var codeHandler = (function () {
    var base64Chars = [
            'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
            'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
            'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
            'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
            'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
            'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
            'w', 'x', 'y', 'z', '0', '1', '2', '3',
            '4', '5', '6', '7', '8', '9', '+', '/'
        ],
        encode = {
            'base64': codeBase64
        },
        decode = {
            'base64': decodeBase64
        }
    handleFormat = {
        'utf-8': toUTF8Binary
    };
    function stringToBinary(str, size, encodeType) {
        //  str-字符串 , size - 转换后的二进制位数 ,encodeType - 采用什么格式去保存二进制编码
        var i,
            len,
            binary = '';
        for (i = 0 , len = str.length; i < len; i++) {
            binary = binary + handleFormat[encodeType.toLowerCase()](str.charCodeAt(i));
        }
        //console.log(binary);
        return binary;
    }

    // 转换为以UTF-8格式的二进制数据
    function toUTF8Binary(unicode) {
        var len,
            binary = '',
            star = 0,
            bitStream = unicode.toString(2), // 转换为二进制比特流
            bitLen = bitStream.length,
            i;
        if (unicode >= 0x000000 && unicode <= 0x00007F) {
            binary = bitStream;
            for (i = 0 , len = 8; i < len - bitLen; i++) {
                binary = 0 + binary; // 不足8位补0
            }
        } else if (unicode >= 0x000080 && unicode <= 0x0007FF) {
            binary = bitStream;
            for (i = 0 , len = 11; i < len - bitLen; i++) {
                binary = 0 + binary; // 不足11位补0
            }
            binary = '110' + binary.substr(0, 5) + '10' + binary.substr(5, 6);
        }
        else if (unicode >= 0x000800 && unicode <= 0x00FFFF) {
            binary = bitStream;
            for (i = 0 , len = 16; i < len - bitLen; i++) {
                binary = 0 + binary; // 不足16位补0
            }
            ;
            binary = '1110' +
                binary.substr(0, 4) +
                '10' +
                binary.substr(4, 6) +
                '10' +
                binary.substr(10, 6);
        }
        else if (unicode >= 0x010000 && unicode <= 0x10FFFF) {
            binary = bitStream;
            for (i = 0 , len = 21; i < len - bitLen; i++) {
                binary = 0 + binary; // 不足21位补0
            }
            binary = '11110' +
                binary.substr(0, 3) +
                '10' +
                binary.substr(3, 6) +
                '10' +
                binary.substr(9, 6) +
                '10' +
                binary.substr(15, 6);
        }
        return binary;
    }

    // 编码成base64格式
    function base64Parse(binary24, flag) {
        var i,
            len,
            result = '',
            decode;
        if (flag == 1) {
            for (i = 0; i < 4; i++) {
                decode = parseInt(binary24.substr(i * 6, 6), 2);
                result = result + base64Chars[decode];
            }
        }
        else {
            for (i = 0 , len = Math.floor(flag / 6); i < len + 1; i++) {
                decode = parseInt(binary24.substr(i * 6, 6), 2);
                result = result + base64Chars[decode];
            }
            for (i = 0; i < 3 - len; i++) {
                result = result + '=';
            }
        }
        return result;
    }

    // 解析为base64格式的二进制数据
    function codeBase64(str) {
        var i,
            len,
            rem,
            mer,
            result = '',
            strBinaryAry = [],
            binary = stringToBinary(str, 8, 'utf-8'); // base64是基于utf-8格式保存的二进制数据转换的
        len = binary.length;
        mer = Math.floor(len / 24);
        rem = len % 24;
        for (i = 0; i < mer; i++) {
            result = result + base64Parse(binary.substr(i * 24, 24), 1);
        }
        remCode = binary.substr(len - rem, rem);
        if (rem > 0) {
            for (i = 0; i < 24 - rem; i++) {
                remCode = remCode + 0;
            }
            result = result + base64Parse(remCode, rem)
        }
        return result;

    }

    // 解码base64格式的数据
    function decodeBase64(str) {
        var i,
            j,
            k,
            len,
            t = 0,
            curbinary,
            start = 0,
            flag = [
                {
                    str: '0',
                    len: 8
                },
                {
                    str: '110',
                    len: 11
                },
                {
                    str: '1110',
                    len: 16
                },
                {
                    str: '11110',
                    len: 21
                }],
            binary = '',
            newStr = '';
        for (i = 0 , len = str.length; i < len; i++) {
            var curbinary = base64Chars.indexOf(str.charAt(i)).toString(2);
            if (curbinary != '-1') {

                for (j = 0; curbinary.length < 6; j++) {
                    curbinary = 0 + curbinary;
                }
                binary = binary + curbinary;
            }
            if (i >= len - 2 && str.charAt(i) == '=') {
                ++t;
            }
        }
        if (t == 0) {
            len = binary.length;
        }
        else {
            len = binary.length - (6 - 2 * t)
        }

        for (; start < len;) {
            for (j = 0; j < 4; j++) {

                if (binary.indexOf(flag[j].str, start) == start) {
                    if (flag[j].len == 8) {
                        newStr = newStr + String.fromCharCode(parseInt(binary.substr(start, 8), 2));
                    }
                    else if (flag[j].len == 11) {
                        newStr = newStr +
                            String.fromCharCode(parsetInt(binary.substr(start + 3, 5) +
                                binary.substr(start + 10, 6), 2));
                    }
                    else if (flag[j].len == 16) {
                        newStr = newStr +
                            String.fromCharCode(parsetInt(binary.substr(start + 4, 4) +
                                binary.substr(start + 10, 6) +
                                binary.substr(start + 18, 6), 2));
                    }
                    else if (flag[j].len == 21) {
                        newStr = newStr +
                            String.fromCharCode(parseInt(binary.substr(start + 5, 3) +
                                binary.substr(start + 10, 6) + binary.substr(start + 18, 6) +
                                binary.substr(start + 26, 6), 2));
                    }
                    start = start + flag[j].len;
                    break;
                }
            }
        }
        binary = null;
        return newStr;
    }

    return {
        encode: function (str, type) {
            return encode[type](str);
        },
        decode: function (str, type) {
            return decode[type](str);
        }
    };
})();