import { Node } from "../core/Node.ts";
import { Attribute } from "../geometry/Attribute.ts";
import { Geometry } from "../geometry/Geometry.ts";
import type { SpotLight } from "../lights/SpotLight.ts";
import { Vector3 } from "../math/Vector3.ts";
import { LineSegments } from "../objects/LineSegments.ts";

/** Visualises a SpotLight as a cone wireframe. */
export class SpotLightHelper extends Node {
	override type = "SpotLightHelper";

	#light: SpotLight;

	constructor(light: SpotLight) {
		super();

		this.#light = light;
		this.#buildCone();
		this.update();
	}

	#buildCone(): void {
		const segments = 8;
		const positions: number[] = [];

		const angle = this.#light?.angle ?? Math.PI / 6;
		const distance = this.#light?.distance ?? 1;
		const radius = Math.tan(angle) * distance;

		for (let i = 0; i < segments; i++) {
			const theta = (i / segments) * Math.PI * 2;
			const x = Math.cos(theta) * radius;
			const z = Math.sin(theta) * radius;
			positions.push(0, 0, 0, x, -distance, z);
		}

		for (let i = 0; i < segments; i++) {
			const t0 = (i / segments) * Math.PI * 2;
			const t1 = ((i + 1) / segments) * Math.PI * 2;
			positions.push(
				Math.cos(t0) * radius,
				-distance,
				Math.sin(t0) * radius,
				Math.cos(t1) * radius,
				-distance,
				Math.sin(t1) * radius,
			);
		}

		const geometry = new Geometry();
		geometry.setAttribute(
			"position",
			new Attribute(new Float32Array(positions), 3),
		);

		for (const child of [...this.children]) {
			this.remove(child);
			if ("geometry" in child) {
				(child as { geometry?: { dispose(): void } }).geometry?.dispose();
			}
		}

		this.add(new LineSegments(geometry));
	}

	update(): void {
		const light = this.#light;
		if (!light) return;
		this.position.copy(light.position);
		if (light.direction) {
			const d = light.direction;
			this.lookAt(
				new Vector3(
					light.position.x + d.x,
					light.position.y + d.y,
					light.position.z + d.z,
				),
			);
		}
		this.#buildCone();
	}

	dispose(): void {
		for (const child of this.children) {
			if ("geometry" in child) {
				(child as { geometry?: { dispose(): void } }).geometry?.dispose();
			}
		}
	}
}