import { Geometry } from "../Geometry.ts";

/** Parametric UV sphere. */
export class SphereGeometry extends Geometry {
	declare type: string;
	declare parameters: Record<string, unknown>;

	constructor(
		radius = 1,
		widthSegments = 32,
		heightSegments = 16,
		phiStart = 0,
		phiLength: number = Math.PI * 2,
		thetaStart = 0,
		thetaLength: number = Math.PI,
	) {
		super();

		this.type = "SphereGeometry";
		this.parameters = {
			radius,
			widthSegments,
			heightSegments,
			phiStart,
			phiLength,
			thetaStart,
			thetaLength,
		};

		const ws = Math.max(3, Math.floor(widthSegments));
		const hs = Math.max(2, Math.floor(heightSegments));

		const positions: number[] = [];
		const normals: number[] = [];
		const uvs: number[] = [];
		const indices: number[] = [];

		// Grid of (ws+1) x (hs+1) vertices
		const grid: number[][] = [];

		let index = 0;

		for (let iy = 0; iy <= hs; iy++) {
			const row: number[] = [];
			const v = iy / hs;
			for (let ix = 0; ix <= ws; ix++) {
				const u = ix / ws;
				const phi = phiStart + u * phiLength;
				const theta = thetaStart + v * thetaLength;

				const sinTheta = Math.sin(theta);
				const cosTheta = Math.cos(theta);
				const sinPhi = Math.sin(phi);
				const cosPhi = Math.cos(phi);

				const nx = -cosPhi * sinTheta;
				const ny = cosTheta;
				const nz = sinPhi * sinTheta;

				positions.push(radius * nx, radius * ny, radius * nz);
				normals.push(nx, ny, nz);
				uvs.push(u, 1 - v);

				row.push(index++);
			}
			grid.push(row);
		}

		for (let iy = 0; iy < hs; iy++) {
			for (let ix = 0; ix < ws; ix++) {
				const a = grid[iy][ix + 1];
				const b = grid[iy][ix];
				const c = grid[iy + 1][ix];
				const d = grid[iy + 1][ix + 1];

				if (iy !== 0 || thetaStart > 0) indices.push(a, b, d);
				if (iy !== hs - 1 || thetaLength + thetaStart < Math.PI) {
					indices.push(b, c, d);
				}
			}
		}

		const IndexArray = index > 65535 ? Uint32Array : Uint16Array;

		this.setPositions(new Float32Array(positions));
		this.setNormals(new Float32Array(normals));
		this.setUVs(new Float32Array(uvs));
		this.setIndex(new IndexArray(indices));
	}
}