import type { User, Session } from 'better-auth';
import type { Result } from '~~/types/result';
import { Ok, Err } from '~~/types/result';
import { createAuthClient } from 'better-auth/vue';

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

export interface AuthState {
    user: User | null;
    session: Session | null;
    isLoading: boolean;
}

export const useAuth = () => {
    const url = useRequestURL();
    const headers = useRequestHeaders();
    const client = createAuthClient({
        baseURL: url.origin,
        fetchOptions: {
            headers
        }
    });

    const state = useState<AuthState>('auth:state', () => ({
        user: null,
        session: null,
        isLoading: false,
    }));

    const isAuthenticated = computed(() => !!state.value.session);
    const userId = computed(() => state.value.user?.id ?? null);

    const fetchSession = async (): Promise<Result<{ session: Session | null; user: User | null }, AuthError>> => {
        state.value.isLoading = true;

        try {
            const { data } = await client.getSession();

            if (data) {
                state.value.session = data.session;
                state.value.user = data.user;
                return Ok({ session: data.session, user: data.user });
            }

            state.value.session = null;
            state.value.user = null;
            return Ok({ session: null, user: null });
        } catch (error) {
            console.error('Failed to fetch session:', error);
            return Err(AuthError.NetworkError);
        } finally {
            state.value.isLoading = false;
        }
    };

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

        try {
            const { data, error } = await client.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 });
            }

            state.value.user = 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 {
            state.value.isLoading = false;
        }
    };

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

        try {
            const { data, error } = await client.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 });
            }

            state.value.user = data.user;

            const triplit = useTriplitClient();
            if ('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 {
            state.value.isLoading = false;
        }
    };

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

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

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

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

            const triplit = useTriplitClient();
            if ('disconnect' in triplit) {
                triplit.disconnect();
            }

            clearNuxtData();

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

    return {
        client,
        user: computed(() => state.value.user),
        session: computed(() => state.value.session),
        isLoading: computed(() => state.value.isLoading),
        isAuthenticated,
        userId,
        fetchSession,
        signIn,
        signUp,
        signOut,
    };
};