veridian/app/composables/useAuth.ts

import type { BetterAuthClientOptions, InferSessionFromClient, InferUserFromClient, User } from 'better-auth/client';
import { createAuthClient } from 'better-auth/vue';
import { Err, Ok, type Result } from '~~/types/result';
import { assert } from '~~/utils/assert';

export enum AuthError {
    NotAuthenticated = 'NOT_AUTHENTICATED',
    SignInFailed = 'SIGN_IN_FAILED',
    SignUpFailed = 'SIGN_UP_FAILED',
    SignOutFailed = 'SIGN_OUT_FAILED',
    NetworkError = 'NETWORK_ERROR',
}

type sessionData = {
    session: InferSessionFromClient<BetterAuthClientOptions> | null;
    user: InferUserFromClient<BetterAuthClientOptions> | null;
};

export const useAuth = () => {
    const authClient = createAuthClient({});
    const session = useState<InferSessionFromClient<BetterAuthClientOptions> | null>('auth:session', () => null);
    const user = useState<InferUserFromClient<BetterAuthClientOptions> | null>('auth:user', () => null);
    const sessionFetching = import.meta.server ? ref(false) : useState('auth:sessionFetching', () => false);

    let sessionPromise: Promise<Result<sessionData, AuthError>> | null = null;

    const fetchSession = async (): Promise<Result<sessionData, AuthError>> => {
        if (sessionPromise) {
            console.log('already fetching session');
            return sessionPromise;
        }

        let finish: (value: Result<sessionData, AuthError>) => void;
        sessionFetching.value = true;
        sessionPromise = new Promise(async (resolve, reject) => {
            finish = resolve;
        });
        let data: {
            session: InferSessionFromClient<BetterAuthClientOptions>;
            user: InferUserFromClient<BetterAuthClientOptions>;
        } | null = null;

        try {
            if (import.meta.server) {
                data =
                    (
                        await useFetch<{
                            session: InferSessionFromClient<BetterAuthClientOptions>;
                            user: InferUserFromClient<BetterAuthClientOptions>;
                        }>('/api/auth/get-session')
                    ).data.value ?? null;
            } else {
                data = (await authClient.getSession()).data;
            }
        } catch (error) {
            console.error('Failed to fetch session:', error);
            sessionFetching.value = false;
            finish!(Err(AuthError.NetworkError));
            return sessionPromise;
        }

        session.value = data?.session || null;
        user.value = data?.user || null;
        sessionFetching.value = false;
        sessionFetching.value = false;
        finish!(Ok({ session: data?.session || null, user: data?.user || null }));
        return sessionPromise;
    };

    if (import.meta.client) {
        authClient.$store.listen('$sessionSignal', async (signal) => {
            if (!signal) return;
            await fetchSession();

            if (!session.value) return;

            const triplit = useTriplitClient();
            if ('updateOptions' in triplit) {
                triplit.updateOptions({
                    token: session.value.token,
                });
            }
        });
    }

    const signIn = async (
        email: string,
        password: string
    ): Promise<Result<{ user: User; token: string }, { error: AuthError, data?: any }>> => {
        sessionFetching.value = true;

        try {
            const { data, error } = await authClient.signIn.email({
                email,
                password,
            });

            if (error) {
                console.error('Sign in failed:', error);
                return Err({ error: AuthError.SignInFailed, data: error });
            }

            if (!data) {
                return Err({ error: AuthError.SignInFailed });
            }

            user.value = data.user;

            const triplit = useTriplitClient();
            if ('startSession' in triplit && data.token) {
                await triplit.startSession(data.token);
            }

            clearNuxtData();

            return Ok({ user: data.user, token: data.token });
        } catch (err) {
            console.error('Sign in error:', err);
            return Err({ error: AuthError.NetworkError });
        } finally {
            sessionFetching.value = false;
        }
    };

    const signUp = async (
        email: string,
        password: string,
        name: string
    ): Promise<Result<{ user: User; token: string }, { error: AuthError, data?: any }>> => {
        sessionFetching.value = true;

        try {
            const { data, error } = await authClient.signUp.email({
                email,
                password,
                name,
            });

            if (error) {
                console.error('Sign up failed:', error);
                return Err({ error: AuthError.SignUpFailed, data: error });
            }

            if (!data || !data.token) {
                return Err({ error: AuthError.SignUpFailed });
            }

            user.value = data.user;

            const triplit = useTriplitClient();
            assert('startSession' in triplit);
            await triplit.startSession(data.token);

            clearNuxtData();

            return Ok({ user: data.user, token: data.token });
        } catch (err) {
            console.error('Sign up error:', err);
            return Err({ error: AuthError.NetworkError });
        } finally {
            sessionFetching.value = false;
        }
    };

    const signOut = async (): Promise<Result<void, AuthError>> => {
        sessionFetching.value = true;

        try {
            const { error } = await authClient.signOut();

            if (error) {
                console.error('Sign out failed:', error);
                return Err(AuthError.SignOutFailed);
            }

            user.value = null;
            session.value = null;

            const triplit = useTriplitClient();
            assert('disconnect' in triplit);
            triplit.disconnect();

            clearNuxtData();

            return Ok(undefined);
        } catch (err) {
            console.error('Sign out error:', err);
            return Err(AuthError.NetworkError);
        } finally {
            sessionFetching.value = false;
        }
    };

    return {
        client: authClient,
        session,
        user,
        loggedIn: computed(() => !!session.value),
        signIn,
        signUp,
        signOut,
        fetchSession,
    };
};