<template>
  <div
    id="notifications"
    v-shortkey="shortcutEnabled ? { next: ['j'] } : {}"
    @shortkey="handleKey"
  >
    <div
      v-shortkey="{ linux: ['ctrl', 'r'], mac: ['meta', 'r'] }"
      @shortkey="reload()"
    ></div>
    <DynamicScroller
      :items="handledNotifications"
      :min-item-size="20"
      id="scroller"
      class="scroller"
      ref="scroller"
    >
      <template v-slot="{ item, index, active }">
        <template v-if="item.id === 'loading-card'">
          <DynamicScrollerItem
            :item="item"
            :active="active"
            :size-dependencies="[item.id]"
            :data-index="index"
            :watchData="true"
          >
            <StatusLoading
              :since_id="item.since_id"
              :max_id="item.max_id"
              :loading="loadingMore"
              @load_since="fetchNotificationsSince"
            />
          </DynamicScrollerItem>
        </template>
        <template v-else>
          <DynamicScrollerItem
            :item="item"
            :active="active"
            :size-dependencies="[item.url]"
            :data-index="index"
            :watchData="true"
          >
            <notification
              :message="item"
              :focused="item.id === focusedId"
              :overlaid="modalOpened"
              :filters="filters"
              v-on:update="updateToot"
              @focusNext="focusNext"
              @focusPrev="focusPrev"
              @focusRight="focusSidebar"
              @selectNotification="focusNotification(item)"
            >
            </notification>
          </DynamicScrollerItem>
        </template>
      </template>
    </DynamicScroller>
    <div
      :class="openSideBar ? 'upper-with-side-bar' : 'upper'"
      v-show="!heading"
    >
      <el-button type="primary" :icon="ElIconArrowUp" @click="upper" circle>
      </el-button>
    </div>
  </div>
</template>

<script>
import { ArrowUp as ElIconArrowUp } from '@element-plus/icons'
import { mapState, mapGetters } from 'vuex'
import moment from 'moment'
import Notification from '~/src/renderer/components/organisms/Notification'
import StatusLoading from '~/src/renderer/components/organisms/StatusLoading'
import reloadable from '~/src/renderer/components/mixins/reloadable'
import { Event } from '~/src/renderer/components/event'
import { ScrollPosition } from '~/src/renderer/components/utils/scroll'

export default {
  data() {
    return {
      focusedId: null,
      scrollPosition: null,
      observer: null,
      scrollTime: null,
      resizeTime: null,
      loadingMore: false,
      ElIconArrowUp,
    }
  },
  name: 'notifications',
  components: { Notification, StatusLoading },
  mixins: [reloadable],
  computed: {
    ...mapState({
      openSideBar: (state) => state.TimelineSpace.Contents.SideBar.openSideBar,
      startReload: (state) => state.TimelineSpace.HeaderMenu.reload,
      backgroundColor: (state) => state.App.theme.background_color,
    }),
    ...mapState('TimelineSpace/Contents/Notifications', {
      notifications: (state) => state.notifications,
      lazyLoading: (state) => state.lazyLoading,
      heading: (state) => state.heading,
      scrolling: (state) => state.scrolling,
    }),
    ...mapGetters('TimelineSpace/Contents/Notifications', [
      'handledNotifications',
      'filters',
    ]),
    ...mapGetters('TimelineSpace/Modals', ['modalOpened']),
    shortcutEnabled: function () {
      if (this.modalOpened) {
        return false
      }
      if (!this.focusedId) {
        return true
      }
      // Sometimes notifications are deleted, so perhaps focused notification don't exist.
      const currentIndex = this.handledNotifications.findIndex(
        (notification) => this.focusedId === notification.id
      )
      return currentIndex === -1
    },
  },
  mounted() {
    this.$store.commit(
      'TimelineSpace/SideMenu/changeUnreadNotifications',
      false
    )
    this.$store.dispatch('TimelineSpace/Contents/Notifications/resetBadge')
    document
      .getElementById('scroller')
      .addEventListener('scroll', this.onScroll)

    Event.$on('focus-timeline', () => {
      // If focusedId does not change, we have to refresh focusedId because Toot component watch change events.
      const previousFocusedId = this.focusedId
      this.focusedId = 0
      this.$nextTick(function () {
        this.focusedId = previousFocusedId
      })
    })

    if (this.heading && this.handledNotifications.length > 0) {
      this.$store.dispatch('TimelineSpace/Contents/Notifications/saveMarker')
    }
    const el = document.getElementById('scroller')
    this.scrollPosition = new ScrollPosition(el)
    this.scrollPosition.prepare()

    this.observer = new ResizeObserver(() => {
      if (
        this.loadingMore ||
        (this.scrollPosition &&
          !this.heading &&
          !this.lazyLoading &&
          !this.scrolling)
      ) {
        this.resizeTime = moment()
        this.scrollPosition.restore()
      }
    })

    const scrollWrapper = el.getElementsByClassName(
      'vue-recycle-scroller__item-wrapper'
    )[0]
    this.observer.observe(scrollWrapper)
  },
  beforeUpdate() {
    if (
      this.$store.state.TimelineSpace.SideMenu.unreadNotifications &&
      this.heading
    ) {
      this.$store.commit(
        'TimelineSpace/SideMenu/changeUnreadNotifications',
        false
      )
    }
    if (this.scrollPosition) {
      this.scrollPosition.prepare()
    }
  },
  beforeDestroy() {
    Event.$off('focus-timeline')
    this.observer.disconnect()
  },
  destroyed() {
    this.$store.commit(
      'TimelineSpace/Contents/Notifications/changeHeading',
      true
    )
    this.$store.commit(
      'TimelineSpace/Contents/Notifications/archiveNotifications'
    )
    if (
      document.getElementById('scroller') !== undefined &&
      document.getElementById('scroller') !== null
    ) {
      document
        .getElementById('scroller')
        .removeEventListener('scroll', this.onScroll)
      document.getElementById('scroller').scrollTop = 0
    }
  },
  watch: {
    startReload: function (newState, oldState) {
      if (!oldState && newState) {
        this.reload().finally(() => {
          this.$store.commit('TimelineSpace/HeaderMenu/changeReload', false)
        })
      }
    },
    focusedId: function (newState, _oldState) {
      if (newState >= 0 && this.heading) {
        this.$store.commit(
          'TimelineSpace/Contents/Notifications/changeHeading',
          false
        )
      } else if (newState === null && !this.heading) {
        this.$store.commit(
          'TimelineSpace/Contents/Notifications/changeHeading',
          true
        )
        this.$store.dispatch('TimelineSpace/Contents/Notifications/resetBadge')
      }
    },
    notifications: function (newState, _oldState) {
      if (this.heading && newState.length > 0) {
        this.$store.dispatch('TimelineSpace/Contents/Notifications/saveMarker')
      }
    },
  },
  methods: {
    onScroll(event) {
      if (moment().diff(this.resizeTime) < 500) {
        return
      }
      this.scrollTime = moment()
      if (!this.scrolling) {
        this.$store.commit(
          'TimelineSpace/Contents/Notifications/changeScrolling',
          true
        )
      }

      if (
        event.target.clientHeight + event.target.scrollTop >=
          document.getElementById('scroller').scrollHeight - 10 &&
        !this.lazyloading
      ) {
        this.$store
          .dispatch(
            'TimelineSpace/Contents/Notifications/lazyFetchNotifications',
            this.handledNotifications[this.handledNotifications.length - 1]
          )
          .then((statuses) => {
            if (statuses === null) {
              return
            }
            if (statuses.length > 0) {
              this.$store.commit(
                'TimelineSpace/Contents/Notifications/changeScrolling',
                true
              )
              setTimeout(() => {
                this.$store.commit(
                  'TimelineSpace/Contents/Notifications/changeScrolling',
                  false
                )
              }, 500)
            }
          })
          .catch(() => {
            this.$message({
              message: this.$t('message.notification_fetch_error'),
              type: 'error',
            })
          })
      }

      if (event.target.scrollTop > 10 && this.heading) {
        this.$store.commit(
          'TimelineSpace/Contents/Notifications/changeHeading',
          false
        )
      } else if (event.target.scrollTop <= 10 && !this.heading) {
        this.$store.commit(
          'TimelineSpace/Contents/Notifications/changeHeading',
          true
        )
        this.$store.dispatch('TimelineSpace/Contents/Notifications/resetBadge')
        this.$store.dispatch('TimelineSpace/Contents/Notifications/saveMarker')
      }

      setTimeout(() => {
        const now = moment()
        if (now.diff(this.scrollTime) >= 150) {
          this.scrollTime = null
          this.$store.commit(
            'TimelineSpace/Contents/Notifications/changeScrolling',
            false
          )
        }
      }, 150)
    },
    fetchNotificationsSince(since_id) {
      this.loadingMore = true
      this.$store
        .dispatch(
          'TimelineSpace/Contents/Notifications/fetchNotificationsSince',
          since_id
        )
        .finally(() => {
          setTimeout(() => {
            this.loadingMore = false
          }, 500)
        })
    },
    async reload() {
      this.$store.commit('TimelineSpace/changeLoading', true)
      try {
        await this.reloadable()
        this.$store.dispatch('TimelineSpace/Contents/Notifications/resetBadge')
      } finally {
        this.$store.commit('TimelineSpace/changeLoading', false)
      }
    },
    updateToot(message) {
      this.$store.commit(
        'TimelineSpace/Contents/Notifications/updateToot',
        message
      )
    },
    upper() {
      this.$refs.scroller.scrollToItem(0)
      this.focusedId = null
    },
    focusNext() {
      const currentIndex = this.handledNotifications.findIndex(
        (notification) => this.focusedId === notification.id
      )
      if (currentIndex === -1) {
        this.focusedId = this.handledNotifications[0].id
      } else if (currentIndex < this.handledNotifications.length) {
        this.focusedId = this.handledNotifications[currentIndex + 1].id
      }
    },
    focusPrev() {
      const currentIndex = this.handledNotifications.findIndex(
        (notification) => this.focusedId === notification.id
      )
      if (currentIndex === 0) {
        this.focusedId = null
      } else if (currentIndex > 0) {
        this.focusedId = this.handledNotifications[currentIndex - 1].id
      }
    },
    focusNotification(notification) {
      this.focusedId = notification.id
    },
    focusSidebar() {
      Event.$emit('focus-sidebar')
    },
    handleKey(event) {
      switch (event.srcKey) {
        case 'next':
          this.focusedId = this.handledNotifications[0].id
          break
      }
    },
  },
}
</script>

<style lang="scss" scoped>
#notifications {
  height: 100%;
  overflow: auto;
  scroll-behavior: auto;

  .scroller {
    height: 100%;
  }

  .loading-card {
    height: 60px;
  }

  .loading-card:empty {
    height: 0;
  }

  .upper {
    position: fixed;
    bottom: 20px;
    right: 20px;
  }

  .upper-with-side-bar {
    position: fixed;
    bottom: 20px;
    right: calc(20px + var(--current-sidebar-width));
    transition: all 0.5s;
  }
}
</style>

<style lang="scss" src="@/assets/timeline-transition.scss"></style>
