import { Loader } from "./Loader.ts";
import { DefaultLoadingManager } from "./LoadingManager.ts";

/** Loads files via the fetch API. */
export class FileLoader extends Loader {
	#responseType = "";

	#mimeType: string | undefined = undefined;

	setResponseType(type: string): this {
		this.#responseType = type;
		return this;
	}

	setMimeType(type: string): this {
		this.#mimeType = type;
		return this;
	}

	override load(
		url: string,
		onLoad?: ((data: unknown) => void) | undefined,
		_onProgress?: ((event: ProgressEvent) => void) | undefined,
		onError?: ((err: unknown) => void) | undefined,
	): void {
		const manager = this.manager ?? DefaultLoadingManager;
		const fullUrl = this.path + url;

		manager.itemStart(fullUrl);

		const headers: Record<string, string> = { ...this.requestHeader };
		if (this.#mimeType) {
			headers["Accept"] = this.#mimeType;
		}

		const responseType = this.#responseType || "text";

		fetch(fullUrl, { headers })
			.then((response) => {
				if (!response.ok) {
					throw new Error(
						`FileLoader: fetch failed - ${response.status} ${response.statusText}`,
					);
				}
				return (response as unknown as Record<string, () => Promise<unknown>>)[
					responseType
				]();
			})
			.then((data) => {
				onLoad?.(data);
				manager.itemEnd(fullUrl);
			})
			.catch((err: unknown) => {
				onError?.(err);
				manager.itemError(fullUrl);
			});
	}
}