<?php

namespace App\Services;

use App\Enums\FuelType;
use App\Models\Station;
use App\Models\StationPrice;
use App\Models\StationPriceCurrent;
use Illuminate\Support\Carbon;
use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Log;
use Throwable;
use ValueError;

class FuelPriceService
{
    private const string TOKEN_CACHE_KEY = 'fuel_finder_access_token';

    public function __construct(
        private readonly StationTaggingService $taggingService,
        private readonly ApiLogger $apiLogger,
    ) {}

    public function getAccessToken(): string
    {
        return Cache::remember(self::TOKEN_CACHE_KEY, 3540, function (): string {
            $url = config('services.fuel_finder.base_url').'/oauth/generate_access_token';
            $response = $this->apiLogger->send('fuel_finder', 'POST', $url, fn () => Http::timeout(10)
                ->post($url, [
                    'client_id' => config('services.fuel_finder.client_id'),
                    'client_secret' => config('services.fuel_finder.client_secret'),
                ]));

            return $response->json('data.access_token');
        });
    }

    /**
     * Poll the prices endpoint, deduplicate, and persist changes.
     *
     * @return int Number of new price records inserted
     */
    public function pollPrices(): int
    {
        $token = $this->getAccessToken();
        $inserted = 0;
        $batch = 1;

        do {
            try {
                $baseUrl = config('services.fuel_finder.base_url').'/pfs/fuel-prices';
                $params = ['batch-number' => $batch];
                $logUrl = $baseUrl.'?'.http_build_query($params);
                $response = $this->apiLogger->send('fuel_finder', 'GET', $logUrl, fn () => Http::timeout(30)
                    ->withToken($token)
                    ->get($baseUrl, $params));

                $stations = $response->json() ?? [];
            } catch (Throwable $e) {
                Log::error('FuelPriceService: price batch fetch failed', [
                    'batch' => $batch,
                    'error' => $e->getMessage(),
                ]);
                break;
            }

            if (empty($stations)) {
                break;
            }

            $inserted += $this->processPriceBatch($stations);
            $batch++;
        } while (true);

        return $inserted;
    }

    /**
     * Fetch and upsert all station metadata.
     * Called on full daily refresh before pollPrices().
     */
    public function refreshStations(): void
    {
        $token = $this->getAccessToken();
        $batch = 1;

        do {
            try {
                $baseUrl = config('services.fuel_finder.base_url').'/pfs';
                $params = ['batch-number' => $batch];
                $logUrl = $baseUrl.'?'.http_build_query($params);
                $response = $this->apiLogger->send('fuel_finder', 'GET', $logUrl, fn () => Http::timeout(30)
                    ->withToken($token)
                    ->get($baseUrl, $params));

                $stations = $response->json() ?? [];
            } catch (Throwable $e) {
                Log::error('FuelPriceService: station batch fetch failed', [
                    'batch' => $batch,
                    'error' => $e->getMessage(),
                ]);
                break;
            }

            if (empty($stations)) {
                break;
            }

            $this->upsertStations($stations);
            $batch++;
        } while (true);
    }

    /** @param array<int, array<string, mixed>> $apiStations */
    public function upsertStations(array $apiStations): void
    {
        $now = now();
        $rows = [];

        foreach ($apiStations as $data) {
            $station = new Station([
                'node_id' => $data['node_id'],
                'trading_name' => $data['trading_name'],
                'brand_name' => $data['brand_name'] ?? null,
                'is_same_trading_and_brand' => $data['is_same_trading_and_brand_name'] ?? false,
                'is_supermarket' => false,
                'is_motorway_service_station' => $data['is_motorway_service_station'] ?? false,
                'is_supermarket_service_station' => $data['is_supermarket_service_station'] ?? false,
                'temporary_closure' => $data['temporary_closure'] ?? false,
                'permanent_closure' => $data['permanent_closure'] ?? false,
                'permanent_closure_date' => $data['permanent_closure_date'] ?? null,
                'public_phone_number' => $data['public_phone_number'] ?? null,
                'address_line_1' => $data['location']['address_line_1'] ?? null,
                'address_line_2' => $data['location']['address_line_2'] ?? null,
                'city' => $data['location']['city'] ?? null,
                'county' => $data['location']['county'] ?? null,
                'country' => $data['location']['country'] ?? null,
                'postcode' => $data['location']['postcode'],
                'lat' => $data['location']['latitude'],
                'lng' => $data['location']['longitude'],
                'amenities' => $data['amenities'] ?? [],
                'opening_times' => $data['opening_times'] ?? null,
                'fuel_types' => $data['fuel_types'] ?? [],
                'last_seen_at' => $now,
            ]);

            $this->taggingService->tag($station);
            $rows[] = $station->getAttributes();
        }

        Station::upsert($rows, ['node_id'], array_keys($rows[0] ?? []));
    }

    /**
     * Process one batch of API price data.
     *
     * Loads current prices for all stations in the batch, inserts a new
     * station_prices row only when the price has changed, and upserts
     * station_prices_current to reflect the latest known price.
     *
     * @param  array<int, array<string, mixed>>  $apiBatch
     */
    private function processPriceBatch(array $apiBatch): int
    {
        $stationIds = array_column($apiBatch, 'node_id');

        // Load current prices for all stations in this batch in one query
        $currentPrices = StationPriceCurrent::whereIn('station_id', $stationIds)
            ->get()
            ->groupBy('station_id')
            ->map(fn ($rows) => $rows->keyBy(fn ($r) => $r->fuel_type->value));

        $now = now();
        $newPrices = [];
        $upsertRows = [];

        foreach ($apiBatch as $station) {
            $stationId = $station['node_id'];

            foreach ($station['fuel_prices'] ?? [] as $priceData) {
                try {
                    $fuelType = FuelType::fromApiValue($priceData['fuel_type']);
                } catch (ValueError) {
                    continue; // Skip unknown fuel types
                }

                $pricePence = (int) round($priceData['price'] * 100);
                $effectiveAt = Carbon::parse($priceData['price_change_effective_timestamp']);
                $reportedAt = Carbon::parse($priceData['price_last_updated']);
                $currentPricePence = $currentPrices[$stationId][$fuelType->value]->price_pence ?? null;

                $row = [
                    'station_id' => $stationId,
                    'fuel_type' => $fuelType->value,
                    'price_pence' => $pricePence,
                    'price_effective_at' => $effectiveAt,
                    'price_reported_at' => $reportedAt,
                    'recorded_at' => $now,
                ];

                // Always upsert current; only write history when price changed
                $upsertRows[] = $row;

                if ($currentPricePence !== $pricePence) {
                    $newPrices[] = $row;
                }
            }
        }

        if (! empty($newPrices)) {
            StationPrice::insert($newPrices);
        }

        if (! empty($upsertRows)) {
            StationPriceCurrent::upsert(
                $upsertRows,
                ['station_id', 'fuel_type'],
                ['price_pence', 'price_effective_at', 'price_reported_at', 'recorded_at'],
            );
        }

        return count($newPrices);
    }
}