import type { Source } from 'maplibre-gl';
import { ref, type Ref, unref } from 'vue';

export class SourceLib {

	private static readonly REFS = new Map<string, Ref<Source | undefined | null>>();

	static genSourceOpts<T extends object, O extends object>(type: string, props: object, sourceOpts: Array<keyof O>): T {

		return Object.keys(props)
					 .filter(opt => (props as any)[ opt ] !== undefined && sourceOpts.indexOf(opt as any) !== -1)
					 .reduce((obj, opt) => {
						 (obj as any)[ opt ] = unref((props as any)[ opt ]);
						 return obj;
					 }, { type } as T);

	}

	static getSourceRef<T extends Source>(mcid: number, source: any): Ref<T | undefined | null> {

		const isString = typeof source === 'string',
			  key      = String(mcid) + (isString ? source : '');
		let r          = SourceLib.REFS.get(key);
		if (!r) {
			r = ref(isString ? null : undefined);
			SourceLib.REFS.set(key, r);
		}
		return r as Ref<T | undefined | null>;

	}

}