import { createEffect, createSignal } from "solid-js";

export function ReadProgressBar() {
	const articleContentElement: HTMLElement | null =
		document.getElementById("article-content");
	if (!articleContentElement) return null;

	const [width, setWidth] = createSignal("0%");

	const handleScroll = () => {
		const articleHeight = articleContentElement.scrollHeight;
		const topPosition = articleContentElement.getBoundingClientRect().top;
		const windowHeight = window.innerHeight;

		if (articleHeight <= windowHeight) {
			setWidth("100%");
			return;
		}

		const elementScrollTop = -topPosition;
		const scrollableHeight = articleHeight - windowHeight;
		const percentage = (elementScrollTop / scrollableHeight) * 100;
		const clampedPercentage = Math.max(0, Math.min(100, percentage));

		setWidth(`${clampedPercentage}%`);
	};

	createEffect(() => {
		window.addEventListener("scroll", handleScroll);
		window.addEventListener("resize", handleScroll);

		handleScroll();

		return () => {
			window.removeEventListener("scroll", handleScroll);
			window.removeEventListener("resize", handleScroll);
		};
	});

	return (
		<div
			aria-hidden="true"
			class="fixed inset-x-0 bottom-0 lg:top-0 z-50 h-1 w-full bg-violet-50 pointer-events-none"
		>
			<div
				class="bg-violet-300 h-full transition-all duration-300 ease-out"
				style={{ width: width() }}
			/>
		</div>
	);
}
