import {SDFLoaderSync} from './SDFLoaderSync';
import {Poly} from '../../../../engine/Poly';
import {sanitizeUrl} from '../../../UrlHelper';
import {LIBRARY_INSTALL_HINT} from './../../../loader/common';
import type {ManifoldToplevel} from './SDFCommon';
import {Module} from './SDFCommon';

let _resolves: Resolve[] = [];
let _importStarted = false;
type Resolve = (value: ManifoldToplevel | PromiseLike<ManifoldToplevel>) => void;
let _manifold: ManifoldToplevel | undefined;
export class SDFLoader {
	static async core(): Promise<ManifoldToplevel> {
		if (_manifold) {
			return _manifold;
		}
		return new Promise(async (resolve, reject) => {
			if (_importStarted) {
				_resolves.push(resolve);
				return;
			}
			_importStarted = true;

			const onError = () => {
				const message = `failed to load Manifold library. Make sure to install it to use the SDFBuilder node (${LIBRARY_INSTALL_HINT})`;

				reject(new Error(message));
			};

			const root = Poly.libs.root();
			const ManifoldPath = Poly.libs.ManifoldPath();
			if (root || ManifoldPath) {
				const version = Poly.version().replace(/\./g, '-');
				const wasmUrl = sanitizeUrl(`${root || ''}${ManifoldPath || ''}/manifold.wasm?v=${version}`);
				try {
					const response = await fetch(wasmUrl, {method: 'HEAD'});
					if (!response.ok) {
						onError();
						return;
					}

					const manifold: ManifoldToplevel = await (Module as any)({
						locateFile: () => wasmUrl,
					});
					manifold.setup();
					_manifold = manifold;

					SDFLoaderSync.__setManifold(manifold);

					resolve(manifold);
					if (_resolves.length > 0) {
						for (const _resolve of _resolves) {
							_resolve(manifold);
						}
						_resolves.length = 0;
					}
				} catch (err) {
					console.error(err);
					onError();
				}
			}
		});
	}
}