import * as THREE from 'three';
import { describe, expect, it } from 'vitest';
import { buildPier } from '../src/core/geometry';
import type { TerrainGrid } from '../src/core/ground-model';
import { buildPierScene, frameMatrix } from '../src/view/scene';
import { terrainGeometry } from '../src/view/terrain';
import { loadP1 } from './helpers';

const model = buildPier(loadP1());

function grid(over: Partial<TerrainGrid>): TerrainGrid {
  return { origin: [259815.676, 179088.094], step: 5, nx: 2, ny: 2, z: [30, 31, 32, 33], ...over };
}

describe('지형 격자 → 장면 메시 (terrain.ts)', () => {
  it('a node maps to the same scene point as the pier frame (x = E − pivot E, z = −(N − pivot N))', () => {
    // A national-grid point on the first stretch: origin + 3·u − 2·nrm (the frame used by the pier scene).
    const st = model.stretches[0];
    const q = { e: st.origin.e + 3 * st.u.e - 2 * st.nrm.e, n: st.origin.n + 3 * st.u.n - 2 * st.nrm.n };
    const expected = new THREE.Vector3(3, 0, -2).applyMatrix4(frameMatrix(model));
    const g = terrainGeometry(grid({ origin: [q.n, q.e], z: [0, 0, 0, 0] }), model.pivot);
    const p = new THREE.Vector3().fromBufferAttribute(g.getAttribute('position') as THREE.BufferAttribute, 0);
    expect(p.x).toBeCloseTo(expected.x, 6);
    expect(p.y).toBeCloseTo(expected.y, 6);
    expect(p.z).toBeCloseTo(expected.z, 6);
  });

  it('the grid node at the pier centre sits at the scene origin, with the sampled EL as height', () => {
    const centre = grid({ origin: [model.pivot.n - 2.5, model.pivot.e - 2.5], step: 5, nx: 2, ny: 2, z: [28.9, 1, 1, 1] });
    const g = terrainGeometry(centre, model.pivot);
    const p = new THREE.Vector3().fromBufferAttribute(g.getAttribute('position') as THREE.BufferAttribute, 0);
    expect(p.x).toBeCloseTo(-2.5, 9);
    expect(p.z).toBeCloseTo(2.5, 9);
    expect(p.y).toBeCloseTo(28.9, 5);                         // stored as Float32
  });

  it('a cell with a missing corner is not drawn; a full cell gives two triangles', () => {
    expect(terrainGeometry(grid({ z: [30, null, 32, 33] }), model.pivot).getIndex()!.count).toBe(0);
    expect(terrainGeometry(grid({}), model.pivot).getIndex()!.count).toBe(6);
  });
});

describe('장면에 지형을 넣은 뒤', () => {
  it('the camera size follows the members, not the extent of the terrain', () => {
    const small = grid({ origin: [model.pivot.e - 20, model.pivot.n - 20], step: 10, nx: 5, ny: 5, z: new Array(25).fill(28) });
    const wide = grid({ origin: [model.pivot.e - 200, model.pivot.n - 200], step: 10, nx: 41, ny: 41, z: new Array(41 * 41).fill(28) });
    const a = buildPierScene(model, small).size;
    const b = buildPierScene(model, wide).size;
    expect(b).toBeCloseTo(a, 6);
    expect(buildPierScene(model, wide).parts.ground.children.length).toBe(1);
  });

  it('uses the pier ground pad when the imported grid has no complete terrain cells', () => {
    const empty = grid({ nx: 2, ny: 2, z: [null, null, null, null] });
    const scene = buildPierScene(model, empty);
    expect(scene.parts.ground.children).toHaveLength(1);
    const pad = scene.parts.ground.children[0] as THREE.Mesh;
    expect(pad.geometry.getIndex()!.count).toBeGreaterThan(0);
  });

  it('places the fallback ground pad at the imported pier ground elevation', () => {
    const scene = buildPierScene(model, undefined, 31.25);
    const pad = scene.parts.ground.children[0] as THREE.Mesh;
    pad.geometry.computeBoundingBox();
    expect(pad.geometry.boundingBox!.getCenter(new THREE.Vector3()).y).toBeCloseTo(31.25, 5);
  });

  it('does not draw a fallback ground pad when the imported pier has no terrain elevation', () => {
    expect(buildPierScene(model, undefined, null).parts.ground.children).toHaveLength(0);
  });
});