"""Attach SVG as Word svgBlip alongside a PNG InlineShape (Office 2016+)."""

from __future__ import annotations

from pathlib import Path

from docx.opc.constants import RELATIONSHIP_TYPE as RT
from docx.opc.part import Part
from docx.oxml import OxmlElement
from docx.oxml.ns import qn
from lxml import etree

SVG_CONTENT_TYPE = "image/svg+xml"
SVG_BLIP_URI = "{96DAC541-7B7A-43C6-8E14-B03AE682B59D}"
ASVG_NS = "http://schemas.microsoft.com/office/drawing/2016/SVG/main"
ASVG_SVG_BLIP = f"{{{ASVG_NS}}}svgBlip"


def attach_svg_blip(run, inline_shape, svg_path: str | Path) -> bool:
    """
    After run.add_picture(png), add an SVG part and asvg:svgBlip on the PNG blip.
    Word 2016+ uses the vector; older apps keep the PNG.
    Returns True if the SVG was attached.
    """
    path = Path(svg_path)
    if not path.is_file() or path.stat().st_size <= 0:
        return False
    data = path.read_bytes()
    head = data.lstrip()[:200].lower()
    if not (head.startswith(b"<svg") or head.startswith(b"<?xml") or b"<svg" in head):
        return False

    part = run.part
    package = part.package
    partname = package.next_partname("/word/media/image%d.svg")
    svg_part = Part(partname, SVG_CONTENT_TYPE, data, package)
    r_id = part.relate_to(svg_part, RT.IMAGE)

    blip = inline_shape._inline.graphic.graphicData.pic.blipFill.blip
    ext_lst = blip.find(qn("a:extLst"))
    if ext_lst is None:
        ext_lst = OxmlElement("a:extLst")
        blip.append(ext_lst)

    # Drop any previous svgBlip extension with the same URI.
    for ext in list(ext_lst.findall(qn("a:ext"))):
        if ext.get("uri") == SVG_BLIP_URI:
            ext_lst.remove(ext)

    ext = OxmlElement("a:ext")
    ext.set("uri", SVG_BLIP_URI)
    svg_blip = etree.SubElement(ext, ASVG_SVG_BLIP)
    svg_blip.set(qn("r:embed"), r_id)
    ext_lst.append(ext)
    return True