import * as THREE from 'three';
export default class ResourceTracker {
	constructor() {
		this.resources = new Set();
	}
	track(resource) {
		if (!resource) {
			return resource;
		}

		// handle children and when material is an array of materials or
		// uniform is array of textures
		if (Array.isArray(resource)) {
			resource.forEach(resource => this.track(resource));
			return resource;
		}

		if (resource.dispose || resource instanceof THREE.Object3D) {
			this.resources.add(resource);
		}
		if (resource instanceof THREE.Object3D) {
			this.track(resource.geometry);
			this.track(resource.material);
			this.track(resource.children);
		} else if (resource instanceof THREE.Material) {
			// We have to check if there are any textures on the material
			for (const value of Object.values(resource)) {
				if (value instanceof THREE.Texture) {
					this.track(value);
				}
			}
			// We also have to check if any uniforms reference textures or arrays of textures
			if (resource.uniforms) {
				for (const value of Object.values(resource.uniforms)) {
					if (value) {
						const uniformValue = value.value;
						if (uniformValue instanceof THREE.Texture ||
							Array.isArray(uniformValue)) {
							this.track(uniformValue);
						}
					}
				}
			}
		}
		return resource;
	}
	untrack(resource) {
		this.resources.delete(resource);
	}
	dispose() {
		for (const resource of this.resources) {
			if (resource instanceof THREE.Object3D) {
				if (resource.parent) {
					resource.parent.remove(resource);
				}
			}
			if (resource.dispose) {
				resource.dispose();
			}
		}
		this.resources.clear();
	}
}