<template>
   <el-dialog
     :title="title"
     :visible="visible"
     :close-on-click-modal="false"
     width="1000px"
     destroy-on-close
     append-to-body
     @close="closeDialog"
   >
     <div class="q-picture__img-box">
       <div
         class="q-picture__prev-btn"
         @mouseover="leftBtnStatus = true"
         @mouseleave="leftBtnStatus = false"
       >
         <transition name="btn-fade">
           <el-button
             v-show="leftBtnStatus && isNeeding"
             circle
             icon="el-icon-arrow-left"
             @click="lastImage()"
           />
         </transition>
       </div>
       <img v-show="visible" :src="currentSrc" alt="" v-loading="loading" @load="loading = false" />
       <div
         class="q-picture__next-btn"
         @mouseover="rightBtnStatus = true"
         @mouseleave="rightBtnStatus = false"
       >
         <transition name="btn-fade">
           <el-button
             v-show="rightBtnStatus && isNeeding"
             circle
             icon="el-icon-arrow-right"
             @click="nextImage()"
           />
         </transition>
       </div>
     </div>
   </el-dialog>
 </template>
 <script>
 export default {
   name: "PicturePreviewer",
   props: {
     visible: { type: Boolean, default: false },
     pageable: { type: Boolean, default: true },
     recyclable: { type: Boolean, default: true },
     src: { type: [String, Array], required: true },
     title: { type: String, default: "圖片預(yù)覽" },
     current: { type: Number, default: 0 }
   },
   data() {
     return {
       currentKey: -1,
       leftBtnStatus: false,
       rightBtnStatus: false,
       loading: false
     };
   },
   computed: {
     isNeeding: function () {
       return typeof this.src === "object" && this.pageable && this.src && this.src.length > 1;
     },
     currentSrc: function () {
       if (typeof this.src === "string") return this.src;
       if (this.src && this.src.length) {
         return this.src[this.currentKey] || "";
       }
       return "";
     }
   },
   methods: {
     closeDialog() {
       this.$emit("update:visible", false);
     },
     lastImage() {
       if (this.currentKey - 1 === -1) {
         if (this.recyclable) this.currentKey = this.src.length - 1;
         else this.$message.info("當(dāng)前已經(jīng)是第一張圖片");
       } else {
         this.currentKey = this.currentKey - 1;
       }
     },
     nextImage() {
       if (this.currentKey + 1 === this.src.length) {
         if (this.recyclable) this.currentKey = 0;
         else this.$message.info("當(dāng)前已經(jīng)是最后一張圖片");
       } else {
         this.currentKey = this.currentKey + 1;
       }
     }
   },
   watch: {
     current: {
       handler: function (val) {
         if (val) this.currentKey = val;
         else this.currentKey = 0;
       },
       immediate: true
     }
   }
 };
 </script>

 <template>
   <div
     class="q-upload__preview"
     ref="pictures"
     :title="messageInfo"
     @mouseenter="horizontalRolling"
   >
     <slot name="preSlot"></slot>
     <input
       class="q-upload__file-input"
       type="file"
       ref="fileInput"
       name="fileInput"
       @change="fileChange"
       :accept="accept"
     />
     <div
       class="q-upload__file-label"
       v-loading="fileLoading"
       @click="selectFile"
       v-show="fileLists.length < limitNum && !disabled"
     >
       <i class="el-icon-plus"></i>
     </div>
     <slot name="middle"></slot>
     <div class="q-upload__pre-img" v-for="(i, k) in fileLists" :key="i.smallUrl">
       <img class="q-upload__img" :src="i.smallUrl ? i.smallUrl : i.url" />
       <div class="q-upload__mask">
         <i v-if="prev" class="el-icon-zoom-in" @click="imgPreview(i, k)"></i>
         <i class="el-icon-delete" v-if="!disabled" @click="imgRemove(k)"></i>
       </div>
     </div>
     <slot name="endSlot"></slot>
     <picture-previewer
       :visible.sync="dialogImageVisible"
       :src="imageUrls"
       :current="currentImage"
     />
   </div>
 </template>
 <script>
 import Utils from "../../src/utils/commonUtils";
 export default {
   name: "ImageUpload",
   props: {
     active: { type: String, default: "/api/file/upload" },
     accept: { type: String, default: "" },
     limitNum: { type: Number, default: 9 },
     size: { type: Number, default: 10 },
     prev: { type: Boolean, default: true },
     disabled: { type: Boolean, default: false },
     value: { type: Array, default: () => [] }
   },
   data() {
     return {
       fileLoading: false,
       dialogImageVisible: false,
       dialogImageUrl: "",
       currentImage: 0,
       fileLists: [],
       messageInfo: ""
     };
   },
   computed: {
     imageUrls: function () {
       return this.fileLists.map(o => o.url);
     }
   },
   methods: {
     async validateImage(file) {
       const isJPEG = file.type === "image/jpeg";
       const isJPG = file.type === "image/jpg";
       const isPNG = file.type === "image/png";
       const isBMP = file.type === "image/bmp";
       const isLtSize = file.size / 1024 / 1024 < this.size;
       if (!(isJPEG || isJPG || isPNG || isBMP)) {
         return {
           status: false,
           message: `上傳圖片必須是${this.accept}格式!`
         };
       }
       if (!isLtSize) {
         return {
           status: false,
           message: "上傳圖片大小不能超過 " + this.size + " MB!"
         };
       }
       return { status: true, message: "" };
     },
     // 選擇文件
     selectFile() {
       this.$refs.fileInput.value = null; // 置空，防止刪除后無法再次選擇
       this.$refs.fileInput.click();
       return true;
     },
     // 文件選取之后·
     async fileChange(el) {
       const file = [...el.target.files][0];
       let { status, message } = await this.validateImage(file);
       if (status) {
         this.fileLoading = true;
         await this.customHttpRequest(file);
       } else {
         this.$message.error(message);
         return false;
       }
     },
     // 上傳
     async customHttpRequest(file) {
       try {
         let fData = Utils.createUploadForm(file);
         let {
           data: { data, status, message }
         } = await this.$http.post(this.active, fData.formData, fData.config);
         if (status) {
           this.fileLists.unshift(data);
           this.$emit("success", data);
         } else {
           this.$message.error(message);
           this.$emit("error");
         }
       } finally {
         this.fileLoading = false;
       }
     },
     imgPreview(file, k) {
       this.dialogImageUrl = file.url;
       this.dialogImageVisible = true;
       this.currentImage = k;
     },
     imgRemove(index) {
       this.fileLists.splice(index, 1);
       this.$emit("input", this.fileLists);
       this.$emit("change", this.fileLists);
       this.$emit("blur", this.fileLists);
     },
     horizontalRolling() {
       if (this.$refs["pictures"].clientWidth < this.$refs["pictures"].scrollWidth) {
         this.messageInfo = "滾動滾輪查看所有信息";
       } else {
         this.messageInfo = "";
       }
       this.$refs["pictures"].addEventListener("mousewheel", this.$_scrollEvent);
       this.$once("hook:beforeDestroy", () => {
         this.$refs["pictures"].removeEventListener("mousewheel", this.$_scrollEvent);
       });
     },
     $_scrollEvent(e) {
       let left = this.$refs["pictures"].scrollLeft;
       this.$refs["pictures"].scrollLeft = e.deltaY > 0 ? left + 40 : left - 40;
     }
   },
   watch: {
     value: {
       deep: true,
       immediate: true,
       handler: function () {
         this.fileLists = typeof this.value === "string" ? JSON.parse(this.value) : this.value;
         if (!this.fileLists) this.fileLists = [];
       }
     },
     fileLists: {
       deep: true,
       immediate: false,
       handler: function () {
         if (this.value && this.value.length > this.limitNum) {
           this.$message.warning(`最多可以上傳【 ${this.limitNum} 】張圖片！！`);
         }
         this.$emit("input", this.fileLists);
         this.$emit("change", this.fileLists);
       }
     }
   }
 };
 </script>