python main.py input.pdf --output-dir chapters/

pip install pdfplumber

import argparse

import os

import re

import pdfplumber





def is_heading(obj, min_font_size=12, bold_keywords=['bold', 'Bold']):

    """Determine if a text object is a heading based on font characteristics."""

    font_name = obj.get('fontname', '')

    size = obj.get('size', 0)

    if size >= min_font_size:

        if any(keyword in font_name for keyword in bold_keywords):

            return True

    return False





def extract_headings_and_text(pdf_path):

    """Extract structured content: list of (heading, content) tuples."""

    chapters = []

    current_heading = 'Introduction'

    current_content = []



    with pdfplumber.open(pdf_path) as pdf:

        for page in pdf.pages:

            text_objects = page.chars

            if not text_objects:

                continue



            # Group into lines by y-position

            lines = {}

            for obj in text_objects:

                y_key = round(obj['top'])

                lines.setdefault(y_key, []).append(obj)



            for y_key in sorted(lines.keys()):

                line_chars = lines[y_key]

                text = ''.join([c['text'] for c in line_chars])

                bbox = (min(c['x0'] for c in line_chars),

                        min(c['top'] for c in line_chars),

                        max(c['x1'] for c in line_chars),

                        max(c['bottom'] for c in line_chars))

                # Use first char to represent line style

                if is_heading(line_chars[0]):

                    if current_heading and current_content:

                        chapters.append((current_heading, '\n'.join(current_content)))

                    current_heading = text.strip()

                    current_content = []

                else:

                    current_content.append(text.strip())



    if current_heading and current_content:

        chapters.append((current_heading, '\n'.join(current_content)))

    return chapters





def save_chapters(chapters, output_dir):

    """Save each chapter as a markdown file and generate TOC."""

    os.makedirs(output_dir, exist_ok=True)

    toc_lines = ['# Table of Contents\n']



    for i, (heading, content) in enumerate(chapters):

        filename = f'{i+1:02d}_{re.sub(r"[^a-zA-Z0-9]", "_", heading.strip())[:50]}.md'

        filepath = os.path.join(output_dir, filename)

        with open(filepath, 'w', encoding='utf-8') as f:

            f.write(f'# {heading}\n\n{content}\n')

        toc_lines.append(f'{i+1}. [{heading}]({filename})')



    # Write TOC

    toc_path = os.path.join(output_dir, '_toc.md')

    with open(toc_path, 'w', encoding='utf-8') as f:

        f.write('\n'.join(toc_lines))





def main():

    parser = argparse.ArgumentParser(description='Split PDF into Markdown chapters.')

    parser.add_argument('pdf_path', help='Path to input PDF')

    parser.add_argument('--output-dir', '-o', default='chapters', help='Output directory')

    args = parser.parse_args()



    if not os.path.exists(args.pdf_path):

        print(f'PDF file not found: {args.pdf_path}')

        return



    chapters = extract_headings_and_text(args.pdf_path)

    save_chapters(chapters, args.output_dir)

    print(f'Saved {len(chapters)} chapters to {args.output_dir}/')



if __name__ == '__main__':

    main()