/** Returns a tuple consisting of a running index starting from 0, and the item of the iterable */
export function* enumerate<T>(iterable: Iterable<T>) {
	let index = 0;
	for (const item of iterable) {
		yield [index++, item] as [number, T];
	}
}

/** Filters an iterable based on the passed predicate function */
export function* filter<T, S extends T>(it: Iterable<T>, predicate: (value: T) => value is S) {
	for (const value of it) {
		if (predicate(value)) {
			yield value;
		}
	}
}

/** Converts a name to an id */
export function toId(name: string) {
	return name.toLowerCase().replace(/[^a-z0-9]+/g, "-");
}

/** Returns adjacent pairs from iterable */
export function* pairs<T>(iterable: Iterable<T>) {
	let first;
	let second;
	for (const [index, item] of enumerate(iterable)) {
		[first, second] = [second, item];
		if (index >= 1) {
			yield [first, second] as [T, T];
		}
	}
}

/**
	Returns true if all sets are equal
	@param sets set to compare
	@returns true if all sets are the same size and have the same elements
*/
export function setEquals<T>(...sets: Set<T>[]) {
	if (sets.length < 2) {
		throw TypeError("At least two sets must be passed to setEquals");
	}
	const ref = sets[0];
	const rest = sets.slice(1);
	if (rest.some(set => set.size !== ref.size)) {
		return false;
	}
	for (const set of rest) {
		for (const el of set) {
			if (!ref.has(el)) {
				return false;
			}
		}
	}
	return true;
}