/*
	SPDX-FileCopyrightText: © 2025 Hornwitser <code@hornwitser.no>
	SPDX-License-Identifier: AGPL-3.0-or-later
*/
import { pipeline } from "node:stream";
import { createEventStream } from "~/server/streams";

export default defineEventHandler(async (event) => {
	const session = await getServerSession(event, false);

	let lastEventId: number | undefined;
	const lastEventIdHeader = event.headers.get("Last-Event-ID");
	const lastEventIdQuery = getQuery(event)["lastEventId"];
	if (lastEventIdHeader) {
		if (!/^[0-9]{1,15}$/.test(lastEventIdHeader)) {
			throw createError({
				statusCode: 400,
				statusMessage: "Bad Request",
				message: "Malformed Last-Event-ID header",
			});
		}
		lastEventId = Number.parseInt(lastEventIdHeader, 10);
	} else if (lastEventIdQuery) {
		if (typeof lastEventIdQuery !== "string" || !/^[0-9]{1,15}$/.test(lastEventIdQuery)) {
			throw createError({
				statusCode: 400,
				statusMessage: "Bad Request",
				message: "Malformed lastEventId",
			});
		}
		lastEventId = Number.parseInt(lastEventIdQuery, 10);
	} else {
		throw createError({
			statusCode: 400,
			statusMessage: "Bad Request",
			message: "lastEventId is required",
		});
	}

	const source = event.headers.get("x-forwarded-for") ?? "";
	const stream = await createEventStream(event, source, lastEventId, session);

	// Workaround to properly handle stream errors. See https://github.com/unjs/h3/issues/986
	setHeader(event, "Access-Control-Allow-Origin", "*");
	setHeader(event, "Content-Type", "text/event-stream");
	pipeline(stream as unknown as NodeJS.ReadableStream, event.node.res, (err) => { /* ignore */ });
	event._handled = true;
});