<?php

declare(strict_types=1);

namespace App\Services;

use App\Enums\MessageType;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Log;

/**
 * Multi-provider AI service supporting OpenAI-compatible APIs.
 * Providers: OpenRouter, OpenAI, StepFun, llama.cpp, QwenCloud, etc.
 */
class AIService
{
    /** @var string The API base URL */
    protected string $baseUrl;

    /** @var string The API key */
    protected string $apiKey;

    /** @var string The model name */
    protected string $model;

    /** @var string The provider name for logging */
    protected string $provider;

    /** @var array Default headers */
    protected array $headers = [];

    /**
     * Get the configured default AI provider/model for translations.
     *
     * @return array{provider: string, model: string}
     */
    public static function getTranslationDefaults(): array
    {
        $provider = \App\Models\Setting::where('key', 'ai_default_provider')->value('value');
        $model = \App\Models\Setting::where('key', 'ai_default_model')->value('value');

        $provider = $provider ?: config('services.ai.default_provider', 'openrouter');
        $model = $model ?: config('services.ai.providers.'.$provider.'.model', 'inclusionai/ling-3.0-tiny:free');

        return [
            'provider' => $provider,
            'model' => $model,
        ];
    }

    /**
     * Create a new AIService instance.
     *
     * @param string|null $provider Optional provider name. If null, uses default from config.
     * @param string|null $model Optional model name. If null, uses provider default.
     */
    public function __construct(?string $provider = null, ?string $model = null)
    {
        $defaultProvider = config('services.ai.default_provider', 'openrouter');
        $defaults = self::getTranslationDefaults();

        $this->loadProvider($provider ?? $defaults['provider'] ?? $defaultProvider);

        if ($model) {
            $this->model = $model;
        } elseif (!empty($defaults['model'])) {
            $this->model = $defaults['model'];
        }
    }

    /**
     * Load provider configuration.
     */
    protected function loadProvider(string $provider): void
    {
        $this->provider = $provider;
        $config = config("services.ai.providers.{$provider}", []);

        $this->baseUrl = rtrim($config['base_url'] ?? '', '/') . '/';
        $this->apiKey = $config['api_key'] ?? '';
        $this->model = $config['model'] ?? 'gpt-3.5-turbo';

        // Set default headers
        $this->headers = [
            'Content-Type' => 'application/json',
        ];

        if (!empty($this->apiKey)) {
            // Some providers use 'Authorization: Bearer', others use 'x-api-key'
            $this->headers['Authorization'] = 'Bearer ' . $this->apiKey;
        }

        // Provider-specific headers
        if ($provider === 'openrouter') {
            $this->headers['HTTP-Referer'] = config('app.url');
            $this->headers['X-Title'] = config('app.name');
        }
    }

    /**
     * Generate a message based on the configured message type.
     *
     * @param string $subject The subject/topic for the message
     * @param string $userMessage Additional user instructions
     * @param array $context Optional context (language, introduction, etc.)
     * @param \App\Enums\MessageType|null $messageType The type of message to generate
     */
    public function generateInsight(string $subject, string $userMessage, array $context = [], ?MessageType $messageType = null): array
    {
        if (empty($this->apiKey)) {
            return [
                'success' => false,
                'error' => __('API key not configured for provider: :provider', ['provider' => $this->provider]),
            ];
        }

        // Get language preference from context
        $language = $context['language'] ?? 'en';
        unset($context['language']);

        $languageNames = [
            'pt_BR' => 'Brazilian Portuguese',
            'en' => 'English',
            'es' => 'Spanish',
        ];
        $languageName = $languageNames[$language] ?? 'English';

        $messageType = $messageType ?? MessageType::Insight;

        $baseSystemPrompt = "You are an expert learning assistant for the subject: {$subject}. ";
        $languageInstruction = "CRITICAL LANGUAGE INSTRUCTION - You MUST follow this exactly:\n"
            . "Your entire response MUST be written ONLY in {$languageName} ({$language}).\n"
            . "Do NOT use any other language. Do NOT include English translations or explanations.\n"
            . "If the subject is a language course (like English), you may use that language as examples,\n"
            . "but all instructions, explanations, and tips MUST be in {$languageName}.\n"
            . "This is mandatory. Start your response directly with the content in {$languageName}.";

        $systemPrompt = match ($messageType) {
            MessageType::LanguageLesson => $baseSystemPrompt
                . "You are acting as a specialized Language Teacher. "
                . "CRITICAL LANGUAGE RULE FOR LESSONS:\n"
                . "- Explanations, instructions, and tips MUST be written in {$languageName} ({$language}).\n"
                . "- BUT all target-language content (examples, vocabulary, practice sentences) MUST be in the language being taught: English.\n"
                . "- Do NOT translate English examples into {$languageName}. Keep English content pure.\n"
                . "- For Practical Examples and Practice Sentences: the ENGLISH sentence comes FIRST, then its Portuguese translation AFTER a hyphen.\n"
                . "- Example: 'The experiment shows that light travels faster than sound. - O experimento mostra que a luz viaja mais rápido que o som.'\n\n"
                . "ABSOLUTE RULES FOR PRACTICAL EXAMPLES AND PRACTICE SENTENCES:\n"
                . "1. The English sentence MUST come FIRST.\n"
                . "2. After the English sentence, add a hyphen and the Portuguese translation.\n"
                . "3. Do NOT write the Portuguese sentence first.\n"
                . "4. Do NOT repeat the same sentence twice.\n"
                . "5. Do NOT mix languages in the same sentence.\n\n"
                . "Create a complete language lesson structured exactly as follows:\n\n"
                . "## Insight\n"
                . "A brief, motivating introduction/insight about the language concept being taught. Write this in {$languageName}.\n\n"
                . "## Grammar Explanation\n"
                . "Explain ONE specific grammar point clearly and concisely. "
                . "Include rules, usage, and common mistakes. Write this in {$languageName}.\n\n"
                . "## Vocabulary Building\n"
                . "List 5-8 essential words/phrases IN ENGLISH. For each, provide:\n"
                . "- The word/phrase IN ENGLISH wrapped in a <span class=\"tts\" data-text=\"[English word/phrase]\">[English word/phrase]</span> tag\n"
                . "- Its meaning in {$languageName}\n"
                . "- An example sentence IN ENGLISH wrapped in a <span class=\"tts\" data-text=\"[English example sentence]\">[English example sentence]</span> tag\n\n"
                . "## Practical Examples\n"
                . "Provide 3-5 practical example sentences IN ENGLISH showing real-world usage. "
                . "Format each line EXACTLY as:\n"
                . "<span class=\"tts\" data-text=\"[English sentence]\">[English sentence]</span> - [Portuguese translation]\n"
                . "Do NOT put Portuguese first. English MUST be first.\n\n"
                . "## Practice Sentences\n"
                . "Provide 5-7 complete sentences IN ENGLISH for the user to practice speaking. "
                . "Format each line EXACTLY as:\n"
                . "/[Complete IPA for the full English sentence]/ <span class=\"tts\" data-text=\"[English sentence]\">[English sentence]</span> - [Portuguese translation]\n"
                . "The IPA must be COMPLETE for the FULL English sentence. Do NOT truncate IPA.\n\n"
                . "WRONG FORMAT (DO NOT USE):\n"
                . "- [Portuguese sentence] - [English sentence]\n"
                . "CORRECT FORMAT (MANDATORY):\n"
                . "- [English sentence] - [Portuguese sentence]\n\n"
                . "Make it engaging, structured, and suitable for self-study.\n\n"
                . $languageInstruction,

            MessageType::GameSimulator => $baseSystemPrompt
                . "You are acting as a Game and Simulator Strategy Expert. "
                . "Create content that includes:\n"
                . "- An insight or strategic tip related to the subject\n"
                . "- Practical strategies and tactics\n"
                . "- Commands, shortcuts, or step-by-step instructions where applicable\n"
                . "- Scenarios or simulation tips\n"
                . "Make it actionable and engaging.\n\n"
                . $languageInstruction,

            MessageType::TechnicalTeaching => $baseSystemPrompt
                . "You are acting as a Specialized Technical Teacher. "
                . "Create content that includes:\n"
                . "- An insight about the technical subject\n"
                . "- Description and practical use of components/tools\n"
                . "- Types of components/tools and their differences\n"
                . "- Service techniques and best practices\n"
                . "- Repair techniques and troubleshooting\n"
                . "- How to read technical diagrams/schematics\n"
                . "- Practical examples and applied exercises when relevant\n"
                . "Be direct, technical, and educational. Use clear step-by-step explanations.\n\n"
                . $languageInstruction,

            default => $baseSystemPrompt
                . "Provide insightful, educational content. Be concise and practical.\n\n"
                . $languageInstruction,
        };

        $userMessageWithLanguage = "[IMPORTANTE: Responda EXCLUSIVAMENTE em {$languageName}. "
            . "NÃO use inglês. NÃO traduza. NÃO misture idiomas. "
            . "Toda a resposta deve ser APENAS em {$languageName}.]\n\n"
            . $userMessage;

        if ($messageType === MessageType::TechnicalTeaching && str_contains(strtolower($subject), 'eletrônica')) {
            $userMessageWithLanguage .= "\n\nSPECIAL INSTRUCTION: For each lesson, include explanation, technical description, and practical applications of specific electronic components. Examples: LM555, AT89C2051, BC557.\n";
            $userMessageWithLanguage .= "CRITICAL: Write ALL content in Brazilian Portuguese. Even technical terms must be explained in Portuguese. Do NOT write in English.";
        }

        $messages = [
            ['role' => 'system', 'content' => $systemPrompt],
            ['role' => 'user', 'content' => $userMessageWithLanguage],
        ];

        // Add context if provided
        if (!empty($context)) {
            $contextStr = "Context information:\n";
            foreach ($context as $key => $value) {
                $contextStr .= "- {$key}: {$value}\n";
            }
            array_unshift($messages, ['role' => 'system', 'content' => $contextStr]);
        }

        try {
            $response = Http::withHeaders($this->headers)
                ->timeout(120)
                ->post($this->baseUrl . 'chat/completions', [
                    'model' => $this->model,
                    'messages' => $messages,
                ]);

            $data = $response->json();

            if (!$data || !isset($data['choices'][0]['message'])) {
                $errorMsg = $data['error']['message'] ?? ($data['error'] ?? __('Unknown API error'));
                Log::error("AI Service ({$this->provider}) error response", [
                    'response' => $data,
                    'subject' => $subject,
                    'message_type' => $messageType->value,
                ]);
                return [
                    'success' => false,
                    'error' => $errorMsg,
                ];
            }

            $message = $data['choices'][0]['message'];
            $content = $message['content'] ?? $message['reasoning'] ?? null;

            if ($content) {
                return [
                    'success' => true,
                    'content' => $content,
                    'input_tokens' => $data['usage']['prompt_tokens'] ?? 0,
                    'output_tokens' => $data['usage']['completion_tokens'] ?? 0,
                ];
            }

            Log::error("AI Service ({$this->provider}): Empty response content", [
                'response' => $data,
                'subject' => $subject,
                'message_type' => $messageType->value,
            ]);

            return [
                'success' => false,
                'error' => __('The AI model returned an empty response. Please try again.'),
            ];
        } catch (\Exception $e) {
            Log::error("AI Service ({$this->provider}) error: " . $e->getMessage(), [
                'subject' => $subject,
                'message_type' => $messageType->value,
            ]);
            return [
                'success' => false,
                'error' => $e->getMessage(),
            ];
        }
    }

    /**
     * Get the current provider name.
     */
    public function getProvider(): string
    {
        return $this->provider;
    }

    /**
      * Get the current model name.
      */
     public function getModel(): string
     {
         return $this->model;
     }

     /**
      * Translate text to the specified language using AI.
      *
      * @param string $text The text to translate
      * @param string $targetLanguage The target language code (pt_BR, en, es)
      * @param string|null $subject Optional subject context for better translation
      */
     public function translate(string $text, string $targetLanguage, ?string $subject = null): array
     {
         if (empty($this->apiKey)) {
             return [
                 'success' => false,
                 'error' => __('API key not configured for provider: :provider', ['provider' => $this->provider]),
             ];
         }

         $languageNames = [
             'pt_BR' => 'Brazilian Portuguese',
             'en' => 'English',
             'es' => 'Spanish',
         ];
         $languageName = $languageNames[$targetLanguage] ?? 'English';

         $subjectContext = $subject ? "This is about: {$subject}.\n" : '';

         $systemPrompt = "You are a professional translator. Translate the following text to {$languageName} ({$targetLanguage}).\n\n"
             . "RULES:\n"
             . "1. Translate ONLY the content, preserving the original meaning, tone, and structure.\n"
             . "2. Keep all markdown formatting, HTML tags, and special characters exactly as they are.\n"
             . "3. Do NOT add any explanations, notes, or translations of your own.\n"
             . "4. Do NOT translate code blocks, URLs, or technical terms that are commonly kept in English.\n"
             . "5. Return ONLY the translated text, nothing else.\n"
             . "6. The entire response must be in {$languageName}.";

         $userMessage = "{$subjectContext}Translate this text to {$languageName}:\n\n{$text}";

         $messages = [
             ['role' => 'system', 'content' => $systemPrompt],
             ['role' => 'user', 'content' => $userMessage],
         ];

         try {
             $response = Http::withHeaders($this->headers)
                 ->timeout(120)
                 ->post($this->baseUrl . 'chat/completions', [
                     'model' => $this->model,
                     'messages' => $messages,
                 ]);

             $data = $response->json();

             if (!$data || !isset($data['choices'][0]['message'])) {
                 $errorMsg = $data['error']['message'] ?? ($data['error'] ?? __('Unknown API error'));
                 Log::error("AI Service ({$this->provider}) translation error", [
                     'response' => $data,
                     'target_language' => $targetLanguage,
                 ]);
                 return [
                     'success' => false,
                     'error' => $errorMsg,
                 ];
             }

             $message = $data['choices'][0]['message'];
             $content = $message['content'] ?? $message['reasoning'] ?? null;

             if ($content) {
                 return [
                     'success' => true,
                     'content' => $content,
                     'input_tokens' => $data['usage']['prompt_tokens'] ?? 0,
                     'output_tokens' => $data['usage']['completion_tokens'] ?? 0,
                 ];
             }

             Log::error("AI Service ({$this->provider}): Empty translation response", [
                 'response' => $data,
                 'target_language' => $targetLanguage,
             ]);

             return [
                 'success' => false,
                 'error' => __('The AI model returned an empty response. Please try again.'),
             ];
         } catch (\Exception $e) {
             Log::error("AI Service ({$this->provider}) translation error: " . $e->getMessage(), [
                 'target_language' => $targetLanguage,
             ]);
             return [
                 'success' => false,
                 'error' => $e->getMessage(),
             ];
         }
     }

    /**
     * Send a chat message to the AI and get a response.
     *
     * @param array<int, array{role: string, content: string}> $messages
     */
    public function chat(array $messages): array
    {
        if (empty($this->apiKey)) {
            return [
                'success' => false,
                'error' => __('API key not configured for provider: :provider', ['provider' => $this->provider]),
            ];
        }

        try {
            $response = Http::withHeaders($this->headers)
                ->timeout(120)
                ->post($this->baseUrl . 'chat/completions', [
                    'model' => $this->model,
                    'messages' => $messages,
                ]);

            $data = $response->json();

            if (!$data || !isset($data['choices'][0]['message'])) {
                $errorMsg = $data['error']['message'] ?? ($data['error'] ?? __('Unknown API error'));
                Log::error("AI Service ({$this->provider}) chat error", [
                    'response' => $data,
                ]);
                return [
                    'success' => false,
                    'error' => $errorMsg,
                ];
            }

            $message = $data['choices'][0]['message'];
            $content = $message['content'] ?? $message['reasoning'] ?? null;

            if ($content) {
                return [
                    'success' => true,
                    'content' => $content,
                    'input_tokens' => $data['usage']['prompt_tokens'] ?? 0,
                    'output_tokens' => $data['usage']['completion_tokens'] ?? 0,
                ];
            }

            Log::error("AI Service ({$this->provider}): Empty chat response", [
                'response' => $data,
            ]);

            return [
                'success' => false,
                'error' => __('The AI model returned an empty response. Please try again.'),
            ];
        } catch (\Exception $e) {
            Log::error("AI Service ({$this->provider}) chat error: " . $e->getMessage(), []);
            return [
                'success' => false,
                'error' => $e->getMessage(),
            ];
        }
    }
}