import os
from pypdf import PdfReader, PdfWriter

def change_pdf_metadata(directory, new_metadata):
    # List all PDF files in the directory
    pdf_files = [f for f in os.listdir(directory) if f.endswith('.pdf')]

    if len(pdf_files) != len(new_metadata):
        print("The number of PDF files and new metadata entries does not match.")
        return

    for pdf_file, metadata in zip(pdf_files, new_metadata):
        file_path = os.path.join(directory, pdf_file)
        try:
            # Read the existing PDF
            reader = PdfReader(file_path)
            writer = PdfWriter()

            # Copy all pages to the writer
            for page in reader.pages:
                writer.add_page(page)

            # Update the metadata
            writer.add_metadata({
                '/Title': metadata['title'],
                '/Author': metadata['author'],
            })

            # Write out the updated PDF
            output_path = os.path.join(directory, f"../modif/{pdf_file}")
            # For a new filename, use prefix "f"New_{pdf_file}"
            with open(output_path, 'wb') as output_file:
                writer.write(output_file)

            print(f"Changed metadata of {pdf_file} to Title: {metadata['title']}, Author: {metadata['author']}")
        except Exception as e:
            print(f"Could not change metadata for {pdf_file}: {e}")

# Directory containing the PDF files
directory = "my_PDF_files"

# List of new metadata entries
new_metadata = [
    {"title": "New title of Document 1", "author": "Author 1"},
    {"title": "New title of Document 2", "author": "Author 2"},
    {"title": "New title of Document 3", "author": "Author 3"},
    {"title": "New title of Document 4", "author": "Author 4"},
    # Add more metadata entries as needed
]

change_pdf_metadata(directory, new_metadata)