---
type Fallback = 'none' | 'animate' | 'swap';

export interface Props {
	fallback?: Fallback;
}

const { fallback = 'animate' } = Astro.props;
---

<style is:global>
	/* Route announcer */
	.astro-route-announcer {
		position: absolute;
		left: 0;
		top: 0;
		clip: rect(0 0 0 0);
		clip-path: inset(50%);
		overflow: hidden;
		white-space: nowrap;
		width: 1px;
		height: 1px;
	}
</style>
<meta name="astro-view-transitions-enabled" content="true" />
<meta name="astro-view-transitions-fallback" content={fallback} />
<script>
	import type { Options } from 'astro:transitions/client';
	import { supportsViewTransitions, navigate } from 'astro:transitions/client';
	// NOTE: import from `astro/virtual-modules/prefetch.js` as `astro:prefetch` requires the `prefetch` config to be enabled
	// @ts-ignore
	import { init } from 'astro/virtual-modules/prefetch.js';

	type Fallback = 'none' | 'animate' | 'swap';
	let lastClickedElementLeavingWindow: EventTarget | null = null;

	function getFallback(): Fallback {
		const el = document.querySelector('[name="astro-view-transitions-fallback"]');
		if (el) {
			return el.getAttribute('content') as Fallback;
		}
		return 'animate';
	}

	function isReloadEl(el: HTMLElement | SVGAElement): boolean {
		return el.dataset.astroReload !== undefined;
	}

	const leavesWindow = (ev: MouseEvent) =>
		(ev.button && ev.button !== 0) || // left clicks only
		ev.metaKey || // new tab (mac)
		ev.ctrlKey || // new tab (windows)
		ev.altKey || // download
		ev.shiftKey; // new window

	if (supportsViewTransitions || getFallback() !== 'none') {
		if (import.meta.env.DEV && window.matchMedia('(prefers-reduced-motion)').matches) {
			console.warn(
				`[transitions]: all view transition animations, including fallback animation, are disabled as this device has the prefer-reduced-motion setting enabled.`,
			);
		}
		document.addEventListener('click', (ev) => {
			let link = ev.target;

			lastClickedElementLeavingWindow = leavesWindow(ev) ? link : null;

			if (ev.composed) {
				link = ev.composedPath()[0];
			}
			if (link instanceof Element) {
				link = link.closest('a, area');
			}
			if (
				!(link instanceof HTMLAnchorElement) &&
				!(link instanceof SVGAElement) &&
				!(link instanceof HTMLAreaElement)
			)
				return;
			// This check verifies that the click is happening on an anchor
			// that is going to another page within the same origin. Basically it determines
			// same-origin navigation, but omits special key combos for new tabs, etc.
			const linkTarget = link instanceof HTMLElement ? link.target : link.target.baseVal;
			const href = link instanceof HTMLElement ? link.href : link.href.baseVal;
			const origin = new URL(href, location.href).origin;
			if (
				isReloadEl(link) ||
				link.hasAttribute('download') ||
				!link.href ||
				(linkTarget && linkTarget !== '_self') ||
				origin !== location.origin ||
				lastClickedElementLeavingWindow ||
				ev.defaultPrevented
			) {
				// No page transitions in these cases,
				// Let the browser standard action handle this
				return;
			}
			ev.preventDefault();
			navigate(href, {
				history: link.dataset.astroHistory === 'replace' ? 'replace' : 'auto',
				sourceElement: link,
			});
		});

		document.addEventListener('submit', (ev) => {
			let el = ev.target as HTMLElement;
			const submitter = ev.submitter;

			const clickedWithKeys = submitter && submitter === lastClickedElementLeavingWindow;
			lastClickedElementLeavingWindow = null;

			if (el.tagName !== 'FORM' || ev.defaultPrevented || isReloadEl(el) || clickedWithKeys) {
				return;
			}
			const form = el as HTMLFormElement;
			const formData = new FormData(form, submitter);
			// form.action and form.method can point to an <input name="action"> or <input name="method">
			// in which case should fall back to the form attribute
			const formAction =
				typeof form.action === 'string' ? form.action : form.getAttribute('action');
			const formMethod =
				typeof form.method === 'string' ? form.method : form.getAttribute('method');
			// Use the form action, if defined; otherwise, fall back to current path.
			let action = submitter?.getAttribute('formaction') ?? formAction ?? location.pathname;
			// Use the form method, if defined; otherwise, fall back to "get"
			const method = submitter?.getAttribute('formmethod') ?? formMethod ?? 'get';

			// the "dialog" method is a special keyword used within <dialog> elements
			// https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#attr-fs-method
			if (method === 'dialog' || location.origin !== new URL(action, location.href).origin) {
				// No page transitions in these cases,
				// Let the browser standard action handle this
				return;
			}

			const options: Options = { sourceElement: submitter ?? form };
			if (method === 'get') {
				const params = new URLSearchParams(formData as any);
				const url = new URL(action);
				url.search = params.toString();
				action = url.toString();
			} else {
				options.formData = formData;
			}

			ev.preventDefault();
			navigate(action, options);
		});

		// @ts-expect-error injected by vite-plugin-transitions for treeshaking
		if (!__PREFETCH_DISABLED__) {
			init({ prefetchAll: true });
		}
	}
</script>
