import re
import os


def replace_css_links(directory):
    affected_files = []
    changes = {}

    # Collect affected files and changes
    for filename in os.listdir(directory):
        if re.match(r"\d+_\d+_index\.html", filename):
            file_path = os.path.join(directory, filename)
            with open(file_path, "r", encoding="utf-8") as file:
                content = file.read()

            match = re.match(r"(\d+)_(\d+)_index\.html", filename)
            if match:
                new_stylesheet = f"{match.group(1)}_{match.group(2)}_style.css"
                if '<link rel="stylesheet" href="style.css">' in content:
                    affected_files.append(filename)
                    changes[filename] = new_stylesheet

    # Display affected files
    if affected_files:
        print("Files to be affected:")
        for file in affected_files:
            print(f"- {file}: style.css -> {changes[file]}")
    else:
        print("No files will be affected.")
        return

    # User confirmation
    user_input = input(
        "Do you want to proceed with these changes? (Y/n): ").strip().lower()
    if user_input != 'y' and user_input != '':
        print("Operation cancelled.")
        return

    # Execute changes
    for filename in affected_files:
        file_path = os.path.join(directory, filename)
        with open(file_path, "r", encoding="utf-8") as file:
            content = file.read()

        modified_content = re.sub(
            r'<link rel="stylesheet" href="style\.css">',
            f'<link rel="stylesheet" href="{changes[filename]}">',
            content
        )

        with open(file_path, "w", encoding="utf-8") as file:
            file.write(modified_content)

        print(f"Updated {filename}.")

    print("All changes have been completed.")


# Usage example
# replace_css_links("./")