import gradio as gr
import PyPDF2
import os

def merge_pdfs(pdf_list, output_filename):
    """
    Merge multiple PDF files into a single PDF file with a specified filename.

    Parameters:
    pdf_list (list): List of uploaded PDF files (file-like objects).
    output_filename (str): Desired name of the output merged PDF file.

    Returns:
    str: Path to the merged PDF file.
    """
    pdf_merger = PyPDF2.PdfMerger()
    
    # If no extension is provided, add .pdf
    if not output_filename.lower().endswith('.pdf'):
        output_filename += '.pdf'
    
    for pdf_file in pdf_list:
        pdf_file_path = pdf_file.name  # Get the path from the uploaded file object
        pdf_merger.append(pdf_file_path)

    with open(output_filename, 'wb') as output_pdf:
        pdf_merger.write(output_pdf)

    return output_filename

# Gradio interface
def gradio_pdf_merge(pdf_files, output_filename):
    output_pdf_path = merge_pdfs(pdf_files, output_filename)
    return output_pdf_path

# Create the Gradio interface
gr_interface = gr.Interface(
    fn=gradio_pdf_merge,  # The function to run when files are uploaded
    inputs=[
        gr.Files(file_types=['.pdf'], label="Upload PDF files"),  # Allow multiple PDFs to be uploaded
        gr.Textbox(label="Output PDF filename", placeholder="Enter the output filename (e.g., merged.pdf)")  # Input for output filename
    ],
    outputs=gr.File(label="Merged PDF")  # Return the merged PDF file
)

# Launch the interface
gr_interface.launch()