import { useCallback, useEffect, useMemo, useState } from 'react'
import { Button, DotLoading, Empty, Segmented, Toast } from 'antd-mobile'
import { Celebrate } from '../../components/RingProgress.jsx'
import { checkinApi } from '../../api/checkin.js'
import useRefreshOnVisible from '../../hooks/useRefreshOnVisible.js'
import {
  toDateStr, addDays, addMonths, monthGrid, weekdayLabels, dayLabel, fmtMonth,
} from './date.js'

// 日历视图: 月历网格 + 今天/昨天/明天 三视图 + 日期标记 (F-CL-*)
export default function CalendarView({ date, onDateChange }) {
  const today = toDateStr()
  const [month, setMonth] = useState(() => date.slice(0, 7))
  const [cal, setCal] = useState(null)     // 月历数据
  const [detail, setDetail] = useState(null) // 选中日详情
  const [err, setErr] = useState('')
  const [bursts, setBursts] = useState({})

  const loadCal = useCallback((silent) => {
    if (!silent) setErr('')
    checkinApi.calendar(month)
      .then(setCal)
      .catch((e) => { if (!silent) setErr(e.message) })
  }, [month])

  const loadDetail = useCallback((silent) => {
    checkinApi.day(date).then(setDetail).catch(() => {})
  }, [date])

  useEffect(() => { loadCal(false) }, [loadCal])
  useEffect(() => { setDetail(null); loadDetail(false) }, [loadDetail])
  useRefreshOnVisible(() => { loadCal(true); loadDetail(true) })

  // 切换日期时, 若跨月则同步月份
  useEffect(() => {
    const m = date.slice(0, 7)
    setMonth((cur) => (cur === m ? cur : m))
  }, [date])

  const days = useMemo(() => monthGrid(month), [month])
  const byDate = useMemo(() => {
    const map = new Map()
    ;(cal?.days || []).forEach((d) => map.set(d.date, d))
    return map
  }, [cal])

  const quickValue = useMemo(() => {
    if (date === today) return 0
    if (date === addDays(today, -1)) return -1
    if (date === addDays(today, 1)) return 1
    return null
  }, [date, today])

  async function checkFromCalendar(item) {
    if (!item.canCheck) return
    const snapshot = detail
    setDetail((d) => ({
      ...d,
      items: d.items.map((x) => {
        if (x.id !== item.id) return x
        const done = x.done + 1
        const countOnDate = (x.countOnDate || 0) + 1
        return {
          ...x, done, countOnDate,
          percent: Math.min(1, done / x.target),
          completed: done >= x.target,
          over: Math.max(0, done - x.target),
          dayDone: countOnDate >= x.expectedPerDay,
        }
      }),
    }))
    try {
      const res = await checkinApi.check(item.id, date)
      const fresh = await checkinApi.day(date)
      setDetail(fresh)
      if (res.item.completed) setBursts((m) => ({ ...m, [item.id]: (m[item.id] || 0) + 1 }))
      loadCal(true)
    } catch (e) {
      setDetail(snapshot)
      Toast.show({ content: e.message || '打卡失败' })
    }
  }

  const items = detail?.items || []
  const isFuture = !!detail?.isFuture

  return (
    <div className="calendar-view">
      <div className="cal-month-bar">
        <span className="cal-arrow" onClick={() => setMonth((m) => addMonths(m, -1))}>‹</span>
        <span className="cal-month">{fmtMonth(month)}</span>
        <span className="cal-arrow" onClick={() => setMonth((m) => addMonths(m, 1))}>›</span>
        <span className="cal-today-btn" onClick={() => onDateChange(today)}>回到今天</span>
      </div>

      <div className="cal-quick">
        <Segmented
          options={[
            { label: '昨天', value: -1 },
            { label: '今天', value: 0 },
            { label: '明天', value: 1 },
          ]}
          value={quickValue}
          onChange={(v) => onDateChange(addDays(today, Number(v)))}
        />
      </div>

      {err && <div className="error-banner">{err}<span className="retry-link" onClick={() => loadCal(false)}>重试</span></div>}

      <div className="cal-grid">
        <div className="cal-weekday">
          {weekdayLabels().map((w) => <span key={w}>{w}</span>)}
        </div>
        <div className="cal-days">
          {days.map((d) => {
            const info = byDate.get(d)
            const inMonth = d.slice(0, 7) === month
            const status = info?.status || 'empty'
            return (
              <div
                key={d}
                className={
                  'cal-day' + (inMonth ? '' : ' out') + (d === date ? ' selected' : '') +
                  (info?.isToday ? ' today' : '') + (info?.isFuture ? ' future' : '')
                }
                onClick={() => onDateChange(d)}
              >
                <span className="cal-day-num">{Number(d.slice(8, 10))}</span>
                {inMonth && status !== 'empty' && (
                  <span className={'cal-dot ' + status} />
                )}
              </div>
            )
          })}
        </div>
      </div>

      {cal && (
        <div className="cal-rate">本月完成率 <strong>{Math.round((cal.rate || 0) * 100)}%</strong></div>
      )}

      <div className="cal-detail">
        <div className="cal-detail-title">
          {dayLabel(date, today)} · {date}
          {isFuture && <span className="habit-badge">计划（不可打卡）</span>}
        </div>

        {detail === null && <div className="monitor-loading"><DotLoading /> 加载中...</div>}
        {detail !== null && items.length === 0 && <Empty description="当天没有打卡项" />}

        {items.map((item) => (
          <div key={item.id} className={'cal-item' + (item.completed ? ' done' : '')}>
            <span className="cal-item-dot" style={{ background: item.color }} />
            <span className="cal-item-name">{item.name}</span>
            <span className="cal-item-meta">
              {item.periodLabel} {item.target} 次 · 当日 {item.countOnDate || 0}/{item.expectedPerDay}
            </span>
            <span className="cal-item-right">
              {item.canCheck ? (
                <Button size="mini" color={item.dayDone ? 'default' : 'primary'} onClick={() => checkFromCalendar(item)}>
                  {item.dayDone ? '已达标' : '打卡'}
                </Button>
              ) : (
                <span className="cal-item-plan">{item.dayDone ? '计划' : '待办'}</span>
              )}
            </span>
            <Celebrate fire={bursts[item.id] || 0} color={item.color} />
          </div>
        ))}
      </div>
    </div>
  )
}