app.py

import os
import time
import tempfile
import uuid
import google.generativeai as genai
import requests
import re
from flask import Flask, request, render_template, send_from_directory, jsonify
from moviepy.video.io.VideoFileClip import VideoFileClip
from moviepy.audio.io.AudioFileClip import AudioFileClip
from werkzeug.utils import secure_filename
from dotenv import load_dotenv
import threading
import logging
from gtts import gTTS
import io
from pathlib import Path

# Initialize Flask app
load_dotenv()
app = Flask(__name__)

# Configuration
GEMINI_API_KEY = os.getenv("GEMINI_API_KEY")
TTS_API_URL = os.getenv("TTS_API_URL", "")  # Optional
MAX_CONTENT_LENGTH = 500 * 1024 * 1024  # 500MB
MAX_TTS_RETRIES = 3
TTS_CHUNK_SIZE = 2000  # Characters per chunk

# File storage setup
UPLOAD_FOLDER = 'uploads'
DOWNLOAD_FOLDER = 'downloads'
Path(UPLOAD_FOLDER).mkdir(exist_ok=True)
Path(DOWNLOAD_FOLDER).mkdir(exist_ok=True)
app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER
app.config['DOWNLOAD_FOLDER'] = DOWNLOAD_FOLDER
app.config['MAX_CONTENT_LENGTH'] = MAX_CONTENT_LENGTH
app.secret_key = os.urandom(24)

# Processing status tracking
processing_status = {}

# Language and voice options
LANGUAGE_MAPPING = {
    "Arabic (Egyptian)": "ar-EG",
    "English (US)": "en-US",
    "Hindi (India)": "hi-IN",
    "Tamil (India)": "ta-IN",
    "Telugu (India)": "te-IN"
}

VOICE_TYPES = {
    "Male": "male",
    "Female": "female"
}

GEMINI_PROMPTS = {
    "api": """
    You are an AI scriptwriter. Your task is to watch the provided video and transcribe ALL spoken dialogue into a SINGLE, CONTINUOUS block of modern, colloquial Tamil.

**CRITICAL INSTRUCTIONS:**
1.  **Single Script:** Combine all dialogue into one continuous script.
2.  **NO Timestamps or Speaker Labels:** Do NOT include any timestamps or speaker identifiers.
3.  **Incorporate Performance:** Add English style prompts (e.g., `Say happily:`, `Whisper mysteriously:`) and performance tags (e.g., `[laugh]`, `[sigh]`) directly into the text for an expressive narration.

**EXAMPLE OUTPUT:**
Say happily: வணக்கம்! [laugh] எப்படி இருக்கீங்க? Whisper mysteriously: அந்த ரகசியம் எனக்கு மட்டும் தான் தெரியும்
    """,
    "gtts": """
    You are an expert AI scriptwriter. Transcribe ALL spoken dialogue into a SINGLE, 
    CONTINUOUS block of modern {language}. Return ONLY the clean transcribed text.
    """
}

# Configure logging
logging.basicConfig(
    level=logging.INFO,
    format='%(asctime)s - %(levelname)s - %(message)s'
)
logger = logging.getLogger(__name__)

def split_text_into_chunks(text, chunk_size=TTS_CHUNK_SIZE):
    """Split text into chunks respecting sentence boundaries"""
    sentences = re.split(r'(?<=[.!?])\s+', text)
    chunks = []
    current_chunk = ""
    
    for sentence in sentences:
        if len(current_chunk) + len(sentence) < chunk_size:
            current_chunk += sentence + " "
        else:
            chunks.append(current_chunk.strip())
            current_chunk = sentence + " "
    
    if current_chunk:
        chunks.append(current_chunk.strip())
    
    return chunks

def generate_tts_audio(text, language_code, voice_type, tts_provider):
    """Generate TTS audio using selected provider with retry logic"""
    chunks = split_text_into_chunks(text)
    audio_segments = []
    
    for chunk in chunks:
        for attempt in range(MAX_TTS_RETRIES):
            try:
                if tts_provider == "api":
                    # Use custom TTS API
                    payload = {
                        "text": chunk,
                        "language": language_code,
                        "voice_type": voice_type
                    }
                    response = requests.post(TTS_API_URL, json=payload, timeout=300)
                    
                    if response.status_code == 200:
                        audio_segments.append(io.BytesIO(response.content))
                        break
                    elif response.status_code == 429:  # Rate limit
                        retry_after = int(response.headers.get('Retry-After', 5))
                        logger.warning(f"TTS API rate limited. Retrying after {retry_after}s")
                        time.sleep(retry_after)
                        continue
                    else:
                        raise Exception(f"TTS API error: {response.status_code}")
                else:
                    # Use gTTS
                    tts = gTTS(
                        text=chunk,
                        lang=language_code.split('-')[0],
                        slow=False
                    )
                    buffer = io.BytesIO()
                    tts.write_to_fp(buffer)
                    buffer.seek(0)
                    audio_segments.append(buffer)
                    break
                    
            except Exception as e:
                logger.warning(f"TTS attempt {attempt + 1} failed: {str(e)}")
                if attempt == MAX_TTS_RETRIES - 1:
                    raise Exception(f"Failed to generate TTS after {MAX_TTS_RETRIES} attempts")
                time.sleep(2 ** attempt)  # Exponential backoff
    
    # Combine audio segments
    combined_audio = io.BytesIO()
    for segment in audio_segments:
        combined_audio.write(segment.getvalue())
    combined_audio.seek(0)
    return combined_audio

def generate_transcription(video_path, prompt):
    """Generate transcript using Gemini with retry logic"""
    max_retries = 3
    for attempt in range(max_retries):
        try:
            video_file = genai.upload_file(video_path, mime_type="video/mp4")
            model = genai.GenerativeModel("models/gemini-pro-vision")
            response = model.generate_content([prompt, video_file])
            genai.delete_file(video_file.name)
            
            if hasattr(response, 'text'):
                return response.text.strip()
            raise Exception("No valid transcription generated")
        
        except Exception as e:
            if attempt == max_retries - 1:
                raise
            logger.warning(f"Transcription attempt {attempt + 1} failed: {str(e)}")
            time.sleep(5 * (attempt + 1))

def dub_video(video_path, audio_buffer):
    """Dub video with new audio"""
    video = None
    audio = None
    temp_audio_path = None
    
    try:
        # Save audio buffer to temp file
        temp_audio_path = f"temp_audio_{uuid.uuid4().hex}.mp3"
        with open(temp_audio_path, 'wb') as f:
            f.write(audio_buffer.read())

        # Process video
        video = VideoFileClip(video_path)
        audio = AudioFileClip(temp_audio_path)
        
        # Ensure audio length matches video
        if audio.duration > video.duration:
            audio = audio.subclip(0, video.duration)
        
        video = video.set_audio(audio)
        
        # Save output
        output_filename = f"dubbed_{uuid.uuid4().hex}.mp4"
        output_path = os.path.join(app.config['DOWNLOAD_FOLDER'], output_filename)
        
        video.write_videofile(
            output_path,
            codec="libx264",
            audio_codec="aac",
            threads=4,
            verbose=False,
            preset='medium',
            ffmpeg_params=['-crf', '23', '-movflags', '+faststart']
        )
        
        return output_path

    finally:
        # Cleanup resources
        if video:
            video.close()
        if audio:
            audio.close()
        if temp_audio_path and os.path.exists(temp_audio_path):
            os.unlink(temp_audio_path)

def process_video_background(task_id, video_path, language, voice_type, tts_provider):
    """Background video processing"""
    try:
        processing_status[task_id] = {
            'status': 'processing',
            'progress': 0,
            'message': 'Starting transcription',
            'start_time': time.time()
        }

        # Stage 1: Transcription
        processing_status[task_id]['message'] = 'Transcribing video content'
        prompt = GEMINI_PROMPTS[tts_provider].format(language=language)
        script = generate_transcription(video_path, prompt)
        processing_status[task_id]['progress'] = 33
        processing_status[task_id]['script'] = script

        # Stage 2: Audio Generation
        processing_status[task_id]['message'] = 'Generating audio narration'
        language_code = LANGUAGE_MAPPING.get(language, "en-US")
        audio_buffer = generate_tts_audio(script, language_code, voice_type, tts_provider)
        processing_status[task_id]['progress'] = 66

        # Stage 3: Video Dubbing
        processing_status[task_id]['message'] = 'Creating dubbed video'
        output_path = dub_video(video_path, audio_buffer)
        processing_status[task_id]['progress'] = 100
        processing_status[task_id]['status'] = 'complete'
        processing_status[task_id]['result_path'] = output_path

    except Exception as e:
        processing_status[task_id]['status'] = 'error'
        processing_status[task_id]['message'] = str(e)
        logger.error(f"Processing failed: {str(e)}")

    finally:
        # Cleanup
        if os.path.exists(video_path):
            os.unlink(video_path)

@app.route('/')
def index():
    """Render main page"""
    return render_template(
        'index.html',
        languages=list(LANGUAGE_MAPPING.keys()),
        voice_types=list(VOICE_TYPES.keys()),
        default_language="English (US)",
        tts_api_available=bool(TTS_API_URL)
    )

@app.route('/upload', methods=['POST'])
def upload_video():
    """Handle video upload"""
    if 'video' not in request.files:
        return jsonify({'error': 'No file uploaded'}), 400
    
    file = request.files['video']
    if file.filename == '':
        return jsonify({'error': 'No file selected'}), 400

    # Validate file extension
    allowed_extensions = {'mp4', 'mov', 'webm', 'avi'}
    if '.' not in file.filename or file.filename.rsplit('.', 1)[1].lower() not in allowed_extensions:
        return jsonify({'error': 'Invalid file type'}), 400

    # Save file with unique name
    task_id = uuid.uuid4().hex
    filename = secure_filename(f"{task_id}_{file.filename}")
    video_path = os.path.join(app.config['UPLOAD_FOLDER'], filename)
    
    try:
        file.save(video_path)
    except Exception as e:
        return jsonify({'error': f'Failed to save file: {str(e)}'}), 500

    # Get processing options
    language = request.form.get('language', 'English (US)')
    voice_type = request.form.get('voice_type', 'Male')
    tts_provider = request.form.get('tts_provider', 'gtts')

    # Validate TTS provider selection
    if tts_provider == "api" and not TTS_API_URL:
        return jsonify({'error': 'TTS API is not configured'}), 400

    # Start background processing
    processing_status[task_id] = {
        'status': 'uploaded',
        'progress': 0,
        'message': 'Starting processing',
        'start_time': time.time()
    }

    thread = threading.Thread(
        target=process_video_background,
        args=(task_id, video_path, language, voice_type, tts_provider)
    )
    thread.start()

    return jsonify({'task_id': task_id})

@app.route('/status/<task_id>')
def get_status(task_id):
    """Check processing status"""
    if task_id not in processing_status:
        return jsonify({'error': 'Invalid task ID'}), 404
    
    status = processing_status[task_id]
    response = {
        'status': status['status'],
        'progress': status.get('progress', 0),
        'message': status.get('message', ''),
    }

    if status['status'] == 'complete':
        response['result_url'] = url_for(
            'download', 
            filename=os.path.basename(status['result_path'])
        )
        response['script'] = status.get('script', '')
    elif status['status'] == 'error':
        response['error_details'] = status.get('message', 'Unknown error')
    
    return jsonify(response)

@app.route('/download/<filename>')
def download(filename):
    """Serve processed video with security checks"""
    try:
        # Security check
        if not filename.startswith('dubbed_') or not filename.endswith('.mp4'):
            return "Invalid file", 400
        
        # Validate path
        download_path = Path(app.config['DOWNLOAD_FOLDER']) / filename
        if not download_path.exists():
            return "File not found", 404
            
        return send_from_directory(
            app.config['DOWNLOAD_FOLDER'],
            filename,
            as_attachment=True,
            mimetype='video/mp4'
        )
    except Exception as e:
        logger.error(f"Download failed: {str(e)}")
        return "Download error", 500

if __name__ == '__main__':
    if not GEMINI_API_KEY:
        raise ValueError("GEMINI_API_KEY is required in .env file")
    app.run(host="0.0.0.0", port=7860, threaded=True)