import gradio as gr
import os
import tempfile
import subprocess
from pathlib import Path

def merge_videos_clips(video_files):
    """
    Merge multiple video clips smoothly without gaps between them.
    Uses ffmpeg to concatenate videos with a filter to ensure seamless transitions.
    """
    if not video_files or len(video_files) < 2:
        return None, "Please upload at least 2 video clips to merge."
    
    try:
        # Create a temporary directory for processing
        with tempfile.TemporaryDirectory() as temp_dir:
            # Create a file list for ffmpeg concatenation
            file_list_path = os.path.join(temp_dir, "file_list.txt")
            
            with open(file_list_path, 'w') as f:
                for video_file in video_files:
                    # Write the file path in the format ffmpeg expects
                    f.write(f"file '{video_file}'\n")
            
            # Output file path
            output_path = os.path.join(temp_dir, "merged_video.mp4")
            
            # Use ffmpeg to concatenate videos with a filter to ensure seamless transitions
            # The concat filter ensures no gaps between clips
            cmd = [
                'ffmpeg',
                '-f', 'concat',
                '-safe', '0',
                '-i', file_list_path,
                '-c', 'copy',
                '-vf', 'setpts=N/FRAME_RATE/TB',  # Ensure consistent timing
                '-af', 'apad=pad_dur=0',  # No audio padding
                '-shortest',
                output_path
            ]
            
            # Run ffmpeg command
            result = subprocess.run(cmd, capture_output=True, text=True)
            
            if result.returncode != 0:
                return None, f"Error during video merging: {result.stderr}"
            
            # Check if output file was created
            if not os.path.exists(output_path):
                return None, "Failed to create merged video file."
            
            return output_path, "✅ Videos merged successfully! No gaps between clips."
    
    except Exception as e:
        return None, f"Error during video processing: {str(e)}"

def create_video_merger_app():
    """Create the Gradio application for video merging."""
    
    with gr.Blocks(title="Video Clip Merger - Smooth Concatenation", theme=gr.themes.Soft()) as demo:
        # Header with title and description
        gr.Markdown(
            """
            <div style="text-align: center; margin-bottom: 20px;">
                <h1>🎬 Video Clip Merger (Smooth Concatenation)</h1>
                <p>Upload multiple video clips and merge them seamlessly without gaps</p>
                <p style="color: #666; font-size: 0.9em;">
                    This tool eliminates pauses between clips and ensures smooth playback.
                    Built with <a href="https://huggingface.co/spaces/akhaliq/anycoder" target="_blank" style="color: #1976d2;">anycoder</a>
                </p>
            </div>
            """
        )
        
        with gr.Row():
            with gr.Column(scale=1):
                gr.Markdown("### 📤 Upload Video Clips")
                gr.Markdown(
                    """
                    Upload 2 or more video clips in MP4, MOV, or AVI format. 
                    Videos will be merged in the order they appear in the list.
                    """
                )
                
                video_input = gr.Files(
                    label="Upload Video Clips",
                    file_types=["video"],
                    type="filepath"
                )
                
                gr.Markdown("### ⚙️ Settings")
                merge_btn = gr.Button("🔄 Merge Videos", variant="primary", size="lg")
                
            with gr.Column(scale=1):
                gr.Markdown("### 📹 Merged Result")
                
                video_output = gr.Video(
                    label="Merged Video",
                    elem_classes="video-output"
                )
                
                status_output = gr.Textbox(
                    label="Status",
                    lines=3,
                    placeholder="Status messages will appear here..."
                )
        
        # Example section
        gr.Markdown(
            """
            ### ℹ️ How to Use
            1. Upload at least 2 video clips using the file uploader
            2. Click the "Merge Videos" button
            3. Wait for processing to complete
            4. Download your smoothly merged video
            
            ### 🎯 Features
            - ✅ Seamless video concatenation without gaps
            - ✅ Supports MP4, MOV, AVI formats
            - ✅ Maintains original video quality
            - ✅ Preserves audio tracks
            """
        )
        
        # Event handler for merge button
        merge_btn.click(
            fn=merge_videos_clips,
            inputs=video_input,
            outputs=[video_output, status_output],
            api_name="merge_videos",
            api_visibility="public"
        )
        
        # Add footer with link
        gr.Markdown(
            """
            <div style="text-align: center; margin-top: 30px; padding: 20px; background: #f5f5f5; border-radius: 10px;">
                <p>Made with ❤️ using Gradio & FFmpeg</p>
                <p>For more tools like this, visit <a href="https://huggingface.co/spaces/akhaliq/anycoder" target="_blank">anycoder</a></p>
            </div>
            """
        )
    
    return demo

# Create and launch the app
if __name__ == "__main__":
    app = create_video_merger_app()
    app.launch(
        theme=gr.themes.Soft(),
        footer_links=[
            {"label": "Built with anycoder", "url": "https://huggingface.co/spaces/akhaliq/anycoder"}
        ]
    )