import {$, $$, elementExists} from 'select-dom';
import {RequireAtLeastOne} from 'type-fest';
import {isDefined} from 'ts-extras';

import getCallerID from './caller-id.js';

type Position = 'append' | 'prepend' | 'before' | 'after' | 'forEach';

// NOTE: Do not turn the Callback into an async function or else the deduplication won't work. A placeholder element MUST be returned synchronously. The deduplication logic is DOM-based.
type Attachment<NewElement extends Element, Callback = (E: Element) => NewElement> = RequireAtLeastOne<{
	className?: string;
	append: Callback;
	prepend: Callback;
	before: Callback;
	after: Callback;
	forEach: Callback;
	allowMissingAnchor?: boolean;
}, Position>;

export default function attachElement<NewElement extends Element>(
	// eslint-disable-next-line @typescript-eslint/ban-types --  Allows dom traversing without requiring `!`
	anchor: Element | string | undefined | null,
	{
		className = 'rgh-' + getCallerID(),
		append,
		prepend,
		before,
		after,
		forEach,
		allowMissingAnchor = false,
	}: Attachment<NewElement>): NewElement[] {
	const anchorElement = typeof anchor === 'string' ? $(anchor) : anchor;
	if (!anchorElement) {
		if (allowMissingAnchor) {
			return [];
		}

		throw new Error('Element not found');
	}

	if (elementExists('.' + className, anchorElement.parentElement ?? anchorElement)) {
		return [];
	}

	const call = (position: Position, create: (anchorElement: Element) => NewElement): NewElement => {
		const element = create(anchorElement);
		element.classList.add(className);

		// Attach the created element, unless the callback already took care of that
		if (position !== 'forEach') {
			anchorElement[position](element);
		}

		return element;
	};

	return [
		append && call('append', append),
		prepend && call('prepend', prepend),
		before && call('before', before),
		after && call('after', after),
		forEach && call('forEach', forEach),
		// eslint-disable-next-line unicorn/no-array-callback-reference -- It only works this way. TS, AMIRITE?
	].filter(isDefined);
}

export function attachElements<NewElement extends Element>(anchors: string | string[], {
	className = 'rgh-' + getCallerID(),
	...options
}: Attachment<NewElement>): NewElement[] {
	return $$(`:is(${String(anchors)}):not(.${className})`)
		.flatMap(anchor => attachElement(anchor, {...options, className}));
}