import { api, setOnUnauthorizedCallback } from '@/services/api';
import type { ApiError, User } from '@/types';
import React, { createContext, useCallback, useContext, useEffect, useState, type ReactNode } from 'react';

interface AuthState {
  user: User | null;
  isLoading: boolean;
  isInitializing: boolean;
  isAuthenticated: boolean;
  error: ApiError | null;
}

type CheckEmailResult = { exists: boolean; name?: string | null };
type OtpResult = { success: boolean; skipOtp: boolean };
type UserProfileUpdate = Partial<User> & {
  firstName?: string | null;
  lastName?: string | null;
  phone?: string | null;
  email?: string;
};

interface AuthContextType extends AuthState {
  checkEmail: (email: string) => Promise<CheckEmailResult>;
  requestOtp: (email: string) => Promise<OtpResult>;
  verifyOtp: (email: string, code: string) => Promise<boolean>;
  logout: () => Promise<void>;
  clearError: () => void;
  refreshAuth: () => Promise<void>;
  updateUser: (updates: UserProfileUpdate) => void;
}

const AuthContext = createContext<AuthContextType | null>(null);

export function AuthProvider({ children }: { children: ReactNode }) {
  const [state, setState] = useState<AuthState>({
    user: null,
    isLoading: false,
    isInitializing: true,
    isAuthenticated: false,
    error: null,
  });

  const checkAuth = useCallback(async () => {
    try {
      console.log(`[AuthContext] checkAuth: Checking token...`);
      const token = await api.getToken();
      console.log(`[AuthContext] checkAuth: Token exists=${!!token}, length=${token?.length || 0}`);
      const isAuth = await api.isAuthenticated();
      console.log(`[AuthContext] checkAuth: isAuth=${isAuth}`);

      if (isAuth) {
        console.log(`[AuthContext] checkAuth: Getting stored user...`);
        const user = await api.getStoredUser();
        console.log(`[AuthContext] checkAuth: User found=${!!user}`);

        setState({
          user,
          isLoading: false,
          isInitializing: false,
          isAuthenticated: !!user,
          error: null,
        });
      } else {
        console.log(`[AuthContext] checkAuth: No token, setting unauth`);
        setState({
          user: null,
          isLoading: false,
          isInitializing: false,
          isAuthenticated: false,
          error: null,
        });
      }
    } catch (error) {
      console.error(`[AuthContext] checkAuth Error:`, error);
      setState({
        user: null,
        isLoading: false,
        isInitializing: false,
        isAuthenticated: false,
        error: { message: 'Failed to check authentication' },
      });
    } finally {
      console.log(`[AuthContext] checkAuth: Finished`);
    }
  }, []);

  // Auto-logout when WellNuo API returns 401 (token expired)
  // Token now expires after 365 days, so this should rarely happen
  useEffect(() => {
    setOnUnauthorizedCallback(() => {
      console.log('[AuthContext] Received 401 - session expired, logging out...');
      api.logout().then(() => {
        setState({
          user: null,
          isLoading: false,
          isInitializing: false,
          isAuthenticated: false,
          error: { message: 'Session expired. Please login again.' },
        });
      });
    });
  }, []);

  // Check authentication on mount
  useEffect(() => {
    console.log('[AuthContext] checkAuth starting...');
    checkAuth();
  }, [checkAuth]);

  const checkEmail = useCallback(async (email: string): Promise<CheckEmailResult> => {
    setState((prev) => ({ ...prev, isLoading: true, error: null }));

    try {
      // Dev email - check via API like any other user
      // (no more bypass - dev user needs to go through OTP flow)

      // Check email via API
      const response = await api.checkEmail(email);

      if (response.ok && response.data) {
        setState((prev) => ({ ...prev, isLoading: false }));
        return { exists: response.data.exists, name: response.data.name };
      }

      // API failed - assume new user
      setState((prev) => ({ ...prev, isLoading: false }));
      return { exists: false };
    } catch (error) {
      setState((prev) => ({
        ...prev,
        isLoading: false,
        error: { message: 'Network error. Please check your connection.' },
      }));
      return { exists: false };
    }
  }, []);

  const requestOtp = useCallback(async (email: string): Promise<OtpResult> => {
    setState((prev) => ({ ...prev, isLoading: true, error: null }));

    try {
      // Dev email also goes through normal OTP flow now
      // (no more bypass - need real OTP for WellNuo token)

      // Send OTP via Brevo API
      const response = await api.requestOTP(email);

      if (response.ok) {
        setState((prev) => ({ ...prev, isLoading: false }));
        return { success: true, skipOtp: false };
      }

      // API failed
      setState((prev) => ({
        ...prev,
        isLoading: false,
        error: { message: 'Failed to send verification code. Please try again.' },
      }));
      return { success: false, skipOtp: false };
    } catch (error) {
      setState((prev) => ({
        ...prev,
        isLoading: false,
        error: { message: 'Network error. Please check your connection.' },
      }));
      return { success: false, skipOtp: false };
    }
  }, []);

  const verifyOtp = useCallback(async (email: string, code: string): Promise<boolean> => {
    setState((prev) => ({ ...prev, isLoading: true, error: null }));

    try {
      // Verify OTP via WellNuo API (for all users including dev)
      const verifyResponse = await api.verifyOTP(email, code);

      if (verifyResponse.ok && verifyResponse.data) {
        const user: User = {
          user_id: verifyResponse.data.user.id,
          email: email,
          firstName: verifyResponse.data.user.first_name || null,
          lastName: verifyResponse.data.user.last_name || null,
          max_role: 'USER',
          privileges: '',
        };

        setState({
          user,
          isLoading: false,
          isAuthenticated: true,
          error: null,
        });

        return true;
      }

      // Wrong OTP code
      setState((prev) => ({
        ...prev,
        isLoading: false,
        error: { message: 'Invalid verification code. Please try again.' },
      }));
      return false;
    } catch (error) {
      setState((prev) => ({
        ...prev,
        isLoading: false,
        error: { message: error instanceof Error ? error.message : 'Verification failed' },
      }));
      return false;
    }
  }, []);

  const refreshAuth = useCallback(async () => {
    await checkAuth();
  }, [checkAuth]);

  const updateUser = useCallback((updates: UserProfileUpdate) => {
    setState((prev) => {
      if (!prev.user) return prev;
      return { ...prev, user: { ...prev.user, ...updates } };
    });
  }, []);

  const logout = useCallback(async () => {
    setState((prev) => ({ ...prev, isLoading: true }));

    try {
      await api.logout();
    } finally {
      setState({
        user: null,
        isLoading: false,
        isAuthenticated: false,
        error: null,
      });
    }
  }, []);

  const clearError = useCallback(() => {
    setState((prev) => ({ ...prev, error: null }));
  }, []);

  return (
    <AuthContext.Provider value={{ ...state, checkEmail, requestOtp, verifyOtp, logout, clearError, refreshAuth, updateUser }}>
      {children}
    </AuthContext.Provider>
  );
}

export function useAuth() {
  const context = useContext(AuthContext);
  if (!context) {
    throw new Error('useAuth must be used within an AuthProvider');
  }
  return context;
}