<?php

namespace App\Services;

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

/**
 * Service to handle translation via third-party providers.
 * Follows a driver-based architecture for flexibility.
 */
class TranslationProviderService
{
    /**
     * @var string The current driver to use.
     */
    protected string $driver;

    /**
     * @var SettingService
     */
    protected SettingService $settingService;

    /**
     * TranslationProviderService constructor.
     */
    public function __construct(SettingService $settingService)
    {
        $this->settingService = $settingService;
        $this->driver = $this->settingService->get('translation_driver', config('cms.translation_driver', 'mock'));
    }

    /**
     * Set the driver dynamically.
     *
     * @param string $driver
     * @return $this
     */
    public function setDriver(string $driver): self
    {
        $this->driver = $driver;
        return $this;
    }

    /**
     * Translate text from one language to another.
     *
     * @param string $text The text to translate.
     * @param string $from The source locale.
     * @param string $to The target locale.
     * @return string|null The translated text or null on failure.
     */
    public function translate(string $text, string $from, string $to): ?string
    {
        if ($from === $to) {
            return $text;
        }

        return match ($this->driver) {
            'google' => $this->translateWithGoogle($text, $from, $to),
            'deepl'  => $this->translateWithDeepL($text, $from, $to),
            'openai' => $this->translateWithOpenAI($text, $from, $to),
            'mock'   => $this->translateWithMock($text, $from, $to),
            default  => $this->translateWithMock($text, $from, $to),
        };
    }

    /**
     * Mock translation for development and testing.
     *
     * @param string $text
     * @param string $from
     * @param string $to
     * @return string
     */
    protected function translateWithMock(string $text, string $from, string $to): string
    {
        return "[{$to}] " . $text;
    }

    /**
     * Translate using Google Translate API.
     * Checks settings first, then falls back to config/services.php.
     *
     * @param string $text
     * @param string $from
     * @param string $to
     * @return string|null
     */
    protected function translateWithGoogle(string $text, string $from, string $to): ?string
    {
        $apiKey = $this->settingService->get('google_translate_key', config('services.google.translate_key'));

        if (!$apiKey) {
            Log::error("Google Translate API key not found.");
            return $this->translateWithMock($text, $from, $to);
        }

        try {
            $response = Http::post("https://translation.googleapis.com/language/translate/v2", [
                'q' => $text,
                'source' => $from,
                'target' => $to,
                'format' => 'text',
                'key' => $apiKey,
            ]);

            if ($response->successful()) {
                return $response->json('data.translations.0.translatedText');
            }

            Log::error("Google Translate API error: " . $response->body());
        } catch (\Exception $e) {
            Log::error("Google Translate Exception: " . $e->getMessage());
        }

        return null;
    }

    /**
     * Translate using DeepL API.
     *
     * @param string $text
     * @param string $from
     * @param string $to
     * @return string|null
     */
    protected function translateWithDeepL(string $text, string $from, string $to): ?string
    {
        $apiKey = $this->settingService->get('deepl_api_key', config('services.deepl.key'));

        if (!$apiKey) {
            Log::error("DeepL API key not found.");
            return $this->translateWithMock($text, $from, $to);
        }

        // DeepL uses 'source_lang' and 'target_lang' and requires upper-case codes
        $from = strtoupper($from);
        $to = strtoupper($to);

        // Handle regional variants if necessary (e.g. EN -> EN-US, EN-GB)
        // For simplicity, we'll use the 2-letter code if it's not a variant
        if ($to === 'EN') $to = 'EN-US';
        if ($to === 'PT') $to = 'PT-PT';

        try {
            $response = Http::withHeaders([
                'Authorization' => 'DeepL-Auth-Key ' . $apiKey,
            ])->post("https://api-free.deepl.com/v2/translate", [
                'text' => [$text],
                'source_lang' => $from,
                'target_lang' => $to,
            ]);

            // Try the Pro API if the Free one fails with 403 or 456
            if ($response->status() === 403 || $response->status() === 456) {
                $response = Http::withHeaders([
                    'Authorization' => 'DeepL-Auth-Key ' . $apiKey,
                ])->post("https://api.deepl.com/v2/translate", [
                    'text' => [$text],
                    'source_lang' => $from,
                    'target_lang' => $to,
                ]);
            }

            if ($response->successful()) {
                return $response->json('translations.0.text');
            }

            Log::error("DeepL API error: " . $response->body());
        } catch (\Exception $e) {
            Log::error("DeepL Exception: " . $e->getMessage());
        }

        return null;
    }

    /**
     * Translate using OpenAI API (GPT-4o-mini).
     *
     * @param string $text
     * @param string $from
     * @param string $to
     * @return string|null
     */
    protected function translateWithOpenAI(string $text, string $from, string $to): ?string
    {
        $apiKey = $this->settingService->get('openai_api_key', config('services.openai.key'));

        if (!$apiKey) {
            Log::error("OpenAI API key not found.");
            return $this->translateWithMock($text, $from, $to);
        }

        try {
            $response = Http::withToken($apiKey)->post("https://api.openai.com/v1/chat/completions", [
                'model' => 'gpt-4o-mini',
                'messages' => [
                    ['role' => 'system', 'content' => "You are a professional translator. Translate the given text from {$from} to {$to}. Respond ONLY with the translated text."],
                    ['role' => 'user', 'content' => $text],
                ],
                'temperature' => 0.3,
            ]);

            if ($response->successful()) {
                return trim($response->json('choices.0.message.content'));
            }

            Log::error("OpenAI API error: " . $response->body());
        } catch (\Exception $e) {
            Log::error("OpenAI Exception: " . $e->getMessage());
        }

        return null;
    }
}