import { useState, useMemo } from 'react';
import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
import { Card, Button, Modal, Stack, Group, Grid, Select, TextInput, NumberInput, Table, Badge, Text, Container } from '@mantine/core';
import { DateInput } from '@mantine/dates';
import { Plus } from 'lucide-react';
import { QUERY_KEYS } from '@/constants/QUERY_KEYS';
import { api } from '@/services/api';
import { vehiclesService } from '@/services/vehicles.service';
import { freightBrand } from '@/theme/freight-brand';

interface MaintenanceSchedule {
  id: string;
  vehicleId: string;
  maintenanceType: string;
  description: string;
  scheduledDate: string;
  completedDate?: string;
  status: string;
  estimatedCost?: number;
  actualCost?: number;
  serviceProvider?: string;
}

export function MaintenancePage() {
  const [selectedVehicle, setSelectedVehicle] = useState<string | null>(null);
  const [openScheduleModal, setOpenScheduleModal] = useState(false);
  const [formData, setFormData] = useState({
    maintenanceType: 'PREVENTIVE',
    description: '',
    scheduledDate: new Date(),
    estimatedCost: 0,
    serviceProvider: '',
    notes: '',
  });

  const queryClient = useQueryClient();

  const { data: vehicles } = useQuery({
    queryKey: QUERY_KEYS.VEHICLES.list(),
    queryFn: async () => {
      const res = await vehiclesService.getAll({ limit: 1000 });
      return res.data || [];
    },
  });

  const { data: upcoming, isLoading } = useQuery({
    queryKey: QUERY_KEYS.MAINTENANCE.upcoming(selectedVehicle || ''),
    queryFn: () => selectedVehicle ? api.get(`/maintenance/upcoming/${selectedVehicle}`) : Promise.resolve([]),
    enabled: !!selectedVehicle,
  });

  const scheduleMutation = useMutation({
    mutationFn: async () => {
      if (!selectedVehicle) return;
      return api.post('/maintenance/schedules', {
        vehicleId: selectedVehicle,
        ...formData,
      });
    },
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: QUERY_KEYS.MAINTENANCE.upcoming(selectedVehicle || '') });
      setOpenScheduleModal(false);
      setFormData({
        maintenanceType: 'PREVENTIVE',
        description: '',
        scheduledDate: new Date(),
        estimatedCost: 0,
        serviceProvider: '',
        notes: '',
      });
    },
  });

  const vehicleOptions = useMemo(
    () => vehicles?.map(v => ({ label: v.registrationNumber || v.id, value: v.id })) || [],
    [vehicles]
  );

  const statusColor = (status: string) => {
    const colors: Record<string, string> = {
      SCHEDULED: 'edr-blue',
      IN_PROGRESS: 'edr-amber-soft',
      COMPLETED: 'edr-green',
      OVERDUE: 'edr-red',
    };
    return colors[status] || 'edr-slate';
  };

  return (
    <Container size="xl" py="xl">
      <Stack gap="md">
      <Card>
        <Card.Section p="md" withBorder>
          <Group justify="space-between">
            <Text fw={500}>Schedule Maintenance</Text>
            <Button onClick={() => setOpenScheduleModal(true)} color="edr-green" leftSection={<Plus size={16} />}>
              New Schedule
            </Button>
          </Group>
        </Card.Section>
        <Card.Section p="md">
          <Select
            label="Select Vehicle"
            placeholder="Pick a vehicle"
            data={vehicleOptions}
            value={selectedVehicle}
            onChange={setSelectedVehicle}
          />
        </Card.Section>
      </Card>

      {selectedVehicle && (
        <Card>
          <Card.Section p="md" withBorder>
            <Text fw={500}>Upcoming Maintenance</Text>
          </Card.Section>
          <Card.Section p="md">
            {isLoading ? (
              <Text>Loading...</Text>
            ) : (upcoming || []).length > 0 ? (
              <Table>
                <Table.Thead>
                  <Table.Tr>
                    <Table.Th>Type</Table.Th>
                    <Table.Th>Description</Table.Th>
                    <Table.Th>Scheduled</Table.Th>
                    <Table.Th>Est. Cost</Table.Th>
                    <Table.Th>Status</Table.Th>
                  </Table.Tr>
                </Table.Thead>
                <Table.Tbody>
                  {(upcoming as MaintenanceSchedule[]).map(m => (
                    <Table.Tr key={m.id}>
                      <Table.Td>{m.maintenanceType}</Table.Td>
                      <Table.Td>{m.description}</Table.Td>
                      <Table.Td>{new Date(m.scheduledDate).toLocaleDateString()}</Table.Td>
                      <Table.Td>${m.estimatedCost?.toFixed(2) || '—'}</Table.Td>
                      <Table.Td>
                        <Badge color={statusColor(m.status)}>{m.status}</Badge>
                      </Table.Td>
                    </Table.Tr>
                  ))}
                </Table.Tbody>
              </Table>
            ) : (
              <Text c="dimmed">No upcoming maintenance</Text>
            )}
          </Card.Section>
        </Card>
      )}

      <Modal
        opened={openScheduleModal}
        onClose={() => setOpenScheduleModal(false)}
        title="Schedule Maintenance"
        size="md"
      >
        <Stack gap="md">
          <Select
            label="Type"
            data={['PREVENTIVE', 'CORRECTIVE', 'INSPECTION', 'REPAIR']}
            value={formData.maintenanceType}
            onChange={v => setFormData({ ...formData, maintenanceType: v || 'PREVENTIVE' })}
          />
          <TextInput
            label="Description"
            placeholder="What needs to be done?"
            value={formData.description}
            onChange={e => setFormData({ ...formData, description: e.currentTarget.value })}
          />
          <DateInput
            label="Scheduled Date"
            value={formData.scheduledDate}
            onChange={d => setFormData({ ...formData, scheduledDate: d || new Date() })}
          />
          <NumberInput
            label="Estimated Cost"
            value={formData.estimatedCost}
            onChange={v => setFormData({ ...formData, estimatedCost: Number(v) })}
          />
          <TextInput
            label="Service Provider"
            placeholder="e.g., John's Auto Repair"
            value={formData.serviceProvider}
            onChange={e => setFormData({ ...formData, serviceProvider: e.currentTarget.value })}
          />
          <TextInput
            label="Notes"
            placeholder="Additional notes"
            value={formData.notes}
            onChange={e => setFormData({ ...formData, notes: e.currentTarget.value })}
          />
          <Group justify="flex-end">
            <Button variant="light" onClick={() => setOpenScheduleModal(false)}>
              Cancel
            </Button>
            <Button onClick={() => scheduleMutation.mutate()} loading={scheduleMutation.isPending}>
              Schedule
            </Button>
          </Group>
        </Stack>
      </Modal>
      </Stack>
    </Container>
  );
}