/* =============================================================================
 * E03_StabSection_UI_View3D.ts
 * E03 [3D 보기](PLAN 532-3) — 복사본 노선면(GET …/stab/corridor3d · 1 m 솎음)에 측점 안전율 색칠(표시만).
 *   색 = 가장 가까운 측점의 그 조건 최소 (안전율 ÷ 기준) 띠(횡단 등안전율과 같은 띠 · logic `bandIndex`) ·
 *   해석 없는 측점 = 회색. createRouteViewer 는 DB 지표면 · 색 고리가 없어 쓰지 않고 three 를 바로 씀.
 * ========================================================================== */

import * as THREE from "three";
import { OrbitControls } from "three/examples/jsm/controls/OrbitControls.js";
import { el } from "@ui/ui_template_elements";
import { t } from "@ui/ui_template_locale";
import { openModal } from "@ui/ui_template_modal";
import { legend, muted } from "./E03_StabSection_UI_Parts";
import {
  bandIndex,
  RATIO_BREAKS,
  type Condition,
  type StationRow,
} from "./logic/E03_StabSection_Logic";

interface Corridor3d {
  origin: [number, number, number];
  ribbons: {
    kind: string;
    side: string;
    colCount: number;
    chainages: number[];
    positions: number[];
  }[];
}

/** 측점 하나 그 조건 최소 비(안전율 ÷ 기준)의 띠 */
function stationBand(row: StationRow, condition: Condition): number | null {
  let best: number | null = null;
  for (const c of Object.values(row.cases[condition] ?? {})) {
    const band = bandIndex(c.fs, c.required);
    if (band !== null && (best === null || band < best)) best = band;
  }
  return best;
}

function cssColor(name: string): THREE.Color {
  const value = getComputedStyle(document.documentElement).getPropertyValue(name).trim();
  return new THREE.Color(value || "#888888");
}

export async function openView3d(
  data: Corridor3d,
  rows: StationRow[],
  condition: Condition,
  conditionLabel: string,
): Promise<void> {
  const edges = [null, ...RATIO_BREAKS, null];
  const items = [...Array(RATIO_BREAKS.length + 1).keys()].map((i) => ({
    label:
      edges[i] === null
        ? `< ${edges[i + 1]}`
        : edges[i + 1] === null
          ? `≥ ${edges[i]}`
          : `${edges[i]}–${edges[i + 1]}`,
    color: `var(--e03-band-${i})`,
  }));
  items.push({ label: t("E03_Verdict_none"), color: "var(--e03-none)" });
  const legendRow = el("div", {
    className: "e03-legend",
    children: [muted(`${conditionLabel} · ${t("E03_View3d_Legend")}`), legend(items)],
  });
  const host = el("div", { className: "e03-view3d__canvas" });
  let teardown = (): void => undefined;
  openModal({
    title: t("E03_View3d"),
    closeLabel: t("Common_Btn_Close"),
    wide: true,
    dialogClass: "e03-view3d",
    mount: (body) => {
      body.closest<HTMLElement>(".ui-modal")!.dataset.role = "view3d";
      body.append(legendRow, host);
    },
    beforeClose: () => (teardown(), true),
  });

  const renderer = new THREE.WebGLRenderer({ antialias: true });
  renderer.setPixelRatio(window.devicePixelRatio);
  host.append(renderer.domElement);
  const scene = new THREE.Scene();
  scene.background = cssColor("--e03-plot");
  scene.add(new THREE.AmbientLight(0xffffff, 0.75));
  const sun = new THREE.DirectionalLight(0xffffff, 0.9);
  sun.position.set(200, 400, 300);
  scene.add(sun);

  // 측점 누가 → 색
  const sorted = rows.slice().sort((a, b) => a.chainage_m - b.chainage_m);
  const bandColors = [...Array(RATIO_BREAKS.length + 1).keys()].map((i) =>
    cssColor(`--e03-band-${i}`),
  );
  const noneColor = cssColor("--e03-none");
  const colorAt = (chainage: number): THREE.Color => {
    let lo = 0;
    let hi = sorted.length - 1;
    while (hi - lo > 1) {
      const mid = (lo + hi) >> 1;
      if (sorted[mid].chainage_m <= chainage) lo = mid;
      else hi = mid;
    }
    const near =
      sorted.length &&
      Math.abs(sorted[hi].chainage_m - chainage) < Math.abs(sorted[lo].chainage_m - chainage)
        ? sorted[hi]
        : sorted[lo];
    const band = near ? stationBand(near, condition) : null;
    return band === null ? noneColor : bandColors[band];
  };

  const group = new THREE.Group();
  for (const ribbon of data.ribbons) {
    const rowsN = ribbon.chainages.length;
    const cols = ribbon.colCount;
    if (rowsN < 2 || cols < 2) continue;
    const pos = new Float32Array(rowsN * cols * 3);
    const col = new Float32Array(rowsN * cols * 3);
    for (let r = 0; r < rowsN; r += 1) {
      const c3 = colorAt(ribbon.chainages[r]);
      for (let c = 0; c < cols; c += 1) {
        const i = (r * cols + c) * 3;
        const [x, y, z] = ribbon.positions.slice(i, i + 3);
        pos.set([x, z, -y], i);
        col.set([c3.r, c3.g, c3.b], i);
      }
    }
    const index: number[] = [];
    for (let r = 0; r + 1 < rowsN; r += 1) {
      for (let c = 0; c + 1 < cols; c += 1) {
        const a = r * cols + c;
        index.push(a, a + cols, a + 1, a + 1, a + cols, a + cols + 1);
      }
    }
    const geometry = new THREE.BufferGeometry();
    geometry.setAttribute("position", new THREE.BufferAttribute(pos, 3));
    geometry.setAttribute("color", new THREE.BufferAttribute(col, 3));
    geometry.setIndex(index);
    geometry.computeVertexNormals();
    const material = new THREE.MeshLambertMaterial({ vertexColors: true, side: THREE.DoubleSide });
    group.add(new THREE.Mesh(geometry, material));
  }
  scene.add(group);

  const box = new THREE.Box3().setFromObject(group);
  const sphere = box.getBoundingSphere(new THREE.Sphere());
  const camera = new THREE.PerspectiveCamera(45, 1, 0.5, Math.max(sphere.radius * 20, 1000));
  camera.position
    .copy(sphere.center)
    .add(new THREE.Vector3(0, sphere.radius * 1.9, sphere.radius * 1.6));
  const controls = new OrbitControls(camera, renderer.domElement);
  controls.target.copy(sphere.center);
  controls.update();

  let frame = 0;
  const resize = (): void => {
    const w = Math.max(host.clientWidth, 1);
    const h = Math.max(host.clientHeight, 1);
    renderer.setSize(w, h, false);
    camera.aspect = w / h;
    camera.updateProjectionMatrix();
  };
  const loop = (): void => {
    frame = requestAnimationFrame(loop);
    controls.update();
    renderer.render(scene, camera);
  };
  const observer = new ResizeObserver(resize);
  observer.observe(host);
  resize();
  loop();
  (window as unknown as { __e03View3d?: unknown }).__e03View3d = {
    meshes: group.children.length,
    vertices: group.children.reduce(
      (n, m) => n + ((m as THREE.Mesh).geometry.getAttribute("position").count ?? 0),
      0,
    ),
  };

  const dispose = (): void => {
    cancelAnimationFrame(frame);
    observer.disconnect();
    controls.dispose();
    group.traverse((o) => {
      if (o instanceof THREE.Mesh) {
        o.geometry.dispose();
        (o.material as THREE.Material).dispose();
      }
    });
    renderer.dispose();
  };
  teardown = dispose;
}