<?php
/**
 * TTS Helper class to handle Text-to-Speech with ElevenLabs or Twilio
 */
class TWP_TTS_Helper {
    
    private static $instance = null;
    private $elevenlabs_api = null;
    private $use_elevenlabs = false;
    
    /**
     * Get singleton instance
     */
    public static function get_instance() {
        if (self::$instance === null) {
            self::$instance = new self();
        }
        return self::$instance;
    }
    
    /**
     * Constructor
     */
    private function __construct() {
        // Check if ElevenLabs is configured
        $api_key = get_option('twp_elevenlabs_api_key');
        $voice_id = get_option('twp_elevenlabs_voice_id');
        
        if (!empty($api_key) && !empty($voice_id)) {
            $this->use_elevenlabs = true;
            require_once plugin_dir_path(dirname(__FILE__)) . 'includes/class-twp-elevenlabs-api.php';
            $this->elevenlabs_api = new TWP_ElevenLabs_API();
        }
    }
    
    /**
     * Get cache key for text
     */
    private function get_cache_key($text) {
        $voice_id = get_option('twp_elevenlabs_voice_id');
        $model_id = get_option('twp_elevenlabs_model_id', 'eleven_multilingual_v2');
        return 'twp_tts_' . md5($text . $voice_id . $model_id);
    }
    
    /**
     * Get cached audio URL if exists
     */
    private function get_cached_audio($text) {
        $cache_key = $this->get_cache_key($text);
        $cached_data = get_transient($cache_key);
        
        if ($cached_data !== false) {
            // Verify the file still exists
            if (file_exists($cached_data['file_path'])) {
                error_log("TWP TTS: Using cached audio for text: " . substr($text, 0, 50) . "...");
                return $cached_data;
            } else {
                // File was deleted, remove from cache
                delete_transient($cache_key);
            }
        }
        
        return false;
    }
    
    /**
     * Save audio to cache
     */
    private function cache_audio($text, $audio_data) {
        $cache_key = $this->get_cache_key($text);
        // Cache for 30 days
        set_transient($cache_key, $audio_data, 30 * DAY_IN_SECONDS);
    }
    
    /**
     * Add TTS to TwiML Response
     * 
     * @param \Twilio\TwiML\VoiceResponse $twiml The TwiML response object
     * @param string $text The text to speak
     * @param array $options Options for voice settings (used for Twilio fallback)
     * @return bool Success status
     */
    public function add_tts_to_twiml($twiml, $text, $options = []) {
        // Default Twilio voice options
        $default_options = [
            'voice' => 'alice',
            'language' => 'en-US'
        ];
        $options = array_merge($default_options, $options);
        
        if ($this->use_elevenlabs) {
            // First check cache
            $cached_audio = $this->get_cached_audio($text);
            
            if ($cached_audio !== false) {
                $twiml->play($cached_audio['file_url']);
                return true;
            }
            
            // Not in cache, generate new audio
            $audio_result = $this->elevenlabs_api->text_to_speech($text);
            
            if ($audio_result && isset($audio_result['success']) && $audio_result['success']) {
                // Cache the result
                $this->cache_audio($text, [
                    'file_url' => $audio_result['file_url'],
                    'file_path' => $audio_result['file_path']
                ]);
                
                // Use the generated audio file
                $twiml->play($audio_result['file_url']);
                error_log("TWP TTS: Generated new ElevenLabs audio for text: " . substr($text, 0, 50) . "...");
                return true;
            } else {
                // Log the failure and fall back to Twilio
                error_log("TWP TTS: ElevenLabs failed, falling back to Twilio. Error: " . 
                         (isset($audio_result['error']) ? $audio_result['error'] : 'Unknown error'));
            }
        }
        
        // Fall back to Twilio's built-in TTS
        $twiml->say($text, $options);
        error_log("TWP TTS: Using Twilio voice for text: " . substr($text, 0, 50) . "...");
        return true;
    }
    
    /**
     * Generate TTS audio file (for pre-generation)
     * 
     * @param string $text The text to convert
     * @return array|false Array with file_url on success, false on failure
     */
    public function generate_tts_audio($text) {
        if (!$this->use_elevenlabs) {
            return false;
        }
        
        // First check cache
        $cached_audio = $this->get_cached_audio($text);
        if ($cached_audio !== false) {
            return [
                'success' => true,
                'file_url' => $cached_audio['file_url'],
                'file_path' => $cached_audio['file_path'],
                'cached' => true
            ];
        }
        
        // Not in cache, generate new audio
        $result = $this->elevenlabs_api->text_to_speech($text);
        
        if ($result && isset($result['success']) && $result['success']) {
            // Cache the result
            $this->cache_audio($text, [
                'file_url' => $result['file_url'],
                'file_path' => $result['file_path']
            ]);
            
            return [
                'success' => true,
                'file_url' => $result['file_url'],
                'file_path' => $result['file_path'],
                'cached' => false
            ];
        }
        
        return false;
    }
    
    /**
     * Check if ElevenLabs is configured and available
     * 
     * @return bool
     */
    public function is_elevenlabs_available() {
        return $this->use_elevenlabs;
    }
    
    /**
     * Get configured voice info
     * 
     * @return array
     */
    public function get_voice_info() {
        if ($this->use_elevenlabs) {
            return [
                'provider' => 'elevenlabs',
                'voice_id' => get_option('twp_elevenlabs_voice_id'),
                'model_id' => get_option('twp_elevenlabs_model_id', 'eleven_multilingual_v2')
            ];
        }
        
        return [
            'provider' => 'twilio',
            'voice' => 'alice',
            'language' => 'en-US'
        ];
    }
    
    /**
     * Clean up old TTS files (maintenance)
     */
    public function cleanup_old_files($hours = 24) {
        $upload_dir = wp_upload_dir();
        $path = $upload_dir['path'];
        
        // Only clean up TTS files older than specified hours
        $expire_time = time() - ($hours * 3600);
        
        $files = glob($path . '/tts_*.mp3');
        if ($files) {
            foreach ($files as $file) {
                if (filemtime($file) < $expire_time) {
                    unlink($file);
                    error_log("TWP TTS: Cleaned up old file: " . basename($file));
                }
            }
        }
    }
}