"""PDF renderer using WeasyPrint.

This module provides PDF rendering from HTML content using WeasyPrint.
"""

from pathlib import Path

from py_dvt_ate.reporting.exceptions import PDFConversionError


class PDFRenderer:
    """Renders PDF documents from HTML content using WeasyPrint.

    WeasyPrint converts HTML/CSS to PDF with support for page layout,
    headers/footers, and professional typography.
    """

    def __init__(self) -> None:
        """Initialise the PDF renderer."""
        self._weasyprint: type | None = None

    def _get_weasyprint(self) -> type:
        """Lazy-load WeasyPrint to avoid import errors when not installed.

        Returns:
            The WeasyPrint HTML class.

        Raises:
            PDFConversionError: If WeasyPrint is not installed.
        """
        if self._weasyprint is None:
            try:
                from weasyprint import HTML

                self._weasyprint = HTML
            except ImportError as e:
                msg = (
                    "WeasyPrint is required for PDF generation. "
                    "Install it with: pip install py_dvt_ate[reports]"
                )
                raise PDFConversionError(msg) from e
        return self._weasyprint

    def render_to_file(self, html: str, path: Path) -> None:
        """Render HTML content to a PDF file.

        Args:
            html: HTML content to convert.
            path: Output path for the PDF file.

        Raises:
            PDFConversionError: If PDF conversion fails.
        """
        try:
            HTML = self._get_weasyprint()
            path.parent.mkdir(parents=True, exist_ok=True)
            HTML(string=html).write_pdf(path)
        except PDFConversionError:
            raise
        except Exception as e:
            msg = f"Failed to convert HTML to PDF: {e}"
            raise PDFConversionError(msg) from e

    def render_to_bytes(self, html: str) -> bytes:
        """Render HTML content to PDF bytes.

        Args:
            html: HTML content to convert.

        Returns:
            PDF document as bytes.

        Raises:
            PDFConversionError: If PDF conversion fails.
        """
        try:
            HTML = self._get_weasyprint()
            result: bytes = HTML(string=html).write_pdf()
            return result
        except PDFConversionError:
            raise
        except Exception as e:
            msg = f"Failed to convert HTML to PDF: {e}"
            raise PDFConversionError(msg) from e