import type { JSX, ValidComponent } from "@solidjs/web";
import { dynamic } from "@solidjs/web";
import { createMemo, omit, Show } from "solid-js";
import { composeRefs, userRef } from "../../internals/compose-refs";
import { mergeRootProps } from "../../internals/merge-root-props";
import { resolveClassStyle } from "../../internals/resolve-class-style";
import type { BaseUIComponentProps } from "../../internals/types";
import { useComboboxRootContext } from "../root/combobox-root-context";

export type ComboboxEmptyState = Record<string, never>;

export interface ComboboxEmptyProps
	extends BaseUIComponentProps<"div", ComboboxEmptyState> {
	as?: ValidComponent;
}

const EMPTY_STATE: ComboboxEmptyState = {};

/**
 * Renders its children only when the items list is empty. Announces
 * changes politely via `role="status"`.
 */
export function ComboboxEmpty(props: ComboboxEmptyProps): JSX.Element {
	const root = useComboboxRootContext();

	// Items-mode counts the filtered items; static-children mode (no `items`
	// prop) counts the registered children currently matching the query.
	const empty = createMemo<boolean>(() =>
		root.items() !== undefined
			? root.flatFilteredItems().length === 0
			: root.visibleItemCount() === 0,
	);

	const internal = {
		role: "status" as const,
		"aria-live": "polite" as const,
		"aria-atomic": true,
		get children() {
			return <Show when={empty()}>{props.children}</Show>;
		},
	};

	const userClassStyle = resolveClassStyle(props, () => EMPTY_STATE);
	// Strip children explicitly so user's children getter doesn't shadow ours.
	const userProps = omit(props, "as", "class", "style", "attrs", "children");

	let merged: Record<string, unknown> = mergeRootProps(
		internal,
		userClassStyle,
	);
	merged = mergeRootProps(merged, userProps);

	const setEmptyRef = (el: HTMLElement | null): void => {
		root.emptyRef.current = el;
	};

	const Tag = dynamic(() => props.as ?? "div");
	return <Tag {...merged} ref={composeRefs(setEmptyRef, userRef(props))} />;
}