import { useState } from 'react'
import {
  Dialog,
  DialogTitle,
  DialogContent,
  DialogActions,
  Button,
  TextField,
  Box,
  Typography,
  Alert,
  IconButton,
  Divider,
  CircularProgress,
} from '@mui/material'
import EditIcon from '@mui/icons-material/Edit'
import DeleteIcon from '@mui/icons-material/Delete'
import { LocalizationProvider, DateTimePicker } from '@mui/x-date-pickers'
import { AdapterDayjs } from '@mui/x-date-pickers/AdapterDayjs'
import dayjs from 'dayjs'
import {
  useScheduledMessages,
  useCreateScheduledMessage,
  useUpdateScheduledMessage,
  useDeleteScheduledMessage,
} from './api'

function formatDate(d) {
  try {
    return new Date(d).toLocaleString()
  } catch {
    return d
  }
}

export default function ScheduleMessageModal({ session, onClose }) {
  const [message, setMessage] = useState('')
  const [scheduledAt, setScheduledAt] = useState(() => dayjs().add(1, 'hour'))
  const [editingId, setEditingId] = useState(null)
  const [error, setError] = useState('')
  const [success, setSuccess] = useState('')

  const { data: scheduledMessages, isLoading } = useScheduledMessages(session?.id)
  const createMutation = useCreateScheduledMessage()
  const updateMutation = useUpdateScheduledMessage()
  const deleteMutation = useDeleteScheduledMessage()

  const handleClose = () => {
    setMessage('')
    setScheduledAt(dayjs().add(1, 'hour'))
    setEditingId(null)
    setError('')
    setSuccess('')
    onClose()
  }

  const handleEdit = (msg) => {
    setMessage(msg.message)
    setScheduledAt(dayjs(msg.scheduled_at))
    setEditingId(msg.id)
    setError('')
    setSuccess('')
  }

  const handleCancelEdit = () => {
    setMessage('')
    setScheduledAt(dayjs().add(1, 'hour'))
    setEditingId(null)
    setError('')
    setSuccess('')
  }

  const handleSave = async () => {
    setError('')
    setSuccess('')
    if (!message.trim()) {
      setError('El mensaje no puede estar vacío')
      return
    }
    if (!session) return
    const isoDate = scheduledAt.toISOString()
    try {
      if (editingId) {
        await updateMutation.mutateAsync({
          id: editingId,
          sessionId: session.id,
          message: message.trim(),
          scheduledAt: isoDate,
        })
        setSuccess('Mensaje programado actualizado')
      } else {
        await createMutation.mutateAsync({
          sessionId: session.id,
          message: message.trim(),
          scheduledAt: isoDate,
        })
        setSuccess('Mensaje programado creado')
      }
      setMessage('')
      setScheduledAt(dayjs().add(1, 'hour'))
      setEditingId(null)
    } catch (err) {
      setError(err.message)
    }
  }

  const handleDelete = async (id) => {
    if (!session) return
    if (!window.confirm('¿Eliminar este mensaje programado?')) return
    setError('')
    setSuccess('')
    try {
      await deleteMutation.mutateAsync({ id, sessionId: session.id })
      setSuccess('Mensaje programado eliminado')
    } catch (err) {
      setError(err.message)
    }
  }

  return (
    <Dialog open={!!session} onClose={handleClose} maxWidth="sm" fullWidth>
      <DialogTitle>
        Programar mensaje: {session?.name || session?.phone || session?.id}
      </DialogTitle>
      <DialogContent>
        <LocalizationProvider dateAdapter={AdapterDayjs}>
          <Box sx={{ display: 'flex', flexDirection: 'column', gap: 2, mt: 1 }}>
            <DateTimePicker
              label="Fecha y hora"
              value={scheduledAt}
              onChange={(v) => setScheduledAt(v)}
              ampm={false}
              slotProps={{
                textField: {
                  fullWidth: true,
                  size: 'small',
                  readOnly: true,
                },
              }}
              disablePast
            />
            <TextField
              fullWidth
              size="small"
              label="Mensaje"
              multiline
              minRows={3}
              maxRows={6}
              value={message}
              onChange={(e) => setMessage(e.target.value)}
              placeholder="Escribe el mensaje a programar..."
            />
            {error && <Alert severity="error">{error}</Alert>}
            {success && <Alert severity="success">{success}</Alert>}
            <Box sx={{ display: 'flex', gap: 1, justifyContent: 'flex-end' }}>
              {editingId && (
                <Button onClick={handleCancelEdit} color="inherit">
                  Cancelar edición
                </Button>
              )}
              <Button
                variant="contained"
                onClick={handleSave}
                disabled={!message.trim() || createMutation.isPending || updateMutation.isPending}
              >
                {createMutation.isPending || updateMutation.isPending ? (
                  <CircularProgress size={20} color="inherit" />
                ) : editingId ? (
                  'Guardar'
                ) : (
                  'Programar'
                )}
              </Button>
            </Box>
          </Box>
        </LocalizationProvider>

        <Divider sx={{ my: 2 }} />

        <Typography variant="subtitle2" gutterBottom>
          Mensajes programados pendientes
        </Typography>
        {isLoading ? (
          <Box sx={{ display: 'flex', justifyContent: 'center', py: 2 }}>
            <CircularProgress size={24} />
          </Box>
        ) : scheduledMessages?.length === 0 ? (
          <Typography variant="body2" color="text.secondary">
            No hay mensajes programados pendientes.
          </Typography>
        ) : (
          <Box sx={{ display: 'flex', flexDirection: 'column', gap: 1 }}>
            {scheduledMessages?.map((msg) => (
              <Box
                key={msg.id}
                sx={{
                  p: 1.5,
                  border: '1px solid',
                  borderColor: 'divider',
                  borderRadius: 1,
                  display: 'flex',
                  justifyContent: 'space-between',
                  alignItems: 'flex-start',
                  gap: 1,
                }}
              >
                <Box sx={{ flex: 1, minWidth: 0 }}>
                  <Typography variant="body2" sx={{ wordBreak: 'break-word' }}>
                    {msg.message}
                  </Typography>
                  <Typography variant="caption" color="text.secondary">
                    {formatDate(msg.scheduled_at)}
                  </Typography>
                </Box>
                <Box sx={{ display: 'flex', gap: 0.5 }}>
                  <IconButton size="small" onClick={() => handleEdit(msg)} disabled={deleteMutation.isPending}>
                    <EditIcon fontSize="small" />
                  </IconButton>
                  <IconButton size="small" onClick={() => handleDelete(msg.id)} disabled={deleteMutation.isPending}>
                    <DeleteIcon fontSize="small" color="error" />
                  </IconButton>
                </Box>
              </Box>
            ))}
          </Box>
        )}
      </DialogContent>
      <DialogActions>
        <Button onClick={handleClose}>Cerrar</Button>
      </DialogActions>
    </Dialog>
  )
}