audio_processors/ml_mfcc_processor.py

"""
ML MFCC Digit Processor
Uses the trained MFCC + Dense NN model for digit classification
"""

import os
import sys
import time
import logging
from pathlib import Path
from typing import Dict, Any, Optional, Union

import numpy as np
from .base_processor import AudioProcessor

# Add project root to path for ML imports
PROJECT_ROOT = Path(__file__).parent.parent
sys.path.append(str(PROJECT_ROOT))

# Import ML inference
from ml_training.inference import load_classifier

logger = logging.getLogger(__name__)

class MLMFCCProcessor(AudioProcessor):
    """
    ML-based MFCC digit processor using trained Dense NN model.
    
    Performance characteristics (based on training results):
    - Test accuracy: 98.52%
    - Inference time: ~1-2ms
    - Model size: ~0.3MB
    """
    
    name = "ML MFCC + Dense NN (Best)"
    
    def __init__(self, model_dir: str = "models", device: str = "auto"):
        """
        Initialize ML MFCC processor.
        
        Args:
            model_dir: Directory containing trained models
            device: Device to run inference on ('cpu', 'cuda', or 'auto')
        """
        super().__init__(self.name)
        
        self.model_dir = Path(model_dir)
        self.device = device if device != "auto" else None
        self.classifier = None
        self._configured = False
        
        # Performance tracking
        self.prediction_count = 0
        self.total_inference_time = 0.0
        self.last_prediction_time = None
        
        # Try to load the model
        self._initialize_classifier()
        
        logger.info(f"ML MFCC Processor initialized (configured: {self._configured})")
    
    def _initialize_classifier(self):
        """Initialize the ML classifier."""
        try:
            # Check if model directory exists
            if not self.model_dir.exists():
                logger.warning(f"Model directory not found: {self.model_dir}")
                return
            
            # Load the MFCC classifier
            self.classifier = load_classifier(
                model_dir=str(self.model_dir),
                pipeline_type='mfcc',
                device=self.device
            )
            
            self._configured = True
            logger.info("ML MFCC classifier loaded successfully")
            logger.info(f"  Model device: {self.classifier.device}")
            logger.info(f"  Parameters: {sum(p.numel() for p in self.classifier.model.parameters()):,}")
            
        except Exception as e:
            logger.error(f"Failed to load ML MFCC classifier: {str(e)}")
            self.classifier = None
            self._configured = False
    
    def is_configured(self) -> bool:
        """Check if the processor is properly configured."""
        return self._configured and self.classifier is not None
    
    def process_audio(self, audio_data: bytes) -> str:
        """
        Process audio and return predicted digit (required by base class).
        
        Args:
            audio_data: Raw audio data in bytes
            
        Returns:
            predicted_digit: Predicted digit as string
        """
        return self.predict(audio_data)
    
    def predict(self, audio_data: bytes) -> str:
        """
        Predict digit from audio data.
        
        Args:
            audio_data: Raw audio data in bytes
            
        Returns:
            predicted_digit: Predicted digit as string
        """
        if not self.is_configured():
            raise RuntimeError("ML MFCC processor not properly configured")
        
        try:
            # Convert audio with optimized format for ML models
            from utils.audio_utils import convert_for_ml_models
            optimized_audio = convert_for_ml_models(audio_data, 'mfcc')
            
            # Convert audio bytes to numpy array
            audio_array = self._bytes_to_audio_array(optimized_audio)
            
            # No audio preprocessing needed - normalization happens at feature level in ML pipeline
            
            # Make prediction using ML classifier
            start_time = time.time()
            result = self.classifier.predict(
                audio_array, 
                return_probabilities=True, 
                return_features=False
            )
            inference_time = time.time() - start_time
            
            # Update performance tracking
            self.prediction_count += 1
            self.total_inference_time += inference_time
            self.last_prediction_time = inference_time
            
            predicted_digit = str(result['predicted_digit'])
            confidence = result['confidence']
            
            # Debug logging for predictions (temporary)
            if hasattr(result, 'probabilities') or 'probabilities' in result:
                probs = result.get('probabilities', [])
                if len(probs) >= 10:
                    top_predictions = [(i, p) for i, p in enumerate(probs)]
                    top_predictions.sort(key=lambda x: x[1], reverse=True)
                    logger.debug(f"MFCC Top 3 predictions: {[(str(d), f'{p:.3f}') for d, p in top_predictions[:3]]}")
            
            logger.debug(f"MFCC predicted '{predicted_digit}' with confidence {confidence:.3f} in {inference_time:.3f}s")
            
            logger.debug(f"ML MFCC prediction: '{predicted_digit}' "
                        f"(confidence: {confidence:.3f}, time: {inference_time*1000:.1f}ms)")
            
            return predicted_digit
            
        except Exception as e:
            logger.error(f"ML MFCC prediction failed: {str(e)}")
            raise
    
    def predict_with_timing(self, audio_data: bytes) -> Dict[str, Any]:
        """
        Predict digit with detailed timing and confidence information.
        
        Args:
            audio_data: Raw audio data in bytes
            
        Returns:
            result: Detailed prediction results
        """
        if not self.is_configured():
            return {
                'success': False,
                'error': 'ML MFCC processor not properly configured',
                'predicted_digit': None,
                'inference_time': 0.0
            }
        
        try:
            # Convert audio with optimized format for ML models
            from utils.audio_utils import convert_for_ml_models
            optimized_audio = convert_for_ml_models(audio_data, 'mfcc')
            
            # Convert audio bytes to numpy array
            audio_array = self._bytes_to_audio_array(optimized_audio)
            
            # No audio preprocessing needed - normalization happens at feature level in ML pipeline
            
            # Make prediction using ML classifier
            start_time = time.time()
            ml_result = self.classifier.predict(
                audio_array, 
                return_probabilities=True, 
                return_features=False
            )
            inference_time = time.time() - start_time
            
            # Update performance tracking
            self.prediction_count += 1
            self.total_inference_time += inference_time
            self.last_prediction_time = inference_time
            
            # Format result
            result = {
                'success': True,
                'predicted_digit': str(ml_result['predicted_digit']),
                'confidence': ml_result['confidence'],
                'inference_time': inference_time,
                'class_probabilities': {
                    str(k): float(v) for k, v in ml_result['class_probabilities'].items()
                },
                'top_3_predictions': [
                    {
                        'digit': str(pred['digit']),
                        'probability': pred['probability']
                    }
                    for pred in ml_result['top_3_predictions']
                ],
                'method': self.name,
                'model_type': 'ml_mfcc',
                'timestamp': time.time()
            }
            
            logger.debug(f"ML MFCC detailed prediction: '{result['predicted_digit']}' "
                        f"(confidence: {result['confidence']:.3f}, "
                        f"time: {inference_time*1000:.1f}ms)")
            
            return result
            
        except Exception as e:
            logger.error(f"ML MFCC prediction with timing failed: {str(e)}")
            return {
                'success': False,
                'error': str(e),
                'predicted_digit': None,
                'inference_time': 0.0,
                'method': self.name,
                'model_type': 'ml_mfcc',
                'timestamp': time.time()
            }
    
    def _bytes_to_audio_array(self, audio_data: bytes) -> np.ndarray:
        """Convert audio bytes to numpy array."""
        try:
            # Try to interpret as int16 PCM first (most common)
            audio_array = np.frombuffer(audio_data, dtype=np.int16)
            
            # Convert to float32 and normalize
            audio_array = audio_array.astype(np.float32) / 32768.0
            
            # If the array is too short, pad it
            if len(audio_array) < 1000:  # Less than ~60ms at 16kHz
                # Pad with zeros to minimum length
                audio_array = np.pad(audio_array, (0, 1000 - len(audio_array)))
            
            return audio_array
            
        except Exception as e:
            logger.error(f"Failed to convert audio bytes to array: {str(e)}")
            # Return a small zero array as fallback
            return np.zeros(1000, dtype=np.float32)
    
    def _preprocess_audio_for_mfcc(self, audio_array: np.ndarray) -> np.ndarray:
        """
        Apply MFCC-specific audio preprocessing to improve model performance.
        This compensates for missing scaler normalization.
        
        Args:
            audio_array: Raw audio array
            
        Returns:
            preprocessed_audio: Audio array optimized for MFCC feature extraction
        """
        try:
            # Remove DC component
            audio_array = audio_array - np.mean(audio_array)
            
            # Apply gentle normalization to handle volume variations
            # This helps compensate for the missing feature scaler
            max_val = np.max(np.abs(audio_array))
            if max_val > 0:
                audio_array = audio_array / max_val * 0.7  # Scale to 70% of max to avoid clipping
            
            # Apply a gentle high-pass filter to remove low-frequency noise
            # This improves MFCC feature quality
            from scipy import signal
            if len(audio_array) > 100:  # Only apply if we have enough samples
                # Simple high-pass filter at ~300Hz for 8kHz sample rate
                sos = signal.butter(2, 300, btype='high', fs=8000, output='sos')
                audio_array = signal.sosfilt(sos, audio_array)
            
            # Ensure we don't have any NaN or inf values
            audio_array = np.nan_to_num(audio_array, nan=0.0, posinf=0.0, neginf=0.0)
            
            logger.debug(f"MFCC preprocessing applied: range=[{np.min(audio_array):.3f}, {np.max(audio_array):.3f}], "
                        f"mean={np.mean(audio_array):.3f}, std={np.std(audio_array):.3f}")
            
            return audio_array
            
        except ImportError:
            # Fallback if scipy is not available - just normalize
            logger.warning("Scipy not available, using basic normalization")
            audio_array = audio_array - np.mean(audio_array)
            max_val = np.max(np.abs(audio_array))
            if max_val > 0:
                audio_array = audio_array / max_val * 0.7
            return audio_array
            
        except Exception as e:
            logger.error(f"MFCC preprocessing failed: {str(e)}")
            # Return original array if preprocessing fails
            return audio_array
    
    def get_stats(self) -> Dict[str, Any]:
        """Get processor performance statistics."""
        stats = super().get_stats()
        
        if self.prediction_count > 0:
            stats.update({
                'ml_predictions': self.prediction_count,
                'average_inference_time': self.total_inference_time / self.prediction_count,
                'last_inference_time': self.last_prediction_time,
                'throughput_per_second': self.prediction_count / self.total_inference_time if self.total_inference_time > 0 else 0,
                'model_configured': self.is_configured()
            })
        
        if self.classifier:
            # Get ML classifier performance stats
            ml_stats = self.classifier.get_performance_stats()
            stats['ml_classifier_stats'] = ml_stats
        
        return stats
    
    def get_model_info(self) -> Dict[str, Any]:
        """Get information about the loaded model."""
        if not self.is_configured():
            return {'error': 'Model not loaded'}
        
        try:
            info = {
                'pipeline_type': 'mfcc',
                'model_class': self.classifier.model.__class__.__name__,
                'device': str(self.classifier.device),
                'parameters': sum(p.numel() for p in self.classifier.model.parameters()),
                'feature_extractor': self.classifier.feature_extractor.__class__.__name__,
                'has_scaler': self.classifier.scaler is not None,
                'expected_sample_rate': 8000,
                'expected_audio_length': 8000  # 1 second at 8kHz
            }
            
            if hasattr(self.classifier, 'model_path'):
                info['model_path'] = str(self.classifier.model_path)
            
            return info
            
        except Exception as e:
            logger.error(f"Failed to get model info: {str(e)}")
            return {'error': str(e)}
    
    def benchmark_speed(self, num_samples: int = 100) -> Dict[str, Any]:
        """Benchmark inference speed."""
        if not self.is_configured():
            return {'error': 'Model not configured'}
        
        try:
            return self.classifier.benchmark_speed(num_samples)
        except Exception as e:
            logger.error(f"Benchmark failed: {str(e)}")
            return {'error': str(e)}