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// SPDX-FileCopyrightText: 2024 Shota FUJI <pockawoooh@gmail.com>
// SPDX-License-Identifier: AGPL-3.0-only

import {
	createContext,
	type FC,
	type ReactNode,
	useEffect,
	useMemo,
	useRef,
	useState,
} from "react";

export interface Route {
	url: Readonly<URL>;
}

export const RouteContext = createContext<Route>({
	url: new URL(location.href),
});

export interface Navigation {
	push(url: string | URL): void;

	forward(): void;
	back(): void;
}

const nativeNavigation: Navigation = {
	push(url) {
		location.href = url instanceof URL ? url.href : url;
	},
	forward() {
		history.forward();
	},
	back() {
		history.back();
	},
};

export const NavigationContext = createContext<Navigation>(nativeNavigation);

export interface InmemoryRouterProviderProps {
	initialURL?: string | URL | undefined;

	baseURL?: string | URL | undefined;

	children: ReactNode;

	onRouteChange?(url: URL): void;
}

export const InmemoryRouterProvider: FC<InmemoryRouterProviderProps> = ({
	initialURL,
	baseURL,
	children,
	onRouteChange,
}) => {
	const [history, setHistory] = useState<{
		current: URL;
		backwards: readonly URL[];
		forwards: readonly URL[];
	}>(() => {
		return {
			current: new URL(initialURL ?? location.href, location.href),
			forwards: [],
			backwards: [],
		};
	});

	const routeChangeCallback = useRef(onRouteChange);
	routeChangeCallback.current = onRouteChange;

	const navigation = useMemo<Navigation>(() => {
		return {
			push(url) {
				setHistory(({ current, backwards }) => {
					const next = new URL(url, current);

					routeChangeCallback.current?.(next);

					return {
						current: next,
						backwards: [current, ...backwards],
						forwards: [],
					};
				});
			},
			forward() {
				setHistory((history) => {
					if (!history.forwards[0]) {
						return history;
					}

					routeChangeCallback.current?.(history.forwards[0]);

					return {
						current: history.forwards[0],
						backwards: [history.current, ...history.backwards],
						forwards: history.forwards.slice(1),
					};
				});
			},
			back() {
				setHistory((history) => {
					if (!history.backwards[0]) {
						return history;
					}

					routeChangeCallback.current?.(history.backwards[0]);

					return {
						current: history.backwards[0],
						backwards: history.backwards.slice(1),
						forwards: [history.current, ...history.forwards],
					};
				});
			},
		};
	}, []);

	const root = useMemo(() => new URL(baseURL ?? location.href, location.href), [baseURL]);

	useEffect(() => {
		const listener = (event: MouseEvent) => {
			if (event.altKey || event.ctrlKey || event.metaKey || event.shiftKey) {
				return;
			}

			if (!(event.target instanceof Element)) {
				return;
			}

			const anchor =
				event.target instanceof HTMLAnchorElement
					? event.target
					: event.target.closest("a");
			if (
				!anchor ||
				!anchor.href ||
				(anchor.hasAttribute("target") && anchor.getAttribute("target") !== "_self")
			) {
				return;
			}

			const href = new URL(anchor.href, history.current);
			if (!href.toString().startsWith(root.toString())) {
				return;
			}

			event.preventDefault();
			event.stopPropagation();

			navigation.push(href);
		};

		document.addEventListener("click", listener);

		return () => void document.removeEventListener("click", listener);
	}, [root, history.current, navigation]);

	const route = useMemo<Route>(() => {
		return { url: history.current };
	}, [history.current]);

	return (
		<NavigationContext.Provider value={navigation}>
			<RouteContext.Provider value={route}>{children}</RouteContext.Provider>
		</NavigationContext.Provider>
	);
};