import React, { useState, useEffect } from 'react';
import { useDispatch, useSelector } from 'react-redux';
import { useNavigate } from 'react-router-dom';
import { loginUser, clearError, updateCacheInfo } from '../store/reducers/authSlice';

const Login = () => {
  const dispatch = useDispatch();
  const navigate = useNavigate();
  const { isAuthenticated, loading, error } = useSelector(state => state.auth);
  
  const [formData, setFormData] = useState({
    email: '',
    password: ''
  });
  
  const [showPassword, setShowPassword] = useState(false);
  const [rememberMe, setRememberMe] = useState(false);
  const [isFocused, setIsFocused] = useState({
    email: false,
    password: false
  });
  
  // Auto-fill remember me preference if available
  useEffect(() => {
    const rememberPref = localStorage.getItem('rememberMePreference');
    if (rememberPref === 'true') {
      setRememberMe(true);
    }
  }, []);
  
  useEffect(() => {
    if (isAuthenticated) {
      navigate('/dashboard');
      return;
    }
    
    // Clear any existing errors when component mounts
    dispatch(clearError());
    
    // Only check for cached auth if not already loading
    if (loading === 'idle') {
      const checkAuthStatus = async () => {
        const token = localStorage.getItem('token');
        if (!token) {
          return; // No token, nothing to check
        }
        
        try {
          // Check if token is expired
          const tokenData = JSON.parse(atob(token.split('.')[1]));
          const isExpired = tokenData.exp * 1000 < Date.now();
          
          if (isExpired) {
            localStorage.removeItem('token');
          }
        } catch (error) {
          // Invalid token format, remove it
          localStorage.removeItem('token');
        }
      };
      
      checkAuthStatus();
    }
  }, [isAuthenticated, loading, navigate, dispatch]);
  
  const handleChange = (e) => {
    setFormData({
      ...formData,
      [e.target.name]: e.target.value
    });
  };
  
  const handleFocus = (field) => {
    setIsFocused({
      ...isFocused,
      [field]: true
    });
  };
  
  const handleBlur = (field) => {
    setIsFocused({
      ...isFocused,
      [field]: false
    });
  };
  
  const handleSubmit = async (e) => {
    e.preventDefault();
    
    // Prevent form submission if already loading
    if (loading === 'pending') {
      return;
    }
    
    try {
      const result = await dispatch(loginUser({
        ...formData,
        rememberMe: rememberMe // Pass remember me flag
      })).unwrap();
      
      // Update Redux store with cache info
      dispatch(updateCacheInfo({
        isRemembered: rememberMe,
        expiresAt: result.expiresAt,
        deviceFingerprint: result.deviceFingerprint
      }));
      
      navigate('/dashboard');
    } catch (err) {
      // Error is handled by the Redux slice
      console.error('Login failed:', err);
    }
  };
  
  const togglePasswordVisibility = () => {
    setShowPassword(!showPassword);
  };
  
  const toggleForm = () => {
    dispatch(clearError());
    navigate('/register');
  };
  
  if (isAuthenticated) {
    return null; // Redirect handled by useEffect
  }
  
  return (
    <div className="min-h-screen bg-gradient-to-br from-primary-50 via-white to-accent-50 flex items-center justify-center p-3 sm:p-4 animate-fade-in">
      <div className="w-full max-w-sm sm:max-w-md">
        {/* Logo and Brand */}
        <div className="text-center mb-6 sm:mb-8 animate-slide-up">
          <div className="inline-flex items-center justify-center w-14 h-14 sm:w-16 sm:h-16 bg-gradient-to-br from-primary-600 to-primary-800 rounded-2xl shadow-lg mb-3 sm:mb-4">
            <span className="text-xl sm:text-2xl font-bold text-white">Lin</span>
          </div>
          <h1 className="text-2xl sm:text-3xl font-bold text-gray-900 mb-1 sm:mb-2">Welcome Back</h1>
          <p className="text-sm sm:text-base text-gray-600">Sign in to your Lin account</p>
        </div>
        
        {/* Auth Card */}
        <div className="bg-white rounded-2xl shadow-xl p-4 sm:p-8 space-y-4 sm:space-y-6 animate-slide-up animate-delay-100">
          {/* Error Message */}
          {error && (
            <div className="bg-red-50 border border-red-200 rounded-lg p-3 sm:p-4 animate-slide-up animate-delay-200">
              <div className="flex items-start space-x-2">
                <svg className="w-4 h-4 sm:w-5 sm:h-5 text-red-500 flex-shrink-0 mt-0.5" fill="currentColor" viewBox="0 0 20 20">
                  <path fillRule="evenodd" d="M10 18a8 8 0 100-16 8 8 0 000 16zM8.707 7.293a1 1 0 00-1.414 1.414L8.586 10l-1.293 1.293a1 1 0 101.414 1.414L10 11.414l1.293 1.293a1 1 0 001.414-1.414L11.414 10l1.293-1.293a1 1 0 00-1.414-1.414L10 8.586 8.707 7.293z" clipRule="evenodd" />
                </svg>
                <span className="text-red-700 text-xs sm:text-sm font-medium">
                  {error}
                </span>
              </div>
            </div>
          )}
          
          {/* Login Form */}
          <form onSubmit={handleSubmit} className="space-y-4 sm:space-y-5">
            {/* Email Field */}
            <div className="space-y-2">
              <label htmlFor="email" className="block text-xs sm:text-sm font-semibold text-gray-700">
                Email Address
              </label>
              <div className="relative">
                <input
                  type="email"
                  id="email"
                  name="email"
                  value={formData.email}
                  onChange={handleChange}
                  onFocus={() => handleFocus('email')}
                  onBlur={() => handleBlur('email')}
                  className={`w-full px-3 sm:px-4 py-2 sm:py-3 rounded-xl border-2 transition-all duration-200 ${
                    isFocused.email
                      ? 'border-primary-500 shadow-md'
                      : 'border-gray-200 hover:border-gray-300'
                  } ${formData.email ? 'text-gray-900' : 'text-gray-500'} focus:outline-none focus:ring-2 focus:ring-primary-500 focus:ring-offset-2 touch-manipulation`}
                  placeholder="Enter your email"
                  required
                  aria-required="true"
                  aria-label="Email address"
                />
                <div className="absolute inset-y-0 right-0 flex items-center pr-3">
                  <svg className="w-4 h-4 sm:w-5 sm:h-5 text-gray-400" fill="currentColor" viewBox="0 0 20 20">
                    <path d="M2.003 5.884L10 9.882l7.997-3.998A2 2 0 0016 4H4a2 2 0 00-1.997 1.884z" />
                    <path d="M18 8.118l-8 4-8-4V14a2 2 0 002 2h12a2 2 0 002-2V8.118z" />
                  </svg>
                </div>
              </div>
            </div>
            
            {/* Password Field */}
            <div className="space-y-2">
              <label htmlFor="password" className="block text-xs sm:text-sm font-semibold text-gray-700">
                Password
              </label>
              <div className="relative">
                <input
                  type={showPassword ? "text" : "password"}
                  id="password"
                  name="password"
                  value={formData.password}
                  onChange={handleChange}
                  onFocus={() => handleFocus('password')}
                  onBlur={() => handleBlur('password')}
                  className={`w-full px-3 sm:px-4 py-2 sm:py-3 rounded-xl border-2 transition-all duration-200 ${
                    isFocused.password
                      ? 'border-primary-500 shadow-md'
                      : 'border-gray-200 hover:border-gray-300'
                  } ${formData.password ? 'text-gray-900' : 'text-gray-500'} focus:outline-none focus:ring-2 focus:ring-primary-500 focus:ring-offset-2 touch-manipulation`}
                  placeholder="Enter your password"
                  required
                  aria-required="true"
                  aria-label="Password"
                />
                <button
                  type="button"
                  onClick={togglePasswordVisibility}
                  className="absolute inset-y-0 right-0 flex items-center pr-3 text-gray-400 hover:text-gray-600 transition-colors touch-manipulation"
                  aria-label={showPassword ? "Hide password" : "Show password"}
                >
                  {showPassword ? (
                    <svg className="w-4 h-4 sm:w-5 sm:h-5" fill="currentColor" viewBox="0 0 20 20">
                      <path d="M10 12a2 2 0 100-4 2 2 0 000 4z" />
                      <path fillRule="evenodd" d="M.458 10C1.732 5.943 5.522 3 10 3s8.268 2.943 9.542 7c-1.274 4.057-5.064 7-9.542 7S1.732 14.057.458 10zM14 10a4 4 0 11-8 0 4 4 0 018 0z" clipRule="evenodd" />
                    </svg>
                  ) : (
                    <svg className="w-4 h-4 sm:w-5 sm:h-5" fill="currentColor" viewBox="0 0 20 20">
                      <path fillRule="evenodd" d="M3.707 2.293a1 1 0 00-1.414 1.414l14 14a1 1 0 001.414-1.414l-1.473-1.473A10.014 10.014 0 0019.542 10C18.268 5.943 14.478 3 10 3a9.958 9.958 0 00-4.512 1.074l-1.78-1.781zm4.261 4.26l1.514 1.515a2.003 2.003 0 012.45 2.45l1.514 1.514a4 4 0 00-5.478-5.478z" clipRule="evenodd" />
                      <path d="M12.454 16.697L9.75 13.992a4 4 0 01-3.742-3.741L2.335 6.578A9.98 9.98 0 00.458 10c1.274 4.057 5.065 7 9.542 7 .847 0 1.669-.105 2.454-.303z" />
                    </svg>
                  )}
                </button>
              </div>
            </div>
            
            {/* Remember Me & Forgot Password */}
            <div className="flex flex-col sm:flex-row sm:items-center sm:justify-between gap-3">
              <div className="flex items-center">
                <input
                  id="remember-me"
                  name="remember-me"
                  type="checkbox"
                  checked={rememberMe}
                  onChange={(e) => {
                    setRememberMe(e.target.checked);
                    // Save preference
                    localStorage.setItem('rememberMePreference', e.target.checked.toString());
                  }}
                  className="h-4 w-4 text-primary-600 focus:ring-primary-500 border-gray-300 rounded transition-colors touch-manipulation"
                  aria-label="Remember me"
                />
                <label htmlFor="remember-me" className="ml-2 block text-xs sm:text-sm text-gray-700">
                  Remember me for 7 days
                </label>
              </div>
              <div className="text-xs sm:text-sm">
                <button
                  type="button"
                  onClick={() => navigate('/forgot-password')}
                  className="font-medium text-primary-600 hover:text-primary-500 transition-colors focus:outline-none focus:underline"
                >
                  Forgot password?
                </button>
              </div>
            </div>
            
            {/* Submit Button */}
            <button
              type="submit"
              disabled={loading === 'pending'}
              className="w-full bg-gradient-to-r from-primary-600 to-primary-800 text-white font-semibold py-2.5 sm:py-3 px-4 rounded-xl hover:from-primary-700 hover:to-primary-900 focus:outline-none focus:ring-2 focus:ring-primary-500 focus:ring-offset-2 transition-all duration-200 transform hover:scale-[1.02] active:scale-[0.98] disabled:opacity-50 disabled:cursor-not-allowed disabled:transform-none touch-manipulation"
              aria-busy={loading === 'pending'}
            >
              {loading === 'pending' ? (
                <div className="flex items-center justify-center">
                  <svg className="animate-spin -ml-1 mr-2 sm:mr-3 h-4 w-4 sm:h-5 sm:w-5 text-white" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24">
                    <circle className="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" strokeWidth="4"></circle>
                    <path className="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4zm2 5.291A7.962 7.962 0 014 12H0c0 3.042 1.135 5.824 3 7.938l3-2.647z"></path>
                  </svg>
                  <span className="text-xs sm:text-sm">Signing in...</span>
                </div>
              ) : (
                <span className="text-xs sm:text-sm">Sign in</span>
              )}
            </button>
          </form>
          
          
          {/* Register Link */}
          <div className="text-center">
            <p className="text-xs sm:text-sm text-gray-600">
              Don't have an account?{' '}
              <button
                type="button"
                onClick={toggleForm}
                className="font-semibold text-primary-600 hover:text-primary-500 transition-colors focus:outline-none focus:underline"
                aria-label="Create a new account"
              >
                Create account
              </button>
            </p>
          </div>
        </div>
        
        {/* Footer */}
        <div className="text-center mt-6 sm:mt-8 text-xs text-gray-500">
          <p>&copy; 2024 Lin. All rights reserved.</p>
        </div>
      </div>
    </div>
  );
};

export default Login;