/**
 * Spring Auth Client
 *
 * This client integrates with the Spring Security + JWT backend.
 * - Uses localStorage for JWT storage (sent via Authorization header)
 * - JWT validation handled server-side
 * - No email confirmation flow (auto-confirmed on registration)
 */

import apiClient from '@app/services/apiClient';
import { AxiosError } from 'axios';
import { BASE_PATH } from '@app/constants/app';
import { type OAuthProvider } from '@app/auth/oauthTypes';
import { resetOAuthState } from '@app/auth/oauthStorage';
import { clearPlatformAuthAfterSignOut } from '@app/extensions/authSessionCleanup';
import {
  getPlatformSessionUser,
  isDesktopSaaSAuthMode,
  refreshPlatformSession,
  savePlatformToken,
} from '@app/extensions/platformSessionBridge';
import { startOAuthNavigation } from '@app/extensions/oauthNavigation';

function getHttpStatus(error: unknown): number | undefined {
  if (error instanceof AxiosError) {
    return error.response?.status;
  }

  if (error && typeof error === 'object' && 'response' in error) {
    const response = (error as { response?: { status?: unknown } }).response;
    if (response && typeof response.status === 'number') {
      return response.status;
    }
  }

  return undefined;
}

// Helper to extract error message from axios error
function getErrorMessage(error: unknown, fallback: string): string {
  if (error instanceof AxiosError) {
    return error.response?.data?.error || error.response?.data?.message || error.message || fallback;
  }
  return error instanceof Error ? error.message : fallback;
}

const OAUTH_REDIRECT_COOKIE = 'stirling_redirect_path';
const OAUTH_REDIRECT_COOKIE_MAX_AGE = 60 * 5; // 5 minutes
const DEFAULT_REDIRECT_PATH = `${BASE_PATH || ''}/auth/callback`;

function normalizeRedirectPath(target?: string): string {
  if (!target || typeof target !== 'string') {
    return DEFAULT_REDIRECT_PATH;
  }

  try {
    const parsed = new URL(target, window.location.origin);
    const path = parsed.pathname || '/';
    const query = parsed.search || '';
    return `${path}${query}`;
  } catch {
    const trimmed = target.trim();
    if (!trimmed) {
      return DEFAULT_REDIRECT_PATH;
    }
    return trimmed.startsWith('/') ? trimmed : `/${trimmed}`;
  }
}

function persistRedirectPath(path: string): void {
  try {
    document.cookie = `${OAUTH_REDIRECT_COOKIE}=${encodeURIComponent(path)}; path=/; max-age=${OAUTH_REDIRECT_COOKIE_MAX_AGE}; SameSite=Lax`;
  } catch (_error) {
    // console.warn('[SpringAuth] Failed to persist OAuth redirect path', _error);
  }
}

// Auth types
export interface User {
  id: string;
  email: string;
  username: string;
  role: string;
  enabled?: boolean;
  is_anonymous?: boolean;
  isFirstLogin?: boolean;
  authenticationType?: string;
  app_metadata?: Record<string, any>;
}

export interface Session {
  user: User;
  access_token: string;
  expires_in: number;
  expires_at?: number;
}

export interface AuthError {
  message: string;
  status?: number;
  code?: string;
  mfaRequired?: boolean;
}

export interface AuthResponse {
  user: User | null;
  session: Session | null;
  error: AuthError | null;
}

export type AuthChangeEvent =
  | 'SIGNED_IN'
  | 'SIGNED_OUT'
  | 'TOKEN_REFRESHED'
  | 'USER_UPDATED';

type AuthChangeCallback = (event: AuthChangeEvent, session: Session | null) => void;

class SpringAuthClient {
  private listeners: AuthChangeCallback[] = [];
  private sessionCheckInterval: NodeJS.Timeout | null = null;

  // Adaptive intervals - calculated based on actual JWT token lifetime
  // Defaults for initial startup (will be recalculated on first token)
  private sessionCheckIntervalMs = 10000; // 10 seconds default
  private tokenRefreshThresholdMs = 30000; // 30 seconds default

  private readonly DESKTOP_SAAS_REFRESH_EARLY_SECONDS = 60;

  constructor() {
    // Start periodic session validation
    this.startSessionMonitoring();
  }

  /**
   * Calculate optimal check interval and refresh threshold based on token lifetime.
   * - Check interval: token lifetime / 6 (check 6 times during token life)
   * - Refresh threshold: token lifetime / 4 (refresh when 25% remaining)
   * - Applies min/max bounds for sanity
   */
  private calculateAdaptiveIntervals(token: string): void {
    try {
      const payload = this.decodeJwtPayload(token);
      if (!payload) {
        console.warn('[SpringAuth] Cannot decode token for adaptive intervals, using defaults');
        return;
      }

      const expSeconds = typeof payload?.exp === 'number' ? payload.exp : 0;
      const iatSeconds = typeof payload?.iat === 'number' ? payload.iat : 0;

      if (expSeconds <= 0 || iatSeconds <= 0) {
        console.warn('[SpringAuth] Token missing exp/iat claims, using default intervals');
        return;
      }

      const tokenLifetimeMs = (expSeconds - iatSeconds) * 1000;

      // Check interval: check 6 times during token lifetime
      // Min: 5 seconds (for very short tokens)
      // Max: 60 seconds (don't check too infrequently)
      this.sessionCheckIntervalMs = Math.max(5000, Math.min(60000, tokenLifetimeMs / 6));

      // Refresh threshold: refresh when 25% of lifetime remaining
      // Min: 30 seconds (give buffer for refresh to complete)
      // Max: 5 minutes (don't wait too long for long-lived tokens)
      this.tokenRefreshThresholdMs = Math.max(30000, Math.min(300000, tokenLifetimeMs / 4));

      console.log('[SpringAuth] 📊 Adaptive intervals calculated:', {
        tokenLifetime: Math.floor(tokenLifetimeMs / 1000) + 's',
        checkInterval: Math.floor(this.sessionCheckIntervalMs / 1000) + 's',
        refreshThreshold: Math.floor(this.tokenRefreshThresholdMs / 1000) + 's',
      });

      // Restart monitoring with new interval
      this.restartSessionMonitoring();
    } catch (error) {
      console.warn('[SpringAuth] Failed to calculate adaptive intervals:', error);
    }
  }

  private decodeJwtPayload(token: string): Record<string, unknown> | null {
    const parts = token.split('.');
    if (parts.length < 2) {
      return null;
    }

    const base64Url = parts[1];
    const base64 = base64Url
      .replace(/-/g, '+')
      .replace(/_/g, '/')
      .padEnd(Math.ceil(base64Url.length / 4) * 4, '=');

    return JSON.parse(atob(base64));
  }

  private getTokenExpiry(token: string): { expiresIn: number; expiresAt: number } {
    try {
      const payload = this.decodeJwtPayload(token);
      if (!payload) {
        throw new Error('Token payload missing');
      }

      const expSeconds = typeof payload?.exp === 'number' ? payload.exp : 0;
      const expiresAt = expSeconds > 0 ? expSeconds * 1000 : Date.now() + 3600 * 1000;
      const expiresIn = Math.max(0, Math.floor((expiresAt - Date.now()) / 1000));

      return { expiresIn, expiresAt };
    } catch {
      // Fallback for non-JWT or malformed tokens.
      const expiresAt = Date.now() + 3600 * 1000;
      return { expiresIn: 3600, expiresAt };
    }
  }

  /**
   * Helper to get CSRF token from cookie
   */
  private getCsrfToken(): string | null {
    const cookies = document.cookie.split(';');
    for (const cookie of cookies) {
      const [name, value] = cookie.trim().split('=');
      if (name === 'XSRF-TOKEN') {
        return decodeURIComponent(value);
      }
    }
    return null;
  }

  /**
   * Get current session
   * JWT is stored in localStorage and sent via Authorization header
   */
  async getSession(): Promise<{ data: { session: Session | null }; error: AuthError | null }> {
    try {
      // Get JWT from localStorage
      let token = localStorage.getItem('stirling_jwt');

      if (!token) {
        // console.debug('[SpringAuth] getSession: No JWT in localStorage');
        return { data: { session: null }, error: null };
      }

      if (await isDesktopSaaSAuthMode()) {
        let tokenExpiry = this.getTokenExpiry(token);
        if (tokenExpiry.expiresIn <= this.DESKTOP_SAAS_REFRESH_EARLY_SECONDS) {
          const refreshed = await refreshPlatformSession();
          if (!refreshed) {
            localStorage.removeItem('stirling_jwt');
            return { data: { session: null }, error: null };
          }

          const refreshedToken = localStorage.getItem('stirling_jwt');
          if (!refreshedToken) {
            localStorage.removeItem('stirling_jwt');
            return { data: { session: null }, error: null };
          }

          token = refreshedToken;
          tokenExpiry = this.getTokenExpiry(token);
        }

        if (tokenExpiry.expiresIn <= 0) {
          localStorage.removeItem('stirling_jwt');
          return { data: { session: null }, error: null };
        }

        const platformUser = await getPlatformSessionUser();

        const session: Session = {
          user: {
            id: platformUser?.email || platformUser?.username || 'desktop-saas-user',
            email: platformUser?.email || '',
            username: platformUser?.username || platformUser?.email || 'User',
            role: 'USER',
          },
          access_token: token,
          expires_in: tokenExpiry.expiresIn,
          expires_at: tokenExpiry.expiresAt,
        };

        return { data: { session }, error: null };
      }

      // Verify with backend
      // Note: We pass the token explicitly here, overriding the interceptor's default
      // console.debug('[SpringAuth] getSession: Verifying JWT with /api/v1/auth/me');
      const response = await apiClient.get('/api/v1/auth/me', {
        headers: {
          'Authorization': `Bearer ${token}`,
        },
        suppressErrorToast: true, // Suppress global error handler (we handle errors locally)
        // Session bootstrap should not trigger global 401 refresh/redirect loops.
        skipAuthRedirect: true,
      });

      // console.debug('[SpringAuth] /me response status:', response.status);
      const data = response.data;
      // console.debug('[SpringAuth] /me response data:', data);

      // Create session object
      const tokenExpiry = this.getTokenExpiry(token);
      const session: Session = {
        user: data.user,
        access_token: token,
        expires_in: tokenExpiry.expiresIn,
        expires_at: tokenExpiry.expiresAt,
      };

      // console.debug('[SpringAuth] getSession: Session retrieved successfully');
      return { data: { session }, error: null };
    } catch (error: unknown) {
      console.error('[SpringAuth] getSession error:', error);

      // If 401/403, token is invalid - try explicit refresh
      const status = getHttpStatus(error);
      if (status === 401 || status === 403) {
        // A 401 during startup can be a race with a concurrent refresh. Try one
        // explicit refresh before treating the session as invalid.
        const refreshResult = await this.refreshSession();
        if (!refreshResult.error && refreshResult.data.session) {
          return refreshResult;
        }
        localStorage.removeItem('stirling_jwt');
        console.debug('[SpringAuth] getSession: Not authenticated');
        return { data: { session: null }, error: null };
      }

      // Don't clear token for other errors (e.g., backend not ready, network issues)
      // The token is still valid, just can't verify it right now
      return {
        data: { session: null },
        error: { message: getErrorMessage(error, 'Unknown error') },
      };
    }
  }

  /**
   * Sign in with email and password
   */
  async signInWithPassword(credentials: {
    email: string;
    password: string;
    mfaCode?: string;
  }): Promise<AuthResponse> {
    try {
      const response = await apiClient.post('/api/v1/auth/login', {
        username: credentials.email,
        password: credentials.password,
        mfaCode: credentials.mfaCode,
      }, {
        withCredentials: true, // Include cookies for CSRF
      });

      const data = response.data;
      const token = data.session.access_token;

      // Store JWT in localStorage
      localStorage.setItem('stirling_jwt', token);
      // console.log('[SpringAuth] JWT stored in localStorage');

      // Sync token to platform-specific storage (Tauri store for desktop)
      await savePlatformToken(token);

      // Calculate adaptive monitoring intervals based on token lifetime
      this.calculateAdaptiveIntervals(token);

      // Dispatch custom event for other components to react to JWT availability
      window.dispatchEvent(new CustomEvent('jwt-available'));

      const session: Session = {
        user: data.user,
        access_token: token,
        expires_in: data.session.expires_in,
        expires_at: Date.now() + data.session.expires_in * 1000,
      };

      // Notify listeners
      this.notifyListeners('SIGNED_IN', session);

      return { user: data.user, session, error: null };
    } catch (error: unknown) {
      console.error('[SpringAuth] signInWithPassword error:', error);
      if (error instanceof AxiosError) {
        const errorCode = error.response?.data?.error as string | undefined;
        const errorMessage =
          error.response?.data?.message ||
          error.response?.data?.error ||
          error.message ||
          'Login failed';
        return {
          user: null,
          session: null,
          error: {
            message: errorMessage,
            status: error.response?.status,
            code: errorCode,
            mfaRequired: errorCode === 'mfa_required',
          },
        };
      }
      return {
        user: null,
        session: null,
        error: { message: getErrorMessage(error, 'Login failed') },
      };
    }
  }

  /**
   * Sign up new user
   */
  async signUp(credentials: {
    email: string;
    password: string;
    options?: { data?: { full_name?: string }; emailRedirectTo?: string };
  }): Promise<AuthResponse> {
    try {
      const response = await apiClient.post('/api/v1/user/register', {
        username: credentials.email,
        password: credentials.password,
      }, {
        withCredentials: true,
      });

      const data = response.data;

      // Note: Spring backend auto-confirms users (no email verification)
      // Return user but no session (user needs to login)
      return { user: data.user, session: null, error: null };
    } catch (error: unknown) {
      console.error('[SpringAuth] signUp error:', error);
      return {
        user: null,
        session: null,
        error: { message: getErrorMessage(error, 'Registration failed') },
      };
    }
  }

  /**
   * Sign in with OAuth/SAML provider (GitHub, Google, Authentik, etc.)
   * This redirects to the Spring OAuth2/SAML2 authorization endpoint
   *
   * @param params.provider - Full auth path from backend (e.g., '/oauth2/authorization/google', '/saml2/authenticate/stirling')
   *                          The backend provides the complete path including the auth type and provider ID
   */
  async signInWithOAuth(params: {
    provider: OAuthProvider;
    options?: { redirectTo?: string; queryParams?: Record<string, any> };
  }): Promise<{ error: AuthError | null }> {
    try {
      const redirectPath = normalizeRedirectPath(params.options?.redirectTo);
      persistRedirectPath(redirectPath);

      // Use the full path provided by the backend
      // This supports both OAuth2 (/oauth2/authorization/...) and SAML2 (/saml2/authenticate/...)
      const redirectUrl = params.provider;
      const handled = await startOAuthNavigation(redirectUrl);
      if (handled) {
        return { error: null };
      }
      // console.log('[SpringAuth] Redirecting to SSO:', redirectUrl);
      // Use window.location.assign for full page navigation
      window.location.assign(redirectUrl);
      return { error: null };
    } catch (error) {
      return {
        error: { message: error instanceof Error ? error.message : 'SSO redirect failed' },
      };
    }
  }

  /**
   * Sign out user (invalidate session)
   */
  async signOut(): Promise<{ error: AuthError | null }> {
    try {
      if (typeof window !== 'undefined') {
        window.sessionStorage.setItem('stirling_sso_auto_login_logged_out', '1');
      }
      const response = await apiClient.post('/api/v1/auth/logout', null, {
        headers: {
          'X-XSRF-TOKEN': this.getCsrfToken() || '',
        },
        withCredentials: true,
      });

      if (response.status === 200) {
        // console.debug('[SpringAuth] signOut: Success');
      }

      // Clean up local storage
      localStorage.removeItem('stirling_jwt');
      try {
        Object.keys(localStorage)
          .filter((key) => key.startsWith('sb-') || key.includes('supabase'))
          .forEach((key) => localStorage.removeItem(key));

        // Clear any cached OAuth redirect/session state
        resetOAuthState();
      } catch (err) {
        console.warn('[SpringAuth] Failed to clear Supabase/local auth tokens', err);
      }

      // Clear cookies that might hold refresh/session tokens
      try {
        document.cookie.split(';').forEach(cookie => {
          const eqPos = cookie.indexOf('=');
          const name = eqPos > -1 ? cookie.substr(0, eqPos).trim() : cookie.trim();
          if (name) {
            document.cookie = `${name}=;expires=Thu, 01 Jan 1970 00:00:00 GMT;path=/;`;
          }
        });
      } catch (err) {
        console.warn('[SpringAuth] Failed to clear cookies on sign out', err);
      }

      try {
        await clearPlatformAuthAfterSignOut();
      } catch (cleanupError) {
        console.warn('[SpringAuth] Failed to run platform auth cleanup', cleanupError);
      }

      // Notify listeners
      this.notifyListeners('SIGNED_OUT', null);

      return { error: null };
    } catch (error: unknown) {
      console.error('[SpringAuth] signOut error:', error);
      // Still remove token even if backend call fails
      localStorage.removeItem('stirling_jwt');
      try {
        await clearPlatformAuthAfterSignOut();
      } catch (cleanupError) {
        console.warn('[SpringAuth] Failed to run platform auth cleanup after error', cleanupError);
      }
      return {
        error: { message: getErrorMessage(error, 'Logout failed') },
      };
    }
  }

  /**
   * Refresh JWT token
   */
  async refreshSession(): Promise<{ data: { session: Session | null }; error: AuthError | null }> {
    try {
      if (await isDesktopSaaSAuthMode()) {
        const refreshed = await refreshPlatformSession();
        if (!refreshed) {
          localStorage.removeItem('stirling_jwt');
          return {
            data: { session: null },
            error: { message: 'Token refresh failed - please log in again' },
          };
        }

        const { data, error } = await this.getSession();
        if (error || !data.session) {
          return {
            data: { session: null },
            error: error || { message: 'Token refresh failed - please log in again' },
          };
        }

        // Calculate adaptive intervals for desktop SaaS mode
        const token = localStorage.getItem('stirling_jwt');
        if (token) {
          this.calculateAdaptiveIntervals(token);
        }

        this.notifyListeners('TOKEN_REFRESHED', data.session);
        return { data, error: null };
      }

      const response = await apiClient.post('/api/v1/auth/refresh', null, {
        headers: {
          'X-XSRF-TOKEN': this.getCsrfToken() || '',
        },
        withCredentials: true,
        suppressErrorToast: true, // Suppress global error handler (we handle errors locally)
      });

      const data = response.data;
      const token = data.session.access_token;

      // Update local storage with new token
      localStorage.setItem('stirling_jwt', token);

      // Sync token to platform-specific storage (Tauri store for desktop)
      await savePlatformToken(token);

      // Calculate adaptive monitoring intervals based on token lifetime
      this.calculateAdaptiveIntervals(token);

      const session: Session = {
        user: data.user,
        access_token: token,
        expires_in: data.session.expires_in,
        expires_at: Date.now() + data.session.expires_in * 1000,
      };

      // Notify listeners
      this.notifyListeners('TOKEN_REFRESHED', session);

      console.debug('[SpringAuth] Token refreshed successfully');

      return { data: { session }, error: null };
    } catch (error: unknown) {
      console.error('[SpringAuth] refreshSession error:', error);
      localStorage.removeItem('stirling_jwt');

      // Handle different error statuses
      const status = getHttpStatus(error);
      if (status === 401 || status === 403) {
        return { data: { session: null }, error: { message: 'Token refresh failed - please log in again' } };
      }

      return {
        data: { session: null },
        error: { message: getErrorMessage(error, 'Token refresh failed') },
      };
    }
  }

  /**
   * Listen to auth state changes
   */
  onAuthStateChange(callback: AuthChangeCallback): { data: { subscription: { unsubscribe: () => void } } } {
    this.listeners.push(callback);

    return {
      data: {
        subscription: {
          unsubscribe: () => {
            this.listeners = this.listeners.filter((cb) => cb !== callback);
          },
        },
      },
    };
  }

  // Private helper methods

  private notifyListeners(event: AuthChangeEvent, session: Session | null) {
    // Use setTimeout to avoid calling callbacks synchronously
    setTimeout(() => {
      this.listeners.forEach((callback) => {
        try {
          callback(event, session);
        } catch (error) {
          console.error('[SpringAuth] Error in auth state change listener:', error);
        }
      });
    }, 0);
  }

  private startSessionMonitoring() {
    // Periodically check session validity
    // Interval is adaptive based on token lifetime (calculated when token is received)
    this.sessionCheckInterval = setInterval(async () => {
      try {
        // Try to get current session
        const { data } = await this.getSession();

        // If we have a session, proactively refresh if needed
        if (data.session) {
          const timeUntilExpiry = (data.session.expires_at || 0) - Date.now();

          // Refresh if token expires soon (threshold is adaptive)
          if (timeUntilExpiry > 0 && timeUntilExpiry < this.tokenRefreshThresholdMs) {
            console.log('[SpringAuth] 🔄 Proactively refreshing token (expires in ' + Math.floor(timeUntilExpiry / 1000) + 's)');
            await this.refreshSession();
          }
        }
      } catch (error) {
        console.error('[SpringAuth] Session monitoring error:', error);
      }
    }, this.sessionCheckIntervalMs);
  }

  private restartSessionMonitoring() {
    // Stop existing interval
    if (this.sessionCheckInterval) {
      clearInterval(this.sessionCheckInterval);
      this.sessionCheckInterval = null;
    }
    // Start with new interval
    this.startSessionMonitoring();
  }

  public destroy() {
    if (this.sessionCheckInterval) {
      clearInterval(this.sessionCheckInterval);
    }
  }
}

export const springAuth = new SpringAuthClient();

/**
 * Get current user
 */
export const getCurrentUser = async () => {
  const { data } = await springAuth.getSession();
  return data.session?.user || null;
};

/**
 * Check if user is anonymous
 */
export const isUserAnonymous = (user: User | null) => {
  return user?.is_anonymous === true;
};

/**
 * Create an anonymous user object for use when login is disabled
 * This provides a consistent User interface throughout the app
 */
export const createAnonymousUser = (): User => {
  return {
    id: 'anonymous',
    email: 'anonymous@local',
    username: 'Anonymous User',
    role: 'USER',
    enabled: true,
    is_anonymous: true,
    app_metadata: {
      provider: 'anonymous',
    },
  };
};

/**
 * Create an anonymous session for use when login is disabled
 */
export const createAnonymousSession = (): Session => {
  return {
    user: createAnonymousUser(),
    access_token: '',
    expires_in: Number.MAX_SAFE_INTEGER,
    expires_at: Number.MAX_SAFE_INTEGER,
  };
};

// Export auth client as default for convenience
export default springAuth;