// pages/walking/walking — 2/2b 遛狗中（进行/暂停同页）
// 计时基于时间戳差值（切后台不丢，R5）；GPS 距离可选累计、按 stride 换算狗步（R3/R6）
const { call } = require('../../utils/cloud.js');
const store = require('../../utils/store.js');
const { formatDuration } = require('../../utils/format.js');
const { BASE_STRIDE, dogStepsFromMeters } = require('../../utils/dogStep.js');

// 两点球面距离（米）
function haversine(lat1, lon1, lat2, lon2) {
  const R = 6371000;
  const toRad = (d) => (d * Math.PI) / 180;
  const dLat = toRad(lat2 - lat1);
  const dLon = toRad(lon2 - lon1);
  const a = Math.sin(dLat / 2) ** 2 +
    Math.cos(toRad(lat1)) * Math.cos(toRad(lat2)) * Math.sin(dLon / 2) ** 2;
  return 2 * R * Math.asin(Math.sqrt(a));
}

Page({
  data: {
    status: 'idle',        // idle | selecting | walking | paused
    timeText: '00:00',
    pooped: false,
    dogs: [],
    selectedIds: [],
    selectedMap: {},       // id→true：供 WXML 判断选中（WXML 表达式不能调用 indexOf）
    activeDogNames: '',
    showEndConfirm: false,
    gps: 'off',            // off | on | denied
    distanceText: '—',
    stepsText: '—',
  },

  _timer: null,
  _locOn: false,
  _locCb: null,
  _lastPoint: null,
  _stride: 0.35,

  onLoad() {
    const dogs = store.getState().dogs || [];
    this.setData({ dogs });

    const session = store.getWalkSession();
    if (session) { this.resumeFrom(session); return; }
    if (dogs.length === 0) {
      wx.showToast({ title: '先添加一只狗狗', icon: 'none' });
      setTimeout(() => wx.navigateBack(), 1200);
      return;
    }
    if (dogs.length === 1) this.startSession([dogs[0]._id]);
    else {
      const def = store.getState().currentDogId || dogs[0]._id;
      this.setData({ status: 'selecting', selectedIds: [def], selectedMap: this.buildSelectMap([def]) });
    }
  },

  onUnload() { this.clearTimer(); this.stopLocation(); },

  // ===== 多狗选择 =====
  // WXML 表达式不支持方法调用（如 selectedIds.indexOf），用 id→true 映射给视图层判断选中
  buildSelectMap(ids) {
    const map = {};
    ids.forEach((id) => { map[id] = true; });
    return map;
  },
  toggleSelect(e) {
    const id = e.currentTarget.dataset.id;
    const ids = this.data.selectedIds.slice();
    const i = ids.indexOf(id);
    if (i >= 0) ids.splice(i, 1); else ids.push(id);
    this.setData({ selectedIds: ids, selectedMap: this.buildSelectMap(ids) });
  },
  confirmSelect() {
    if (!this.data.selectedIds.length) return wx.showToast({ title: '至少选一只', icon: 'none' });
    this.startSession(this.data.selectedIds);
  },

  // ===== 会话生命周期 =====
  startSession(dogIds) {
    const session = { dogIds, startAt: Date.now(), pausedTotal: 0, pausedAt: null, pooped: false, meters: 0, status: 'walking' };
    store.setWalkSession(session);
    store.set({ currentDogId: dogIds[0] });
    this.setActiveNames(dogIds);
    this.setData({ status: 'walking', pooped: false });
    this.startTimer();
    this.startLocation();
  },

  resumeFrom(session) {
    this.setActiveNames(session.dogIds);
    this.setData({ status: session.status, pooped: session.pooped });
    if (session.status === 'walking') { this.startTimer(); this.startLocation(); }
    else this.renderTime();
    this.refreshGps();
  },

  setActiveNames(dogIds) {
    const map = {};
    (this.data.dogs || []).forEach((d) => { map[d._id] = d.name; });
    this.setData({ activeDogNames: dogIds.map((id) => map[id] || '狗狗').join('、') });
  },

  // ===== 计时（时间戳差值）=====
  elapsedSec() {
    const s = store.getWalkSession();
    if (!s) return 0;
    const end = s.status === 'paused' ? s.pausedAt : Date.now();
    return Math.max(0, Math.floor((end - s.startAt - s.pausedTotal) / 1000));
  },
  renderTime() { this.setData({ timeText: formatDuration(this.elapsedSec()) }); },
  startTimer() { this.clearTimer(); this.renderTime(); this._timer = setInterval(() => this.renderTime(), 1000); },
  clearTimer() { if (this._timer) { clearInterval(this._timer); this._timer = null; } },

  // ===== GPS 距离累计（可选增强，R6）=====
  startLocation() {
    if (this._locOn) return;
    const s = store.getWalkSession();
    const primary = (this.data.dogs || []).find((d) => s && d._id === s.dogIds[0]);
    this._stride = (primary && (primary.stride || BASE_STRIDE[primary.sizeLevel])) || 0.35;
    this._lastPoint = null;
    this._locCb = (res) => this.onLoc(res);
    wx.startLocationUpdate({
      success: () => {
        this._locOn = true;
        wx.onLocationChange(this._locCb);
        this.setData({ gps: 'on' });
        this.refreshGps();
      },
      fail: () => { this.setData({ gps: 'denied' }); }, // 未授权 → 降级，只保留时长
    });
  },
  onLoc(res) {
    const s = store.getWalkSession();
    if (!s || s.status !== 'walking') { this._lastPoint = null; return; } // 暂停不累计
    if (res.accuracy && res.accuracy > 50) return;                        // 精度差丢弃
    const p = { lat: res.latitude, lon: res.longitude };
    if (this._lastPoint) {
      const seg = haversine(this._lastPoint.lat, this._lastPoint.lon, p.lat, p.lon);
      if (seg >= 2 && seg <= 50) { // 过滤静止抖动(<2m)与跳点(>50m)
        s.meters = (s.meters || 0) + seg;
        store.setWalkSession(s);
        this.refreshGps();
      }
    }
    this._lastPoint = p;
  },
  refreshGps() {
    if (this.data.gps !== 'on') return;
    const s = store.getWalkSession();
    const m = (s && s.meters) || 0;
    this.setData({
      distanceText: (m / 1000).toFixed(2),
      stepsText: String(dogStepsFromMeters(m, this._stride) || 0),
    });
  },
  stopLocation() {
    if (this._locOn) {
      wx.offLocationChange(this._locCb);
      wx.stopLocationUpdate();
      this._locOn = false;
    }
  },

  // ===== 便便打卡 =====
  togglePoop() {
    const s = store.getWalkSession();
    if (!s) return;
    s.pooped = !s.pooped;
    store.setWalkSession(s);
    this.setData({ pooped: s.pooped });
  },

  // ===== 暂停 / 继续 =====
  pause() {
    const s = store.getWalkSession();
    if (!s || s.status !== 'walking') return;
    s.status = 'paused';
    s.pausedAt = Date.now();
    store.setWalkSession(s);
    this.clearTimer();
    this._lastPoint = null;
    this.setData({ status: 'paused' });
    this.renderTime();
  },
  resume() {
    const s = store.getWalkSession();
    if (!s || s.status !== 'paused') return;
    s.pausedTotal += Date.now() - s.pausedAt;
    s.pausedAt = null;
    s.status = 'walking';
    store.setWalkSession(s);
    this.setData({ status: 'walking' });
    this.startTimer();
  },

  // ===== 结束 =====
  askEnd() { this.setData({ showEndConfirm: true }); },
  cancelEnd() { this.setData({ showEndConfirm: false }); },

  async confirmEnd() {
    const s = store.getWalkSession();
    if (!s) return;
    this.clearTimer();
    this.stopLocation();
    const duration = this.elapsedSec();
    const endAt = Date.now();
    const distanceMeters = this.data.gps === 'on' ? Math.round(s.meters || 0) : null;
    this.setData({ showEndConfirm: false });

    const res = await call('walkSave', {
      action: 'finish',
      dogIds: s.dogIds,
      startAt: s.startAt,
      endAt,
      duration,
      distanceMeters,   // 米；未授权定位时为 null（R6）
      pooped: s.pooped,
    }, { loading: true, loadingText: '生成成果卡' });
    if (!res.ok) return;

    store.setWalkSession(null);
    getApp().globalData.lastSummary = res.data;
    wx.redirectTo({ url: '/pages/summary/summary' });
  },
});