<?php

namespace App\Services;

use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\Http;

final class IllustrationPool
{
    public static function enabled(): bool
    {
        $base = match (app()->environment()) {
            'local' => 'http://resource.loc:8612',
            'production' => 'https://resource-v2.gemcook.net',
            'staging' => 'https://test.clashfreenode.com/resource-v2',
            default => null,
        };
        return $base !== null && config('illustrations.enabled')
            && config('illustrations.base_url') === $base;
    }

    private static function request(string $method, string $path, array $body = []): array
    {
        if (!self::enabled()) throw new \RuntimeException('Illustration service is disabled or not bound to this environment');
        $file = config('illustrations.credential_file');
        if (!$file || !is_file($file)) throw new \RuntimeException('Illustration credential unavailable');
        $credential = json_decode(file_get_contents($file), true, 512, JSON_THROW_ON_ERROR);
        if (($credential['project'] ?? '') !== 'fna-v3' || ($credential['base_url'] ?? '') !== config('illustrations.base_url')
            || !preg_match('/\Arsv2_[a-f0-9]{64}\z/D', $credential['token'] ?? '')) {
            throw new \RuntimeException('Invalid illustration credential configuration');
        }
        try {
            $response = Http::withOptions(['proxy' => '', 'allow_redirects' => false])
                ->withToken($credential['token'])->acceptJson()->withUserAgent('FNA-V3/ResourceV2')
                ->connectTimeout(2)->timeout(8)->send($method, config('illustrations.base_url').'/api/v2/'.$path, ['json' => $body]);
            if (!$response->successful() || !is_array($response->json('data'))) throw new \RuntimeException();
            return $response->json('data');
        } catch (\Throwable $e) {
            // Never include request headers, credential bytes or response bodies in exceptions.
            throw new \RuntimeException('Resource V2 illustration request failed');
        }
    }

    public static function snapshot(string $pool): array
    {
        return Cache::store('file')->remember('illustrations.v2.'.$pool, 60, function () use ($pool) {
            try {
                $data = self::request('GET', 'pools/'.$pool);
                $seen = [];
                while (!empty($data['next'])) {
                    $after = $data['next'];
                    if (isset($seen[$after])) throw new \RuntimeException('Resource pagination did not advance');
                    $seen[$after] = true;
                    $page = self::request('GET', 'pools/'.$pool.'?after='.rawurlencode($after));
                    $data['selections'] = array_replace($data['selections'], $page['selections']);
                    $data['unavailable'] = array_replace($data['unavailable'] ?? [], $page['unavailable'] ?? []);
                    $data['next'] = $page['next'];
                }
                Cache::store('file')->forever('illustrations.v2.last-good.'.$pool, $data);
                return $data;
            } catch (\Throwable $e) {
                $saved = Cache::store('file')->get('illustrations.v2.last-good.'.$pool);
                if (is_array($saved)) return $saved;
                throw $e;
            }
        });
    }

    public static function forget(string $pool): void
    {
        Cache::store('file')->forget('illustrations.v2.'.$pool);
    }

    public static function assign(string $pool, array $keys): array
    {
        $data = self::request('POST', 'pools/'.$pool.'/selections', ['keys' => $keys]);
        self::forget($pool);
        return $data['selections'];
    }

    public static function forArticle(string $pool, string $slug): string
    {
        return self::assign($pool, [$slug])[$slug]['url'];
    }

    public static function thumbnail(array $article, ?string $original): ?string
    {
        if (!self::enabled()) return $original;
        $pool = config('illustrations.categories.'.($article['iCategoryId'] ?? ''));
        if (!$pool || empty($article['sSlug'])) return $original;
        try {
            $snapshot = self::snapshot($pool);
            $reason = $snapshot['unavailable'][$article['sSlug']] ?? null;
            if ($reason) {
                // Repair accidental physical loss, never override deliberate publication/access withdrawal.
                if (in_array($reason, ['file_missing', 'file_corrupt', 'file_symlink'], true)) {
                    try { return self::forArticle($pool, $article['sSlug']); }
                    catch (\Throwable $e) { return null; }
                }
                return null;
            }
            return $snapshot['selections'][$article['sSlug']]['url'] ?? $original;
        } catch (\Throwable $e) {
            // A failed resource service must not invent or reassign an article's image.
            return $original;
        }
    }
}