'use server';

import { cookies } from 'next/headers';
import { redirect } from 'next/navigation';

const API_URL = process.env.API_INTERNAL_URL || process.env.NEXT_PUBLIC_API_URL || 'http://localhost:3001';

export interface AuthUser {
  id: string;
  username: string;
  displayName: string | null;
  role: 'SUPER_ADMIN' | 'ADMIN' | 'USER';
  tenantId: string;
  mustChangePassword: boolean;
  isLocalUser?: boolean;
  hasAvatar?: boolean;
  accentColor?: string | null;
}

export interface LoginResult {
  success: boolean;
  error?: string;
  user?: AuthUser;
}

/**
 * Login action: POST credentials to API, forward session cookie.
 * In development, the API runs on a different port (3001) so we
 * must manually forward the Set-Cookie header from the API response.
 */
export async function login(formData: FormData): Promise<LoginResult> {
  const username = formData.get('username') as string;
  const password = formData.get('password') as string;
  const rememberMe = formData.get('rememberMe') === 'on';

  if (!username || !password) {
    return { success: false, error: 'invalidCredentials' };
  }

  try {
    const response = await fetch(`${API_URL}/auth/login`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ username, password }),
    });

    if (!response.ok) {
      return { success: false, error: 'invalidCredentials' };
    }

    const user: AuthUser = await response.json();

    // Forward the session cookie from the API response to the browser
    const setCookieHeader = response.headers.get('set-cookie');
    if (setCookieHeader) {
      const sessionMatch = setCookieHeader.match(/session=([^;]+)/);
      if (sessionMatch) {
        const cookieStore = await cookies();
        cookieStore.set('session', sessionMatch[1], {
          httpOnly: true,
          secure: process.env.NODE_ENV === 'production',
          sameSite: 'lax',
          ...(rememberMe
            ? { maxAge: 30 * 24 * 60 * 60 }
            : {}),
          path: '/',
        });
      }
    }

    return { success: true, user };
  } catch {
    return { success: false, error: 'networkError' };
  }
}

/**
 * Logout action: POST to API, clear local cookie, redirect to /login.
 */
export async function logout(): Promise<void> {
  const cookieStore = await cookies();
  const session = cookieStore.get('session')?.value;

  try {
    await fetch(`${API_URL}/auth/logout`, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        ...(session ? { Cookie: `session=${session}` } : {}),
      },
      credentials: 'include',
    });
  } catch {
    // Logout should still clear the cookie even if API call fails
  }

  cookieStore.delete('session');
  redirect('/login');
}

export type ChangePasswordResult =
  | { success: false; error: 'wrongCurrentPassword' | 'networkError' };

export async function changePasswordAction(
  currentPassword: string,
  newPassword: string,
): Promise<ChangePasswordResult> {
  const cookieStore = await cookies();
  const session = cookieStore.get('session')?.value;

  if (!session) {
    return { success: false, error: 'networkError' };
  }

  let newSessionToken: string | undefined;
  let newSessionMaxAge: number | undefined;

  try {
    const response = await fetch(`${API_URL}/auth/change-password`, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        Cookie: `session=${session}`,
      },
      body: JSON.stringify({ currentPassword, newPassword }),
    });

    if (!response.ok) {
      const data = await response.json().catch(() => null);
      if (data?.message === 'Current password is incorrect') {
        return { success: false, error: 'wrongCurrentPassword' };
      }
      return { success: false, error: 'networkError' };
    }

    const setCookieHeader = response.headers.get('set-cookie');
    if (setCookieHeader) {
      const sessionMatch = setCookieHeader.match(/session=([^;]+)/);
      const maxAgeMatch = setCookieHeader.match(/Max-Age=(\d+)/i);
      if (sessionMatch) {
        newSessionToken = sessionMatch[1];
        newSessionMaxAge = maxAgeMatch ? parseInt(maxAgeMatch[1], 10) : undefined;
      }
    }
  } catch (err) {
    console.error('[changePasswordAction] fetch threw:', err);
    return { success: false, error: 'networkError' };
  }

  if (newSessionToken) {
    cookieStore.set('session', newSessionToken, {
      httpOnly: true,
      secure: process.env.NODE_ENV === 'production',
      sameSite: 'lax',
      path: '/',
      ...(newSessionMaxAge ? { maxAge: newSessionMaxAge } : {}),
    });
  }

  redirect('/');
}

export interface UploadAvatarResult {
  success: boolean;
  error?: string;
}

/**
 * Upload a profile picture for the currently authenticated user.
 * Forwards the multipart file to POST /users/me/avatar using the session cookie.
 * Returns a discriminated result — does NOT redirect.
 */
export async function uploadAvatarAction(
  formData: FormData,
): Promise<UploadAvatarResult> {
  const cookieStore = await cookies();
  const session = cookieStore.get('session')?.value;

  if (!session) {
    return { success: false, error: 'notAuthenticated' };
  }

  try {
    const response = await fetch(`${API_URL}/users/me/avatar`, {
      method: 'POST',
      headers: {
        Cookie: `session=${session}`,
      },
      body: formData,
    });

    if (!response.ok) {
      const data = await response.json().catch(() => null);
      return { success: false, error: data?.message ?? 'uploadError' };
    }

    return { success: true };
  } catch (err) {
    console.error('[uploadAvatarAction] fetch threw:', err);
    return { success: false, error: 'networkError' };
  }
}

export async function deleteAvatarAction(): Promise<{ success: boolean; error?: string }> {
  const cookieStore = await cookies();
  const session = cookieStore.get('session')?.value;
  if (!session) return { success: false, error: 'notAuthenticated' };
  try {
    const response = await fetch(`${API_URL}/users/me/avatar`, {
      method: 'DELETE',
      headers: { Cookie: `session=${session}` },
    });
    if (!response.ok) return { success: false, error: 'deleteError' };
    return { success: true };
  } catch {
    return { success: false, error: 'networkError' };
  }
}

export async function updateAccentColorAction(
  color: string | null,
): Promise<{ success: boolean; error?: string }> {
  const cookieStore = await cookies();
  const session = cookieStore.get('session')?.value;
  if (!session) return { success: false, error: 'notAuthenticated' };
  try {
    const response = await fetch(`${API_URL}/users/me/accent-color`, {
      method: 'PATCH',
      headers: { 'Content-Type': 'application/json', Cookie: `session=${session}` },
      body: JSON.stringify({ color }),
    });
    if (!response.ok) return { success: false, error: 'saveError' };
    return { success: true };
  } catch {
    return { success: false, error: 'networkError' };
  }
}

export type SessionState =
  | { status: 'authenticated'; user: AuthUser }
  | { status: 'unauthenticated' }
  | { status: 'unavailable' };

/**
 * Klassifiziert die aktuelle Sitzung fuer den Header-Waechter
 * (quick-260917-gyd). Die Unterscheidung ist load-bearing: nur eine
 * nachweislich tote Sitzung (401/403 oder 200 ohne Benutzerobjekt — so
 * antwortet NestJS, wenn `AuthService.getMe` bei geloeschtem Benutzer
 * `null` liefert, z. B. nach Neuanlage der Datenbank) darf das Cookie
 * loeschen und abmelden. Ein API-Ausfall (5xx, Netzwerkfehler, Antwort
 * ohne gueltiges JSON) darf KEINE Abmelde-Schleife ausloesen und liefert
 * deshalb `unavailable`, ohne das Cookie anzufassen.
 *
 * `cookieStore.delete()` ist nur in Server Actions/Route Handlers
 * erlaubt — deshalb passiert die Loeschung hier und nicht im Header.
 */
export async function fetchSessionState(): Promise<SessionState> {
  const cookieStore = await cookies();
  const session = cookieStore.get('session')?.value;

  if (!session) {
    return { status: 'unauthenticated' };
  }

  try {
    const response = await fetch(`${API_URL}/auth/me`, {
      headers: {
        Cookie: `session=${session}`,
      },
      cache: 'no-store',
    });

    if (response.status === 401 || response.status === 403) {
      cookieStore.delete('session');
      return { status: 'unauthenticated' };
    }

    if (!response.ok) {
      return { status: 'unavailable' };
    }

    const body = (await response.text()).trim();
    if (body === '' || body === 'null') {
      cookieStore.delete('session');
      return { status: 'unauthenticated' };
    }

    let parsed: unknown;
    try {
      parsed = JSON.parse(body);
    } catch {
      return { status: 'unavailable' };
    }

    if (parsed && typeof parsed === 'object' && 'id' in parsed) {
      return { status: 'authenticated', user: parsed as AuthUser };
    }

    return { status: 'unavailable' };
  } catch {
    return { status: 'unavailable' };
  }
}

/**
 * Fetch the current authenticated user from the API.
 * Uses the session cookie for authentication.
 */
export async function fetchCurrentUser(): Promise<AuthUser | null> {
  const cookieStore = await cookies();
  const session = cookieStore.get('session')?.value;

  if (!session) {
    return null;
  }

  try {
    const response = await fetch(`${API_URL}/auth/me`, {
      headers: {
        Cookie: `session=${session}`,
      },
      credentials: 'include',
      cache: 'no-store',
    });

    if (!response.ok) {
      return null;
    }

    return await response.json();
  } catch {
    return null;
  }
}