import { GuildMetadata, Member, Channel, Message, Resource, Token } from "./data-types";
import { Fetchable, GuaranteedFetchable } from "./guild-types";

export default class EnsuredFetchable implements GuaranteedFetchable {
	constructor(
		private fetchable: Fetchable
	) {}

	private static guarantee<T>(value: T | null): T {
		if (!value) throw new Error('got null value');
		return value;
	}

	async fetchMetadata(): Promise<GuildMetadata> {
		return EnsuredFetchable.guarantee(await this.fetchable.fetchMetadata());
	}
	async fetchMembers(): Promise<Member[]> {
		return EnsuredFetchable.guarantee(await this.fetchable.fetchMembers());
	}
	async fetchChannels(): Promise<Channel[]> {
		return EnsuredFetchable.guarantee(await this.fetchable.fetchChannels());
	}
	async fetchMessagesRecent(channelId: string, number: number): Promise<Message[]> {
		return EnsuredFetchable.guarantee(await this.fetchable.fetchMessagesRecent(channelId, number));
	}
	async fetchMessagesBefore(channelId: string, messageId: string, number: number): Promise<Message[]> {
		return EnsuredFetchable.guarantee(await this.fetchable.fetchMessagesBefore(channelId, messageId, number));
	}
	async fetchMessagesAfter(channelId: string, messageId: string, number: number): Promise<Message[]> {
		return EnsuredFetchable.guarantee(await this.fetchable.fetchMessagesAfter(channelId, messageId, number));
	}
	async fetchResource(resourceId: string): Promise<Resource> {
		return EnsuredFetchable.guarantee(await this.fetchable.fetchResource(resourceId));
	}
	async fetchTokens(): Promise<Token[]> {
		return EnsuredFetchable.guarantee(await this.fetchable.fetchTokens());
	}
}