// ==UserScript==
// @name         Image Preview
// @namespace    https://mp.weixin.qq.com/s/*
// @version      0.2
// @description  preview any image
// @author       You
// @match        https://mp.weixin.qq.com/s/*
// @match        https://xie.infoq.cn/article/*
// @require      https://cdn.jsdelivr.net/npm/vue@2.6.11

// @grant        none
// @downloadURL none
// ==/UserScript==

(function () {
  // 图片预览组件
  Vue.component('img-preview', {
    props: {
      // 是否显示
      isShow: {
        type: Boolean,
        required: true,
        default: false,
      },

      // 图片url
      picUrl: {
        type: String,
        default: '',
      },
    },
    template: `<transition name="scale">
      <div v-if="isShow && picUrl" class="img-view-wrapper" @click.stop="$emit('update:isShow', false)">
        <img class="img-view" :src="picUrl" alt="not image" />
      </div>
    </transition>`,
    methods: {
      // 固定body不让其滚动
      fixedBody() {
        document.body.style.overflow = 'hidden'
      },
      // 释放body，让其滚动
      looseBody() {
        document.body.style.overflow = 'auto'
      },
    },
    watch: {
      isShow(val) {
        if (val) {
          // 展示
          this.fixedBody()
        } else {
          this.looseBody()
        }
      },
    },
  })

  // 插入DOM元素
  var imgPreviewContainer = document.createElement('div')
  imgPreviewContainer.setAttribute('class', 'img-preview-container')
  document.body.appendChild(imgPreviewContainer)

  addStyle()

  // 挂载
  const vm = new Vue({
    el: imgPreviewContainer,
    data: {
      picUrl: '',
      isShowImgPreview: false,
    },
    template: '<img-preview :pic-url="picUrl" :is-show.sync="isShowImgPreview" />',
    created() {
      // 冒泡阶段处理，避免有些网站把事件拦截掉了
      document.addEventListener('click', (ev) => {
        const img = ev.target
        const { nodeName } = img
        if (nodeName === 'IMG') {
          // 图片
          this.picUrl = img.getAttribute('src')
          this.isShowImgPreview = true
        }
      }, true)
    },
  })

  // 添加样式
  function addStyle() {
    const style = document.createElement('style')
    style.innerHTML = `
      .img-view-wrapper {
        display: flex;
        justify-content: center;
        align-items: center;
        position: fixed;
        top: 0;
        left: 0;
        width: 100vw;
        height: 100vh;
        overflow: auto;
        z-index: 99999 !important;
        background: rgba(0, 0, 0, 0.6);
      }

      .img-view {
        cursor: zoom-out;
        max-width: 100%;
        max-height: 100%;
      }

      .scale-enter-active,
      .scale-leave-active {
        transition: all 0.4s;
      }

      .scale-enter,
      .scale-leave-to {
        transform: scale(0);
      }`
    document.head.appendChild(style)
  }
})()