revite/src/pages/Open.tsx

import { useHistory, useParams } from "react-router-dom";

import { Text } from "preact-i18n";
import { useContext, useEffect } from "preact/hooks";

import { useIntermediate } from "../context/intermediate/Intermediate";
import {
	AppContext,
	ClientStatus,
	StatusContext,
} from "../context/revoltjs/RevoltClient";
import {
	useChannels,
	useForceUpdate,
	useUser,
} from "../context/revoltjs/hooks";

import Header from "../components/ui/Header";

export default function Open() {
	const history = useHistory();
	const client = useContext(AppContext);
	const status = useContext(StatusContext);
	const { id } = useParams<{ id: string }>();
	const { openScreen } = useIntermediate();

	if (status !== ClientStatus.ONLINE) {
		return (
			<Header placement="primary">
				<Text id="general.loading" />
			</Header>
		);
	}

	const ctx = useForceUpdate();
	const channels = useChannels(undefined, ctx);
	const user = useUser(id, ctx);

	useEffect(() => {
		if (id === "saved") {
			for (const channel of channels) {
				if (channel?.channel_type === "SavedMessages") {
					history.push(`/channel/${channel._id}`);
					return;
				}
			}

			client.users
				.openDM(client.user?._id as string)
				.then((channel) => history.push(`/channel/${channel?._id}`))
				.catch((error) => openScreen({ id: "error", error }));

			return;
		}

		if (user) {
			const channel: string | undefined = channels.find(
				(channel) =>
					channel?.channel_type === "DirectMessage" &&
					channel.recipients.includes(id),
			)?._id;

			if (channel) {
				history.push(`/channel/${channel}`);
			} else {
				client.users
					.openDM(id)
					.then((channel) => history.push(`/channel/${channel?._id}`))
					.catch((error) => openScreen({ id: "error", error }));
			}

			return;
		}

		history.push("/");
	}, []);

	return (
		<Header placement="primary">
			<Text id="general.loading" />
		</Header>
	);
}