pdf/rendering/svg_method.py

"""Metodo B — rendering SVG server-side con rettangoli di redazione."""

from __future__ import annotations

from xml.sax.saxutils import escape as xml_escape

from pdf.rendering.base import (
    MethodInfo,
    RenderKind,
    RenderMethod,
    RenderOutput,
    RenderParams,
    boxes_on_page,
)
from pdf.rendering.styles import severity_rgb255


class SvgRenderMethod(RenderMethod):
    info = MethodInfo(
        key="svg",
        label="B · SVG",
        kind=RenderKind.VIEW,
        media_type="image/svg+xml",
        styles=("fill", "outline", "label"),
        default_style="fill",
        description=(
            "SVG vettoriale generato dal server con i riquadri incorporati. "
            "Geometria precisa, nessuna dipendenza client, testo selezionabile."
        ),
    )

    def render(self, params: RenderParams) -> RenderOutput:
        import fitz

        doc = fitz.open(stream=params.pdf_bytes, filetype="pdf")
        page = doc.load_page(params.page)
        mat = fitz.Matrix(params.scale, params.scale)
        svg_text = page.get_svg_image(matrix=mat)
        page_w = page.rect.width * params.scale
        page_h = page.rect.height * params.scale
        doc.close()

        elements = self._build_elements(params)
        svg = svg_text.replace("</svg>", "\n".join(elements) + "\n</svg>")
        return RenderOutput(
            data=svg.encode("utf-8"),
            media_type=self.info.media_type,
            headers={
                "X-Page-Width": f"{page_w:.1f}",
                "X-Page-Height": f"{page_h:.1f}",
                "Cache-Control": "private, max-age=300",
            },
        )

    def _build_elements(self, params: RenderParams) -> list[str]:
        out: list[str] = []
        s = params.scale
        for b in boxes_on_page(params):
            r, g, bl = severity_rgb255(b.get("severity", "media"))
            color = f"rgb({r},{g},{bl})"
            x0, y0 = b["x0"] * s, b["y0"] * s
            w, h = (b["x1"] - b["x0"]) * s, (b["y1"] - b["y0"]) * s
            label = xml_escape(str(b.get("label", "")))
            rect = f'x="{x0:.1f}" y="{y0:.1f}" width="{w:.1f}" height="{h:.1f}"'

            if params.style == "outline":
                out.append(
                    f'<rect {rect} fill="none" stroke="{color}" stroke-width="2" '
                    f'rx="2" ry="2"><title>{label}</title></rect>'
                )
            elif params.style == "label":
                fs = max(7.0, min(h * 0.7, 14.0))
                out.append(
                    f'<rect {rect} fill="{color}" opacity="{params.opacity}" rx="2" ry="2">'
                    f'<title>{label}</title></rect>'
                    f'<text x="{x0 + w / 2:.1f}" y="{y0 + h / 2 + fs / 3:.1f}" '
                    f'font-size="{fs:.1f}" fill="white" text-anchor="middle" '
                    f'font-family="sans-serif" font-weight="bold" '
                    f'pointer-events="none">{label}</text>'
                )
            else:  # fill
                out.append(
                    f'<rect {rect} fill="{color}" opacity="{params.opacity}" '
                    f'rx="2" ry="2"><title>{label}</title></rect>'
                )
        return out