<template>
  <draggable
    v-model="menuList"
    item-key="id"
    ghost-class="draggable-ghost"
    :animation="400"
    @end="onDragEnd"
  >
    <template #item="{ element: parent, index: x }">
      <div class="menu_bottom">
        <!-- 一级菜单 -->
        <div
          @click="menuClicked(parent, x)"
          class="menu_item"
          :class="{ active: props.activeIndex === `${x}` }"
        >
          <Icon icon="ep:fold" color="black" />{{ parent.name }}
        </div>
        <!-- 以下为二级菜单-->
        <div class="submenu" v-if="props.parentIndex === x && parent.children">
          <draggable
            v-model="parent.children"
            item-key="id"
            ghost-class="draggable-ghost"
            :animation="400"
          >
            <template #item="{ element: child, index: y }">
              <div class="subtitle menu_bottom">
                <div
                  class="menu_subItem"
                  v-if="parent.children"
                  :class="{ active: props.activeIndex === `${x}-${y}` }"
                  @click="subMenuClicked(child, x, y)"
                >
                  {{ child.name }}
                </div>
              </div>
            </template>
          </draggable>
          <!-- 二级菜单加号， 当长度 小于 5 才显示二级菜单的加号  -->
          <div
            class="menu_bottom menu_addicon"
            v-if="!parent.children || parent.children.length < 5"
            @click="addSubMenu(x, parent)"
          >
            <Icon icon="ep:plus" class="plus" />
          </div>
        </div>
      </div>
    </template>
  </draggable>

  <!-- 一级菜单加号 -->
  <div class="menu_bottom menu_addicon" v-if="menuList.length < 3" @click="addMenu">
    <Icon icon="ep:plus" class="plus" />
  </div>
</template>

<script setup lang="ts">
import { Menu } from './types'
import draggable from 'vuedraggable'

const props = defineProps<{
  modelValue: Menu[]
  activeIndex: string
  parentIndex: number
  accountId: number
}>()

const emit = defineEmits<{
  (e: 'update:modelValue', v: Menu[])
  (e: 'menu-clicked', parent: Menu, x: number)
  (e: 'submenu-clicked', child: Menu, x: number, y: number)
}>()

const menuList = computed<Menu[]>({
  get: () => props.modelValue,
  set: (val) => emit('update:modelValue', val)
})

// 添加横向一级菜单
const addMenu = () => {
  const index = menuList.value.length
  const menu = {
    name: '菜单名称',
    children: [],
    reply: {
      // 用于存储回复内容
      type: 'text',
      accountId: props.accountId // 保证组件里，可以使用到对应的公众号
    }
  }
  menuList.value[index] = menu
  menuClicked(menu, index - 1)
}

// 添加横向二级菜单；parent 表示要操作的父菜单
const addSubMenu = (i: number, parent: any) => {
  const subMenuKeyLength = parent.children.length // 获取二级菜单key长度
  const addButton = {
    name: '子菜单名称',
    reply: {
      // 用于存储回复内容
      type: 'text',
      accountId: props.accountId // 保证组件里，可以使用到对应的公众号
    }
  }
  parent.children[subMenuKeyLength] = addButton
  subMenuClicked(parent.children[subMenuKeyLength], i, subMenuKeyLength)
}

const menuClicked = (parent: Menu, x: number) => {
  emit('menu-clicked', parent, x)
}

const subMenuClicked = (child: Menu, x: number, y: number) => {
  emit('submenu-clicked', child, x, y)
}

/**
 * 处理一级菜单展开后被拖动
 *
 * @param oldIndex: 一级菜单拖动前的位置
 * @param newIndex: 一级菜单拖动后的位置
 */
const onDragEnd = ({ oldIndex, newIndex }) => {
  // 二级菜单没有展开，直接返回
  if (props.activeIndex === '__MENU_NOT_SELECTED__') {
    return
  }

  let newParent = props.parentIndex
  if (props.parentIndex === oldIndex) {
    newParent = newIndex
  } else if (props.parentIndex === newIndex) {
    newParent = oldIndex
  } else {
    // 如果展开的二级菜单下标`props.parentIndex`不是被移动的菜单的前后下标。
    // 那么使用一个辅助素组来模拟菜单移动，然后找到展开的二级菜单的新下标`newParent`
    let positions = new Array<boolean>(menuList.value.length).fill(false)
    positions[props.parentIndex] = true
    positions.splice(oldIndex, 1)
    positions.splice(newIndex, 0, true)
    newParent = positions.indexOf(true)
  }

  // 找到菜单元素，触发一级菜单点击
  const parent = menuList.value[newParent]
  emit('menu-clicked', parent, newParent)
}
</script>

<style lang="scss" scoped>
.menu_bottom {
  position: relative;
  display: inline-block;
  float: left;
  width: 85.5px;
  text-align: center;
  cursor: pointer;
  background-color: #fff;
  border: 1px solid #ebedee;
  box-sizing: border-box;

  &.menu_addicon {
    height: 46px;
    line-height: 46px;

    .plus {
      color: #2bb673;
    }
  }

  .menu_item {
    display: flex;
    width: 100%;
    height: 44px;
    line-height: 44px;
    // text-align: center;
    box-sizing: border-box;
    align-items: center;
    justify-content: center;

    &.active {
      border: 1px solid #2bb673;
    }
  }

  .menu_subItem {
    height: 44px;
    line-height: 44px;
    text-align: center;
    box-sizing: border-box;

    &.active {
      border: 1px solid #2bb673;
    }
  }
}

/* 第二级菜单 */
.submenu {
  position: absolute;
  bottom: 45px;
  width: 85.5px;

  .subtitle {
    background-color: #fff;
    box-sizing: border-box;
  }
}

.draggable-ghost {
  opacity: 0.5;
  background: #f7fafc;
  border: 1px solid #4299e1;
}
</style>
