app/preview/renderer.py

"""PDF page preview renderer using PyMuPDF and Pillow."""

from __future__ import annotations

from pathlib import Path

from loguru import logger
from PIL import Image

from app.utils.file import ensure_dir, safe_stem


class PreviewRenderer:
    """Renders PDF page preview images using PyMuPDF pixmaps and Pillow."""

    def __init__(
        self,
        out_dir: Path = Path("preview"),
        dpi: int = 150,
        fmt: str = "png",
        max_pages: int = 1,
    ) -> None:
        self._out_dir = Path(out_dir).resolve()
        self._dpi = dpi
        self._fmt = fmt.lower()
        self._max_pages = max_pages

    def render(self, pdf_path: Path) -> Path:
        """
        Render preview image(s) for a PDF document.

        Returns path to the output document preview directory.
        """
        import fitz  # PyMuPDF

        pdf_path = Path(pdf_path).resolve()
        if not pdf_path.exists():
            raise FileNotFoundError(f"PDF file not found: {pdf_path}")

        doc_dir = ensure_dir(self._out_dir / safe_stem(pdf_path))
        doc = fitz.open(pdf_path)

        zoom = self._dpi / 72.0
        matrix = fitz.Matrix(zoom, zoom)

        pages_to_render = min(len(doc), self._max_pages)
        for i in range(pages_to_render):
            page = doc[i]
            pix = page.get_pixmap(matrix=matrix, alpha=False)

            img = Image.frombytes("RGB", (pix.width, pix.height), pix.samples)
            out_file = doc_dir / f"page_{i + 1:04d}.{self._fmt}"
            img.save(out_file)
            logger.debug("Rendered preview: {}", out_file)

        doc.close()
        return doc_dir