import gradio as gr
import pandas as pd
import os
import tempfile
import chardet

def detect_encoding(file_path):
    """
    Function to detect file encoding
    """
    with open(file_path, 'rb') as f:
        result = chardet.detect(f.read())
    return result['encoding']

def merge_csv_files(files):
    """
    Function to merge multiple CSV files into one
    
    Args:
        files: List of uploaded CSV files
    
    Returns:
        Path to the merged CSV file and status message
    """
    if not files or len(files) == 0:
        return None, "No files were uploaded. Please select CSV files to merge."
    
    if len(files) > 30:
        return None, "Maximum 30 files can be merged at once."
    
    try:
        # Read all files into DataFrame list
        dataframes = []
        for file in files:
            # Detect file encoding
            encoding = detect_encoding(file.name)
            try:
                df = pd.read_csv(file.name, encoding=encoding)
            except UnicodeDecodeError:
                # Try other encodings if detected encoding fails
                encodings_to_try = ['cp949', 'euc-kr', 'latin1', 'ISO-8859-1']
                for enc in encodings_to_try:
                    try:
                        df = pd.read_csv(file.name, encoding=enc)
                        break
                    except UnicodeDecodeError:
                        continue
                else:
                    return None, f"Could not determine encoding for '{os.path.basename(file.name)}'."
            
            dataframes.append(df)
        
        # Merge all DataFrames
        if dataframes:
            merged_df = pd.concat(dataframes, ignore_index=True)
            
            # Save to temporary file
            with tempfile.NamedTemporaryFile(delete=False, suffix='.csv') as tmp:
                output_path = tmp.name
            
            # Save merged data in Excel-compatible format (UTF-8 with BOM)
            merged_df.to_csv(output_path, index=False, encoding='utf-8-sig')
            
            return output_path, f"Successfully merged {len(files)} files. Please open with UTF-8 encoding in Excel."
        else:
            return None, "No data to merge."
    
    except Exception as e:
        return None, f"Error occurred: {str(e)}"

# Create a stylish Gradio interface
with gr.Blocks(title="CSVFusion") as app:
    gr.Markdown(
        """
        # 📊 CSVFusion: Intelligent File Merger
        
        *Seamlessly combine multiple CSV files into one unified dataset*
        
        ---
        """
    )
    
    with gr.Row():
        with gr.Column(scale=2):
            gr.Markdown("""
            ### How to use CSVFusion:
            1. Upload up to 30 CSV files using the panel on the right
            2. Click the "Merge Files" button
            3. Download your consolidated CSV file
            
            ### Features:
            - Automatic encoding detection
            - Handles various CSV formats
            - Excel-compatible output (UTF-8)
            - Preserves all data columns
            """)
        
        with gr.Column(scale=3):
            input_files = gr.File(
                file_count="multiple",
                label="Upload CSV Files (Max 30)",
                file_types=[".csv"],
                elem_id="file_upload"
            )
    
    with gr.Row():
        merge_button = gr.Button("Merge Files", variant="primary", size="lg")
    
    with gr.Row():
        with gr.Column():
            status = gr.Textbox(label="Status", placeholder="Ready to merge your files...")
        with gr.Column():
            output_file = gr.File(label="Download Merged CSV")
    
    # Add custom CSS for better visual appeal
    gr.HTML("""
    <style>
    .gradio-container {
        background: linear-gradient(to right, #f9f9f9, #ffffff);
        border-radius: 12px;
    }
    #file_upload {
        border: 2px dashed #3498db;
        border-radius: 8px;
        padding: 20px;
        transition: all 0.3s;
    }
    #file_upload:hover {
        border-color: #2980b9;
        box-shadow: 0 0 10px rgba(52, 152, 219, 0.3);
    }
    .footer {
        text-align: center;
        margin-top: 30px;
        color: #7f8c8d;
        font-size: 0.9em;
    }
    </style>
    """)
    
    # Add footer
    gr.HTML("""
    <div class="footer">
        <p>CSVFusion © 2025 - A powerful tool for data professionals</p>
    </div>
    """)
    
    merge_button.click(
        fn=merge_csv_files,
        inputs=[input_files],
        outputs=[output_file, status]
    )

# Run the app
if __name__ == "__main__":
    app.launch()