var spawn = require("child_process").spawn;

function hps(n) {
	var suffix = "Hash/s";
	if (n > 1000000) {
		n = n / 1000000;
		suffix ="M"+suffix;
	} else if (n > 1000) {
		n = n / 1000;
		suffix = "k"+suffix;
	}

	return (n.toFixed(2))+" "+suffix;
}

function mineProc(cb1, cb2, merk, dif, en1, en2, cnt) {
	var obj = {
		coinb1: cb1, coinb2: cb2, merkleBranch: merk,
		difficulty: dif, exnounce1: en1, exnounce2: en2, iters: cnt
	};

	var child = spawn(
		"node", [ __dirname+"/mining-process.js", JSON.stringify(obj) ]);

	child.output = "";
	child.hps = 0;

	child.stderr.on("data", d => process.stderr.write(d));
	child.stdout.on("data", d => {
		var s = d.toString();
		if (s[0] === "o")
			child.output = s.substr(1);
		else if (s[0] === "h")
			child.hps = parseInt(s.substr(1));
		else
			console.error("Warning: Unexpected child output,", s);
	});

	return child;
}

function mine(
		coinb1, coinb2, merkleBranch,
		difficulty, exnounce1, exnounce2_len) {

	var cores = 4;

	var max = Math.pow(2, exnounce2_len * 8) - 2;
	var parts = Math.ceil(max / cores);


	return new Promise((resolve, reject) => {
		var childs = [];
		var childsLeft = cores;
		var inter = null;

		function rej(hash) {
			clearInterval(inter);
			resolve(hash);
		}

		for (var i = 0; i < cores; ++i) {
			var num = parts * i;
			if (num + parts > max)
				max - parts;
			var buf = Buffer.alloc(exnounce2_len, '\0');
			buf.writeUInt32BE(num);
			var exnounce2 = buf.toString("hex");

			var child = mineProc(
				coinb1, coinb2, merkleBranch,
				difficulty, exnounce1, exnounce2, parts);

			var obj = {
				coinb1, coinb2, merkleBranch,
				difficulty, exnounce1, exnounce2_len
			};

			childs[i] = child;
		}

		childs.forEach(child => {
			child.on("exit", code => {
				console.error("Child exited with code", code);
				if (code === 0) {
					childsLeft -= 1;
					childs.forEach(x => x !== child && x.kill());
					rej(child.output.trim());
				} else {
					childsLeft -= 1;
					if (childsLeft <= 0)
						rej(false);
				}
			});
		});

		inter = setInterval(() => {
			var sum = 0;
			childs.forEach(c => sum += c.hps);
			console.log(hps(sum));
		}, 2000);
	});
}

class CPUMiner {
	constructor() {
		this.work = null;
		this.difficulty = 1;
		this.exnounce1 = null;
		this.exnounce2_len = null;
	}

	async startWork(work) {
		console.log("Starting work", work.id);
		if (this.exnounce1 == null) {
			console.log("Ignoring work because extranounce is null.");
			return false;
		}

		this.work = work;
		return await mine(
			this.work.coinb1,
			this.work.coinb2,
			this.work.berkleBranch,
			this.difficulty,
			this.exnounce1,
			this.exnounce2_len);
	}

	setDifficulty(difficulty) {
		this.difficulty = difficulty;
	}

	setNounce(en1, en2_len) {
		this.exnounce1 = en1;
		this.exnounce2_len = en2_len;
	}

	async wait() {
	}
}

module.exports = CPUMiner;