set_link_category.py

import os
import yaml
import sys

def add_link_category(posts_dir):
    """
    Adds a `link_category` front matter entry to all posts in the specified directory.
    The value is set to the first category in the `categories` list if it exists and
    `link_category` is not already set.
    """
    for root, _, files in os.walk(posts_dir):
        for file in files:
            if file.endswith(".md"):
                file_path = os.path.join(root, file)
                with open(file_path, 'r') as f:
                    lines = f.readlines()

                # Check if the file has front matter
                if lines[0].strip() == '---':
                    front_matter_end = lines[1:].index('---\n') + 1
                    front_matter_lines = lines[1:front_matter_end]
                    front_matter = yaml.safe_load(''.join(front_matter_lines))

                    # Check if `categories` exists and is a list
                    if 'categories' in front_matter and isinstance(front_matter['categories'], list):
                        first_category = front_matter['categories'][0]

                        # Only add `link_category` if it is not already set
                        if 'link_category' not in front_matter:
                            # Add the `link_category` line to the front matter
                            front_matter_lines.append(f"link_category: {first_category}\n")
                            with open(file_path, 'w') as f:
                                f.write('---\n')
                                f.writelines(front_matter_lines)
                                f.write('---\n')
                                f.writelines(lines[front_matter_end + 1:])

                            print(f"Updated {file_path} with link_category: {first_category}")
                        else:
                            print(f"{file_path} already has link_category set, skipping.")
                    else:
                        print(f"No categories found in {file_path}, skipping.")
                else:
                    print(f"No front matter found in {file_path}, skipping.")

if __name__ == "__main__":
    if len(sys.argv) != 2:
        print("Usage: python3 set_link_category.py <jekyll_project_path>")
        sys.exit(1)

    # Get the Jekyll project path from the command-line argument
    jekyll_project_path = sys.argv[1]
    posts_directory = os.path.join(jekyll_project_path, "_posts")

    if not os.path.isdir(posts_directory):
        print(f"Error: The directory '{posts_directory}' does not exist.")
        sys.exit(1)

    add_link_category(posts_directory)