/**
 * 找对象页 U19-U20（重构：用 ui-user-card + matchStore.like + recommendationService.discover）
 *
 * 不变量（AGENTS.md）：
 *   - 第 2 条：Required 不可自动放宽——Discover 搜索仅透传筛选条件到后端，
 *     由后端按 PartnerPreference 做硬约束过滤，前端不做任何"放宽再查"。
 *   - 第 4 条：Block 即时禁止互动——本页 Like 后由 matchStore 从列表移除。
 *   - 第 6 条：单向意向不泄露——Pass/Like 未 Mutual 时对方不收到通知。
 *   - 第 9 条：PostgreSQL 是 Source of Truth——搜索结果不在 Store 持久化，
 *     列表状态为页面局部状态（BaseStore 原则 2）。
 */
const { matchStore, appStore, authStore } = require('../../stores');
const { recommendationService } = require('../../services');
const { to } = require('../../constants');

const DEFAULT_AGE_MIN = 18;
const DEFAULT_AGE_MAX = 60;
const PAGE_SIZE = 20;

Page({
  data: {
    users: [],
    loading: false,
    loadingMore: false,
    cursor: null,
    hasMore: true,

    // 搜索栏关键词（编辑中）
    keywordInput: '',
    showFilter: false,

    // 临时筛选（编辑中）
    tempRegion: '',
    tempAgeMin: DEFAULT_AGE_MIN,
    tempAgeMax: DEFAULT_AGE_MAX,

    // 已应用筛选
    applied: { keyword: '', region: '', ageMin: DEFAULT_AGE_MIN, ageMax: DEFAULT_AGE_MAX },
    hasActiveFilter: false,

    regions: ['丹阳', '镇江', '南京'],
    actionLoadingUserId: '',

    emptyActions: [
      { text: '清空筛选', event: 'reset', variant: 'primary' },
      { text: '去今日推荐', event: 'home', variant: 'secondary' },
    ],
  },

  onLoad() {
    if (!authStore.state.isLoggedIn) return;
    this.fetchDiscover(true);
  },

  /** 拉取搜索结果（首页） */
  async fetchDiscover(first) {
    if (this.data.loading) return;
    this.setData({ loading: true });
    try {
      const result = await recommendationService.discover(this._buildParams());
      const items = result.items || [];
      this.setData({
        users: first ? items : [...this.data.users, ...items],
        cursor: result.nextCursor || null,
        hasMore: !!result.nextCursor,
        loading: false,
      });
    } catch (err) {
      this.setData({ loading: false });
      appStore.toastError(err);
    }
  },

  /** 加载更多 */
  async loadMore() {
    if (this.data.loadingMore || !this.data.hasMore || !this.data.cursor) return;
    this.setData({ loadingMore: true });
    try {
      const result = await recommendationService.discover({
        ...this._buildParams(),
        cursor: this.data.cursor,
      });
      const items = result.items || [];
      this.setData({
        users: [...this.data.users, ...items],
        cursor: result.nextCursor || null,
        hasMore: !!result.nextCursor,
      });
    } catch (err) {
      appStore.toastError(err);
    } finally {
      this.setData({ loadingMore: false });
    }
  },

  /** 构造请求参数（仅透传，后端守 Required 硬约束） */
  _buildParams() {
    const { applied } = this.data;
    const params = { pageSize: PAGE_SIZE };
    if (applied.keyword) params.keyword = applied.keyword;
    if (applied.region) params.region = applied.region;
    if (applied.ageMin !== DEFAULT_AGE_MIN) params.ageMin = applied.ageMin;
    if (applied.ageMax !== DEFAULT_AGE_MAX) params.ageMax = applied.ageMax;
    return params;
  },

  // ============ 搜索栏 ============

  onKeywordInput(e) {
    this.setData({ keywordInput: e.detail.value });
  },

  /** 关键词搜索（键盘确认或点搜索图标） */
  onSearch() {
    const keyword = (this.data.keywordInput || '').trim();
    const applied = { ...this.data.applied, keyword };
    this.setData({
      applied,
      hasActiveFilter: this._hasActiveFilter(applied),
    });
    this.fetchDiscover(true);
  },

  // ============ 筛选面板 ============

  toggleFilter() {
    this.setData({ showFilter: !this.data.showFilter });
  },

  onRegionTap(e) {
    const val = e.currentTarget.dataset.val;
    this.setData({ tempRegion: this.data.tempRegion === val ? '' : val });
  },

  onMinAgeChange(e) {
    let min = e.detail.value;
    if (min > this.data.tempAgeMax) min = this.data.tempAgeMax;
    this.setData({ tempAgeMin: min });
  },

  onMaxAgeChange(e) {
    let max = e.detail.value;
    if (max < this.data.tempAgeMin) max = this.data.tempAgeMin;
    this.setData({ tempAgeMax: max });
  },

  onApplyFilter() {
    const { tempRegion, tempAgeMin, tempAgeMax, keywordInput } = this.data;
    const applied = {
      keyword: (keywordInput || '').trim(),
      region: tempRegion,
      ageMin: tempAgeMin,
      ageMax: tempAgeMax,
    };
    this.setData({
      applied,
      hasActiveFilter: this._hasActiveFilter(applied),
      showFilter: false,
    });
    this.fetchDiscover(true);
  },

  onResetFilter() {
    const applied = { keyword: '', region: '', ageMin: DEFAULT_AGE_MIN, ageMax: DEFAULT_AGE_MAX };
    this.setData({
      keywordInput: '',
      tempRegion: '',
      tempAgeMin: DEFAULT_AGE_MIN,
      tempAgeMax: DEFAULT_AGE_MAX,
      applied,
      hasActiveFilter: false,
      showFilter: false,
    });
    this.fetchDiscover(true);
  },

  _hasActiveFilter(applied) {
    return !!(
      applied.keyword ||
      applied.region ||
      applied.ageMin !== DEFAULT_AGE_MIN ||
      applied.ageMax !== DEFAULT_AGE_MAX
    );
  },

  onEmptyAction(e) {
    const { event } = e.detail || {};
    if (event === 'reset') {
      this.onResetFilter();
    } else if (event === 'home') {
      wx.switchTab({ url: '/pages/index/index' });
    }
  },

  // ============ 卡片操作 ============

  /** 卡片点击：查看资料 */
  onViewDetail(e) {
    const { userId } = e.detail || {};
    if (!userId) return;
    wx.navigateTo({ url: to.detail(userId) });
  },

  /** 喜欢（actions slot 按钮，catchtap 阻止冒泡到卡片） */
  async onLike(e) {
    const userId = e.currentTarget.dataset.userId;
    if (!userId || this.data.actionLoadingUserId) return;
    this.setData({ actionLoadingUserId: userId });
    try {
      const result = await matchStore.like(userId);
      // 从列表移除（无论是否 Mutual，已做出判断）
      this.setData({ users: this.data.users.filter((u) => u.userId !== userId) });
      if (result && result.mutualMatch) {
        appStore.toastSuccess('双向喜欢！可以开始聊天了');
        if (result.matchedConversationId) {
          wx.navigateTo({ url: to.chat(result.matchedConversationId) });
        }
      } else {
        appStore.toastSuccess('已表达喜欢');
      }
    } catch (err) {
      appStore.toastError(err);
    } finally {
      this.setData({ actionLoadingUserId: '' });
    }
  },

  // ============ 列表交互 ============

  onPullDownRefresh() {
    this.fetchDiscover(true).finally(() => wx.stopPullDownRefresh());
  },

  onReachBottom() {
    this.loadMore();
  },
});