/**
 images压缩扩展模块
 changlin_zhao@qq.com
 2023.5.23
 **/
layui.define(['upload','layer'],function(exports){

    var layer = layui.layer;

    var Compressor = {
        upload: function (obj) {
            // opthions = {
            //     width: option[0],
            //     height: option[1],
            //     quality: option[2]
            // }
            obj.preview(function(index, file, result){
                canvasDataURL(result, {quality: 0.7},  function(base64Codes){
                    obj.upload(index, convertBase64UrlTo(base64Codes, file.name));
                });
            });
        }
    }

    // 已知 base64
    // canvasDataURL(base64, {quality: 0.7},  function(base64Codes){
    //     // base64Codes 为压缩后的
    //     // 其中 convertBase64UrlTo(base64Codes, file.name) 可返回 File 对象和 Blob
    //     obj.upload(index, convertBase64UrlTo(base64Codes, file.name));
    // });

    // 未知 base64
    // imageCompress(file, {quality: 0.7},  function(base64Codes){
    //     // base64Codes 为压缩后的
    //     obj.upload(index, convertBase64UrlTo(base64Codes, file.name));
    // });

    /**
     * 读取文件
     * @param {file or Blob} file 上传文件
     * @param {object} config 压缩配置 可配置压缩长宽、质量等
     * @param {function} callback
     */
    function imageCompress(file, config, callback){
        var ready = new FileReader();
        ready.readAsDataURL(file);

        ready.onload=function(){
            canvasDataURL(this.result, config, callback)
        }
    }

    /**
     *
     * @param {string} path
     * @param {object} config  -- {width: '', height: '', quality: 0.7}
     * @param {function} callback
     */
    function canvasDataURL(path, config, callback){
        var img = new Image();
        img.src = path;

        img.onload = function(){
            var that = this, quality = 0.7;
            var w = that.width, h = that.height, scale = w / h;
            w = config.width || w;
            h = config.height || (w / scale);

            //生成canvas
            var canvas = document.createElement('canvas');
            var ctx = canvas.getContext('2d');
            var anw = document.createAttribute("width");
            anw.nodeValue = w;
            var anh = document.createAttribute("height");
            anh.nodeValue = h;
            canvas.setAttributeNode(anw);
            canvas.setAttributeNode(anh);
            ctx.drawImage(that, 0, 0, w, h);

            if(config.quality && config.quality <= 1 && config.quality > 0){
                quality = config.quality;
            }
            callback(canvas.toDataURL('image/jpeg', quality));
        }
    }

    /**
     * 将图片 base64 转为 File 对象或者 Blob
     * @param {*} urlData 图片 base64
     * @param {*} filename 图片名 没有图片名将转为 Blob
     */
    function convertBase64UrlTo(urlData, filename = null){
        var base64Arr = urlData.split(','), mime = base64Arr[0].match(/:(.*?);/)[1],
            bstr = atob(base64Arr[1]), n = bstr.length, u8arr = new Uint8Array(n);
        while(n--){
            u8arr[n] = bstr.charCodeAt(n);
        }

        return filename ? new File([u8arr], filename, {type:mime}) : new Blob([u8arr], {type:mime});
    }

    //输出 imagecut接口
    exports('imagecut', Compressor);

});