parser.py

import re

def slugify(text):
    """Generates a slug suitable for use as an HTML id."""
    return re.sub(r'[^\w\-]+', '', re.sub(r'\s+', '-', text.strip())).lower()

def markdown_to_html(markdown_text):
    text = markdown_text

    # Code: `inline code`
    text = re.sub(r'`([^`]*)`', r'<code>\1</code>', text)

    # Bold: **bold**
    text = re.sub(r'\*\*(.+?)\*\*', r'<strong>\1</strong>', text)

    # Italics: *italics*
    # To avoid double-processing within <strong>, do italics after bold
    text = re.sub(r'\*(.+?)\*', r'<em>\1</em>', text)

    # Links: [text](url)
    text = re.sub(r'\[(.+?)\]\((.+?)\)', r'<a href="\2">\1</a>', text)

    # Line breaks (Markdown: two spaces at end of line or '\n' inside paragraph)
    text = re.sub(r'([^\n]) {2,}\n', r'\1<br>\n', text)

    # Headings with ID
    def heading_repl(match):
        hashes = match.group(1)
        heading_text = match.group(2).strip()
        level = len(hashes)
        heading_id = slugify(heading_text)
        return f'<h{level} id="{heading_id}">{heading_text}</h{level}>'

    text = re.sub(r'^(#{1,3})\s+(.+)$', heading_repl, text, flags=re.MULTILINE)
    
    # Paragraphs (blocks separated by blank lines, avoid wrapping headings/code/HTML)
    lines = text.split('\n')
    html_lines = []
    buffer = []
    for line in lines:
        stripped = line.strip()
        if not stripped:
            if buffer:
                html_lines.append('<p>' + ' '.join(buffer) + '</p>')
                buffer = []
        elif re.match(r'<h[1-3]|<code>|<a |<strong>|<em>', stripped):
            if buffer:
                html_lines.append('<p>' + ' '.join(buffer) + '</p>')
                buffer = []
            html_lines.append(stripped)
        else:
            buffer.append(stripped)
    if buffer:
        html_lines.append('<p>' + ' '.join(buffer) + '</p>')
    return '\n'.join(html_lines)

# --- Test Harness ---

if __name__ == "__main__":
    sample_markdown = """
# Sample Title

Here is a **bold** statement, and *emphasis* as well.

Now an [inline link](http://github.com) and some `inline code`.

## Subheading Example

Paragraph with two spaces and  
a line break.

### Tiny Heading

Just text.

Another paragraph after blank line.
"""

    print("Input Markdown:\n", sample_markdown)
    print("\nGenerated HTML:\n")
    print(markdown_to_html(sample_markdown))