import { useState } from 'react'
import {
  Drawer, Box, Typography, IconButton, Chip, Divider,
  TextField, Button, Select, MenuItem, FormControl, InputLabel, Autocomplete,
} from '@mui/material'
import { X, Calendar, Activity, FileText, ExternalLink, Eye } from 'lucide-react'
import { useReminderStore } from '../../stores/reminderStore'
import {
  useReminder, useCompleteReminder, useDismissReminder,
  useSnoozeReminder, useCreateReminder,
} from '../../hooks/useReminders'
import { usePropertyById, useProperties } from '../../hooks/useProperties'
import { ReminderPriorityBadge } from './ReminderPriorityBadge'
import { ReminderTypeBadge } from './ReminderTypeBadge'
import { ReminderDaysIndicator } from './ReminderDaysIndicator'
import { ReminderStatus, ReminderType, ReminderPriority } from '../../domain/reminder'
import type { Property } from '../../domain/property'
import {
  SHADOW_RISK_COLOR, SHADOW_RISK_LABEL,
  STATUS_CHIP_COLOR, STATUS_LABEL,
  SectionTitle, DateRow, ActivityEntry,
} from './reminderDetailHelpers'

// ── Constants ────────────────────────────────────────────────────────────────

const TYPE_LABELS: Record<ReminderType, string> = {
  LEASE_EXPIRY:          'Mietablauf',
  BREAK_OPTION:          'Break-Option',
  RENT_REVIEW:           'Mietanpassung',
  INSPECTION:            'Inspektion',
  INSURANCE_RENEWAL:     'Versicherung',
  MAINTENANCE:           'Unterhalt',
  SCHATTENMARKT_RELEASE: 'Pre-Market',
  CUSTOM:                'Individuell',
}

const TYPE_SECOND_DATE: Partial<Record<ReminderType, 'contractEndDate' | 'breakOptionDate' | 'eventDate'>> = {
  [ReminderType.LEASE_EXPIRY]:          'contractEndDate',
  [ReminderType.BREAK_OPTION]:          'breakOptionDate',
  [ReminderType.RENT_REVIEW]:           'eventDate',
  [ReminderType.SCHATTENMARKT_RELEASE]: 'eventDate',
}

const TYPE_SECOND_LABEL: Partial<Record<ReminderType, string>> = {
  [ReminderType.LEASE_EXPIRY]:          'Vertragsende',
  [ReminderType.BREAK_OPTION]:          'Break-Option',
  [ReminderType.RENT_REVIEW]:           'Ereignisdatum',
  [ReminderType.SCHATTENMARKT_RELEASE]: 'Ereignisdatum',
}

const MOCK_TODAY = new Date('2026-05-20')

function calcPriority(dueDateStr: string): ReminderPriority {
  const days = Math.ceil((new Date(dueDateStr).getTime() - MOCK_TODAY.getTime()) / (1000 * 60 * 60 * 24))
  if (days <= 14) return ReminderPriority.URGENT
  if (days <= 30) return ReminderPriority.HIGH
  if (days <= 60) return ReminderPriority.MEDIUM
  return ReminderPriority.LOW
}

// ── Create Form ───────────────────────────────────────────────────────────────

function CreateForm({ onClose }: { onClose: () => void }) {
  const { data: properties = [] } = useProperties()
  const create = useCreateReminder()

  const [type, setType] = useState<ReminderType>(ReminderType.LEASE_EXPIRY)
  const [selectedProperty, setSelectedProperty] = useState<Property | null>(null)
  const [tenantName, setTenantName] = useState('')
  const [dueDate, setDueDate] = useState('')
  const [note, setNote] = useState('')

  function handlePropertyChange(_: unknown, prop: Property | null) {
    setSelectedProperty(prop)
    setTenantName(prop?.currentTenant ?? '')
  }

  function handleSubmit() {
    if (!selectedProperty || !dueDate) return
    create.mutate(
      {
        type,
        priority: calcPriority(dueDate),
        status: ReminderStatus.ACTIVE,
        propertyId: selectedProperty.id,
        propertyTitle: selectedProperty.title,
        propertyCity: selectedProperty.location.city,
        propertyDistrict: selectedProperty.location.district,
        tenantName: tenantName || '—',
        dueDate,
        eventDate: dueDate,
        areaSqm: selectedProperty.areaSqm,
        currentRentPerSqm: selectedProperty.rentPricePerSqm,
        currency: 'CHF',
        shadowMarketRisk: 'NONE',
        schattenmarktEnabled: false,
        note: note || undefined,
        organizationId: selectedProperty.organizationId ?? 'org-1',
      },
      { onSuccess: onClose },
    )
  }

  const canSubmit = !!selectedProperty && !!dueDate && !create.isPending

  return (
    <Box sx={{ display: 'flex', flexDirection: 'column', gap: 2.5 }}>
      {/* Typ */}
      <FormControl size="small" fullWidth>
        <InputLabel>Typ</InputLabel>
        <Select
          value={type}
          label="Typ"
          onChange={e => setType(e.target.value as ReminderType)}
        >
          {Object.values(ReminderType).map(t => (
            <MenuItem key={t} value={t}>{TYPE_LABELS[t]}</MenuItem>
          ))}
        </Select>
      </FormControl>

      {/* Objekt */}
      <Autocomplete
        options={properties}
        getOptionLabel={p => p.title}
        value={selectedProperty}
        onChange={handlePropertyChange}
        size="small"
        renderInput={params => (
          <TextField {...params} label="Objekt" placeholder="Objekt auswählen…" />
        )}
      />

      {/* Mieter — nur wenn Objekt ausgewählt */}
      {selectedProperty && (
        <TextField
          label="Mieter"
          size="small"
          fullWidth
          value={tenantName}
          onChange={e => setTenantName(e.target.value)}
          placeholder="Mietername eingeben…"
        />
      )}

      {/* Fälligkeitsdatum */}
      <TextField
        label="Fälligkeitsdatum"
        type="date"
        size="small"
        fullWidth
        value={dueDate}
        onChange={e => setDueDate(e.target.value)}
        slotProps={{ inputLabel: { shrink: true } }}
      />

      {/* Notiz */}
      <TextField
        label="Notiz (optional)"
        multiline
        rows={3}
        size="small"
        fullWidth
        value={note}
        onChange={e => setNote(e.target.value)}
        placeholder="Kontext oder Hinweise…"
      />

      <Button
        variant="contained"
        fullWidth
        disabled={!canSubmit}
        onClick={handleSubmit}
        sx={{ textTransform: 'none', fontWeight: 600 }}
      >
        {create.isPending ? 'Wird erstellt…' : 'Reminder erstellen'}
      </Button>
    </Box>
  )
}

// ── Main Drawer ───────────────────────────────────────────────────────────────

export function ReminderDetailDrawer() {
  const { selectedId, drawerOpen, setDrawerOpen, setSelectedId } = useReminderStore()
  const { data: reminder } = useReminder(selectedId ?? '')
  const { data: reminderProperty } = usePropertyById(reminder?.propertyId ?? '')
  const complete = useCompleteReminder()
  const dismiss = useDismissReminder()
  const snooze = useSnoozeReminder()

  const [noteValue, setNoteValue] = useState('')
  const [snoozeDate, setSnoozeDate] = useState('')

  function handleClose() {
    setDrawerOpen(false)
    setSelectedId(null)
  }

  const isCreateMode = !selectedId

  const secondDateKey = reminder ? TYPE_SECOND_DATE[reminder.type] : undefined
  const secondDateLabel = reminder ? TYPE_SECOND_LABEL[reminder.type] : undefined
  const secondDateValue = secondDateKey && reminder ? reminder[secondDateKey] : undefined
  const showSecondDate = secondDateValue && reminder && secondDateValue !== reminder.dueDate

  const showPreMarket = reminder &&
    reminder.shadowMarketRisk !== 'NONE' &&
    reminder.shadowMarketRisk !== 'LOW'

  const isActionable = reminder &&
    (reminder.status === ReminderStatus.ACTIVE || reminder.status === ReminderStatus.SNOOZED)

  return (
    <Drawer
      anchor="right"
      open={drawerOpen}
      onClose={handleClose}
      slotProps={{ paper: { sx: { width: 460, display: 'flex', flexDirection: 'column' } } }}
    >
      {/* ── Header ── */}
      <Box sx={{ px: 2.5, py: 2, borderBottom: '1px solid #e2e8f0', flexShrink: 0 }}>
        <Box sx={{ display: 'flex', alignItems: 'flex-start', gap: 1 }}>
          <Box sx={{ flex: 1, display: 'flex', flexDirection: 'column', gap: 1, minWidth: 0 }}>
            {isCreateMode ? (
              <Typography variant="subtitle1" sx={{ fontWeight: 700, color: '#0f172a' }}>
                Neuer Reminder
              </Typography>
            ) : reminder ? (
              <>
                <Box sx={{ display: 'flex', gap: 1, flexWrap: 'wrap', alignItems: 'center' }}>
                  <ReminderTypeBadge type={reminder.type} />
                  <ReminderPriorityBadge priority={reminder.priority} />
                  <Chip
                    label={STATUS_LABEL[reminder.status]}
                    color={STATUS_CHIP_COLOR[reminder.status]}
                    size="small"
                    sx={{ height: 20, fontSize: '0.7rem' }}
                  />
                </Box>
                <ReminderDaysIndicator dueDate={reminder.dueDate} />
              </>
            ) : null}
          </Box>
          <IconButton size="small" onClick={handleClose} sx={{ flexShrink: 0, color: '#94a3b8' }}>
            <X size={18} />
          </IconButton>
        </Box>
      </Box>

      {/* ── Body ── */}
      <Box sx={{ flex: 1, overflowY: 'auto', p: 2.5, display: 'flex', flexDirection: 'column' }}>

        {/* Create mode */}
        {isCreateMode && <CreateForm onClose={handleClose} />}

        {/* Detail mode */}
        {reminder && (
          <Box sx={{ display: 'flex', flexDirection: 'column', gap: 0 }}>
            {/* 1. Objekt */}
            <Box sx={{ mb: 2.5 }}>
              <Typography variant="body1" sx={{ fontWeight: 700, lineHeight: 1.3, mb: 0.25 }}>
                {reminder.propertyTitle}
              </Typography>
              <Typography variant="caption" color="text.secondary" sx={{ display: 'block', mb: 1 }}>
                {reminder.propertyCity}{reminder.propertyDistrict ? ` · ${reminder.propertyDistrict}` : ''}&nbsp;·&nbsp;{reminder.tenantName}
              </Typography>

              <Box sx={{ display: 'flex', alignItems: 'center', gap: 1.5, flexWrap: 'wrap' }}>
                {reminderProperty?.leaseContractUrl ? (
                  <Box sx={{ display: 'flex', alignItems: 'center', gap: 0.5 }}>
                    <FileText size={12} color="#64748b" />
                    <Button
                      size="small"
                      variant="outlined"
                      endIcon={<ExternalLink size={10} />}
                      href={reminderProperty.leaseContractUrl}
                      target="_blank"
                      rel="noopener noreferrer"
                      sx={{
                        textTransform: 'none', fontSize: '0.68rem',
                        py: 0.125, px: 0.75, borderColor: '#cbd5e1', color: '#334155',
                      }}
                    >
                      {reminderProperty.leaseContractName ?? 'Mietvertrag'}
                    </Button>
                  </Box>
                ) : (
                  <Box sx={{ display: 'flex', alignItems: 'center', gap: 0.5 }}>
                    <FileText size={12} color="#cbd5e1" />
                    <Typography variant="caption" sx={{ color: '#cbd5e1' }}>Kein Vertrag</Typography>
                  </Box>
                )}

                {showPreMarket && (
                  <Box sx={{ display: 'flex', alignItems: 'center', gap: 0.4 }}>
                    <Eye size={11} color={SHADOW_RISK_COLOR[reminder.shadowMarketRisk]} />
                    <Typography variant="caption" sx={{
                      color: SHADOW_RISK_COLOR[reminder.shadowMarketRisk],
                      fontWeight: 600, fontSize: '0.68rem',
                    }}>
                      Pre-Mkt: {SHADOW_RISK_LABEL[reminder.shadowMarketRisk]}
                    </Typography>
                  </Box>
                )}
              </Box>
            </Box>

            <Divider sx={{ mb: 2.5 }} />

            {/* 2. Fristen */}
            <Box sx={{ mb: 2.5 }}>
              <SectionTitle icon={<Calendar size={14} color="#64748b" />}>Fristen</SectionTitle>
              <Box sx={{ display: 'flex', flexDirection: 'column', gap: 1 }}>
                <DateRow label="Fälligkeit" value={reminder.dueDate} />
                {showSecondDate && (
                  <DateRow label={secondDateLabel!} value={secondDateValue} />
                )}
                {reminder.snoozedUntil && (
                  <DateRow label="Schlummert bis" value={reminder.snoozedUntil} />
                )}
              </Box>
            </Box>

            <Divider sx={{ mb: 2.5 }} />

            {/* 3. Notiz */}
            <Box sx={{ mb: isActionable ? 0 : 2.5 }}>
              <Typography variant="subtitle2" sx={{ fontWeight: 700, mb: 1, fontSize: '0.8125rem' }}>
                Notiz
              </Typography>
              <TextField
                multiline
                rows={3}
                fullWidth
                size="small"
                value={noteValue || (reminder.note ?? '')}
                onChange={e => setNoteValue(e.target.value)}
                placeholder="Notiz hinzufügen…"
                sx={{ '& .MuiInputBase-root': { fontSize: '0.8125rem' } }}
              />
            </Box>

            {/* 4. Aktionen */}
            {isActionable && (
              <>
                <Divider sx={{ my: 2.5 }} />
                <Box sx={{ mb: 2.5, display: 'flex', flexDirection: 'column', gap: 1.5 }}>
                  <Typography variant="subtitle2" sx={{ fontWeight: 700, fontSize: '0.8125rem' }}>
                    Aktionen
                  </Typography>
                  <Box sx={{ display: 'flex', gap: 1.5 }}>
                    <Button
                      variant="contained"
                      color="success"
                      sx={{ textTransform: 'none', flex: 1, fontWeight: 600 }}
                      onClick={() => complete.mutate({ id: reminder.id, note: noteValue || undefined })}
                    >
                      Erledigt
                    </Button>
                    <Button
                      variant="outlined"
                      color="error"
                      sx={{ textTransform: 'none', flex: 1 }}
                      onClick={() => dismiss.mutate({ id: reminder.id, note: noteValue || undefined })}
                    >
                      Verwerfen
                    </Button>
                  </Box>
                  <Box sx={{ display: 'flex', gap: 1, alignItems: 'center' }}>
                    <TextField
                      type="date"
                      size="small"
                      value={snoozeDate}
                      onChange={e => setSnoozeDate(e.target.value)}
                      sx={{ flex: 1, '& .MuiInputBase-root': { fontSize: '0.8125rem' } }}
                    />
                    <Button
                      variant="outlined"
                      size="small"
                      disabled={!snoozeDate}
                      sx={{ textTransform: 'none', whiteSpace: 'nowrap', color: '#64748b', borderColor: '#e2e8f0' }}
                      onClick={() => snoozeDate && snooze.mutate({ id: reminder.id, until: snoozeDate })}
                    >
                      Schlummern bis
                    </Button>
                  </Box>
                </Box>
              </>
            )}

            <Divider sx={{ mb: 2.5 }} />

            {/* 5. Verlauf */}
            <Box>
              <SectionTitle icon={<Activity size={14} color="#64748b" />}>Verlauf</SectionTitle>
              <Box>
                {[...reminder.activity].reverse().map((entry, i) => (
                  <ActivityEntry key={i} entry={entry} />
                ))}
              </Box>
            </Box>
          </Box>
        )}
      </Box>
    </Drawer>
  )
}