"use strict";

var fs   = require("fs");
var util = require("util");

function _clear(done) {
	if(this.timer) {
		clearTimeout(this.timer);
		this.timer = null;
	}
}

function __interval(now) {
	    now   = new Date(now);
	var year  = now.getFullYear();
	var month = now.getMonth();
	var day   = now.getDate();
	var hours = now.getHours();
	var num   = this.options.interval.num;
	var unit  = this.options.interval.unit;

	if(unit === "d")
		hours = 0;
	else
		hours = parseInt(hours / num, 10) * num;

	this.prev = new Date(year, month, day, hours, 0, 0, 0).getTime();

	if(unit === "d")
		this.next = new Date(year, month, day + num, hours, 0, 0, 0).getTime();
	else
		this.next = new Date(year, month, day, hours + num, 0, 0, 0).getTime();
}

function _interval(now) {
	var unit = this.options.interval.unit;

	if(unit === "d" || unit === "h")
		this.__interval(now);
	else {
		var period = 1000 * this.options.interval.num;

		if(unit === "m")
			period *= 60;

		this.prev = parseInt(now / period, 10) * period;
		this.next = this.prev + period;
	}

	return new Date(this.prev);
}

function interval() {
	if(! this.options.interval)
		return;

	var now  = this.now();

	this._interval(now);
	this.timer = setTimeout(this.rotate.bind(this), this.next - now);
	this.timer.unref();
}

function historyWrite(self, res) {
	var files = [];

	for(var i in res)
		files.push(res[i].name);

	fs.writeFile(self.options.history, files.join("\n"), "utf8", function(err) {
		if(err)
			self.emit("warning", err);

		self.emit("history");
	});
}

function historyRemove(self, res, step, number) {
	var file = res.shift();

	fs.unlink(file.name, function(err) {
		if(err)
			self.emit("warning", err);
		else
			self.emit("removed", file.name, number);

		step(self, res);
	});
}

function historyCheckSize(self, res) {
	if(! self.options.maxSize)
		return historyWrite(self, res);

	var size = 0;

	for(var i in res)
		size += res[i].size;

	if(size <= self.options.maxSize)
		return historyWrite(self, res);

	historyRemove(self, res, historyCheckSize, false);
}

function historyCheckFiles(self, res) {
	res.sort(function(a, b) { return a.time - b.time; });

	if(! self.options.maxFiles || res.length <= self.options.maxFiles)
		return historyCheckSize(self, res);

	historyRemove(self, res, historyCheckFiles, true);
}

function historyGather(self, files, idx, res) {
	if(idx === files.length)
		return historyCheckFiles(self, res);

	fs.stat(files[idx], function(err, stats) {
		if(err) {
			if(err.code !== "ENOENT")
				return self.emit("warning", err);
		}
		else if(stats.isFile()) {
			res.push({
				name: files[idx],
				size: stats.size,
				time: stats.ctime.getTime()
			});
		}
		else
			self.emit("warning", "File '" + files[idx] + "' contained in history is not a regular file");

		historyGather(self, files, idx + 1, res);
	});
}

function history(lastfile) {
	var filename = this.options.history;
	var self     = this;

	if(! filename)
		this.options.history = filename = this.generator(null) + ".txt";

	fs.readFile(filename, "utf8", function(err, data) {
		if(err) {
			if(err.code !== "ENOENT")
				return self.emit("warning", err);

			return historyGather(self, [lastfile], 0, []);
		}

		var files = data.split("\n");

		files.push(lastfile);
		historyGather(self, files, 0, []);
	});
}

module.exports = {
	__interval: __interval,
	_clear:     _clear,
	_interval:  _interval,
	history:    history,
	interval:   interval,
};