import type { PavementEntry } from "@util/common_util_structure_pavement";
import type { CrossDesign } from "./B06_Section_Api_Fetch";

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

export function appendRockBoundaryOverlay(
  svg: SVGElement,
  samples: Array<{ offset_m?: number; elevation_m?: number | null; valid: boolean }>,
  offsetM: number,
  x: (offset: number) => number,
  y: (elevation: number) => number,
): void {
  const segments: string[][] = [];
  let current: string[] = [];
  for (const sample of samples) {
    const elevation = sample.elevation_m;
    if (sample.valid === false || elevation === null || !Number.isFinite(elevation ?? NaN)) {
      if (current.length > 1) segments.push(current);
      current = [];
      continue;
    }
    current.push(`${x(sample.offset_m ?? 0)},${y((elevation as number) + offsetM)}`);
  }
  if (current.length > 1) segments.push(current);
  for (const points of segments) {
    const polyline = document.createElementNS(SVG_NS, "polyline");
    polyline.setAttribute("points", points.join(" "));
    polyline.setAttribute("class", "b06-chart__rock-boundary");
    svg.append(polyline);
  }
}

type Edge = { offset_m: number; elevation_m: number };

/** 포장사양 → 무늬(88) — 콘크리트 빗금 · 아스콘 점 · 쇄석 돌. 그 밖 = 채움만. */
const PAVE_MARKS: Record<string, { size: number; marks: string }> = {
  콘크리트: { size: 6, marks: '<path d="M0,6 L6,0" class="b06-chart__pave-mark"/>' },
  아스콘: {
    size: 5,
    marks: '<circle cx="1.5" cy="1.5" r="0.7" class="b06-chart__pave-mark--dot"/>',
  },
  쇄석: {
    size: 9,
    marks:
      '<circle cx="2.5" cy="2.5" r="1.6" class="b06-chart__pave-mark"/>' +
      '<ellipse cx="6.8" cy="6.5" rx="1.8" ry="1.2" class="b06-chart__pave-mark"/>',
  },
};
/** 무늬 id 는 문서 안에서 유일 — 카드 · 다시 그리기마다 새 번호(물넘이 빗금과 같은 방식). */
let paveSeq = 0;

/** 확폭 끈 구간 — 규격 폭 끝(좌 = left − 확폭좌 · 우 = right + 확폭우 · 표고는 두 끝 사이 직선). */
function standardEdges(edges: { left: Edge; right: Edge }, design: CrossDesign) {
  const { left, right } = edges;
  const span = right.offset_m - left.offset_m || 1;
  const at = (offset: number): Edge => ({
    offset_m: offset,
    elevation_m:
      left.elevation_m + ((right.elevation_m - left.elevation_m) * (offset - left.offset_m)) / span,
  });
  return {
    left: at(left.offset_m - (design.widening_left_m ?? 0)),
    right: at(right.offset_m + (design.widening_right_m ?? 0)),
  };
}

/**
 * 포장층 — 노면선(= 포장 윗면) 아래로 두께만큼. 노면공 범위(`section.pavement`)면 그 두께 · 무늬 ·
 * 확폭 켬/끔(여러 건은 아래로 차례로 쌓음) · 없으면 카드 포장 켬일 때 표준 두께 채움만.
 */
export function appendPavementOverlay(
  svg: SVGElement,
  design: CrossDesign,
  x: (offset: number) => number,
  y: (elevation: number) => number,
  pavement?: readonly PavementEntry[] | null,
): void {
  const edges = design.carriageway_edges ?? design.road_edges;
  if (!edges) return;
  const layers = pavement?.length ? pavement : design.paved ? [null] : [];
  let depth = 0;
  for (const entry of layers) {
    const thickness = entry?.thickness_m ?? design.pavement_thickness_m ?? 0.2;
    const { left, right } = entry && !entry.widening_on ? standardEdges(edges, design) : edges;
    const points = [
      `${x(left.offset_m)},${y(left.elevation_m - depth)}`,
      `${x(right.offset_m)},${y(right.elevation_m - depth)}`,
      `${x(right.offset_m)},${y(right.elevation_m - depth - thickness)}`,
      `${x(left.offset_m)},${y(left.elevation_m - depth - thickness)}`,
    ].join(" ");
    depth += thickness;
    const polygon = document.createElementNS(SVG_NS, "polygon");
    polygon.setAttribute("points", points);
    polygon.setAttribute("class", "b06-chart__pavement");
    const spec = entry?.spec;
    const mark = spec ? PAVE_MARKS[spec] : undefined;
    if (spec && mark) {
      // 무늬는 바탕 채움째 한 패턴 — 다각형 한 장(B07 도면 수확이 겹선을 안 담음)
      const id = `b06-pave-hatch-${(paveSeq += 1)}`;
      const defs = document.createElementNS(SVG_NS, "defs");
      defs.innerHTML = `<pattern id="${id}" patternUnits="userSpaceOnUse" width="${mark.size}" height="${mark.size}"><rect width="${mark.size}" height="${mark.size}" class="b06-chart__pave-bg"/>${mark.marks}</pattern>`;
      svg.append(defs);
      polygon.style.fill = `url(#${id})`;
      polygon.dataset.paveSpec = spec;
    }
    svg.append(polygon);
  }
}