'use client'
import { useState, useEffect, useMemo } from 'react'
import { ChevronLeft, ChevronRight, Plus, X, Clock, MapPin, Trash2, Eye, EyeOff } from 'lucide-react'

interface CalendarEvent {
  id: string
  title: string
  start: string
  end: string
  allDay: boolean
  description: string | null
  location: string | null
  owner: string
  ownerName: string
  color: string
}

const WEEKDAYS = ['Пн', 'Вт', 'Ср', 'Чт', 'Пт', 'Сб', 'Вс']
const MONTHS = ['Январь','Февраль','Март','Апрель','Май','Июнь','Июль','Август','Сентябрь','Октябрь','Ноябрь','Декабрь']

function AddEventModal({ defaultDate, onClose, onSaved }: { defaultDate: string; onClose: () => void; onSaved: (e: any) => void }) {
  const [title, setTitle] = useState('')
  const [date, setDate] = useState(defaultDate)
  const [startTime, setStartTime] = useState('10:00')
  const [endTime, setEndTime] = useState('11:00')
  const [allDay, setAllDay] = useState(false)
  const [saving, setSaving] = useState(false)
  const [error, setError] = useState('')

  const inputStyle = {
    padding: '12px 16px', borderRadius: 14,
    background: 'rgba(255,255,255,0.05)', border: '1px solid rgba(255,255,255,0.08)',
    color: 'var(--text-primary)', fontSize: 14, outline: 'none', fontFamily: 'inherit',
  }

  const save = async () => {
    if (!title.trim()) { setError('Введите название'); return }
    setSaving(true); setError('')
    try {
      const body = { title: title.trim(), date, startTime: allDay ? null : startTime, endTime: allDay ? null : endTime, allDay }
      const r = await fetch('/api/calendar', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify(body) })
      const d = await r.json()
      if (d.error) throw new Error(d.error)
      onSaved(d.event)
    } catch (e: any) { setError(e.message || 'Ошибка сохранения'); setSaving(false) }
  }

  return (
    <div style={{ position: 'fixed', inset: 0, background: 'rgba(0,0,0,0.6)', backdropFilter: 'blur(8px)', zIndex: 100, display: 'flex', alignItems: 'center', justifyContent: 'center', padding: 20 }} onClick={onClose}>
      <div style={{ background: 'rgba(18,18,35,0.95)', backdropFilter: 'blur(40px)', border: '1px solid rgba(255,255,255,0.08)', borderRadius: 24, padding: 28, maxWidth: 360, width: '100%', boxShadow: '0 25px 60px rgba(0,0,0,0.5)' }} onClick={e => e.stopPropagation()}>
        <div style={{ display: 'flex', justifyContent: 'space-between', marginBottom: 24 }}>
          <span style={{ fontSize: 18, fontWeight: 700, color: 'var(--text-primary)' }}>Новое событие</span>
          <button onClick={onClose} style={{ color: 'var(--text-secondary)', padding: 4 }}><X size={18} /></button>
        </div>
        <div style={{ display: 'flex', flexDirection: 'column', gap: 12 }}>
          <input value={title} onChange={e => setTitle(e.target.value)} placeholder="Название события" autoFocus style={inputStyle} />
          <input type="date" value={date} onChange={e => setDate(e.target.value)} style={inputStyle} />
          {!allDay && (
            <div style={{ display: 'flex', gap: 8 }}>
              <input type="time" value={startTime} onChange={e => setStartTime(e.target.value)} style={{ ...inputStyle, flex: 1 }} />
              <input type="time" value={endTime} onChange={e => setEndTime(e.target.value)} style={{ ...inputStyle, flex: 1 }} />
            </div>
          )}
          <label style={{ display: 'flex', alignItems: 'center', gap: 8, color: 'var(--text-secondary)', fontSize: 13, cursor: 'pointer' }}>
            <input type="checkbox" checked={allDay} onChange={e => setAllDay(e.target.checked)} /> Весь день
          </label>
          {error && <div style={{ color: '#f87171', fontSize: 13 }}>{error}</div>}
          <button onClick={save} disabled={saving} style={{
            padding: '13px', borderRadius: 14,
            background: saving ? 'rgba(99,102,241,0.2)' : 'linear-gradient(135deg, rgba(99,102,241,0.4), rgba(139,92,246,0.3))',
            border: '1px solid rgba(129,140,248,0.3)', color: '#a5b4fc', fontSize: 14, fontWeight: 600,
            cursor: saving ? 'default' : 'pointer',
          }}>
            {saving ? 'Сохранение...' : 'Создать событие'}
          </button>
        </div>
      </div>
    </div>
  )
}

export default function CalendarTab() {
  const [year, setYear] = useState(new Date().getFullYear())
  const [month, setMonth] = useState(new Date().getMonth())
  const [events, setEvents] = useState<CalendarEvent[]>([])
  const [loading, setLoading] = useState(true)
  const [selectedEvent, setSelectedEvent] = useState<CalendarEvent | null>(null)
  const [showAddModal, setShowAddModal] = useState(false)
  const [addDate, setAddDate] = useState<string>('')
  const [deleting, setDeleting] = useState(false)
  const [confirmDelete, setConfirmDelete] = useState(false)
  const [hiddenOwners, setHiddenOwners] = useState<Set<string>>(new Set())

  useEffect(() => {
    setLoading(true)
    fetch('/api/calendar?range=month&year=' + year + '&month=' + month)
      .then(r => r.json())
      .then(d => { setEvents(d.events || []); setLoading(false) })
      .catch(() => setLoading(false))
  }, [year, month])

  const deleteEvent = async (event: CalendarEvent) => {
    setDeleting(true)
    try {
      const r = await fetch(`/api/calendar?eventId=${event.id}`, { method: 'DELETE' })
      const d = await r.json()
      if (d.error) throw new Error(d.error)
      setEvents(prev => prev.filter(e => e.id !== event.id))
      setSelectedEvent(null)
      setConfirmDelete(false)
    } catch (e: any) { alert(e.message || 'Ошибка удаления') }
    finally { setDeleting(false) }
  }

  // Discover unique calendar owners from loaded events
  const calendarOwners = useMemo(() => {
    const map = new Map<string, { owner: string; ownerName: string; color: string; count: number }>()
    events.forEach(e => {
      const existing = map.get(e.owner)
      if (existing) { existing.count++ }
      else { map.set(e.owner, { owner: e.owner, ownerName: e.ownerName, color: e.color, count: 1 }) }
    })
    return Array.from(map.values())
  }, [events])

  const toggleOwner = (owner: string) => {
    setHiddenOwners(prev => {
      const next = new Set(prev)
      if (next.has(owner)) next.delete(owner)
      else next.add(owner)
      return next
    })
  }

  const filteredEvents = useMemo(() => {
    if (hiddenOwners.size === 0) return events
    return events.filter(e => !hiddenOwners.has(e.owner))
  }, [events, hiddenOwners])

  const upcoming = filteredEvents
    .filter(e => new Date(e.start) >= new Date())
    .slice(0, 6)

  const firstDay = new Date(year, month, 1)
  const lastDay = new Date(year, month + 1, 0)
  const startOffset = (firstDay.getDay() + 6) % 7
  const totalCells = Math.ceil((startOffset + lastDay.getDate()) / 7) * 7
  const cells: (number | null)[] = []
  for (let i = 0; i < totalCells; i++) {
    const dayNum = i - startOffset + 1
    cells.push(dayNum >= 1 && dayNum <= lastDay.getDate() ? dayNum : null)
  }

  const getEventsForDay = (day: number) => {
    return filteredEvents.filter(e => {
      const d = new Date(e.start)
      return d.getFullYear() === year && d.getMonth() === month && d.getDate() === day
    })
  }

  const prevMonth = () => { if (month === 0) { setMonth(11); setYear(y => y - 1) } else setMonth(m => m - 1) }
  const nextMonth = () => { if (month === 11) { setMonth(0); setYear(y => y + 1) } else setMonth(m => m + 1) }
  const today = new Date()

  return (
    <div style={{ flex: 1, display: 'flex', overflow: 'hidden', padding: '16px 24px 24px', gap: 20 }}>
      {/* Main calendar grid */}
      <div style={{ flex: 1, display: 'flex', flexDirection: 'column', minWidth: 0 }}>
        {/* Header */}
        <div style={{ display: 'flex', alignItems: 'center', justifyContent: 'space-between', marginBottom: 14 }}>
          <div style={{ display: 'flex', alignItems: 'center', gap: 12 }}>
            <button onClick={prevMonth} style={{ width: 36, height: 36, borderRadius: 12, background: 'rgba(255,255,255,0.04)', border: '1px solid rgba(255,255,255,0.06)', color: 'var(--text-primary)', display: 'flex', alignItems: 'center', justifyContent: 'center' }}>
              <ChevronLeft size={16} />
            </button>
            <span style={{ fontSize: 20, fontWeight: 700, color: 'var(--text-primary)', minWidth: 180, textAlign: 'center' }}>
              {MONTHS[month]} {year}
            </span>
            <button onClick={nextMonth} style={{ width: 36, height: 36, borderRadius: 12, background: 'rgba(255,255,255,0.04)', border: '1px solid rgba(255,255,255,0.06)', color: 'var(--text-primary)', display: 'flex', alignItems: 'center', justifyContent: 'center' }}>
              <ChevronRight size={16} />
            </button>
          </div>

          <div style={{ display: 'flex', alignItems: 'center', gap: 8 }}>
            {/* Calendar owner filters */}
            {calendarOwners.map(cal => {
              const isHidden = hiddenOwners.has(cal.owner)
              return (
                <button
                  key={cal.owner}
                  onClick={() => toggleOwner(cal.owner)}
                  style={{
                    display: 'flex', alignItems: 'center', gap: 6,
                    padding: '7px 14px', borderRadius: 12,
                    background: isHidden ? 'rgba(255,255,255,0.02)' : `${cal.color}15`,
                    border: `1px solid ${isHidden ? 'rgba(255,255,255,0.06)' : cal.color + '30'}`,
                    color: isHidden ? 'var(--text-tertiary)' : cal.color,
                    fontSize: 12, fontWeight: 600,
                    transition: 'all 0.25s ease',
                    opacity: isHidden ? 0.5 : 1,
                  }}
                >
                  {isHidden ? <EyeOff size={13} /> : <Eye size={13} />}
                  {cal.ownerName}
                  <span style={{
                    fontSize: 10, padding: '1px 6px', borderRadius: 6,
                    background: isHidden ? 'rgba(255,255,255,0.05)' : `${cal.color}20`,
                  }}>
                    {cal.count}
                  </span>
                </button>
              )
            })}

            <button
              onClick={() => { setAddDate(today.toISOString().split('T')[0]); setShowAddModal(true) }}
              style={{
                display: 'flex', alignItems: 'center', gap: 6,
                padding: '8px 18px', borderRadius: 14,
                background: 'linear-gradient(135deg, rgba(99,102,241,0.2), rgba(139,92,246,0.15))',
                border: '1px solid rgba(129,140,248,0.25)',
                color: '#a5b4fc', fontSize: 13, fontWeight: 600,
              }}
            >
              <Plus size={15} />
              Событие
            </button>
          </div>
        </div>

        {/* Weekday headers */}
        <div style={{ display: 'grid', gridTemplateColumns: 'repeat(7, 1fr)', marginBottom: 6 }}>
          {WEEKDAYS.map((d, i) => (
            <div key={d} style={{
              textAlign: 'center', fontSize: 11, fontWeight: 600,
              color: i >= 5 ? 'rgba(248,113,113,0.5)' : 'var(--text-secondary)',
              textTransform: 'uppercase', padding: '6px 0', letterSpacing: '0.05em',
            }}>{d}</div>
          ))}
        </div>

        {/* Calendar cells */}
        <div style={{ display: 'grid', gridTemplateColumns: 'repeat(7, 1fr)', flex: 1, gap: 3 }}>
          {cells.map((day, idx) => {
            if (!day) return <div key={idx} />
            const dayEvents = getEventsForDay(day)
            const isToday = today.getFullYear() === year && today.getMonth() === month && today.getDate() === day
            const dayOfWeek = (startOffset + day - 1) % 7
            const isWeekend = dayOfWeek >= 5
            return (
              <div
                key={idx}
                onClick={() => {
                  if (dayEvents.length === 1) setSelectedEvent(dayEvents[0])
                  else if (dayEvents.length === 0) {
                    setAddDate(`${year}-${String(month + 1).padStart(2, '0')}-${String(day).padStart(2, '0')}`)
                    setShowAddModal(true)
                  }
                }}
                style={{
                  borderRadius: 12, padding: '5px 4px',
                  background: isToday ? 'linear-gradient(135deg, rgba(99,102,241,0.15), rgba(139,92,246,0.08))' : 'rgba(255,255,255,0.015)',
                  border: isToday ? '1px solid rgba(129,140,248,0.3)' : '1px solid transparent',
                  cursor: 'pointer', minHeight: 56,
                  display: 'flex', flexDirection: 'column', gap: 2,
                  transition: 'all 0.2s ease',
                }}
              >
                <span style={{
                  fontSize: 12, fontWeight: isToday ? 700 : 500,
                  color: isToday ? '#a5b4fc' : isWeekend ? 'rgba(248,113,113,0.6)' : 'var(--text-secondary)',
                  textAlign: 'right', paddingRight: 4,
                }}>{day}</span>
                {dayEvents.slice(0, 2).map(e => (
                  <div key={e.id} onClick={ev => { ev.stopPropagation(); setSelectedEvent(e) }} style={{
                    fontSize: 10, fontWeight: 600,
                    background: e.color + '1a', border: `1px solid ${e.color}30`,
                    color: e.color, borderRadius: 6, padding: '2px 5px',
                    overflow: 'hidden', textOverflow: 'ellipsis', whiteSpace: 'nowrap', cursor: 'pointer',
                  }}>
                    {e.title}
                  </div>
                ))}
                {dayEvents.length > 2 && (
                  <div style={{ fontSize: 9, color: 'var(--text-secondary)', textAlign: 'center' }}>+{dayEvents.length - 2}</div>
                )}
              </div>
            )
          })}
        </div>
      </div>

      {/* Right panel */}
      <div style={{
        width: 220, flexShrink: 0, display: 'flex', flexDirection: 'column', gap: 10,
        overflowY: 'auto', background: 'rgba(255,255,255,0.02)', borderRadius: 22,
        padding: '20px 16px', border: '1px solid rgba(255,255,255,0.04)',
      }}>
        <div style={{ fontSize: 11, fontWeight: 600, color: 'var(--text-secondary)', textTransform: 'uppercase', letterSpacing: '0.1em', marginBottom: 4 }}>Ближайшие</div>
        {upcoming.length === 0 && !loading && (
          <div style={{ fontSize: 13, color: 'var(--text-secondary)', padding: '20px 0', textAlign: 'center' }}>Нет событий</div>
        )}
        {upcoming.map(e => {
          const d = new Date(e.start)
          return (
            <div key={e.id} onClick={() => setSelectedEvent(e)} style={{
              borderRadius: 16, padding: '14px',
              background: `${e.color}0c`, border: `1px solid ${e.color}1a`,
              cursor: 'pointer', transition: 'all 0.25s ease',
            }}>
              <div style={{ display: 'flex', alignItems: 'center', gap: 8, marginBottom: 8 }}>
                <div style={{ width: 32, height: 32, borderRadius: 10, background: `${e.color}1a`, display: 'flex', alignItems: 'center', justifyContent: 'center', flexShrink: 0 }}>
                  <span style={{ fontSize: 14, fontWeight: 700, color: e.color }}>{d.getDate()}</span>
                </div>
                <div style={{ fontSize: 10, color: e.color, fontWeight: 600 }}>{MONTHS[d.getMonth()].slice(0, 3)}</div>
              </div>
              <div style={{ fontSize: 13, fontWeight: 600, color: 'var(--text-primary)', overflow: 'hidden', textOverflow: 'ellipsis', whiteSpace: 'nowrap' }}>{e.title}</div>
              <div style={{ fontSize: 11, color: 'var(--text-secondary)', marginTop: 4 }}>
                {e.allDay ? 'Весь день' : d.toLocaleTimeString('ru-RU', { hour: '2-digit', minute: '2-digit' })}
              </div>
              <div style={{ fontSize: 10, color: e.color, marginTop: 4, fontWeight: 500 }}>{e.ownerName}</div>
            </div>
          )
        })}
      </div>

      {/* Event detail modal */}
      {selectedEvent && (
        <div style={{ position: 'fixed', inset: 0, background: 'rgba(0,0,0,0.6)', backdropFilter: 'blur(8px)', zIndex: 100, display: 'flex', alignItems: 'center', justifyContent: 'center', padding: 20 }} onClick={() => { setSelectedEvent(null); setConfirmDelete(false) }}>
          <div style={{
            background: 'rgba(18,18,35,0.95)', backdropFilter: 'blur(40px)',
            border: '1px solid rgba(255,255,255,0.08)', borderRadius: 24, padding: 28,
            maxWidth: 380, width: '100%', boxShadow: '0 25px 60px rgba(0,0,0,0.5)',
          }} onClick={e => e.stopPropagation()}>
            <div style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'flex-start', marginBottom: 20 }}>
              <div style={{ display: 'flex', gap: 14 }}>
                <div style={{ width: 4, borderRadius: 3, background: selectedEvent.color, alignSelf: 'stretch', minHeight: 44, flexShrink: 0 }} />
                <div>
                  <div style={{ fontSize: 18, fontWeight: 700, color: 'var(--text-primary)' }}>{selectedEvent.title}</div>
                  <div style={{ fontSize: 13, color: selectedEvent.color, fontWeight: 500, marginTop: 3 }}>{selectedEvent.ownerName}</div>
                </div>
              </div>
              <button onClick={() => { setSelectedEvent(null); setConfirmDelete(false) }} style={{ color: 'var(--text-secondary)', padding: 4 }}><X size={18} /></button>
            </div>
            <div style={{ display: 'flex', flexDirection: 'column', gap: 10 }}>
              <div style={{ display: 'flex', alignItems: 'center', gap: 10, padding: '10px 14px', borderRadius: 12, background: 'rgba(255,255,255,0.03)', color: 'var(--text-secondary)', fontSize: 13 }}>
                <Clock size={15} />
                {selectedEvent.allDay ? 'Весь день' : `${new Date(selectedEvent.start).toLocaleString('ru-RU', { day: 'numeric', month: 'long', hour: '2-digit', minute: '2-digit' })} — ${new Date(selectedEvent.end).toLocaleTimeString('ru-RU', { hour: '2-digit', minute: '2-digit' })}`}
              </div>
              {selectedEvent.location && (
                <div style={{ display: 'flex', alignItems: 'center', gap: 10, padding: '10px 14px', borderRadius: 12, background: 'rgba(255,255,255,0.03)', color: 'var(--text-secondary)', fontSize: 13 }}>
                  <MapPin size={15} /> {selectedEvent.location}
                </div>
              )}
              {selectedEvent.description && (
                <div style={{ fontSize: 13, color: 'var(--text-secondary)', marginTop: 4, lineHeight: 1.6 }}>{selectedEvent.description}</div>
              )}
              <div style={{ marginTop: 8, borderTop: '1px solid rgba(255,255,255,0.06)', paddingTop: 14 }}>
                {!confirmDelete ? (
                  <button onClick={() => setConfirmDelete(true)} style={{
                    display: 'flex', alignItems: 'center', gap: 6,
                    padding: '10px 14px', borderRadius: 12,
                    background: 'rgba(239,68,68,0.08)', border: '1px solid rgba(239,68,68,0.2)',
                    color: '#f87171', fontSize: 13, fontWeight: 600,
                    width: '100%', justifyContent: 'center',
                  }}>
                    <Trash2 size={14} /> Удалить событие
                  </button>
                ) : (
                  <div style={{ display: 'flex', gap: 8 }}>
                    <button onClick={() => deleteEvent(selectedEvent)} disabled={deleting} style={{
                      flex: 1, padding: '10px 14px', borderRadius: 12,
                      background: deleting ? 'rgba(239,68,68,0.1)' : 'rgba(239,68,68,0.2)',
                      border: '1px solid rgba(239,68,68,0.35)',
                      color: '#f87171', fontSize: 13, fontWeight: 600,
                    }}>
                      {deleting ? 'Удаление...' : 'Да, удалить'}
                    </button>
                    <button onClick={() => setConfirmDelete(false)} style={{
                      flex: 1, padding: '10px 14px', borderRadius: 12,
                      background: 'rgba(255,255,255,0.04)', border: '1px solid rgba(255,255,255,0.08)',
                      color: 'var(--text-secondary)', fontSize: 13, fontWeight: 600,
                    }}>
                      Отмена
                    </button>
                  </div>
                )}
              </div>
            </div>
          </div>
        </div>
      )}

      {showAddModal && (
        <AddEventModal
          defaultDate={addDate}
          onClose={() => setShowAddModal(false)}
          onSaved={(newEvent) => { setEvents(prev => [...prev, newEvent]); setShowAddModal(false) }}
        />
      )}
    </div>
  )
}
