<?php

namespace App\Services;

use App\DTOs\GutendexBook;
use Illuminate\Http\Client\ConnectionException;
use Illuminate\Http\Client\RequestException;
use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Log;

class GutendexClient
{
    protected string $baseUrl;
    protected int $timeout;
    protected int $retryMaxAttempts;
    protected int $retryBackoff;
    protected bool $cacheEnabled;
    protected int $cacheTtl;
    protected int $rateLimit;

    public function __construct()
    {
        $this->baseUrl = config('gutendex.api_url', 'https://gutendex.com');
        $this->timeout = config('gutendex.timeout', 30);
        $this->retryMaxAttempts = config('gutendex.retry.max_attempts', 3);
        $this->retryBackoff = config('gutendex.retry.backoff_multiplier', 2);
        $this->cacheEnabled = config('gutendex.cache.enabled', true);
        $this->cacheTtl = config('gutendex.cache.ttl', 86400);
        $this->rateLimit = config('gutendex.rate_limit_delay', 1000);
    }

    /**
     * Search for books with optional query and filters.
     *
     * @param string|null $query Search query
     * @param int $page Page number
     * @param array $filters Additional filters (language, topic, author, etc.)
     * @return array API response with results
     */
    public function searchBooks(?string $query = null, int $page = 1, array $filters = []): array
    {
        $params = array_merge(['page' => $page], $filters);

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

        $cacheKey = 'gutendex:search:' . md5(json_encode($params));

        if ($this->cacheEnabled && Cache::has($cacheKey)) {
            Log::info('Gutendex: Cache hit for search', ['params' => $params]);
            return Cache::get($cacheKey);
        }

        $response = $this->makeRequest('GET', '/books', $params);

        if ($this->cacheEnabled && isset($response['results'])) {
            Cache::put($cacheKey, $response, $this->cacheTtl);
        }

        return $response;
    }

    /**
     * Get a specific book by its Gutenberg ID.
     *
     * @param int $gutenbergId The Gutenberg book ID
     * @return GutendexBook|null
     */
    public function getBook(int $gutenbergId): ?GutendexBook
    {
        $cacheKey = 'gutendex:book:' . $gutenbergId;

        if ($this->cacheEnabled && Cache::has($cacheKey)) {
            Log::info('Gutendex: Cache hit for book', ['id' => $gutenbergId]);
            return Cache::get($cacheKey);
        }

        try {
            $response = $this->makeRequest('GET', "/books/{$gutenbergId}");

            if (empty($response)) {
                return null;
            }

            $book = GutendexBook::fromApiResponse($response);

            if ($this->cacheEnabled) {
                Cache::put($cacheKey, $book, $this->cacheTtl);
            }

            return $book;
        } catch (\Exception $e) {
            Log::error('Gutendex: Failed to fetch book', [
                'id' => $gutenbergId,
                'error' => $e->getMessage(),
            ]);
            return null;
        }
    }

    /**
     * Get books by language.
     *
     * @param string $language Language code (e.g., 'en', 'fr')
     * @param int $page Page number
     * @return array
     */
    public function getBooksByLanguage(string $language = 'en', int $page = 1): array
    {
        return $this->searchBooks(null, $page, ['languages' => $language]);
    }

    /**
     * Get books filtered by copyright status.
     *
     * @param string $copyright 'true', 'false', or 'null'
     * @param int $page Page number
     * @return array
     */
    public function getBooksByCopyright(string $copyright = 'false', int $page = 1): array
    {
        return $this->searchBooks(null, $page, ['copyright' => $copyright]);
    }

    /**
     * Fetch full text content from a given URL.
     *
     * @param string $textUrl URL to the full text
     * @return string|null The text content or null on failure
     */
    public function fetchFullText(string $textUrl): ?string
    {
        try {
            Log::info('Gutendex: Fetching full text', ['url' => $textUrl]);

            $response = Http::timeout($this->timeout * 2)
                ->retry($this->retryMaxAttempts, $this->retryBackoff * 1000)
                ->get($textUrl);

            if ($response->successful()) {
                $text = $response->body();
                Log::info('Gutendex: Successfully fetched full text', [
                    'url' => $textUrl,
                    'size' => strlen($text),
                ]);
                return $text;
            }

            Log::warning('Gutendex: Failed to fetch full text', [
                'url' => $textUrl,
                'status' => $response->status(),
            ]);

            return null;
        } catch (ConnectionException $e) {
            Log::error('Gutendex: Connection error fetching full text', [
                'url' => $textUrl,
                'error' => $e->getMessage(),
            ]);
            return null;
        } catch (\Exception $e) {
            Log::error('Gutendex: Error fetching full text', [
                'url' => $textUrl,
                'error' => $e->getMessage(),
            ]);
            return null;
        }
    }

    /**
     * Get books with pagination info.
     *
     * @param array $filters Filters to apply
     * @param int $page Page number
     * @return array Contains 'books' (GutendexBook[]), 'count', 'next', 'previous'
     */
    public function getBooksWithPagination(array $filters = [], int $page = 1): array
    {
        $response = $this->searchBooks(null, $page, $filters);

        $books = array_map(
            fn($bookData) => GutendexBook::fromApiResponse($bookData),
            $response['results'] ?? []
        );

        return [
            'books' => $books,
            'count' => $response['count'] ?? 0,
            'next' => $response['next'] ?? null,
            'previous' => $response['previous'] ?? null,
        ];
    }

    /**
     * Check if the Gutendex API is accessible.
     *
     * @return bool
     */
    public function checkConnection(): bool
    {
        try {
            $response = Http::timeout(10)->get($this->baseUrl . '/books?page=1');
            return $response->successful();
        } catch (\Exception $e) {
            Log::error('Gutendex: Connection check failed', ['error' => $e->getMessage()]);
            return false;
        }
    }

    /**
     * Make an HTTP request to the Gutendex API with retry logic.
     *
     * @param string $method HTTP method
     * @param string $endpoint API endpoint
     * @param array $params Query parameters
     * @return array Response data
     * @throws RequestException
     */
    protected function makeRequest(string $method, string $endpoint, array $params = []): array
    {
        $url = $this->baseUrl . $endpoint;
        $startTime = microtime(true);

        try {
            $response = Http::timeout($this->timeout)
                ->retry(
                    $this->retryMaxAttempts,
                    function ($exception, $request) {
                        // Exponential backoff
                        return $this->retryBackoff * 1000;
                    },
                    function ($exception, $request) {
                        // Retry on connection errors and 429 rate limit
                        if ($exception instanceof ConnectionException) {
                            return true;
                        }

                        if (method_exists($exception, 'response')) {
                            $response = $exception->response;
                            return $response && $response->status() === 429;
                        }

                        return false;
                    }
                )
                ->acceptJson()
                ->$method($url, $params);

            $duration = microtime(true) - $startTime;

            if ($response->successful()) {
                Log::info('Gutendex: API request successful', [
                    'method' => $method,
                    'endpoint' => $endpoint,
                    'duration' => round($duration, 2) . 's',
                ]);

                // Add rate limit delay
                if ($this->rateLimit > 0) {
                    usleep($this->rateLimit * 1000);
                }

                return $response->json();
            }

            Log::warning('Gutendex: API request failed', [
                'method' => $method,
                'endpoint' => $endpoint,
                'status' => $response->status(),
                'duration' => round($duration, 2) . 's',
            ]);

            return [];
        } catch (ConnectionException $e) {
            Log::error('Gutendex: Connection error', [
                'method' => $method,
                'endpoint' => $endpoint,
                'error' => $e->getMessage(),
            ]);
            throw $e;
        } catch (RequestException $e) {
            $duration = microtime(true) - $startTime;

            Log::error('Gutendex: Request exception', [
                'method' => $method,
                'endpoint' => $endpoint,
                'error' => $e->getMessage(),
                'duration' => round($duration, 2) . 's',
            ]);

            throw $e;
        }
    }

    /**
     * Clear all cached Gutendex data.
     *
     * @return void
     */
    public function clearCache(): void
    {
        Cache::flush();
        Log::info('Gutendex: Cache cleared');
    }
}