import type { CrossDesign } from "./B06_Section_Api_Fetch";

const SVG_NS = "http://www.w3.org/2000/svg";

export function appendPavementOverlay(
  svg: SVGElement,
  design: CrossDesign,
  x: (offset: number) => number,
  y: (elevation: number) => number,
): void {
  const edges = design.carriageway_edges ?? design.road_edges;
  if (!design.paved || !edges) return;
  const thickness = design.pavement_thickness_m ?? 0.2;
  const { left, right } = edges;
  const polygon = document.createElementNS(SVG_NS, "polygon");
  polygon.setAttribute(
    "points",
    [
      `${x(left.offset_m)},${y(left.elevation_m)}`,
      `${x(right.offset_m)},${y(right.elevation_m)}`,
      `${x(right.offset_m)},${y(right.elevation_m - thickness)}`,
      `${x(left.offset_m)},${y(left.elevation_m - thickness)}`,
    ].join(" "),
  );
  polygon.setAttribute("class", "b06-chart__pavement");
  svg.append(polygon);
}