import { basename } from "https://deno.land/std@0.223.0/path/basename.ts";

export function log_from(meta: ImportMeta) {
	const url = new URL(meta.url);
	const file = basename(url.pathname);
	return (...args: unknown[]) => console.log(`[${file}]`, ...args);
}

export function last<T>(items: Iterable<T>) {
	let result = null as T | null;
	for (const item of items) result = item;
	return result;
}

export function days_to_ms(days: number) {
	const ms_per_day = 24 * 60 * 60 * 1000;
	return days * ms_per_day;
}

export async function collect<T>(iterator: AsyncIterable<T>) {
	const collected = [] as T[];
	for await (const item of iterator) collected.push(item);
	return collected;
}

export type Channel<T = void> = ReturnType<typeof channel<T>>;
export function channel<T = void>() {
	const queue = [] as T[];
	let resolve_next = null as null | ((value: T) => void);

	async function receive() {
		if (resolve_next !== null) throw new Error("Receiving twice concurently.");
		if (queue.length > 0) return queue.splice(0, 1)[0];
		const result = await new Promise<T>((resolver) => resolve_next = resolver);
		resolve_next = null;
		return result;
	}

	function send(item: T) {
		if (resolve_next === null) queue.push(item);
		else resolve_next(item);
	}

	return { send, receive };
}

export async function wait(ms: number) {
	await new Promise((resolver) => setTimeout(resolver, ms));
}