import { createCookieSessionStorage, redirect } from 'react-router';

const API_BASE_URL = process.env.API_BASE_URL || 'http://localhost:8080';

export interface AuthTokens {
    accessToken: string;
    refreshToken: string;
    userAccountId: string;
    username: string;
}

interface ApiResponse<T> {
    message: string;
    payload: T;
}

interface LoginPayload {
    userAccountId: string;
    username: string;
    refreshToken: string;
    accessToken: string;
}

type RegistrationPayload = LoginPayload;

interface UpdateUsernamePayload {
    userAccountId: string;
    username: string;
}

interface UpdateEmailPayload {
    userAccountId: string;
    email: string;
    emailConfirmed: boolean;
}

interface UpdateProfilePayload {
    userAccountId: string;
    firstName: string;
    lastName: string;
    dateOfBirth: string;
}

interface UpdatePasswordPayload {
    userAccountId: string;
    changedAt: string;
}

export interface UserAccountDetails {
    username: string;
    firstName: string;
    lastName: string;
    email: string;
    dateOfBirth: string;
}

const sessionStorage = createCookieSessionStorage({
    cookie: {
        name: '__session',
        httpOnly: true,
        maxAge: 60 * 60 * 24 * 21, // 21 days (matches refresh token)
        path: '/',
        sameSite: 'lax',
        secrets: [process.env.SESSION_SECRET || 'dev-secret-change-me'],
        secure: process.env.NODE_ENV === 'production',
    },
});

export const getSession = async (request: Request) => {
    return sessionStorage.getSession(request.headers.get('Cookie'));
};

export const commitSession = async (session: Awaited<ReturnType<typeof getSession>>) => {
    return sessionStorage.commitSession(session);
};

export const destroySession = async (session: Awaited<ReturnType<typeof getSession>>) => {
    return sessionStorage.destroySession(session);
};

export const requireAuth = async (request: Request): Promise<AuthTokens> => {
    const session = await getSession(request);
    const accessToken = session.get('accessToken');
    const refreshToken = session.get('refreshToken');

    if (!accessToken || !refreshToken) {
        throw redirect('/login');
    }

    return {
        accessToken,
        refreshToken,
        userAccountId: session.get('userAccountId'),
        username: session.get('username'),
    };
};

export const getOptionalAuth = async (request: Request): Promise<AuthTokens | null> => {
    const session = await getSession(request);
    const accessToken = session.get('accessToken');

    if (!accessToken) return null;

    return {
        accessToken,
        refreshToken: session.get('refreshToken'),
        userAccountId: session.get('userAccountId'),
        username: session.get('username'),
    };
};

export const login = async (username: string, password: string) => {
    const res = await fetch(`${API_BASE_URL}/api/auth/login`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ username, password }),
    });

    if (!res.ok) {
        const text = await res.text();
        throw new Error(text || `Login failed (${res.status})`);
    }

    const data: ApiResponse<LoginPayload> = await res.json();
    return data.payload;
};

export const register = async (body: {
    username: string;
    firstName: string;
    lastName: string;
    email: string;
    dateOfBirth: string;
    password: string;
}) => {
    const res = await fetch(`${API_BASE_URL}/api/auth/register`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify(body),
    });

    if (!res.ok) {
        const text = await res.text();
        throw new Error(text || `Registration failed (${res.status})`);
    }

    const data: ApiResponse<RegistrationPayload> = await res.json();
    return data.payload;
};

export const refreshTokens = async (refreshToken: string) => {
    const res = await fetch(`${API_BASE_URL}/api/auth/refresh`, {
        method: 'POST',
        headers: { 'X-Refresh-Token': refreshToken },
    });

    if (!res.ok) {
        throw new Error('Token refresh failed');
    }

    const data: ApiResponse<LoginPayload> = await res.json();
    return data.payload;
};

export const getUserAccount = async (userAccountId: string): Promise<UserAccountDetails> => {
    const res = await fetch(`${API_BASE_URL}/api/user/${userAccountId}`);

    if (!res.ok) {
        const text = await res.text();
        throw new Error(text || `Failed to load account details (${res.status})`);
    }

    return res.json();
};

export const confirmEmail = async (token: string, accessToken: string) => {
    const res = await fetch(`${API_BASE_URL}/api/auth/confirm?token=${encodeURIComponent(token)}`, {
        method: 'POST',
        headers: { Authorization: `Bearer ${accessToken}` },
    });

    if (!res.ok) {
        const text = await res.text();
        throw new Error(text || `Confirmation failed (${res.status})`);
    }

    const data: ApiResponse<{ userAccountId: string; confirmedDate: string }> = await res.json();
    return data.payload;
};

const authorizedRequest = async <T>(
    path: string,
    accessToken: string,
    init: { method: string; body?: unknown },
): Promise<T> => {
    const res = await fetch(`${API_BASE_URL}${path}`, {
        method: init.method,
        headers: {
            Authorization: `Bearer ${accessToken}`,
            ...(init.body ? { 'Content-Type': 'application/json' } : {}),
        },
        body: init.body ? JSON.stringify(init.body) : undefined,
    });

    if (!res.ok) {
        const text = await res.text();
        throw new Error(text || `Request failed (${res.status})`);
    }

    const data: ApiResponse<T> = await res.json();
    return data.payload;
};

export const updateUsername = async (accessToken: string, newUsername: string) => {
    return authorizedRequest<UpdateUsernamePayload>('/api/auth/username', accessToken, {
        method: 'PATCH',
        body: { newUsername },
    });
};

export const updateEmail = async (accessToken: string, newEmail: string) => {
    return authorizedRequest<UpdateEmailPayload>('/api/auth/email', accessToken, {
        method: 'PATCH',
        body: { newEmail },
    });
};

export const updateProfile = async (
    accessToken: string,
    firstName: string,
    lastName: string,
    dateOfBirth: string,
) => {
    return authorizedRequest<UpdateProfilePayload>('/api/auth/profile', accessToken, {
        method: 'PATCH',
        body: { firstName, lastName, dateOfBirth },
    });
};

export const updatePassword = async (
    accessToken: string,
    currentPassword: string,
    newPassword: string,
) => {
    return authorizedRequest<UpdatePasswordPayload>('/api/auth/password', accessToken, {
        method: 'PATCH',
        body: { currentPassword, newPassword },
    });
};

export const deleteAccount = async (accessToken: string) => {
    await authorizedRequest<null>('/api/auth/account', accessToken, { method: 'DELETE' });
};

export const createAuthSession = async (payload: LoginPayload, redirectTo: string) => {
    const session = await sessionStorage.getSession();
    session.set('accessToken', payload.accessToken);
    session.set('refreshToken', payload.refreshToken);
    session.set('userAccountId', payload.userAccountId);
    session.set('username', payload.username);

    return redirect(redirectTo, {
        headers: { 'Set-Cookie': await commitSession(session) },
    });
};