export function* findAll(className: string): IterableIterator<HTMLElement> {
	let elements = document.getElementsByClassName(className)

	for(let i = 0; i < elements.length; ++i) {
		yield elements[i] as HTMLElement
	}
}

export function delay<T>(millis: number, value?: T): Promise<T> {
	return new Promise(resolve => setTimeout(() => resolve(value), millis))
}

export function plural(count: number, singular: string): string {
	return (count === 1 || count === -1) ? (count + " " + singular) : (count + " " + singular + "s")
}

export function canUseWebP(): boolean {
	return document.createElement("canvas").toDataURL("image/webp").indexOf("data:image/webp") === 0
}

export function swapElements(a: Node, b: Node) {
	let parent = b.parentNode
	let bNext = b.nextSibling

	// Special case for when a is the next sibling of b
	if(bNext === a) {
		// Just put a before b
		parent.insertBefore(a, b)
	} else {
		// Insert b right before a
		a.parentNode.insertBefore(b, a)

		// Now insert a where b was
		if(bNext) {
			// If there was an element after b, then insert a right before that
			parent.insertBefore(a, bNext)
		} else {
			// Otherwise just append it as the last child
			parent.appendChild(a)
		}
	}
}