app.py

import os
import time
import tempfile
import uuid
import google.generativeai as genai
import requests
import yt_dlp
from flask import Flask, request, render_template, send_from_directory, url_for, flash
from moviepy.video.io.VideoFileClip import VideoFileClip
from moviepy.audio.io.AudioFileClip import AudioFileClip
from moviepy.video.compositing.CompositeVideoClip import CompositeVideoClip
from werkzeug.utils import secure_filename
from dotenv import load_dotenv

# --- 1. INITIALIZE FLASK APP AND LOAD SECRETS ---
load_dotenv()
app = Flask(__name__)

# Load secrets from the loaded environment variables
GEMINI_API_KEY = os.getenv("GEMINI_API_KEY")
TTS_API_URL = os.getenv("TTS_API_URL")

# Check if secrets were loaded correctly
if not GEMINI_API_KEY:
    raise ValueError("SECURITY ERROR: GEMINI_API_KEY not found in .env file!")
if not TTS_API_URL:
    raise ValueError("CONFIGURATION ERROR: TTS_API_URL not found in .env file!")

# Configure the Gemini API
genai.configure(api_key=GEMINI_API_KEY)

# Configure directories and app settings
UPLOAD_FOLDER = 'uploads'
DOWNLOAD_FOLDER = 'downloads'
os.makedirs(UPLOAD_FOLDER, exist_ok=True)
os.makedirs(DOWNLOAD_FOLDER, exist_ok=True)
app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER
app.config['DOWNLOAD_FOLDER'] = DOWNLOAD_FOLDER
app.config['MAX_CONTENT_LENGTH'] = 100 * 1024 * 1024  # 100 MB upload limit
app.secret_key = os.urandom(24) # Secure key for flash messages

# --- 2. VOICE CHOICES & GEMINI PROMPT ---
VOICE_CHOICES = {"Male (Charon)": "Charon", "Female (Zephyr)": "Zephyr"}
GEMINI_PROMPT = """
You are an expert 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 from all speakers 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.
"""

# --- 3. CORE LOGIC HELPER FUNCTIONS ---

def download_youtube_video(url, output_folder):
    """Downloads a YouTube video to a specified folder using the yt-dlp library."""
    print(f"📥 Downloading video from YouTube URL: {url}")
    unique_filename = f"{uuid.uuid4()}.mp4"
    output_path_template = os.path.join(output_folder, os.path.splitext(unique_filename)[0])
    ydl_opts = {
        'format': 'bestvideo[ext=mp4]+bestaudio[ext=m4a]/best[ext=mp4]/best',
        'outtmpl': output_path_template, 'merge_output_format': 'mp4',
        'quiet': False, 'noplaylist': True, 'progress': True,
    }
    try:
        with yt_dlp.YoutubeDL(ydl_opts) as ydl:
            ydl.download([url])
        downloaded_file_path = f"{output_path_template}.mp4"
        if os.path.exists(downloaded_file_path):
            print(f"✅ Download complete! File saved to: {downloaded_file_path}")
            return downloaded_file_path
        raise FileNotFoundError("Downloaded video file not found after yt-dlp process.")
    except Exception as e:
        print(f"❌ An error occurred during YouTube download: {e}")
        raise

def generate_tamil_script(video_file_path):
    """Generates a single, continuous Tamil script from the video using Gemini."""
    print("Uploading file to Gemini for transcription...")
    video_file = genai.upload_file(video_file_path, mime_type="video/mp4")
    print("Waiting for Gemini file processing...")
    while video_file.state.name == "PROCESSING":
        time.sleep(5)
        video_file = genai.get_file(video_file.name)
    if video_file.state.name != "ACTIVE":
        raise Exception(f"Gemini file processing failed: {video_file.state.name}")
    print("Generating narrator script...")
    model = genai.GenerativeModel(model_name="models/gemini-2.5-flash")
    response = model.generate_content([GEMINI_PROMPT, video_file])
    genai.delete_file(video_file.name)
    if hasattr(response, 'text') and response.text:
        return " ".join(response.text.strip().splitlines())
    raise Exception("No valid script was generated by Gemini.")

def generate_single_audio_track(dialogue_text, voice_name, is_cheerful, output_path):
    """Generates one audio track for the entire script via TTS API."""
    print(f"Requesting audio from TTS API (Voice: {voice_name}, Cheerful: {is_cheerful})")
    payload = {"text": dialogue_text, "voice_name": voice_name, "cheerful": is_cheerful}
    response = requests.post(TTS_API_URL, json=payload, timeout=300)
    if response.status_code == 200:
        with open(output_path, "wb") as f:
            f.write(response.content)
        return True
    raise Exception(f"Error from TTS API: {response.status_code} - {response.text}")

def replace_video_audio(video_path, new_audio_path, output_path):
    """Replaces the audio of a video using the modern, correct MoviePy method."""
    print("Replacing video audio using MoviePy...")
    video_clip, audio_clip = None, None
    try:
        video_clip = VideoFileClip(video_path)
        audio_clip = AudioFileClip(new_audio_path)
        video_clip.audio = audio_clip
        video_clip.write_videofile(output_path, codec="libx264", audio_codec="aac", logger='bar')
    finally:
        if audio_clip: audio_clip.close()
        if video_clip: video_clip.close()

# --- 4. FLASK WEB ROUTES ---

@app.route('/', methods=['GET'])
def index():
    """Renders the main upload page."""
    return render_template('index.html')

@app.route('/process', methods=['POST'])
def process_video():
    """Handles video input (upload or URL), processing, and renders the result."""
    input_video_path, temp_audio_path = None, None
    try:
        youtube_url = request.form.get('youtube_url', '').strip()
        if youtube_url:
            input_video_path = download_youtube_video(youtube_url, app.config['UPLOAD_FOLDER'])
            filename = os.path.basename(input_video_path)
        elif 'video' in request.files and request.files['video'].filename != '':
            file = request.files['video']
            filename = secure_filename(file.filename)
            input_video_path = os.path.join(app.config['UPLOAD_FOLDER'], filename)
            file.save(input_video_path)
        else:
            flash("Please either upload a video file or provide a YouTube URL.")
            return render_template('index.html')

        voice_choice = request.form['voice_choice']
        is_cheerful = 'cheerful' in request.form
        voice_name = VOICE_CHOICES[voice_choice]
        script = generate_tamil_script(input_video_path)
        
        with tempfile.NamedTemporaryFile(suffix=".wav", delete=False) as temp_audio:
            temp_audio_path = temp_audio.name
        
        generate_single_audio_track(script, voice_name, is_cheerful, temp_audio_path)
        final_video_name = f"dubbed_{filename}"
        final_video_path = os.path.join(app.config['DOWNLOAD_FOLDER'], final_video_name)
        replace_video_audio(input_video_path, temp_audio_path, final_video_path)
        
        flash("Video processing complete!", "success")
        return render_template('index.html', 
                               result_video=url_for('serve_video', filename=final_video_name), 
                               script=script)
    except Exception as e:
        print(f"An error occurred during processing: {e}")
        flash(f"An unexpected error occurred: {e}. Please check the console and try again.", "error")
        return render_template('index.html')
    finally:
        if input_video_path and os.path.exists(input_video_path):
            os.remove(input_video_path)
        if temp_audio_path and os.path.exists(temp_audio_path):
            os.remove(temp_audio_path)

@app.route('/downloads/<filename>')
def serve_video(filename):
    """Serves the final dubbed video."""
    return send_from_directory(app.config['DOWNLOAD_FOLDER'], filename)

# --- 5. APPLICATION ENTRY POINT ---
if __name__ == '__main__':
  app.run(host="0.0.0.0", port=7860)