import { useQuery } from "@tanstack/react-query";
import { Card, Container, Grid, Group, Loader, Select, Stack, Text, Title } from "@mantine/core";
import Breadcrumbs from "@/components/ui/Breadcrumbs";
import { api } from "@/auth/http";
import { QUERY_KEYS } from "@/constants/QUERY_KEYS";
import { vehiclesService, type Vehicle as VehicleType } from "@/services/vehicles.service";
import { useState } from "react";

export default function FuelStatsPage() {
  const [selectedVehicleId, setSelectedVehicleId] = useState<string>("");
  const [monthsBack, setMonthsBack] = useState<string>("12");

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

  // Fetch fuel stats
  const { data: statsData, isFetching: isStatsFetching } = useQuery({
    queryKey: ["fuel-stats", selectedVehicleId, monthsBack],
    queryFn: async () => {
      if (!selectedVehicleId) return null;
      const res = await api.get(`/fuel/stats/${selectedVehicleId}?months=${monthsBack}`);
      return res.data;
    },
    enabled: !!selectedVehicleId,
  });

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

  const selectedVehicle = vehiclesData?.find((v: VehicleType) => v.id === selectedVehicleId);

  const costPerKm =
    statsData && selectedVehicle?.actualDistanceKm
      ? (statsData.totalCost / selectedVehicle.actualDistanceKm).toFixed(2)
      : "—";

  const efficiency = statsData
    ? (statsData.totalLiters > 0 ? (selectedVehicle?.actualDistanceKm || 0) / statsData.totalLiters : 0).toFixed(2)
    : "—";

  return (
    <Container size="xl" py="xl" px="lg">
      <Breadcrumbs items={[{ label: "Fleet" }, { label: "Fuel Management" }, { label: "Statistics" }]} />

      <Group justify="space-between" mb="lg">
        <Title order={1}>Fuel Consumption Analysis</Title>
      </Group>

      {/* Filters */}
      <Card withBorder mb="lg" padding="md">
        <Grid>
          <Grid.Col span={{ base: 12, sm: 6 }}>
            <Select
              label="Vehicle"
              placeholder="Select vehicle to analyze"
              data={vehicleOptions}
              value={selectedVehicleId}
              onChange={(val) => setSelectedVehicleId(val || "")}
              searchable
            />
          </Grid.Col>
          <Grid.Col span={{ base: 12, sm: 6 }}>
            <Select
              label="Period"
              data={[
                { value: "3", label: "Last 3 months" },
                { value: "6", label: "Last 6 months" },
                { value: "12", label: "Last 12 months" },
              ]}
              value={monthsBack}
              onChange={(val) => setMonthsBack(val || "12")}
            />
          </Grid.Col>
        </Grid>
      </Card>

      {selectedVehicleId && statsData ? (
        <>
          {/* Stats Cards */}
          <Grid mb="lg">
            <Grid.Col span={{ base: 12, sm: 6, md: 3 }}>
              <Card withBorder padding="lg">
                <Text size="sm" c="dimmed" fw={500}>
                  Total Purchases
                </Text>
                <Text fw={700} size="lg">
                  {Number(statsData.totalPurchases) || 0}
                </Text>
              </Card>
            </Grid.Col>
            <Grid.Col span={{ base: 12, sm: 6, md: 3 }}>
              <Card withBorder padding="lg">
                <Text size="sm" c="dimmed" fw={500}>
                  Total Fuel
                </Text>
                <Text fw={700} size="lg">
                  {(Number(statsData.totalLiters) || 0).toFixed(2)} L
                </Text>
              </Card>
            </Grid.Col>
            <Grid.Col span={{ base: 12, sm: 6, md: 3 }}>
              <Card withBorder padding="lg">
                <Text size="sm" c="dimmed" fw={500}>
                  Total Cost
                </Text>
                <Text fw={700} size="lg">
                  ETB {(Number(statsData.totalCost) || 0).toLocaleString("en-US", { maximumFractionDigits: 2 })}
                </Text>
              </Card>
            </Grid.Col>
            <Grid.Col span={{ base: 12, sm: 6, md: 3 }}>
              <Card withBorder padding="lg">
                <Text size="sm" c="dimmed" fw={500}>
                  Avg Price/L
                </Text>
                <Text fw={700} size="lg">
                  ETB {(Number(statsData.averagePricePerLiter) || 0).toFixed(2)}
                </Text>
              </Card>
            </Grid.Col>
          </Grid>

          {/* Efficiency Metrics */}
          <Grid mb="lg">
            <Grid.Col span={{ base: 12, sm: 6 }}>
              <Card withBorder padding="lg">
                <Text size="sm" c="dimmed" fw={500}>
                  Fuel Efficiency
                </Text>
                <Text fw={700} size="lg">
                  {efficiency} km/L
                </Text>
              </Card>
            </Grid.Col>
            <Grid.Col span={{ base: 12, sm: 6 }}>
              <Card withBorder padding="lg">
                <Text size="sm" c="dimmed" fw={500}>
                  Cost per KM
                </Text>
                <Text fw={700} size="lg">
                  ETB {costPerKm}
                </Text>
              </Card>
            </Grid.Col>
          </Grid>

          {/* Summary */}
          <Card withBorder padding="lg">
            <Stack gap="md">
              <div>
                <Text fw={600} mb="xs">
                  Summary
                </Text>
                <Text size="sm">
                  {selectedVehicle?.plateNumber} consumed{" "}
                  <Text fw={700} span>
                    {(Number(statsData.totalLiters) || 0).toFixed(2)} liters
                  </Text>{" "}
                  over the last {monthsBack} months, costing{" "}
                  <Text fw={700} span>
                    ETB {(Number(statsData.totalCost) || 0).toLocaleString("en-US", { maximumFractionDigits: 2 })}
                  </Text>
                  . Average fuel price was{" "}
                  <Text fw={700} span>
                    ETB {(Number(statsData.averagePricePerLiter) || 0).toFixed(2)} per liter
                  </Text>
                  .
                </Text>
              </div>
            </Stack>
          </Card>
        </>
      ) : selectedVehicleId && isStatsFetching ? (
        <Card withBorder padding="lg">
          <Group justify="center">
            <Loader />
          </Group>
        </Card>
      ) : (
        <Card withBorder padding="lg">
          <Text c="dimmed" ta="center">
            Select a vehicle to view fuel consumption statistics
          </Text>
        </Card>
      )}
    </Container>
  );
}