/// <reference lib="dom" />

type BasicProperties<T> = {
	[K in keyof T as T[K] extends string | number | boolean ? K : never]: T[K];
};

export type Child = Node | string | null;
export type SwelOpts<T extends keyof HTMLElementTagNameMap> = Partial<
	BasicProperties<HTMLElementTagNameMap[T]>
> & {
	on: Partial<{
		[Ev in keyof HTMLElementEventMap]: (
			this: HTMLElement,
			ev: HTMLElementEventMap[Ev],
		) => void;
	}>;
	children: (Node | string)[] | null;
	attributes: Record<string, string | boolean | number>;
	className: string;
	style: Record<string, string | boolean | number> | null;
};

export type Renderable = Child | Child[];

interface Swel {
	<T extends keyof HTMLElementTagNameMap>(
		tag: T,
		opts?: Partial<SwelOpts<T>>,
	): HTMLElementTagNameMap[T];

	<T extends keyof HTMLElementTagNameMap>(
		tag: T,
		children?: Child[],
	): HTMLElementTagNameMap[T];

	<T extends keyof HTMLElementTagNameMap>(
		tag: T,
		child?: Child,
	): HTMLElementTagNameMap[T];

	<T extends keyof HTMLElementTagNameMap>(
		tag: T,
		opts?: Partial<Omit<SwelOpts<T>, "children">>,
		children?: Child[],
	): HTMLElementTagNameMap[T];

	<T extends keyof HTMLElementTagNameMap>(
		tag: T,
		opts?: Partial<Omit<SwelOpts<T>, "children">>,
		child?: Child,
	): HTMLElementTagNameMap[T];

	<T extends keyof HTMLElementTagNameMap>(
		tag: T,
		opts?: Partial<Omit<SwelOpts<T>, "children">>,
		renderable?: Renderable,
	): HTMLElementTagNameMap[T];

	<T extends keyof HTMLElementTagNameMap>(
		tag: T,
		renderable?: Renderable,
	): HTMLElementTagNameMap[T];
}

export const swel: Swel = <T extends keyof HTMLElementTagNameMap>(
	tag: T,
	opts?: Partial<SwelOpts<T>> | Renderable,
	children?: Renderable,
): HTMLElementTagNameMap[T] => {
	let o: Partial<SwelOpts<T>> | null = null;
	if (children) {
		let c: Child[] | null;
		if (Array.isArray(children)) {
			c = children;
		} else {
			c = [children];
		}

		o = {
			...(opts as any),
			children: c,
		};
	} else if (opts) {
		if (Array.isArray(opts)) {
			o = { children: opts } as any;
		} else if (typeof opts === "string" || opts instanceof Node) {
			o = { children: [opts] } as any;
		} else {
			o = opts;
		}
	} else {
		o = {};
	}
	let o_ = o!;
	if (o_.children) {
		o_.children = o_.children.filter((c) => !!c) as any;
	}

	return swel_(tag, o);
};

const swel_ = <T extends keyof HTMLElementTagNameMap>(
	tag: T,
	opts: Partial<SwelOpts<T>> | null,
): HTMLElementTagNameMap[T] => {
	const el = document.createElement(tag) as unknown as HTMLElementTagNameMap[T];
	if (opts) {
		const { children, on, attributes, style, ...rest } = opts;

		if (children) {
			el.append(...children);
		}
		if (on) {
			Object.entries(on).forEach(([ev, h]) => {
				el.addEventListener(ev, h as any);
			});
		}
		if (attributes) {
			Object.entries(attributes).map(([k, v]) => {
				el.setAttribute(k, v as unknown as string);
			});
		}
		if (style) {
			Object.entries(style).map(([k, v]) => {
				Reflect.set(el.style, k, v);
			});
		}

		Object.assign(el, rest);
	}

	return el;
};