/**
 * 获得base64
 * @param {Object} obj
 * @param {Number} [obj.width] 图片需要压缩的宽度，高度会跟随调整
 * @param {Number} [obj.quality=0.8] 压缩质量，不压缩为1
 * @param {Function} [obj.before(this, blob, file)] 处理前函数,this指向的是input:file
 * @param {Function} obj.success(obj) 处理后函数
 * @example
 *
 */
$.fn.localResizeIMG = function (obj) {
    this.on('change', function () {
        if (this.files.length == 0) {
            return;
        }
        var UploadNum = 1;
        if (obj.UploadNum != undefined && obj.UploadNum != null && obj.UploadNum != "") {
            UploadNum = obj.UploadNum;
            if (UploadNum < 1) UploadNum = 1;
        }
        if (this.files.length > UploadNum) {
            alert("最多只能选择" + UploadNum + "个文件");
            return;
        }
        var error = "";
        var listResult = new Array();
            for (var i = 0; i < this.files.length; i++) {
                var file = this.files[i];
                if (file.size == 0) {
                    error = file.name+"大小为0KB,不允许上传";
                    break;
                }
                if (obj.sizeLimit != 0) {
                    var sizeLimit = 0;
                    if (obj.sizeLimit.indexOf("kb") >= 0) {
                        sizeLimit = parseInt(obj.sizeLimit.substr(0, obj.sizeLimit.length - 2) * 1024);
                    } else if (obj.sizeLimit.indexOf("mb") >= 0) {
                        sizeLimit = parseInt(obj.sizeLimit.substr(0, obj.sizeLimit.length - 2) * 1024 * 1024);
                    } else {
                        sizeLimit = parseInt(obj.sizeLimit);
                    }
                    if (file.size > sizeLimit) {
                        error = file.name + "超出限制,不能大于" + obj.sizeLimit;
                        break;
                    }
                }
                if (obj.fileTypeExts == "*") obj.fileTypeExts = "";
                var extStart = file.name.lastIndexOf(".") + 1;
                var ext = file.name.substring(extStart, file.name.length).toLowerCase();
                if (obj.fileTypeExts != "") {
                    var ss = obj.fileTypeExts.split(",");
                    var bk = false;
                    for (var i = 0; i < ss.length; i++) {
                        var s = ss[i].substr(2, ss[i].length).toLowerCase();
                        if (ext == s) { bk = true; break; }
                    }
                    if (bk == false) {
                        error = file.name + "上传文件格式错误";
                        break;
                    }
                }

                if (ext != "bmp" && ext != "png" && ext != "gif" && ext != "jpg" && ext != "jpge") {
                    var reader = new FileReader();
                    reader.readAsDataURL(file);
                    reader.onload = function (e) {
                        var base64 = e.target.result;
                        // 生成结果
                        var result = {
                            name: file.name,
                            filetype: ext,
                            size: file.size,
                            base64: base64,
                            clearBase64: base64.substr(base64.indexOf(',') + 1),
                            error: ""
                        };
                        listResult.push(result);
                    };
                    continue;
                }
                var URL = window.URL || window.webkitURL;
                var blob = URL.createObjectURL(file);
                _create(listResult,blob, file, ext);
            }
            if (error != "") {
                alert(error);
                this.value = "";
                return;
            }
            //执行回调
            this.value = ''; // 清空临时数据
            obj.success(listResult);
        });

    /**
     * 生成base64
     * @param blob 通过file获得的二进制
     */
    function _create(listResult,blob, file, ext) {
        var img = new Image();
        img.src = blob;

        img.onload = function () {
            var that = this;

            //生成比例
            var w = that.width,
                h = that.height,
                scale = w / h;
            if (obj.width > 0) {
                w = obj.width || w;
                //h = w / scale;
                h = obj.height || h;
            }

            //生成canvas
            var canvas = document.createElement('canvas');
            var ctx = canvas.getContext('2d');
            $(canvas).attr({
                width: w,
                height: h
            });
            ctx.drawImage(that, 0, 0, w, h);

            /**
             * 生成base64
             * 兼容修复移动设备需要引入mobileBUGFix.js
             */
            var base64 = canvas.toDataURL('image/jpeg', obj.quality || 0.8);

            // 修复IOS
            if (navigator.userAgent.match(/iphone/i)) {
                var mpImg = new MegaPixImage(img);
                mpImg.render(canvas, {
                    maxWidth: w,
                    maxHeight: h,
                    quality: obj.quality || 0.8
                });
                base64 = canvas.toDataURL('image/jpeg', obj.quality || 0.8);
            }

            // 修复android
            if (navigator.userAgent.match(/Android/i)) {
                var encoder = new JPEGEncoder();
                base64 = encoder.encode(ctx.getImageData(0, 0, w, h), obj.quality * 100 || 80);
            }

            // 生成结果
            var result = {
                name: file.name,
                filetype: ext,
                size: file.size,
                base64: base64,
                clearBase64: base64.substr(base64.indexOf(',') + 1),
                error: ""
            };
            listResult.push(result);
        };
    }
};


    // 例子
    /*
    $('input:file').localResizeIMG({
        width: 100,
        quality: 0.1,
        //before: function (that, blob) {},
        success: function (result) {
            var img = new Image();
            img.src = result.base64;

            $('body').append(img);
            console.log(result);
        }
    });
*/