<?php

namespace App\Services;

use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Log;

/**
 * Google Directions API → fertige GeoJSON-Linie + Distanz/Dauer fürs HUD.
 * Der API-Key bleibt im Backend, das Frontend bekommt nur das Ergebnis.
 */
class RouteService
{
    public function route(string $origin, string $destination, string $mode = 'driving'): ?array
    {
        $key = config('services.google.maps_key');
        if (empty($key)) {
            Log::warning('Google Maps Key fehlt - Routing nicht möglich');

            return null;
        }

        // Bis zu 2 Versuche bei transienten Fehlern (Timeout, 5xx, ZERO_RESULTS).
        $response = null;
        $data = null;
        $status = null;
        $lastErr = null;

        for ($attempt = 1; $attempt <= 2; $attempt++) {
            try {
                $response = Http::timeout((int) config('services.google.directions_timeout', 8))
                    ->retry(0)  // wir handeln retry selbst
                    ->get('https://maps.googleapis.com/maps/api/directions/json', [
                        'origin' => $origin,
                        'destination' => $destination,
                        'mode' => $mode,
                        'language' => 'de',
                        'region' => 'at',
                        'key' => $key,
                    ]);

                if (! $response->successful()) {
                    $lastErr = 'HTTP '.$response->status();
                    Log::warning('Directions API HTTP-Fehler', ['attempt' => $attempt, 'status' => $response->status()]);
                    if ($attempt < 2) {
                        usleep(400_000);
                        continue;
                    }

                    return null;
                }

                $data = $response->json();
                $status = $data['status'] ?? null;

                // ZERO_RESULTS oder UNKNOWN_ERROR sind oft transient bei ÖPNV - retry
                if (in_array($status, ['ZERO_RESULTS', 'UNKNOWN_ERROR', 'OVER_QUERY_LIMIT'], true) && $attempt < 2) {
                    Log::info('Directions transient '.$status.', retry');
                    usleep(500_000);
                    continue;
                }

                break;
            } catch (\Throwable $e) {
                $lastErr = $e->getMessage();
                Log::warning('Directions exception', ['attempt' => $attempt, 'e' => $lastErr]);
                if ($attempt < 2) {
                    usleep(400_000);
                    continue;
                }

                return null;
            }
        }

        try {
            if ($status !== 'OK' || empty($data['routes'])) {
                Log::warning('Directions: keine Route nach '.($attempt ?? 1).' Versuchen', [
                    'status' => $status,
                    'msg' => $data['error_message'] ?? $lastErr,
                    'origin' => $origin,
                    'destination' => $destination,
                ]);

                return null;
            }

            $route = $data['routes'][0];
            $leg = $route['legs'][0];

            return [
                'distance_text' => $leg['distance']['text'] ?? '',
                'distance_m' => $leg['distance']['value'] ?? 0,
                'duration_text' => $leg['duration']['text'] ?? '',
                'duration_s' => $leg['duration']['value'] ?? 0,
                'start_address' => $leg['start_address'] ?? '',
                'end_address' => $leg['end_address'] ?? '',
                'start_location' => $leg['start_location'] ?? null,
                'end_location' => $leg['end_location'] ?? null,
                'bounds' => $route['bounds'] ?? null,
                'geojson' => $this->decodePolyline($route['overview_polyline']['points'] ?? ''),
                'mode' => $mode,
                'steps' => $this->normalizeSteps($leg['steps'] ?? []),
            ];
        } catch (\Throwable $e) {
            Log::warning('RouteService exception', ['e' => $e->getMessage()]);

            return null;
        }
    }

    /**
     * Google-Steps → schlankeres Format für die Sidebar mit Transit-Details.
     */
    protected function normalizeSteps(array $steps): array
    {
        $out = [];
        foreach ($steps as $s) {
            $mode = $s['travel_mode'] ?? 'WALKING';
            $instruction = strip_tags(str_replace(
                ['<div', '</div>'], [' <div', '</div> '],
                (string) ($s['html_instructions'] ?? ''),
            ));
            $instruction = trim((string) preg_replace('/\s+/u', ' ', $instruction));

            $entry = [
                'mode' => $mode,
                'instruction' => $instruction,
                'distance' => $s['distance']['text'] ?? '',
                'duration' => $s['duration']['text'] ?? '',
            ];

            if ($mode === 'TRANSIT' && ! empty($s['transit_details'])) {
                $td = $s['transit_details'];
                $line = $td['line'] ?? [];
                $entry['transit'] = [
                    'line' => $line['short_name'] ?? ($line['name'] ?? ''),
                    'line_name' => $line['name'] ?? '',
                    'color' => $line['color'] ?? '#666',
                    'text_color' => $line['text_color'] ?? '#fff',
                    'vehicle' => $line['vehicle']['type'] ?? 'BUS',
                    'departure_stop' => $td['departure_stop']['name'] ?? '',
                    'arrival_stop' => $td['arrival_stop']['name'] ?? '',
                    'departure_time' => $td['departure_time']['text'] ?? '',
                    'arrival_time' => $td['arrival_time']['text'] ?? '',
                    'num_stops' => (int) ($td['num_stops'] ?? 0),
                    'headsign' => $td['headsign'] ?? '',
                ];
            }

            $out[] = $entry;
        }

        return $out;
    }

    /**
     * Google Polyline-Format → GeoJSON LineString-Feature.
     * https://developers.google.com/maps/documentation/utilities/polylinealgorithm
     */
    protected function decodePolyline(string $encoded): array
    {
        $points = [];
        $index = $lat = $lng = 0;
        $len = strlen($encoded);

        while ($index < $len) {
            $shift = $result = 0;
            do {
                $b = ord($encoded[$index++]) - 63;
                $result |= ($b & 0x1f) << $shift;
                $shift += 5;
            } while ($b >= 0x20 && $index < $len);
            $lat += ($result & 1) ? ~($result >> 1) : ($result >> 1);

            $shift = $result = 0;
            do {
                $b = ord($encoded[$index++]) - 63;
                $result |= ($b & 0x1f) << $shift;
                $shift += 5;
            } while ($b >= 0x20 && $index < $len);
            $lng += ($result & 1) ? ~($result >> 1) : ($result >> 1);

            $points[] = [$lng / 1e5, $lat / 1e5];
        }

        return [
            'type' => 'Feature',
            'geometry' => ['type' => 'LineString', 'coordinates' => $points],
            'properties' => new \stdClass,
        ];
    }
}