main.py

import os
import re
import subprocess
import tempfile
from pathlib import Path

from fastapi import FastAPI, File, Form, UploadFile
from fastapi.responses import FileResponse, Response
from fastapi.staticfiles import StaticFiles

app = FastAPI()

# Page break marker pattern - matches ---pagebreak---, <!-- pagebreak -->, \pagebreak
_PAGE_BREAK_RE = re.compile(
    r"^(?:---\s*pagebreak\s*---|<!--\s*pagebreak\s*-->|\\pagebreak)\s*$",
    re.MULTILINE | re.IGNORECASE,
)
_PAGE_BREAK_HTML = '<div class="pagebreak"></div>'


def convert_eisvogel(markdown_content: str, filename: str) -> tuple[bytes | None, str | None]:
    """Convert markdown to PDF using Eisvogel/LuaLaTeX."""
    with tempfile.TemporaryDirectory() as tmp_dir:
        md_path = os.path.join(tmp_dir, f"{filename}.md")
        pdf_path = os.path.join(tmp_dir, f"{filename}.pdf")

        with open(md_path, "w", encoding="utf-8") as f:
            f.write(markdown_content)

        result = subprocess.run(
            ["pandoc", "--defaults=/app/defaults.yaml", md_path, "-o", pdf_path],
            capture_output=True,
            text=True,
        )

        if result.returncode != 0:
            return None, f"Conversion failed: {result.stderr}"

        if os.path.exists(pdf_path):
            with open(pdf_path, "rb") as f:
                return f.read(), None
        return None, "PDF file was not generated."


def convert_github(markdown_content: str, filename: str) -> tuple[bytes | None, str | None]:
    """Convert markdown to PDF using GitHub-style rendering."""
    with tempfile.TemporaryDirectory() as tmp_dir:
        md_path = os.path.join(tmp_dir, f"{filename}.md")
        html_path = os.path.join(tmp_dir, f"{filename}.html")
        pdf_path = os.path.join(tmp_dir, f"{filename}.pdf")

        processed_content = _PAGE_BREAK_RE.sub(_PAGE_BREAK_HTML, markdown_content)

        with open(md_path, "w", encoding="utf-8") as f:
            f.write(processed_content)

        result = subprocess.run(
            ["pandoc", "--defaults=/app/defaults-github.yaml", md_path, "-o", html_path],
            capture_output=True,
            text=True,
        )
        if result.returncode != 0:
            return None, f"HTML conversion failed: {result.stderr}"

        result = subprocess.run(
            ["node", "/app/scripts/html-to-pdf.js", html_path, pdf_path, "--page-numbers"],
            capture_output=True,
            text=True,
        )
        if result.returncode != 0:
            return None, f"PDF conversion failed: {result.stderr}"

        if os.path.exists(pdf_path):
            with open(pdf_path, "rb") as f:
                return f.read(), None
        return None, "PDF file was not generated."


@app.post("/convert")
async def convert(file: UploadFile = File(...), style: str = Form("eisvogel")):
    content = (await file.read()).decode("utf-8")
    filename = Path(file.filename).stem

    if style == "github":
        pdf_bytes, error = convert_github(content, filename)
    else:
        pdf_bytes, error = convert_eisvogel(content, filename)

    if error:
        return Response(content=error, status_code=500, media_type="text/plain")

    return Response(
        content=pdf_bytes,
        media_type="application/pdf",
        headers={"Content-Disposition": f'attachment; filename="{filename}.pdf"'},
    )


@app.get("/")
async def index():
    return FileResponse("static/index.html")


# Mount static files after routes so it doesn't shadow them
app.mount("/static", StaticFiles(directory="static"), name="static")