module.exports = { 
    encode: function (text){

                    if (/([^\u0000-\u00ff])/.test(text)){
                        throw new Error("Can't base64 encode non-ASCII characters.");
                    } 

                    var digits = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_",
                        i = 0,
                        cur, prev, byteNum,
                        result=[];      

                    while(i < text.length){

                        cur = text.charCodeAt(i);
                        byteNum = i % 3;

                        switch(byteNum){
                            case 0: //first byte
                                result.push(digits.charAt(cur >> 2));
                                break;

                            case 1: //second byte
                                result.push(digits.charAt((prev & 3) << 4 | (cur >> 4)));
                                break;

                            case 2: //third byte
                                result.push(digits.charAt((prev & 0x0f) << 2 | (cur >> 6)));
                                result.push(digits.charAt(cur & 0x3f));
                                break;
                        }

                        prev = cur;
                        i++;
                    }

                    if (byteNum == 0){
                        result.push(digits.charAt((prev & 3) << 4));
                        result.push("==");
                    } else if (byteNum == 1){
                        result.push(digits.charAt((prev & 0x0f) << 2));
                        result.push("=");
                    }

                    return result.join("");
            },
    decode: function (text){

            text = text.replace(/\s/g,"");

            if(!(/^[a-z0-9\-_\s]+\={0,2}$/i.test(text)) || text.length % 4 > 0){
                throw new Error("Not a base64-encoded string.");
            }   

            //local variables
            var digits = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/",
                cur, prev, digitNum,
                i=0,
                result = [];

            text = text.replace(/=/g, "");

            while(i < text.length){

                cur = digits.indexOf(text.charAt(i));
                digitNum = i % 4;

                switch(digitNum){

                    //case 0: first digit - do nothing, not enough info to work with

                    case 1: //second digit
                        result.push(String.fromCharCode(prev << 2 | cur >> 4));
                        break;

                    case 2: //third digit
                        result.push(String.fromCharCode((prev & 0x0f) << 4 | cur >> 2));
                        break;

                    case 3: //fourth digit
                        result.push(String.fromCharCode((prev & 3) << 6 | cur));
                        break;
                }

                prev = cur;
                i++;
            }

            return result.join("");
        }
};