src/streamlit_app.py

import streamlit as st
from pathlib import Path
import base64
import datetime
import markdown2
from weasyprint import HTML, CSS

# --- Configuration & Setup ---

# Define the layouts based on the specification.
# The 'size' key uses CSS-compatible dimensions.
LAYOUTS = {
    "A4 Portrait": {"size": "210mm 297mm", "icon": "📄"},
    "A4 Landscape": {"size": "297mm 210mm", "icon": "📄"},
    "Letter Portrait": {"size": "8.5in 11in", "icon": "📄"},
    "Letter Landscape": {"size": "11in 8.5in", "icon": "📄"},
    "Wide 16:9": {"aspect_ratio": "16/9", "icon": "📺"},
    "Vertical 9:16": {"aspect_ratio": "9/16", "icon": "📱"},
    "Square 1:1": {"aspect_ratio": "1/1", "icon": "🖼️"},
}

# Directory to save the generated PDFs
OUTPUT_DIR = Path("generated_pdfs")
OUTPUT_DIR.mkdir(exist_ok=True)

# --- Helper Functions ---

def get_file_download_link(file_path: Path) -> str:
    """Generates a base64-encoded download link for a file."""
    with open(file_path, "rb") as f:
        data = base64.b64encode(f.read()).decode()
    return f'<a href="data:application/octet-stream;base64,{data}" download="{file_path.name}">Download</a>'

def display_file_explorer():
    """Renders a simple file explorer in the Streamlit app."""
    st.header("📂 File Explorer")

    # Display Source Markdown files
    st.subheader("Source Markdown Files (.md)")
    md_files = list(Path(".").glob("*.md"))
    if not md_files:
        st.info("No Markdown files found in the current directory. Create a `.md` file to begin.")
    else:
        for md_file in md_files:
            col1, col2 = st.columns([0.8, 0.2])
            with col1:
                st.write(f"📝 `{md_file.name}`")
            with col2:
                st.markdown(get_file_download_link(md_file), unsafe_allow_html=True)

    # Display Generated PDF files
    st.subheader("Generated PDF Files")
    pdf_files = sorted(list(OUTPUT_DIR.glob("*.pdf")), reverse=True)
    if not pdf_files:
        st.info("No PDFs generated yet. Click the button above.")
    else:
        for pdf_file in pdf_files:
            col1, col2 = st.columns([0.8, 0.2])
            with col1:
                st.write(f"📄 `{pdf_file.name}`")
            with col2:
                st.markdown(get_file_download_link(pdf_file), unsafe_allow_html=True)

def generate_pdf_from_markdown(md_path: Path):
    """
    Reads a markdown file and generates PDFs for all defined layouts.
    """
    try:
        md_content = md_path.read_text(encoding="utf-8")
        html_content = markdown2.markdown(md_content, extras=["tables", "fenced-code-blocks", "cuddled-lists"])
        
        # Basic styling for the PDF
        base_css = """
        @import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;700&display=swap');
        body { font-family: 'Inter', sans-serif; line-height: 1.6; }
        h1, h2, h3 { font-weight: 700; }
        code {
            background-color: #f0f0f0;
            padding: 2px 4px;
            border-radius: 3px;
            font-family: monospace;
        }
        pre { background-color: #f0f0f0; padding: 1em; border-radius: 5px; overflow: auto; }
        table { border-collapse: collapse; width: 100%; }
        th, td { border: 1px solid #ddd; padding: 8px; }
        th { background-color: #f2f2f2; }
        """

        date_str = datetime.datetime.now().strftime("%Y-%m-%d")
        
        for name, properties in LAYOUTS.items():
            st.write(f"   - Generating `{name}` format...")
            
            page_css = f"@page {{ size: {properties.get('size', 'A4')}; margin: 2cm; }}"
            if 'aspect_ratio' in properties:
                # For aspect ratio, we fix width and calculate height. This is an approximation.
                # A more robust solution might require more complex CSS.
                page_css = f"@page {{ size: 210mm calc(210mm * {properties['aspect_ratio']}); margin: 1cm; }}"

            final_css = CSS(string=base_css + page_css)
            
            output_filename = f"{md_path.stem}_{name.replace(' ', '-')}_{date_str}.pdf"
            output_path = OUTPUT_DIR / output_filename
            
            HTML(string=html_content).write_pdf(output_path, stylesheets=[final_css])
            
    except Exception as e:
        st.error(f"Failed to process {md_path.name}: {e}")


# --- Streamlit App UI ---

st.set_page_config(layout="wide", page_title="PDF Generator")

st.title("📄 Markdown to PDF Generator")
st.markdown("This tool finds all `.md` files in this directory, converts them to PDF in various layouts, and provides download links.")

# Create a sample markdown file if none exists
if not list(Path(".").glob("*.md")):
    with open("sample.md", "w", encoding="utf-8") as f:
        f.write("# Sample Document\n\n")
        f.write("This is a sample markdown file created for you. You can edit this file or add your own `.md` files to this directory.\n\n")
        f.write("- Item 1\n- Item 2\n\n")
        f.write("`code snippet`\n\n")
        f.write("Click the button below to start the PDF generation process.")
    st.rerun()


if st.button("🚀 Generate PDFs from all Markdown Files", type="primary"):
    markdown_files = list(Path(".").glob("*.md"))
    
    if not markdown_files:
        st.warning("No `.md` files found. Please add a markdown file to the directory.")
    else:
        with st.spinner("Generating PDFs... This may take a moment."):
            progress_bar = st.progress(0)
            total_steps = len(markdown_files)
            
            for i, md_file in enumerate(markdown_files):
                st.info(f"Processing: **{md_file.name}**")
                generate_pdf_from_markdown(md_file)
                progress_bar.progress((i + 1) / total_steps)

        st.success("✅ PDF generation complete!")
        # Use st.rerun() to immediately refresh the file explorer
        st.rerun()

# Display the file explorer section
display_file_explorer()