
	this.baseMap = baseMap;
}

Game.prototype.main = function() {	
	var {biomes, ctx, colonized} = this;
	var dat = ctx.getImageData(0,0,3200,1600);
	var data = dat.data;
	var out = new Uint8Array(4);

	for (let k = 0; k < 3200*1600/10; k++) {
		let i = Math.floor(Math.random() * biomes.data.length / 4);
		if (!colonized[i]) continue;	

		var x = i % 3200;
		var y = Math.floor(i / 3200);

		let rgba = getRGBA(biomes.data,i,out);
				
		if (isLand(rgba))
			setRGBA(data,i,[255,128,128,255]);

		let weight = 10;

		let broken = false;

		for (let dx = -1; dx <= 1; dx++) {
			for (let dy = -1; dy <= 1; dy++ ) {
				weight--;
				let x2 = x + dx;
				let y2 = y + dy;

				let i = x2 + y2 * 3200;

				if (!validXY(x2,y2)) continue;	
				let rgba = getRGBA(biomes.data,i,out);
				let rgbaH = rgba[0] * 0x10000 + rgba[1] * 0x100 + rgba[2];

				if (Math.random() > ((rgbaH in BIASES) ? BIASES[rgbaH] : 0.2) / weight) {
					continue;
				}
				if (colonized[y2 * 3200 + x2] == 1) {
					continue;
				}

				colonized[y2 * 3200 + x2] = 1;
				broken = true;
				break;
			}
			if (broken) break;
		}
	}

	ctx.putImageData(dat,0,0,0,0,3200,1600);
}

Game.prototype.map = function() {
	var {biomes, ctx} = this;	
	var dat = ctx.getImageData(0,0,3200,1600);
	var data = dat.data;

	var out = new Uint8Array(4);
	for (let i = 0; i < biomes.data.length; i++) {
		let rgba = getRGBA(biomes.data,i, out);

		if (!isLand(rgba,i)) {
			setRGBA(data,i,[255,255,255,255])
		} else {	
			setRGBA(data,i,[0,0,0,255]);
		}
	}
	
	ctx.putImageData(dat,0,0,0,0,3200,1600);
}

Game.prototype.place = function() {
	var {biomes,ctx,colonized} = this;
	var out = new Uint8Array(4);

	let i = 0;

	while (true) {
		i = Math.floor(Math.random() * biomes.data.length / 4);

		let rgba = getRGBA(biomes.data,i,out);

		if (isLand(rgba)) break;
	}
	colonized[i] = 1;
}

Game.prototype.loop = function() {
	let that = this;
	setInterval(function() { that.main() } ,1000 / 60);
}

Game.prototype.startGame = function() {
	var canvas = document.querySelector("#canvas");
	var ctx = canvas.getContext("2d",{ willReadFrequently: true });

	this.ctx = ctx;

	ctx.drawImage(this.img,0, 0,3200,1600);

	var dat = ctx.getImageData(0,0,3200,1600);
	this.biomes = dat;

	this.colonized = new Uint8Array(3200*1600);

	this.map();
	this.place();
	this.loop();
}

Game.prototype.init = function() { 	
	let that = this;
	this.img.src = this.baseMap;
	this.img.onload = function() { that.startGame() };
}

new Game("base.png").init();