"""
Shared PDF generation helper for any model using the hospital letterhead.
"""

import io
import base64

from django.conf import settings
from django.template.loader import render_to_string
from weasyprint import HTML


def _get_logo_data_uri():
    """Load the HH_P_ICON as a base64 data URI for embedding in PDF."""
    try:
        from PIL import Image as PILImage

        logo_img = PILImage.open(settings.BASE_DIR / "static" / "img" / "HH_P_ICON.png")
        logo_img.thumbnail((600, 600), PILImage.LANCZOS)
        buf = io.BytesIO()
        logo_img.save(buf, format="PNG", optimize=True)
        return "data:image/png;base64," + base64.b64encode(buf.getvalue()).decode()
    except Exception:
        return None


def generate_letterhead_pdf(template_name, context, filename):
    """Render a template with the hospital letterhead and return an HttpResponse with the PDF."""
    from django.http import HttpResponse

    logo_path = _get_logo_data_uri()
    full_context = {**context, "logo_path": logo_path}

    html_string = render_to_string(template_name, full_context)
    pdf_file = HTML(string=html_string, base_url=str(settings.BASE_DIR / "static")).write_pdf()

    response = HttpResponse(pdf_file, content_type="application/pdf")
    response["Content-Disposition"] = f'attachment; filename="{filename}"'
    return response