/*
	SPDX-FileCopyrightText: © 2025 Hornwitser <code@hornwitser.no>
	SPDX-License-Identifier: AGPL-3.0-or-later
*/
import type { H3Event } from "h3";
import {
	nextSessionId,
	readSessions,
	readSubscriptions,
	readUsers,
	type ServerSession,
	type ServerUser,
	writeSessions,
	writeSubscriptions
} from "~/server/database";
import { broadcastEvent } from "../streams";
import type { ApiSession } from "~/shared/types/api";

async function removeSessionSubscription(sessionId: number) {
	const subscriptions = await readSubscriptions();
	const index = subscriptions.findIndex(subscription => subscription.sessionId === sessionId);
	if (index !== -1) {
		subscriptions.splice(index, 1);
		await writeSubscriptions(subscriptions);
	}
}

async function clearServerSessionInternal(event: H3Event, sessions: ServerSession[]) {
	const existingSessionCookie = await getSignedCookie(event, "session");
	if (existingSessionCookie) {
		const sessionId = parseInt(existingSessionCookie, 10);
		const session = sessions.find(session => session.id === sessionId);
		if (session) {
			session.finished = true;
			broadcastEvent({
				type: "session-expired",
				sessionId,
			});
			await removeSessionSubscription(sessionId);
			return true;
		}
	}
	return false;
}

export async function clearServerSession(event: H3Event) {
	const sessions = await readSessions();
	if (await clearServerSessionInternal(event, sessions)) {
		await writeSessions(sessions);
	}
	deleteCookie(event, "session");
}

export async function setServerSession(event: H3Event, account: ServerUser) {
	const sessions = await readSessions();
	const runtimeConfig = useRuntimeConfig(event);
	await clearServerSessionInternal(event, sessions);

	const now = Date.now();
	const newSession: ServerSession = {
		accountId: account.id,
		access: account.type,
		expiresAtMs: now + runtimeConfig.sessionExpiresTimeout * 1000,
		discardAtMs: now + runtimeConfig.sessionDiscardTimeout * 1000,
		finished: false,
		id: await nextSessionId(),
	};

	sessions.push(newSession);
	await writeSessions(sessions);
	await setSignedCookie(event, "session", String(newSession.id), runtimeConfig.sessionDiscardTimeout)
}

async function rotateSession(event: H3Event, sessions: ServerSession[], session: ServerSession) {
	const runtimeConfig = useRuntimeConfig(event);
	const users = await readUsers();
	const account = users.find(user => user.id === session.accountId);
	const now = Date.now();
	const newSession: ServerSession = {
		accountId: account?.id,
		access: account?.type ?? "anonymous",
		expiresAtMs: now + runtimeConfig.sessionExpiresTimeout * 1000,
		discardAtMs: now + runtimeConfig.sessionDiscardTimeout * 1000,
		finished: false,
		id: await nextSessionId(),
	};
	session.successor = newSession.id;
	sessions.push(newSession);
	await writeSessions(sessions);
	await setSignedCookie(event, "session", String(newSession.id), runtimeConfig.sessionDiscardTimeout)
	return newSession;
}

export async function getServerSession(event: H3Event, ignoreExpired: boolean) {
	const sessionCookie = await getSignedCookie(event, "session");
	if (sessionCookie) {
		const sessionId = parseInt(sessionCookie, 10);
		const sessions = await readSessions();
		const session = sessions.find(session => session.id === sessionId);
		if (session) {
			if (session.finished) {
				return undefined;
			}
			if (!ignoreExpired && session.successor !== undefined) {
				throw createError({
					statusCode: 403,
					statusMessage: "Forbidden",
					message: "Session has been taken by another agent.",
					data: { code: "SESSION_TAKEN" },
				});
			}
			const now = Date.now();
			if (now >= session?.discardAtMs) {
				return undefined;
			}
			if (!ignoreExpired && now >= session?.expiresAtMs) {
				return await rotateSession(event, sessions, session);
			}
		}
		return session;
	}
}

export async function requireServerSession(event: H3Event, message: string) {
	const session = await getServerSession(event, false);
	if (!session)
		throw createError({
			statusCode: 401,
			statusMessage: "Unauthorized",
			message,
		});
	return session;
}

export async function requireServerSessionWithUser(event: H3Event) {
	const message = "User session required";
	const session = await requireServerSession(event, message);
	const users = await readUsers();
	const account = users.find(user => user.id === session.accountId);
	if (session.accountId === undefined || !account)
		throw createError({
			statusCode: 401,
			statusMessage: "Uauthorized",
			message,
		});
	return { ...session, accountId: session.accountId };
}


export async function requireServerSessionWithAdmin(event: H3Event) {
	const message = "Admin session required";
	const session = await requireServerSession(event, message);
	const users = await readUsers();
	const account = users.find(user => user.id === session.accountId);
	if (session.access !== "admin" || account?.type !== "admin") {
		throw createError({
			statusCode: 403,
			statusMessage: "Forbidden",
			message,
		});
	}
	return { ...session, accountId: session.accountId };
}

export async function serverSessionToApi(event: H3Event, session: ServerSession): Promise<ApiSession> {
	const users = await readUsers();
	const account = users.find(user => user.id === session.accountId);
	const subscriptions = await readSubscriptions();
	const push = Boolean(
		subscriptions.find(sub => sub.type === "push" && sub.sessionId === session.id)
	);

	return {
		id: session.id,
		account,
		push,
	};
}