/**
 * ActivityStore（规范 §131）
 *
 * 职责：
 *   - 维护活动列表（首页 + 我的活动）
 *   - 维护活动报名状态 / 互选意向（AGENTS 第 6 条：单向意向保密）
 *   - 维护我报名的活动集合，用于徽标与"我的活动"页
 *
 * 不变量（AGENTS.md）：
 *   - 第 1 条：用户永久免费——活动 feeType=paid 字段仅作展示，前端不实现任何支付入口。
 *   - 第 6 条：活动单向意向保密——表达意向走 submitFeedback 的 interestTargetUserIds，
 *     其返回的 newMutuals 仅含双向匹配成功的人；未匹配的人不在前端可见；
 *     Store 不缓存"谁单独选了我"的字段。
 */
const BaseStore = require('./baseStore');
const { activityService } = require('../services');
const { ACTIVITY_STATUS, REGISTRATION_STATUS } = require('../constants');

class ActivityStore extends BaseStore {
  constructor() {
    super({
      /** @type {import('../types').Activity[]} */
      activities: [],
      activitiesCursor: null,
      activitiesHasMore: true,
      activitiesLoading: false,

      /** @type {import('../types').Activity[]} */
      myActivities: [],
      myActivitiesCursor: null,
      myActivitiesHasMore: true,
      myActivitiesLoading: false,

      /** @type {Record<string, import('../types').Activity>} 活动详情缓存 */
      detailCache: {},

      /** @type {Record<string, import('../types').RegistrationStatus>} activityId -> 报名状态 */
      registrationStatusByActivity: {},

      /** 我报名成功且未结束的活动数（徽标用） */
      myActiveCount: 0,

      lastError: null,
    });
  }

  /** 拉取活动列表（首页） */
  async fetchActivities(params = {}) {
    if (this.state.activitiesLoading) return;
    this.setState({ activitiesLoading: true, lastError: null });
    try {
      const result = await activityService.getActivities({
        status: ACTIVITY_STATUS.REGISTRATION_OPEN,
        ...params,
      });
      this.setState({
        activities: result.items || [],
        activitiesCursor: result.nextCursor || null,
        activitiesHasMore: !!result.nextCursor,
        activitiesLoading: false,
      });
      return result;
    } catch (err) {
      this.setState({ activitiesLoading: false, lastError: err });
      throw err;
    }
  }

  /** 加载更多活动 */
  async loadMoreActivities() {
    if (this.state.activitiesLoading || !this.state.activitiesCursor) return;
    this.setState({ activitiesLoading: true });
    try {
      const result = await activityService.getActivities({
        cursor: this.state.activitiesCursor,
        pageSize: 20,
      });
      this.setState({
        activities: [...this.state.activities, ...(result.items || [])],
        activitiesCursor: result.nextCursor || null,
        activitiesHasMore: !!result.nextCursor,
        activitiesLoading: false,
      });
    } catch (err) {
      this.setState({ activitiesLoading: false, lastError: err });
      throw err;
    }
  }

  /** 拉取我的活动 */
  async fetchMyActivities(params = {}) {
    if (this.state.myActivitiesLoading) return;
    this.setState({ myActivitiesLoading: true, lastError: null });
    try {
      const result = await activityService.getMyActivities(params);
      const items = result.items || [];
      this.setState({
        myActivities: items,
        myActivitiesCursor: result.nextCursor || null,
        myActivitiesHasMore: !!result.nextCursor,
        myActivitiesLoading: false,
        myActiveCount: items.filter(
          (a) =>
            a.registrationStatus === REGISTRATION_STATUS.APPROVED &&
            a.status !== ACTIVITY_STATUS.ENDED &&
            a.status !== ACTIVITY_STATUS.CANCELLED,
        ).length,
      });
      return result;
    } catch (err) {
      this.setState({ myActivitiesLoading: false, lastError: err });
      throw err;
    }
  }

  /** 加载更多我的活动 */
  async loadMoreMyActivities() {
    if (this.state.myActivitiesLoading || !this.state.myActivitiesCursor) return;
    this.setState({ myActivitiesLoading: true });
    try {
      const result = await activityService.getMyActivities({
        cursor: this.state.myActivitiesCursor,
        pageSize: 20,
      });
      this.setState({
        myActivities: [...this.state.myActivities, ...(result.items || [])],
        myActivitiesCursor: result.nextCursor || null,
        myActivitiesHasMore: !!result.nextCursor,
        myActivitiesLoading: false,
      });
    } catch (err) {
      this.setState({ myActivitiesLoading: false, lastError: err });
      throw err;
    }
  }

  /** 拉取活动详情（优先取缓存） */
  async fetchActivityDetail(activityId, { force = false } = {}) {
    if (!force && this.state.detailCache[activityId]) {
      return this.state.detailCache[activityId];
    }
    const detail = await activityService.getActivityDetail(activityId);
    this.setState({
      detailCache: { ...this.state.detailCache, [activityId]: detail },
      registrationStatusByActivity: {
        ...this.state.registrationStatusByActivity,
        [activityId]: detail.registrationStatus,
      },
    });
    return detail;
  }

  /**
   * 报名活动
   * @param {string} activityId
   * @param {{ remark?: string }} [payload]
   */
  async register(activityId, payload) {
    const result = await activityService.register(activityId, payload);
    this.setState({
      registrationStatusByActivity: {
        ...this.state.registrationStatusByActivity,
        [activityId]: REGISTRATION_STATUS.PENDING,
      },
    });
    return result;
  }

  /**
   * 提交活动反馈（含表达意向）
   *
   * 原有一个 `submitInterests(activityId, likedUserIds)` 已删除：它请求
   * `POST /activities/{id}/interests` —— **后端没有这个端点**（Phase 16 把
   * 表达意向合并进反馈流程，即本方法的 `interestTargetUserIds`），调用必然 404。
   * 全仓已确认它没有任何页面调用方，属 Phase 16 前的设计残留。
   * 若将来确实需要独立的"提交互选"接口，须由产品先定义语义再补后端端点，
   * 不应让前端留一个指向 404 的方法。
   */
  async submitFeedback(activityId, payload) {
    return activityService.submitFeedback(activityId, payload);
  }
}

const activityStore = new ActivityStore();
module.exports = activityStore;