const CryptoJS = require( "crypto" );

let s_key = null;

const CCryptoHelp = {

    _getKey: function() {
        if( !s_key ) {
            s_key = CryptoJS.enc.Utf8.parse( "#KLDf*#!32!~kle1" );
        }

        return s_key;
    },

    // AES加密
    encrypt: function( str ) {

        if( !str || 0 === str.length ) {
            return "";
        }

        const keyVal = CCryptoHelp._getKey();

        let encrypted = CryptoJS.AES.encrypt( str, keyVal, {
            iv: null,
            mode: CryptoJS.mode.ECB,
            padding: CryptoJS.pad.ZeroPadding
        } );

        return encrypted.toString();
    },

    // AES解密
    decrypt: function( str ) {

        if( !str || 0 === str.length ) {
            return "";
        }

        const keyVal = CCryptoHelp._getKey();

        let decrypt = CryptoJS.AES.decrypt( str, keyVal, {
            iv: null,
            mode: CryptoJS.mode.ECB,
            padding: CryptoJS.pad.ZeroPadding
        } );

        return CryptoJS.enc.Utf8.stringify( decrypt );

        // let decryptedStr = decrypt.toString( CryptoJS.enc.Utf8 );
        // return decryptedStr.toString();
    },

    // MD5加密
    md5FromString: function( str ) {

        if( !str || 0 === str.length ) {
            return "";
        }

        return CryptoJS.MD5( str ).toString().toLowerCase();
    },

    // MD5加密
    md5FromBytes: function( unit8Array ) {

        if( !unit8Array || 0 === unit8Array.length ) {
            return "";
        }

        let str = CryptoJS.enc.Hex.stringify( unit8Array );
        return CryptoJS.MD5( str ).toString().toLowerCase();
    },

    // 十六进制字符串数组，个数如果不足16整数倍则补0
    hexTo16Hex: function( str ) {

        var diff = 16 - ( str.length + 1 ) / 3 % 16;
        for( var i = 0; i < diff; i++ ) {
            str = str + " 00";
        }

        return str;
    },

    // 构建WordArray对象
    int8parse: function( u8arr ) {
        var len = u8arr.length;
        var words = [];
        for( var i = 0; i < len; i++ ) {
            words[ i >>> 2 ] |= ( u8arr[ i ] & 0xff ) << ( 24 - ( i % 4 ) * 8 );
        }
        return CryptoJS.lib.WordArray.create( words, len );
    },

    // 十六进制字符串(空格分割)转成十进制数字的数组
    hexStrToDecArray: function( str ) {
        var strArray = str.split( " " );
        var decArray = [];
        for( var i = 0; i < strArray.length; i++ ) {
            decArray.push( parseInt( strArray[ i ], 16 ) );
        }
        return CCryptoHelp.arrayTo16Array( decArray );
    },

    // 十进制数组转成十六进制字符串
    decArrayToHexStr: function( array ) {
        var hexStr = "";
        for( var i = 0; i < array.length; i++ ) {
            var str = array[ i ].toString( 16 ).toUpperCase();
            if( str.length < 2 ) {
                str = "0" + str;
            }
            hexStr = hexStr + str + " ";
        }
        return hexStr.substr( 0, hexStr.length - 1 );
    },

    // word类型的十进制数组转成十六进制字符串
    wordArrayToHexStr: function( array ) {
        var hexStr = "";
        for( var i = 0; i < array.length; i++ ) {
            var num = array[ i ];
            if( num < 0 ) {
                num = array[ i ] + 0x100000000;
            }
            var str = num.toString( 16 ).toUpperCase();
            var fullStr = str;
            if( str.length < 8 ) {
                for( var j = 0; j < 8 - str.length; j++ ) {
                    fullStr = "0" + fullStr;
                }
            }
            hexStr = hexStr + fullStr;
        }
        var ret = "";
        for( var i = 0; i < hexStr.length; i += 2 ) {
            ret = ret + hexStr.substr( i, 2 ) + " "
        }
        return ret.substr( 0, ret.length - 1 );
    },

    // 数组元素个数必须是16的整数倍，不足的在后面补0
    arrayTo16Array: function( array ) {
        var len = array.length;
        var distLen = parseInt( ( array.length - 1 ) / 16 ) * 16 + 16;
        for( var i = array.length; i < distLen; i++ ) {
            array[ i ] = 0;
        }
        return array;
    },

};

module.exports = CCryptoHelp;