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

function lineReader(stream, cb) {
	stream.on("data", function ondata(d) {
		d.toString().split("\n").forEach(str => {
			str = str.trim();
			if (str === "") return;

			cb(str);
		});
	});
}

module.exports =  class CPrime {
	constructor(maxnum) {
		this.maxqueue = 30;

		this.maxnum = maxnum;
		this.queue = [];
		this.child = spawn("./cprime", [ maxnum ]);
		this.ready = false;

		lineReader(this.child.stderr, str => {
			console.log("stderr: "+str);
			if (str === "done" && !this.ready) {
				this.ready = true;
			}
		});

		lineReader(this.child.stdout, str => {
			if (this.queue.length === 0)
				return;

			var cb = this.queue.shift();
			cb(str);
		});
	}

	factor(num, cb) {
		num = num.replace(/\n/g, "");
		if (num.length > 1000)
			return cb("Invalid input.");

		if (!this.ready)
			return cb("Not ready.");

		if (this.queue.length >= this.maxqueue) {
			console.log("Warning: over "+this.maxqueue+" concurrent requests");
			return cb("Overloaded.");
		}

		this.queue.push(cb);
		this.child.stdin.write(num+"\n");
	}
}