const store = require('../../utils/store.js');
const api = require('../../utils/api.js');
const { toastErr } = require('../../utils/ui.js');

function pad2(n) {
  return n < 10 ? '0' + n : '' + n;
}
function ymd(d) {
  return d.getFullYear() + '-' + pad2(d.getMonth() + 1) + '-' + pad2(d.getDate());
}
// "2026-07-04" → "7月4日"
function fmtMD(date) {
  const p = (date || '').split('-');
  return p.length < 3 ? '' : +p[1] + '月' + +p[2] + '日';
}
function parseYMD(s) {
  const p = (s || '').split('-');
  return p.length < 3 ? null : new Date(+p[0], +p[1] - 1, +p[2]);
}

// 自然月网格。周一为一周起点，首尾补空格对齐星期。
// 按月切而不是「从计划开始日起 30 天」：那样窗口跨两个月，
// 用户看着一个 7月26日—8月25日 的日历，既不像本月也不像下月。
function buildCells(year, month, byDate, todayStr) {
  const first = new Date(year, month - 1, 1);
  const lead = (first.getDay() + 6) % 7;
  const total = new Date(year, month, 0).getDate();
  const cells = [];
  for (let i = 0; i < lead; i++) cells.push({ blank: true });
  for (let d = 1; d <= total; d++) {
    const s = year + '-' + pad2(month) + '-' + pad2(d);
    cells.push({ day: d, date: s, count: (byDate[s] || []).length, today: s === todayStr });
  }
  while (cells.length % 7) cells.push({ blank: true });
  return cells;
}

// off=0 本月，off=1 下月
function monthOf(off) {
  const n = new Date();
  const d = new Date(n.getFullYear(), n.getMonth() + off, 1);
  return { year: d.getFullYear(), month: d.getMonth() + 1 };
}
function monthEnd(off) {
  const m = monthOf(off);
  return m.year + '-' + pad2(m.month) + '-' + pad2(new Date(m.year, m.month, 0).getDate());
}

Page({
  data: {
    pet: {},
    plan: null,
    cells: [],
    monthOff: 0,
    monthLabel: '',
    monthEndLabel: '',
    nextCount: 0,
    pickStart: '',
    pickEnd: '',
    selDate: '',
    selLabel: '',
    dayTasks: [],
    editShow: false,
    editId: '',
    form: { title: '', date: '', description: '', daily: false },
    saving: false,
    sheetShow: false,
    sheetType: '',
  },
  onLoad() {
    this._unsub = store.subscribe((pet) => {
      this.setData({ pet });
      if (this._inited) this.load();
    });
  },
  onUnload() {
    if (this._unsub) this._unsub();
  },
  onShow() {
    store
      .ready()
      .then(() => {
        this._inited = true;
        this.setData({ pet: store.getPet() });
        this.load();
      })
      .catch((e) => toastErr(e));
  },
  load() {
    const id = store.currentPetId();
    if (!id) return;
    api
      .getPlan(id)
      .then((plan) => this.apply(plan))
      .catch(() => this.setData({ plan: null, cells: [], dayTasks: [] }));
  },
  apply(plan) {
    const tasks = plan.tasks || [];
    const byDate = {};
    tasks.forEach((t) => {
      if (!t.date) return;
      (byDate[t.date] = byDate[t.date] || []).push(t);
    });
    this._byDate = byDate;
    this.setData({
      plan: { ...plan, tasks },
      // 能排的区间：不早于计划开始日，不晚于下月月底。和后端 dayOffset 的校验一致
      pickStart: (plan.start_date || '').slice(0, 10),
      pickEnd: monthEnd(1),
    });
    this.renderMonth(this.data.monthOff);
    if (this._pendingSel) {
      // 刚加/改完，跳到那一天，不然用户看不到东西去哪了
      this.selectDay(this._pendingSel);
      this._pendingSel = '';
    }
  },
  renderMonth(off) {
    const m = monthOf(off);
    const todayStr = ymd(new Date());
    const byDate = this._byDate || {};
    const prefix = m.year + '-' + pad2(m.month);
    this.setData({
      monthOff: off,
      monthLabel: m.year + ' 年 ' + m.month + ' 月',
      monthEndLabel: fmtMD(monthEnd(off)),
      cells: buildCells(m.year, m.month, byDate, todayStr),
      nextCount: Object.keys(byDate).filter((d) => d.indexOf(monthOf(1).year + '-' + pad2(monthOf(1).month)) === 0)
        .reduce((n, d) => n + byDate[d].length, 0),
    });
    // 切到本月默认选今天；切到下月默认选 1 号（今天不在那个月里）
    const inMonth = todayStr.indexOf(prefix) === 0;
    this.selectDay(inMonth ? todayStr : prefix + '-01', todayStr);
  },
  switchMonth(e) {
    this.renderMonth(Number(e.currentTarget.dataset.off));
  },
  selectDay(date, todayStr) {
    const t = todayStr || ymd(new Date());
    this.setData({
      selDate: date,
      selLabel: date === t ? '今天的安排' : fmtMD(date) + '的安排',
      dayTasks: (this._byDate || {})[date] || [],
    });
  },
  onTapDay(e) {
    const d = e.currentTarget.dataset.date;
    if (d) this.selectDay(d);
  },

  toggleTask(e) {
    api
      .togglePlanTask(e.currentTarget.dataset.id)
      .then(() => this.load())
      .catch((err) => toastErr(err, '操作失败'));
  },

  // ── 加 / 改 ──
  openAdd() {
    this.setData({
      editShow: true, editId: '',
      form: { title: '', date: this.data.selDate || ymd(new Date()), description: '', daily: false },
    });
  },
  openEdit(e) {
    const t = (this.data.dayTasks || []).find((x) => x.id === e.currentTarget.dataset.id);
    if (!t) return;
    this.setData({
      editShow: true, editId: t.id,
      form: { title: t.title, date: t.date || this.data.selDate, description: t.description || '', daily: false },
    });
  },
  closeEdit() {
    this.setData({ editShow: false });
  },
  noop() {},
  onFormTitle(e) {
    this.setData({ 'form.title': e.detail.value });
  },
  onFormDate(e) {
    this.setData({ 'form.date': e.detail.value });
  },
  onFormDesc(e) {
    this.setData({ 'form.description': e.detail.value });
  },
  onFormDaily(e) {
    this.setData({ 'form.daily': e.detail.value });
  },
  onSubmit() {
    if (this.data.saving) return;
    const f = this.data.form;
    if (!(f.title || '').trim()) return wx.showToast({ title: '写一下做什么', icon: 'none' });
    const id = store.currentPetId();
    if (!id) return;
    this.setData({ saving: true });
    const req = this.data.editId
      ? api.updatePlanTask(this.data.editId, f)
      : api.addPlanTask(id, f);
    req
      .then(() => {
        this.setData({ saving: false, editShow: false });
        // 加完/改完要跳到那一天，不然用户改了日期却看不到东西去哪了
        this._pendingSel = f.date;
        this.load();
      })
      .catch((e) => {
        this.setData({ saving: false });
        toastErr(e, '保存失败');
      });
  },
  onDelete(e) {
    const { id, title } = e.currentTarget.dataset;
    wx.showModal({
      title: '删掉这件事？',
      content: title || '',
      confirmColor: '#EE7D73',
      success: (r) => {
        if (!r.confirm) return;
        api
          .deletePlanTask(id)
          .then(() => this.load())
          .catch((err) => toastErr(err, '删除失败'));
      },
    });
  },

  closeSheet() {
    this.setData({ sheetShow: false });
  },
  onAddPet() {
    wx.navigateTo({ url: '/pages/petform/petform' });
  },
  onShareAppMessage() {
    return { title: '我给毛孩子做了份养护计划', path: '/pages/plan/plan' };
  },
  onShareTimeline() {
    return { title: '我给毛孩子做了份养护计划' };
  },
});