<?php

namespace App\Services;

use Illuminate\Http\Client\PendingRequest;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Log;
use Illuminate\Support\Facades\Storage;
use Illuminate\Support\Str;

class YouTubeService
{
    public function __construct(
        protected ?string $apiKey = null,
        protected ?string $channelId = null,
        protected ?string $playlistId = null,
    ) {
        $this->apiKey = $apiKey ?? config('services.youtube.api_key');
        $this->channelId = $channelId ?? config('services.youtube.channel_id');
        $this->playlistId = $playlistId ?? config('services.youtube.playlist_id');
    }

    public function isConfigured(): bool
    {
        return filled($this->apiKey)
            && (filled($this->channelId) || filled($this->playlistId));
    }

    public function resolveReleasesPlaylistId(): ?string
    {
        if (filled($this->playlistId)) {
            return $this->playlistId;
        }

        $channelId = $this->channelId;

        if (blank($channelId)) {
            return null;
        }

        if (str_starts_with($channelId, 'UC')) {
            return 'UU' . substr($channelId, 2);
        }

        return $channelId;
    }

    /**
     * @return array<int, array<string, mixed>>
     */
    public function getReleases(): array
    {
        $playlistId = $this->resolveReleasesPlaylistId();

        if (blank($playlistId)) {
            throw new \RuntimeException(__('music_productions.youtube_playlist_not_resolved'));
        }

        $releases = [];
        $pageToken = null;

        do {
            $params = [
                'key' => $this->apiKey,
                'playlistId' => $playlistId,
                'part' => 'snippet',
                'maxResults' => 50,
            ];

            if ($pageToken) {
                $params['pageToken'] = $pageToken;
            }

            $response = $this->client()->get('https://www.googleapis.com/youtube/v3/playlistItems', $params);

            if ($response->failed()) {
                Log::error('YouTube releases fetch failed', [
                    'playlist_id' => $playlistId,
                    'status' => $response->status(),
                    'body' => $response->body(),
                ]);

                throw new \RuntimeException($this->formatApiError(
                    __('music_productions.youtube_releases_fetch_failed'),
                    $response
                ));
            }

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

            foreach ($items as $item) {
                $normalized = $this->normalizeReleaseItem($item);

                if ($normalized) {
                    $releases[$normalized['video_id']] = $normalized;
                }
            }

            $pageToken = $data['nextPageToken'] ?? null;
        } while ($pageToken);

        return array_values($releases);
    }

    /**
     * @param  array<string, mixed>  $item
     * @return array<string, mixed>|null
     */
    protected function normalizeReleaseItem(array $item): ?array
    {
        $snippet = $item['snippet'] ?? [];
        $videoId = $snippet['resourceId']['videoId'] ?? null;
        $title = trim($snippet['title'] ?? '');

        if (blank($videoId) || blank($title)) {
            return null;
        }

        if (in_array($title, ['Private video', 'Deleted video', 'Gizli video', 'Silinmiş video'], true)) {
            return null;
        }

        $thumbnails = $snippet['thumbnails'] ?? [];
        $coverUrl = $thumbnails['maxres']['url']
            ?? $thumbnails['standard']['url']
            ?? $thumbnails['high']['url']
            ?? $thumbnails['medium']['url']
            ?? $thumbnails['default']['url']
            ?? null;

        return [
            'video_id' => $videoId,
            'title' => $title,
            'description' => trim($snippet['description'] ?? ''),
            'cover_url' => $coverUrl,
            'published_at' => $snippet['publishedAt'] ?? null,
            'youtube_url' => 'https://www.youtube.com/watch?v=' . $videoId,
        ];
    }

    public function downloadCoverImage(?string $imageUrl, string $videoId): ?string
    {
        if (blank($imageUrl)) {
            return null;
        }

        try {
            $response = Http::timeout(30)->get($imageUrl);

            if ($response->failed()) {
                return null;
            }

            $extension = $this->guessImageExtension($response->header('Content-Type'));
            $path = 'music-productions/covers/youtube-' . $videoId . '.' . $extension;

            Storage::disk('public')->put($path, $response->body());

            return $path;
        } catch (\Throwable $exception) {
            Log::warning('YouTube cover download failed', [
                'video_id' => $videoId,
                'message' => $exception->getMessage(),
            ]);

            return null;
        }
    }

    public function buildDefaultContent(array $release): string
    {
        $title = e($release['title'] ?? '');
        $youtubeUrl = e($release['youtube_url'] ?? '');
        $description = trim($release['description'] ?? '');
        $listenLabel = e(__('music_productions.youtube_watch_on_youtube'));

        $descriptionHtml = filled($description)
            ? '<p>' . nl2br(e($description)) . '</p>'
            : '';

        return <<<HTML
<p><strong>{$title}</strong></p>
{$descriptionHtml}
<p><a href="{$youtubeUrl}" target="_blank" rel="noopener noreferrer">{$listenLabel}</a></p>
HTML;
    }

    protected function client(): PendingRequest
    {
        $request = Http::acceptJson()->timeout(30);

        $referer = config('services.youtube.api_referer');

        if (filled($referer)) {
            $request = $request->withHeaders([
                'Referer' => rtrim($referer, '/') . '/',
            ]);
        }

        return $request;
    }

    protected function formatApiError(string $fallback, \Illuminate\Http\Client\Response $response): string
    {
        $message = $response->json('error.message') ?? trim($response->body());

        if (blank($message)) {
            return $fallback;
        }

        if ($response->status() === 403 && str_contains(strtolower($message), 'referer')) {
            return __('music_productions.youtube_referrer_blocked', [
                'detail' => $message,
            ]);
        }

        return $fallback . ' (HTTP ' . $response->status() . ': ' . $message . ')';
    }

    protected function guessImageExtension(?string $contentType): string
    {
        return match ($contentType) {
            'image/png' => 'png',
            'image/webp' => 'webp',
            'image/gif' => 'gif',
            default => 'jpg',
        };
    }

    public static function uniqueSlug(string $title, ?int $ignoreId = null): string
    {
        $baseSlug = Str::slug($title) ?: 'youtube-release';
        $slug = $baseSlug;
        $counter = 1;

        while (
            \App\Models\MusicProduction::withTrashed()
                ->when($ignoreId, fn ($query) => $query->where('id', '!=', $ignoreId))
                ->where('slug', $slug)
                ->exists()
        ) {
            $slug = $baseSlug . '-' . $counter;
            $counter++;
        }

        return $slug;
    }
}