sync_manager.py

"""
Audio-Video Synchronization Manager for EceMotion Pictures.
Ensures frame-perfect alignment between generated audio and video content.
"""

import os
import tempfile
import subprocess
import numpy as np
import logging
from typing import Tuple, Optional, Dict, Any
from pathlib import Path
import shutil

from config import SYNC_TOLERANCE_MS, FORCE_SYNC, AUDIO_SAMPLE_RATE

logger = logging.getLogger(__name__)

class SyncManager:
    """Manages audio-video synchronization with frame-perfect accuracy."""
    
    def __init__(self, tolerance_ms: int = SYNC_TOLERANCE_MS):
        self.tolerance_ms = tolerance_ms
        self.tolerance_s = tolerance_ms / 1000.0
        self.ffmpeg_available = self._check_ffmpeg()
        
    def _check_ffmpeg(self) -> bool:
        """Check if ffmpeg is available."""
        try:
            subprocess.run(['ffmpeg', '-version'], capture_output=True, check=True)
            return True
        except (subprocess.CalledProcessError, FileNotFoundError):
            logger.warning("ffmpeg not found, using fallback methods")
            return False
    
    def calculate_video_duration(self, num_frames: int, fps: float) -> float:
        """Calculate exact video duration from frame count and FPS."""
        return num_frames / fps
    
    def measure_audio_duration(self, audio_path: str) -> float:
        """Measure actual duration of audio file."""
        if not os.path.exists(audio_path):
            raise FileNotFoundError(f"Audio file not found: {audio_path}")
        
        if self.ffmpeg_available:
            return self._measure_with_ffmpeg(audio_path)
        else:
            return self._measure_with_soundfile(audio_path)
    
    def _measure_with_ffmpeg(self, audio_path: str) -> float:
        """Measure duration using ffmpeg."""
        try:
            cmd = [
                'ffprobe', '-v', 'quiet', '-show_entries', 'format=duration',
                '-of', 'csv=p=0', audio_path
            ]
            result = subprocess.run(cmd, capture_output=True, text=True, check=True)
            duration = float(result.stdout.strip())
            logger.info(f"Audio duration (ffmpeg): {duration:.3f}s")
            return duration
        except (subprocess.CalledProcessError, ValueError) as e:
            logger.error(f"Failed to measure audio duration with ffmpeg: {e}")
            return self._measure_with_soundfile(audio_path)
    
    def _measure_with_soundfile(self, audio_path: str) -> float:
        """Measure duration using soundfile as fallback."""
        try:
            import soundfile as sf
            info = sf.info(audio_path)
            duration = info.duration
            logger.info(f"Audio duration (soundfile): {duration:.3f}s")
            return duration
        except Exception as e:
            logger.error(f"Failed to measure audio duration with soundfile: {e}")
            # Last resort: estimate from file size
            return self._estimate_duration_from_size(audio_path)
    
    def _estimate_duration_from_size(self, audio_path: str) -> float:
        """Estimate duration from file size (very rough estimate)."""
        try:
            file_size = os.path.getsize(audio_path)
            # Rough estimate: 1MB ≈ 1 second for 128kbps audio
            estimated_duration = file_size / (1024 * 1024)
            logger.warning(f"Estimated audio duration from file size: {estimated_duration:.3f}s")
            return estimated_duration
        except Exception as e:
            logger.error(f"Failed to estimate duration: {e}")
            return 10.0  # Default fallback
    
    def measure_video_duration(self, video_path: str) -> float:
        """Measure actual duration of video file."""
        if not os.path.exists(video_path):
            raise FileNotFoundError(f"Video file not found: {video_path}")
        
        if self.ffmpeg_available:
            return self._measure_video_with_ffmpeg(video_path)
        else:
            return self._estimate_video_duration(video_path)
    
    def _measure_video_with_ffmpeg(self, video_path: str) -> float:
        """Measure video duration using ffmpeg."""
        try:
            cmd = [
                'ffprobe', '-v', 'quiet', '-show_entries', 'format=duration',
                '-of', 'csv=p=0', video_path
            ]
            result = subprocess.run(cmd, capture_output=True, text=True, check=True)
            duration = float(result.stdout.strip())
            logger.info(f"Video duration (ffmpeg): {duration:.3f}s")
            return duration
        except (subprocess.CalledProcessError, ValueError) as e:
            logger.error(f"Failed to measure video duration with ffmpeg: {e}")
            return self._estimate_video_duration(video_path)
    
    def _estimate_video_duration(self, video_path: str) -> float:
        """Estimate video duration (fallback method)."""
        try:
            # Try to get duration from filename or use default
            filename = os.path.basename(video_path)
            if '_' in filename:
                # Try to extract duration from filename like "video_10s.mp4"
                parts = filename.split('_')
                for part in parts:
                    if 's' in part:
                        try:
                            duration = float(part.replace('s', ''))
                            logger.info(f"Estimated video duration from filename: {duration:.3f}s")
                            return duration
                        except ValueError:
                            continue
            
            # Default fallback
            logger.warning("Using default video duration estimate: 10.0s")
            return 10.0
        except Exception as e:
            logger.error(f"Failed to estimate video duration: {e}")
            return 10.0
    
    def adjust_audio_to_video(self, audio_path: str, target_duration: float, 
                            output_path: str) -> str:
        """Adjust audio duration to match video duration."""
        if self.ffmpeg_available:
            return self._adjust_audio_with_ffmpeg(audio_path, target_duration, output_path)
        else:
            return self._adjust_audio_with_soundfile(audio_path, target_duration, output_path)
    
    def _adjust_audio_with_ffmpeg(self, audio_path: str, target_duration: float, 
                                 output_path: str) -> str:
        """Adjust audio using ffmpeg."""
        try:
            cmd = [
                'ffmpeg', '-i', audio_path, '-t', str(target_duration),
                '-af', 'apad', '-c:a', 'pcm_s16le', '-y', output_path
            ]
            subprocess.run(cmd, check=True, capture_output=True)
            logger.info(f"Adjusted audio to {target_duration:.3f}s using ffmpeg")
            return output_path
        except subprocess.CalledProcessError as e:
            logger.error(f"Failed to adjust audio with ffmpeg: {e}")
            return self._adjust_audio_with_soundfile(audio_path, target_duration, output_path)
    
    def _adjust_audio_with_soundfile(self, audio_path: str, target_duration: float,
                                   output_path: str) -> str:
        """Adjust audio using soundfile (fallback)."""
        try:
            import soundfile as sf
            
            # Read audio
            audio_data, sample_rate = sf.read(audio_path)
            
            # Calculate target samples
            target_samples = int(target_duration * sample_rate)
            
            if len(audio_data) < target_samples:
                # Pad with silence
                padding = np.zeros(target_samples - len(audio_data))
                if len(audio_data.shape) > 1:  # Stereo
                    padding = np.zeros((target_samples - len(audio_data), audio_data.shape[1]))
                adjusted_audio = np.concatenate([audio_data, padding])
            else:
                # Trim to target length
                adjusted_audio = audio_data[:target_samples]
            
            # Write adjusted audio
            sf.write(output_path, adjusted_audio, sample_rate)
            logger.info(f"Adjusted audio to {target_duration:.3f}s using soundfile")
            return output_path
            
        except Exception as e:
            logger.error(f"Failed to adjust audio with soundfile: {e}")
            # Last resort: just copy the file
            shutil.copy2(audio_path, output_path)
            return output_path
    
    def adjust_video_to_audio(self, video_path: str, target_duration: float,
                            output_path: str) -> str:
        """Adjust video duration to match audio duration."""
        if self.ffmpeg_available:
            return self._adjust_video_with_ffmpeg(video_path, target_duration, output_path)
        else:
            # For video, we can't easily adjust without ffmpeg, so just copy
            shutil.copy2(video_path, output_path)
            return output_path
    
    def _adjust_video_with_ffmpeg(self, video_path: str, target_duration: float,
                                 output_path: str) -> str:
        """Adjust video using ffmpeg."""
        try:
            cmd = [
                'ffmpeg', '-i', video_path, '-t', str(target_duration),
                '-c:v', 'libx264', '-pix_fmt', 'yuv420p', '-y', output_path
            ]
            subprocess.run(cmd, check=True, capture_output=True)
            logger.info(f"Adjusted video to {target_duration:.3f}s using ffmpeg")
            return output_path
        except subprocess.CalledProcessError as e:
            logger.error(f"Failed to adjust video with ffmpeg: {e}")
            # Fallback: just copy
            shutil.copy2(video_path, output_path)
            return output_path
    
    def validate_sync(self, video_path: str, audio_path: str) -> Tuple[bool, float]:
        """Validate that audio and video are properly synchronized."""
        try:
            video_duration = self.measure_video_duration(video_path)
            audio_duration = self.measure_audio_duration(audio_path)
            
            duration_diff = abs(video_duration - audio_duration)
            is_synced = duration_diff <= self.tolerance_s
            
            logger.info(f"Sync validation: video={video_duration:.3f}s, "
                       f"audio={audio_duration:.3f}s, diff={duration_diff:.3f}s, "
                       f"synced={is_synced}")
            
            return is_synced, duration_diff
            
        except Exception as e:
            logger.error(f"Sync validation failed: {e}")
            return False, float('inf')
    
    def synchronize_media(self, video_path: str, audio_path: str, 
                         output_path: str, prefer_audio_duration: bool = True) -> str:
        """
        Synchronize audio and video with frame-perfect accuracy.
        """
        try:
            # Measure durations
            video_duration = self.measure_video_duration(video_path)
            audio_duration = self.measure_audio_duration(audio_path)
            
            duration_diff = abs(video_duration - audio_duration)
            
            # Check if already synchronized
            if duration_diff <= self.tolerance_s:
                logger.info("Media already synchronized, copying to output")
                self._copy_media(video_path, audio_path, output_path)
                return output_path
            
            # Determine target duration
            if prefer_audio_duration:
                target_duration = audio_duration
                logger.info(f"Adjusting video to match audio duration: {target_duration:.3f}s")
            else:
                target_duration = video_duration
                logger.info(f"Adjusting audio to match video duration: {target_duration:.3f}s")
            
            # Create temporary files for adjustments
            with tempfile.TemporaryDirectory() as temp_dir:
                temp_video = os.path.join(temp_dir, "temp_video.mp4")
                temp_audio = os.path.join(temp_dir, "temp_audio.wav")
                
                # Adjust durations
                if prefer_audio_duration:
                    self.adjust_video_to_audio(video_path, target_duration, temp_video)
                    temp_audio = audio_path  # Use original audio
                else:
                    self.adjust_audio_to_video(audio_path, target_duration, temp_audio)
                    temp_video = video_path  # Use original video
                
                # Mux synchronized media
                self._mux_media(temp_video, temp_audio, output_path)
                
                # Validate final sync
                is_synced, final_diff = self.validate_sync(output_path, output_path)
                if not is_synced and FORCE_SYNC:
                    logger.warning(f"Final sync validation failed with diff {final_diff:.3f}s")
                else:
                    logger.info("Media successfully synchronized")
                
                return output_path
                
        except Exception as e:
            logger.error(f"Synchronization failed: {e}")
            # Fallback: just copy video without audio
            shutil.copy2(video_path, output_path)
            return output_path
    
    def _copy_media(self, video_path: str, audio_path: str, output_path: str):
        """Copy and mux media without duration adjustment."""
        self._mux_media(video_path, audio_path, output_path)
    
    def _mux_media(self, video_path: str, audio_path: str, output_path: str):
        """Mux video and audio with precise timing."""
        if self.ffmpeg_available:
            self._mux_with_ffmpeg(video_path, audio_path, output_path)
        else:
            self._mux_with_moviepy(video_path, audio_path, output_path)
    
    def _mux_with_ffmpeg(self, video_path: str, audio_path: str, output_path: str):
        """Mux using ffmpeg."""
        try:
            cmd = [
                'ffmpeg', '-i', video_path, '-i', audio_path,
                '-c:v', 'copy', '-c:a', 'aac', '-b:a', '128k',
                '-shortest', '-fflags', '+shortest',
                '-movflags', '+faststart', '-y', output_path
            ]
            subprocess.run(cmd, check=True, capture_output=True)
            logger.info("Media successfully muxed with ffmpeg")
        except subprocess.CalledProcessError as e:
            logger.error(f"Media muxing with ffmpeg failed: {e}")
            self._mux_with_moviepy(video_path, audio_path, output_path)
    
    def _mux_with_moviepy(self, video_path: str, audio_path: str, output_path: str):
        """Mux using moviepy (fallback)."""
        try:
            from moviepy.editor import VideoFileClip, AudioFileClip
            
            # Load video and audio
            video = VideoFileClip(video_path)
            audio = AudioFileClip(audio_path)
            
            # Set audio duration to match video
            if audio.duration > video.duration:
                audio = audio.subclip(0, video.duration)
            elif audio.duration < video.duration:
                # Pad audio with silence
                from moviepy.audio.AudioClip import AudioClip
                silence = AudioClip(lambda t: 0, duration=video.duration - audio.duration)
                audio = audio.concatenate_audioclips([audio, silence])
            
            # Combine and write
            final_video = video.set_audio(audio)
            final_video.write_videofile(
                output_path,
                codec='libx264',
                audio_codec='aac',
                temp_audiofile='temp-audio.m4a',
                remove_temp=True,
                verbose=False,
                logger=None
            )
            
            # Clean up
            video.close()
            audio.close()
            final_video.close()
            
            logger.info("Media successfully muxed with moviepy")
            
        except Exception as e:
            logger.error(f"Media muxing with moviepy failed: {e}")
            # Last resort: just copy video
            shutil.copy2(video_path, output_path)
    
    def get_optimal_frame_count(self, target_duration: float, fps: float) -> int:
        """Calculate optimal frame count for target duration."""
        frame_count = int(target_duration * fps)
        # Ensure frame count is reasonable
        frame_count = max(8, min(frame_count, 64))  # 1-8 seconds at 8fps
        return frame_count
    
    def estimate_audio_duration(self, text: str, words_per_minute: int = 150) -> float:
        """Estimate audio duration from text length."""
        word_count = len(text.split())
        duration_minutes = word_count / words_per_minute
        return duration_minutes * 60.0  # Convert to seconds

def create_sync_manager() -> SyncManager:
    """Factory function to create a SyncManager instance."""
    return SyncManager()