import { useState } from 'react';
import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
import {
  Card,
  Button,
  Modal,
  Stack,
  Group,
  Select,
  TextInput,
  NumberInput,
  Table,
  Badge,
  Text,
  Title,
  Container,
} from '@mantine/core';
import { Plus } from 'lucide-react';
import Breadcrumbs from '@/components/ui/Breadcrumbs';
import { useToast } from '@/hooks/use-toast';
import { QUERY_KEYS } from '@/constants/QUERY_KEYS';
import { api } from '@/auth/http';
import { vehiclesService, type Vehicle as VehicleType } from '@/services/vehicles.service';

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

const emptyForm = {
  maintenanceType: 'PREVENTIVE',
  description: '',
  scheduledDate: new Date().toISOString().split('T')[0],
  estimatedCost: 0,
  serviceProvider: '',
  notes: '',
};

export function MaintenancePage() {
  const { toast } = useToast();
  const queryClient = useQueryClient();
  const [selectedVehicle, setSelectedVehicle] = useState<string | null>(null);
  const [openScheduleModal, setOpenScheduleModal] = useState(false);
  const [formData, setFormData] = useState(emptyForm);

  const { data: vehiclesData } = 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: async () => {
      if (!selectedVehicle) return [];
      const res = await api.get(`/maintenance/upcoming/${selectedVehicle}`);
      return res.data || [];
    },
    enabled: !!selectedVehicle,
  });

  const upcomingList: MaintenanceSchedule[] = Array.isArray(upcoming) ? upcoming : [];

  const scheduleMutation = useMutation({
    mutationFn: async () => {
      if (!selectedVehicle) return;
      const res = await api.post('/maintenance/schedules', {
        vehicleId: selectedVehicle,
        ...formData,
      });
      return res.data;
    },
    onSuccess: () => {
      toast({ title: 'Maintenance scheduled' });
      queryClient.invalidateQueries({
        queryKey: QUERY_KEYS.MAINTENANCE.upcoming(selectedVehicle || ''),
      });
      setOpenScheduleModal(false);
      setFormData(emptyForm);
    },
    onError: (err: any) => {
      toast({
        title: 'Error',
        description: err?.response?.data?.message ?? 'Failed',
        variant: 'destructive',
      });
    },
  });

  const vehicleOptions =
    vehiclesData?.map((v: VehicleType) => ({
      value: v.id,
      label: v.plateNumber
        ? `${v.plateNumber} - ${v.manufacturer} ${v.model}`
        : v.registrationNumber || v.id,
    })) || [];

  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" px="lg">
      <Breadcrumbs items={[{ label: 'Fleet' }, { label: 'Maintenance' }]} />

      <Group justify="space-between" mb="lg">
        <Title order={1}>Maintenance</Title>
        <Button
          onClick={() => setOpenScheduleModal(true)}
          color="edr-green"
          leftSection={<Plus size={16} />}
          disabled={!selectedVehicle}
        >
          New Schedule
        </Button>
      </Group>

      <Stack gap="md">
        <Card withBorder padding="md">
          <Select
            label="Select Vehicle"
            placeholder="Pick a vehicle"
            data={vehicleOptions}
            value={selectedVehicle}
            onChange={setSelectedVehicle}
            searchable
          />
        </Card>

        {!selectedVehicle ? (
          <Card withBorder padding="lg">
            <Text c="dimmed" ta="center">
              Select a vehicle to view its maintenance schedule
            </Text>
          </Card>
        ) : (
          <Card withBorder>
            <Card.Section p="md" withBorder>
              <Text fw={500}>Upcoming Maintenance</Text>
            </Card.Section>
            <Card.Section p="md">
              {isLoading ? (
                <Text>Loading...</Text>
              ) : upcomingList.length > 0 ? (
                <Table striped highlightOnHover>
                  <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>
                    {upcomingList.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 != null
                            ? `ETB ${Number(m.estimatedCost).toLocaleString('en-US', {
                                minimumFractionDigits: 2,
                                maximumFractionDigits: 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>
        )}
      </Stack>

      <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 })}
          />
          <TextInput
            label="Scheduled Date"
            type="date"
            value={formData.scheduledDate}
            onChange={(e) => setFormData({ ...formData, scheduledDate: e.currentTarget.value })}
          />
          <NumberInput
            label="Estimated Cost"
            min={0}
            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}
              disabled={!selectedVehicle}
            >
              Schedule
            </Button>
          </Group>
        </Stack>
      </Modal>
    </Container>
  );
}