module.exports = {
    isValidChannelName: function (name) {
        return name.match(/^[\w-_]{1,30}$/);
    },

    isValidUserName: function (name) {
        return name.match(/^[\w-_]{1,20}$/);
    },

    randomSalt: function (length) {
        var chars = "abcdefgihjklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
                  + "0123456789!@#$%^&*_+=~";
        var salt = [];
        for(var i = 0; i < length; i++) {
            salt.push(chars[parseInt(Math.random()*chars.length)]);
        }
        return salt.join('');
    },

    maskIP: function (ip) {
        if(ip.match(/^\d+\.\d+\.\d+\.\d+$/)) {
            // standard 32 bit IP
            return ip.replace(/\d+\.\d+\.(\d+\.\d+)/, "x.x.$1");
        } else if(ip.match(/^\d+\.\d+\.\d+/)) {
            // /24 range
            return ip.replace(/\d+\.\d+\.(\d+)/, "x.x.$1.*");
        }
    },

    formatTime: function (sec) {
        if(sec === "--:--")
            return sec;

        sec = Math.floor(+sec);
        var h = "", m = "", s = "";

        if(sec >= 3600) {
            h = "" + Math.floor(sec / 3600);
            if(h.length < 2)
                h = "0" + h;
            sec %= 3600;
        }

        m = "" + Math.floor(sec / 60);
        if(m.length < 2)
            m = "0" + m;

        s = "" + (sec % 60);
        if(s.length < 2)
            s = "0" + s;

        if(h === "")
            return [m, s].join(":");

        return [h, m, s].join(":");
    },

    newRateLimiter: function () {
        return {
            count: 0,
            lastTime: 0,
            throttle: function (opts) {
                if (typeof opts === "undefined")
                    opts = {};

                var burst = +opts.burst,
                    sustained = +opts.sustained,
                    cooldown = +opts.cooldown;

                if (isNaN(burst))
                    burst = 10;

                if (isNaN(sustained))
                    sustained = 2;

                if (isNaN(cooldown))
                    cooldown = burst / sustained;

                // Cooled down, allow and clear buffer
                if (this.lastTime < Date.now() - cooldown*1000) {
                    this.count = 1;
                    this.lastTime = Date.now();
                    return false;
                }

                // Haven't reached burst cap yet, allow
                if (this.count < burst) {
                    this.count++;
                    this.lastTime = Date.now();
                    return false;
                }

                var diff = Date.now() - this.lastTime;
                if (diff < 1000/sustained)
                    return true;

                this.lastTime = Date.now();
                return false;
            }
        };
    },

    formatLink: function (id, type) {
        switch (type) {
            case "yt":
                return "http://youtu.be/" + id;
            case "vi":
                return "http://vimeo.com/" + id;
            case "dm":
                return "http://dailymotion.com/video/" + id;
            case "sc":
                return id;
            case "li":
                return "http://livestream.com/" + id;
            case "tw":
                return "http://twitch.tv/" + id;
            case "jt":
                return "http://justin.tv/" + id;
            case "rt":
                return id;
            case "jw":
                return id;
            case "im":
                return "http://imgur.com/a/" + id;
            case "us":
                return "http://ustream.tv/" + id;
            default:
                return "";
        }
    }
};