<template>
  <div class="component-upload-image">
    <el-upload
      :action="uploadImgUrl"
      list-type="picture-card"
      :on-success="handleUploadSuccess"
      :before-upload="handleBeforeUpload"
      :limit="limit"
      :on-error="handleUploadError"
      :on-exceed="handleExceed"
      name="file"
      :on-remove="handleRemove"
      :show-file-list="true"
      :file-list="fileList"
      :on-preview="handlePictureCardPreview"
      :class="{hide: this.fileList.length >= this.limit}"
    >
      <i class="el-icon-plus"></i>
    </el-upload>

    <!-- 上传提示 -->
<!--    <div class="el-upload__tip" slot="tip" v-if="showTip">
      请上传
      <template v-if="fileSize"> 大小不超过 <b style="color: #f56c6c">{{ fileSize }}MB</b> </template>
      <template v-if="fileType"> 格式为 <b style="color: #f56c6c">{{ fileType.join("/") }}</b> </template>
      的文件
    </div> -->

    <el-dialog
      :visible.sync="dialogVisible"
      title="预览"
      width="800"
      append-to-body
    >
      <img
        :src="dialogImageUrl"
        style="display: block; max-width: 100%; margin: 0 auto"
      />
    </el-dialog>
  </div>
</template>

<script>
import { getToken } from "@/utils/auth";

import { Loading } from 'element-ui';

export default {
  props: {
    value: [String, Object, Array],
    // 图片数量限制
    limit: {
      type: Number,
      default: 10,
    },
    // 大小限制(MB)
    fileSize: {
       type: Number,
      default: 500,
    },
    // 宽高比，如 "16:9"；为空则不校验
    aspectRatio: {
      type: String,
      default: null,
    },
    // 宽高比允许误差（相对误差）
    aspectTolerance: {
      type: Number,
      default: 0.05,
    },
    // 文件类型, 例如['png', 'jpg', 'jpeg']
    fileType: {
      type: Array,
      default: () => ["png", "jpg", "jpeg"],
    },
    // 是否显示提示
    isShowTip: {
      type: Boolean,
      default: true
    }
  },
  data() {
    return {
      finalQuality:1,
      dialogImageUrl: "",
      dialogVisible: false,
      hideUpload: false,
      baseUrl: process.env.VUE_APP_BASE_API,
      uploadImgUrl: process.env.VUE_APP_BASE_API+"/common/uploadOSS", // 上传的图片服务器地址
      headers: {
        Authorization: "Bearer " + getToken(),
      },
      fileList: []
    };
  },
  watch: {
    value: {
      handler(val) {
        if (val) {
          // 首先将值转为数组
          const list = Array.isArray(val) ? val : this.value.split(',');
          // 然后将数组转为对象数组
          this.fileList = list.map(item => {
            if (typeof item === "string") {
              if (item.indexOf(this.baseUrl) === -1) {
                  item = { name: item, url: item };
              } else {
                  item = { name: item, url: item };
              }
            }
            return item;
          });
        } else {
          this.fileList = [];
          return [];
        }
      },
      deep: true,
      immediate: true
    }
  },
  computed: {
    // 是否显示提示
    showTip() {
      return this.isShowTip && (this.fileType || this.fileSize);
    },
  },
  methods: {
    // 删除图片
    handleRemove(file, fileList) {
      const findex = this.fileList.map(f => f.name).indexOf(file.name);
      if(findex > -1) {
        this.fileList.splice(findex, 1);
        this.$emit("input", this.listToString(this.fileList));
      }
    },
    // 上传成功回调
    handleUploadSuccess(res) {
      this.fileList.push({ name: res.url, url: res.url });
      this.$emit("input", this.listToString(this.fileList));
      this.loading.close();
    },
    // 上传前loading加载
    handleBeforeUpload(file) {
      let isImg = false;
      if (this.fileType.length) {
        let fileExtension = "";
        if (file.name.lastIndexOf(".") > -1) {
          fileExtension = file.name.slice(file.name.lastIndexOf(".") + 1);
        }
        isImg = this.fileType.some(type => {
          if (file.type.indexOf(type) > -1) return true;
          if (fileExtension && fileExtension.indexOf(type) > -1) return true;
          return false;
        });
      } else {
        isImg = file.type.indexOf("image") > -1;
      }

      if (!isImg) {
        this.$message.error(
          `文件格式不正确, 请上传${this.fileType.join("/")}图片格式文件!`
        );
        return false;
      }
      // fileSize 默认 500 表示沿用历史 3MB；显式传入且 <=100 时按 MB 校验
      const maxMb = (this.fileSize != null && this.fileSize > 0 && this.fileSize <= 100) ? this.fileSize : 3;
      return new Promise((resolve, reject) => {
        const closeLoading = () => {
          if (this.loading && typeof this.loading.close === 'function') {
            this.loading.close();
            this.loading = null;
          }
        };
        const fail = (msg) => {
          if (msg) {
            this.$message.error(msg);
          }
          closeLoading();
          reject();
        };
        if (file.size / 1024 / 1024 > maxMb) {
          fail(`上传的图片不能超过${maxMb}MB`);
          return;
        }
        const afterRatioCheck = () => {
          // 校验通过后再进入「上传中」态
          this.loading = this.$loading({
            lock: true,
            text: "上传中",
            background: "rgba(0, 0, 0, 0.7)",
          });
          if (file.size / 1024 / 1024 > 1 && maxMb > 1) {
            const loadingInstance = Loading.service({ text: '图片内存过大正在压缩图片...' });
            this.compressImage(file).then((compressedFile) => {
              loadingInstance.close();
              if (compressedFile.size / 1024 / 1024 > maxMb) {
                fail(`图片压缩后仍大于${maxMb}MB`);
              } else {
                resolve(compressedFile);
              }
            }).catch((err) => {
              loadingInstance.close();
              console.error(err);
              fail();
            });
          } else {
            resolve(file);
          }
        };
        if (this.aspectRatio) {
          const parts = String(this.aspectRatio).split(':');
          const rw = Number(parts[0]);
          const rh = Number(parts[1]);
          if (!rw || !rh) {
            afterRatioCheck();
            return;
          }
          const expected = rw / rh;
          const reader = new FileReader();
          reader.onload = (e) => {
            const img = new Image();
            img.onload = () => {
              const actual = img.width / img.height;
              if (Math.abs(actual - expected) / expected > this.aspectTolerance) {
                fail(`封面比例须为 ${this.aspectRatio}（当前约 ${(actual).toFixed(2)}）`);
                return;
              }
              afterRatioCheck();
            };
            img.onerror = () => {
              fail('无法读取图片尺寸');
            };
            img.src = e.target.result;
          };
          reader.onerror = () => {
            fail('无法读取图片');
          };
          reader.readAsDataURL(file);
        } else {
          afterRatioCheck();
        }
      });
      // if (this.fileSize) {
      //   const isLt = file.size / 1024  < this.fileSize;
      //   if (!isLt) {
      //     this.$message.error(`上传头像图片大小不能超过 ${this.fileSize} KB!`);
      //     return false;
      //   }
      // }

    },
    compressImage(file) {
      return new Promise((resolve, reject) => {
        const reader = new FileReader();
        reader.readAsDataURL(file);
        reader.onload = (event) => {
          const img = new Image();
          img.src = event.target.result;
          img.onload = () => {
            const canvas = document.createElement('canvas');
            const ctx = canvas.getContext('2d');
            const width = img.width;
            const height = img.height;
            canvas.width = width;
            canvas.height = height;
            ctx.drawImage(img, 0, 0, width, height);

            let quality = 1; // 初始压缩质量
            let dataURL = canvas.toDataURL('image/jpeg', quality);

            // 逐步压缩，直到图片大小小于500KB并且压缩质量不再降低
            while (dataURL.length / 1024 > 500 && quality > 0.1) {
              quality -= 0.01;
              dataURL = canvas.toDataURL('image/jpeg', quality);
            }
            this.finalQuality = quality; // 存储最终的压缩质量

            if (dataURL.length / 1024 > 1000) {
              reject(new Error('压缩后图片仍然大于1000KB'));
              return;
            }

            const arr = dataURL.split(',');
            const mime = arr[0].match(/:(.*?);/)[1];
            const bstr = atob(arr[1]);
            let n = bstr.length;
            const u8arr = new Uint8Array(n);
            while (n--) {
              u8arr[n] = bstr.charCodeAt(n);
            }
            const compressedFile = new Blob([u8arr], { type: mime });
            compressedFile.name = file.name;
            resolve(compressedFile);
          };
          img.onerror = (error) => {
            reject(error);
          };
        };
        reader.onerror = (error) => {
          reject(error);
        };
      });
    },
    // 文件个数超出
    handleExceed() {
      this.$message.error(`上传文件数量不能超过 ${this.limit} 个!`);
    },
    // 上传失败
    handleUploadError() {
      this.$message({
        type: "error",
        message: "上传失败",
      });
      this.loading.close();
    },
    // 预览
    handlePictureCardPreview(file) {
      this.dialogImageUrl = file.url;
      this.dialogVisible = true;
    },
    // 对象转成指定字符串分隔
    listToString(list, separator) {
      let strs = "";
      separator = separator || ",";
      for (let i in list) {
        strs += list[i].url.replace(this.baseUrl, "") + separator;
      }
      return strs != '' ? strs.substr(0, strs.length - 1) : '';
    }
  }
};
</script>
<style scoped lang="scss">
// .el-upload--picture-card 控制加号部分
::v-deep.hide .el-upload--picture-card {
    display: none;
}
// 去掉动画效果
::v-deep .el-list-enter-active,
::v-deep .el-list-leave-active {
    transition: all 0s;
}

::v-deep .el-list-enter, .el-list-leave-active {
    opacity: 0;
    transform: translateY(0);
}
</style>

