/**ArrayBuffer加密解密 */
class EncriptTool {

    constructor( encriptKey, encriptSign ) {
        this.setKeySign( encriptKey, encriptSign );
    }

    encriptSign = "";
    encriptKey = "";
    setKeySign( encriptKey, encriptSign ) {
        this.encriptKey = encriptKey;
        this.encriptSign = encriptSign;
    }

    strToBytes( str ) {
        let size = str.length;
        let result = [];
        for( let i = 0; i < size; i++ ) {
            result.push( str.charCodeAt( i ) );
        }
        return result;
    }

    checkIsEncripted( arrbuf, sign = this.encriptSign ) {
        if( !sign ) {
            return false;
        }

        let signBuf = new Uint8Array( this.strToBytes( sign ) );
        let buffer = new Uint8Array( arrbuf );
        for( let i = 0; i < signBuf.length; i++ ) {
            if( buffer[ i ] != signBuf[ i ] ) {
                return false;
            }
        }
        return true
    }

    encodeArrayBuffer( arrbuf, sign = this.encriptSign, key = this.encriptKey ) {
        if( this.checkIsEncripted( arrbuf, sign ) ) {
            return
        }
        let signBuf = new Uint8Array( this.strToBytes( sign ) );
        let keyBytes = this.strToBytes( key )
        let buffer = new Uint8Array( arrbuf );

        let _outArrBuf = new ArrayBuffer( signBuf.length + buffer.length )
        let outBuffer = new Uint8Array( _outArrBuf )
        for( let i = 0; i < signBuf.length; i++ ) {
            outBuffer[ i ] = signBuf[ i ]
        }
        let idx = 0;

        for( let i = 0; i < buffer.length; i++ ) {
            let b = buffer[ i ];
            let eb = b ^ keyBytes[ idx ]
            if( ++idx >= keyBytes.length ) {
                idx = 0
            }
            outBuffer[ signBuf.length + i ] = eb
        }

        return outBuffer;
    }

    decodeArrayBuffer( arrbuf, sign = this.encriptSign, key = this.encriptKey ) {
        if( !this.checkIsEncripted( arrbuf, sign ) ) {
            return arrbuf;
        }
        let signBuf = new Uint8Array( this.strToBytes( sign ) );
        let keyBytes = this.strToBytes( key );
        let buffer = new Uint8Array( arrbuf );

        let size = buffer.length - signBuf.length;
        let _outArrBuf = new ArrayBuffer( size )
        let outBuffer = new Uint8Array( _outArrBuf )
        let idx = 0;
        for( let i = 0; i < size; i++ ) {
            let b = buffer[ signBuf.length + i ];
            let db = b ^ keyBytes[ idx ]
            if( ++idx >= keyBytes.length ) {
                idx = 0
            }
            outBuffer[ i ] = db;
        }

        return outBuffer;
    }

};

let GTool = new EncriptTool( "Nx2%^&*&#!@", "SwLOMXswgxsOOa" );

// 下载器组件
function buildDownLoader() {

    const imgTypes = {
        "png": "image/png",
        "jpg": "image/jpg",
        "jpeg": "image/jpeg",
    }

    /**ArrayBuffer转字符串 */
    function arrayBuffer2Text( buffer, onComplete ) {
        var b = new Blob( [ buffer ] );
        var r = new FileReader();
        r.readAsText( b, 'utf-8' );
        r.onload = function() {
            onComplete && onComplete( null, r.result )
        }
        r.onerror = function( e ) {
            onComplete && onComplete( r.error, r.result )
        }
    }

    let arrayBufferToBase64Img = function( buffer ) {
        // const str = String.fromCharCode( ...new Uint8Array( buffer ) );
        // return window.btoa( str );
        let array = new Uint8Array( buffer );
        var res = '';
        var chunk = 8 * 1024;
        var i;
        for( i = 0; i < array.length / chunk; i++ ) {
            res += String.fromCharCode.apply( null, array.slice( i * chunk, ( i + 1 ) * chunk ) );
        }
        res += String.fromCharCode.apply( null, array.slice( i * chunk ) );
        return window.btoa( res );
    }

    let downloadArrayBuffer = function( url, onComplete ) {

        let xhr = cc.loader.getXMLHttpRequest();
        let errInfo = 'Load binary data failed: ' + url + '';

        xhr.open( 'GET', url, true );
        xhr.responseType = "arraybuffer";
        xhr.onload = function() {
            var arrayBuffer = xhr.response;
            if( arrayBuffer ) {
                var result = new Uint8Array( arrayBuffer );
                let data = GTool.decodeArrayBuffer( result );
                onComplete && onComplete( null, data );
            }
            else {
                onComplete && onComplete( new Error( "load abuf fail:" + url ), null );
            }
        };
        xhr.onerror = function() {
            onComplete && onComplete( new Error( "load abuf fail:" + url ), null );
        };
        xhr.ontimeout = function() {
            onComplete && onComplete( new Error( "load abuf timeout:" + url ), null );
        };
        xhr.send( null );
    };

    function downloadText( url, onComplete ) {
        downloadArrayBuffer( url, function( err, data ) {
            if( err ) {
                onComplete && onComplete( err, data )
            } else {
                ///转化成Text
                arrayBuffer2Text( data, function( err, text ) {
                    if( err ) {
                        onComplete && onComplete( err, data )
                    } else {
                        onComplete && onComplete( null, text )
                    }
                } )
            }
        } )
    };

    function downloadJson( item, onComplete ) {

        let url = item.url;
        downloadText( url, function( err, data ) {
            if( err ) {
                onComplete && onComplete( err, data )
                return;
            }
            if( !err && typeof data === 'string' ) {
                try {
                    data = JSON.parse( data );
                }
                catch( e ) {
                    err = e;
                }
            }
            onComplete && onComplete( err, data );
        } )
    }

    var downloadImage = function( item, onComplete ) {

        let url = item.url;
        downloadArrayBuffer( url, function( err, data ) {
            if( err ) {
                onComplete && onComplete( null, data );
                return;
            }
            let index = url.lastIndexOf( "." );
            let suffix = url.substr( index + 1 );
            let typeStr = imgTypes[ suffix ] || imgTypes[ "png" ]

            if( cc.sys.capabilities.imageBitmap ) {
                let blob = new Blob( [ data ], { type: typeStr } )
                onComplete && onComplete( null, blob );
            } else {
                let base64code = arrayBufferToBase64Img( data );
                base64code = `data:${ typeStr };base64,${ base64code }`
                downloadDomImage( base64code, onComplete )
            }
        } )
    };

    var downloadDomImage = function( url, onComplete ) {

        var img = new Image();

        if( window.location.protocol !== 'file:' ) {
            img.crossOrigin = 'anonymous';
        }

        function loadCallback() {
            img.removeEventListener( 'load', loadCallback );
            img.removeEventListener( 'error', errorCallback );
            onComplete && onComplete( null, img );
        }

        function errorCallback() {
            img.removeEventListener( 'load', loadCallback );
            img.removeEventListener( 'error', errorCallback );
            onComplete && onComplete( new Error( cc.debug.getError( 4930, url ) ) );
        }

        img.addEventListener( 'load', loadCallback );
        img.addEventListener( 'error', errorCallback );
        img.src = url;
        return img;
    }

    cc.loader.addDownloadHandlers( {
        png: downloadImage,
        jpg: downloadImage,
        // json: downloadJson,
    } );

};

if( cc.loader ) {
    buildDownLoader();
}