<template>
  <el-breadcrumb class="app-breadcrumb breadcrumb-container" separator="/">
    <el-breadcrumb-item
      v-for="(item, index) in levelList"
      :key="item.path"
    >
      <!-- 面包屑导航最后一个是不可点击的 因为最后一个正是当前所显示的路由 -->
      <span
          v-if="index == levelList.length - 1"
          class="no-redirect"
        >
          {{ item.meta.title }}
      </span>
      <a v-else @click.prevent="handleLink(item)">{{ item.meta.title }}</a>
    </el-breadcrumb-item>
  </el-breadcrumb>
</template>

<script lang="ts">
import { defineComponent, ref, watch, onBeforeMount } from 'vue'
import { useRoute, useRouter, RouteLocationMatched, RouteLocationRaw } from 'vue-router'
import { compile } from 'path-to-regexp'

type PartialRouteLocationMatched = Partial<RouteLocationMatched>

export default defineComponent({
  name: 'Breadcrumb',
  setup() {
    const route = useRoute() // 相当于this.$route对象
    const router = useRouter() // 相当于this.$router对象
    const levelList = ref<Array<PartialRouteLocationMatched>>([]) // 导航列表 存放matched里筛选的路由记录

    // 判断是不是Dashboard路由
    const isDashboard = (route?: PartialRouteLocationMatched) => {
      const name = route && route.name
      if (!name) {
        return false
      }
      return (name as string).trim().toLocaleLowerCase() === 'Dashboard'.toLocaleLowerCase()
    }

    // 获取面包屑导航
    const getBreadcrumb = () => {
      // 对匹配的路由进行过滤 过滤掉没有title属性的路由，没有title就无法作为面包屑导航
      let matched = route.matched.filter(item => item.meta && item.meta.title) as PartialRouteLocationMatched[]
      // 获取第一个匹配路由记录
      const first = matched[0]
      // 我们要把dashboard作为首页 始终固定在面包屑导航第一个 Dashboard/System/Menu Management
      // 如果第一个匹配到的路由记录不是dashboard 我们自己就把它放在记录数组的第一项
      if (!isDashboard(first)) {
        matched = ([{
          path: '/dashboard',
          meta: {
            title: 'Dashboard'
          }
        }] as PartialRouteLocationMatched[]).concat(matched)
      }
      // route.meta.breadcrumb自定义属性 如果为false 匹配到时 将不会再面包屑导航显示该路由
      // {
      //  path: 'menu',
      //  meta: {
      //    title: 'Menu Management',
      //    breadcrumb: false // 不显示在面包屑导航 默认true
      //  }
      // }
      levelList.value = matched.filter(item => item.meta && item.meta.title && item.meta.breadcrumb !== false)
    }

    onBeforeMount(() => {
      getBreadcrumb()
    })

    watch(() => route.path, () => {
      getBreadcrumb()
    })

    // 主要是针对 动态路由 /user/:id 进行动态参数填充
    // path-to-regexp 文档说明 https://www.npmjs.com/package/path-to-regexp
    const pathCompile = (path: string) => {
      // 根据路径变编译成正则函数 并接收具体参数 比如根据正则/user/:id 帮你将:id替换成具体路径
      const toPath = compile(path)  // 比如 path /user/:id
      const params = route.params // { id: 10 }
      return toPath(params) // toPath({ id: 10 }) => /user/10 返回填充后的路径
    }

    // 点击面包屑导航可跳转
    const handleLink = (route: RouteLocationMatched) => {
      const { path, redirect } = route
      // 如果是重定向路由 就走重定向路径
      if (redirect) {
        router.push(redirect as RouteLocationRaw)
        return
      }
      router.push(pathCompile(path))
    }
    return {
      levelList,
      handleLink
    }
  }
})
</script>

<style lang="scss" scoped>
.app-breadcrumb.el-breadcrumb {
  display: inline-block;
  /* float: left; */
  line-height: 50px;
  font-size: 14px;
  margin-left: 8px;
}

.no-redirect {
  color: #97a8be;
  cursor: text;
}
</style>

<style lang="scss">

.breadcrumb-enter-active,
.breadcrumb-leave-active {
  transition: all .5s;
}

.breadcrumb-enter,
.breadcrumb-leave-active {
  opacity: 0;
  transform: translateX(20px);
}

.breadcrumb-leave-active {
  position: absolute;
}

.breadcrumb-move {
  transition: all .5s;
}
</style>