/**
 * Transport Analytics Page
 * Carbon footprint and food miles analysis
 */

import { useState, useEffect } from 'react';
import Link from 'next/link';
import {
  KPICard,
  DateRangePicker,
  LineChart,
  BarChart,
  PieChart,
  AreaChart,
  Gauge,
  DataTable,
} from '../../components/analytics';
import { TimeRange, TransportAnalytics } from '../../lib/analytics/types';

export default function TransportAnalyticsPage() {
  const [timeRange, setTimeRange] = useState<TimeRange>('30d');
  const [loading, setLoading] = useState(true);
  const [data, setData] = useState<TransportAnalytics | null>(null);

  useEffect(() => {
    fetchData();
  }, [timeRange]);

  const fetchData = async () => {
    setLoading(true);
    try {
      const response = await fetch(`/api/analytics/transport?timeRange=${timeRange}`);
      const result = await response.json();
      setData(result.data);
    } catch (error) {
      console.error('Failed to fetch transport analytics:', error);
    } finally {
      setLoading(false);
    }
  };

  const methodColumns = [
    { key: 'method', header: 'Method' },
    { key: 'count', header: 'Events', align: 'right' as const },
    { key: 'distanceKm', header: 'Distance (km)', align: 'right' as const, render: (v: number) => v.toLocaleString() },
    { key: 'carbonKg', header: 'Carbon (kg)', align: 'right' as const, render: (v: number) => v.toFixed(2) },
    {
      key: 'efficiency',
      header: 'Efficiency',
      align: 'right' as const,
      render: (v: number) => (
        <span className={`font-medium ${v >= 80 ? 'text-green-600' : v >= 50 ? 'text-yellow-600' : 'text-red-600'}`}>
          {v}%
        </span>
      ),
    },
  ];

  const routeColumns = [
    { key: 'from', header: 'From' },
    { key: 'to', header: 'To' },
    { key: 'method', header: 'Method' },
    { key: 'distanceKm', header: 'Distance', align: 'right' as const, render: (v: number) => `${v} km` },
    { key: 'frequency', header: 'Frequency', align: 'right' as const },
  ];

  return (
    <div className="min-h-screen bg-gradient-to-br from-green-50 to-emerald-100">
      {/* Header */}
      <div className="bg-gradient-to-r from-teal-600 to-cyan-600 text-white">
        <div className="max-w-7xl mx-auto px-4 py-8">
          <h1 className="text-3xl font-bold">Transport Analytics</h1>
          <p className="text-teal-200 mt-1">Carbon footprint and food miles analysis</p>
        </div>
      </div>

      <div className="max-w-7xl mx-auto px-4 py-8">
        {/* Time Range Selector */}
        <div className="mb-8">
          <DateRangePicker value={timeRange} onChange={setTimeRange} />
        </div>

        {/* Navigation Tabs */}
        <div className="flex space-x-4 mb-8">
          <Link href="/analytics">
            <a className="px-4 py-2 bg-white hover:bg-gray-50 text-gray-700 rounded-lg font-medium shadow">Overview</a>
          </Link>
          <Link href="/analytics/plants">
            <a className="px-4 py-2 bg-white hover:bg-gray-50 text-gray-700 rounded-lg font-medium shadow">Plants</a>
          </Link>
          <Link href="/analytics/transport">
            <a className="px-4 py-2 bg-teal-500 text-white rounded-lg font-medium">Transport</a>
          </Link>
          <Link href="/analytics/farms">
            <a className="px-4 py-2 bg-white hover:bg-gray-50 text-gray-700 rounded-lg font-medium shadow">Farms</a>
          </Link>
          <Link href="/analytics/sustainability">
            <a className="px-4 py-2 bg-white hover:bg-gray-50 text-gray-700 rounded-lg font-medium shadow">Sustainability</a>
          </Link>
        </div>

        {/* KPI Cards */}
        <div className="grid grid-cols-1 md:grid-cols-4 gap-6 mb-8">
          <KPICard
            title="Total Events"
            value={data?.totalEvents || 0}
            trend="up"
            color="blue"
            loading={loading}
          />
          <KPICard
            title="Total Distance"
            value={data?.totalDistanceKm?.toLocaleString() || '0'}
            unit="km"
            trend="stable"
            color="purple"
            loading={loading}
          />
          <KPICard
            title="Carbon Emitted"
            value={data?.totalCarbonKg?.toFixed(1) || '0'}
            unit="kg CO2"
            trend="down"
            color="orange"
            loading={loading}
          />
          <KPICard
            title="Carbon Saved"
            value={data?.carbonSavedKg?.toFixed(1) || '0'}
            unit="kg CO2"
            trend="up"
            color="green"
            loading={loading}
          />
        </div>

        {/* Gauges */}
        <div className="grid grid-cols-2 md:grid-cols-4 gap-6 mb-8">
          <Gauge
            value={data?.totalCarbonKg ? (data.carbonSavedKg / (data.totalCarbonKg + data.carbonSavedKg)) * 100 : 0}
            title="Carbon Reduction"
            unit="%"
          />
          <Gauge
            value={100 - ((data?.averageDistancePerEvent || 0) / 50) * 100}
            title="Distance Efficiency"
            unit="%"
          />
          <Gauge
            value={data?.eventsByMethod?.filter(m => m.efficiency >= 80).length
              ? (data.eventsByMethod.filter(m => m.efficiency >= 80).reduce((s, m) => s + m.count, 0) / data.totalEvents) * 100
              : 0}
            title="Green Transport"
            unit="%"
          />
          <Gauge
            value={75}
            title="Local Sourcing"
            unit="%"
          />
        </div>

        {/* Charts */}
        <div className="grid grid-cols-1 lg:grid-cols-2 gap-6 mb-8">
          {data?.carbonTrend && (
            <AreaChart
              data={data.carbonTrend}
              xKey="label"
              yKey="value"
              title="Carbon Emissions Trend"
              colors={['#f59e0b']}
              height={300}
            />
          )}

          {data?.eventsByMethod && (
            <BarChart
              data={data.eventsByMethod}
              xKey="method"
              yKey="carbonKg"
              title="Carbon by Transport Method"
              height={300}
            />
          )}
        </div>

        {/* Event Types Pie Chart */}
        {data?.eventsByType && (
          <div className="mb-8">
            <div className="grid grid-cols-1 lg:grid-cols-2 gap-6">
              <PieChart
                data={data.eventsByType}
                dataKey="count"
                nameKey="eventType"
                title="Events by Type"
                height={300}
              />
              <PieChart
                data={data.eventsByMethod}
                dataKey="distanceKm"
                nameKey="method"
                title="Distance by Method"
                height={300}
              />
            </div>
          </div>
        )}

        {/* Tables */}
        <div className="grid grid-cols-1 gap-6">
          {data?.eventsByMethod && (
            <DataTable
              data={data.eventsByMethod}
              columns={methodColumns}
              title="Transport Method Breakdown"
              pageSize={8}
            />
          )}

          {data?.mostEfficientRoutes && (
            <DataTable
              data={data.mostEfficientRoutes}
              columns={routeColumns}
              title="Most Efficient Routes"
              pageSize={5}
            />
          )}
        </div>
      </div>
    </div>
  );
}