import React, { useState, useEffect, useRef } from 'react';
import { Button, Input, Card } from '../../ui';
import { PasswordCriteria, validatePassword, getPasswordErrors } from '../../ui/PasswordCriteria';
import { useAuthActions } from '../../../stores/auth.store';
import { showToast } from '../../../utils/toast';
import { useResetPassword } from '../../../api/hooks/auth';

interface PasswordResetFormProps {
  token?: string;
  onSuccess?: () => void;
  onBackClick?: () => void;
  className?: string;
  autoFocus?: boolean;
  mode?: 'request' | 'reset';
}

export const PasswordResetForm: React.FC<PasswordResetFormProps> = ({
  token,
  onSuccess,
  onBackClick,
  className,
  autoFocus = true,
  mode
}) => {
  const [email, setEmail] = useState('');
  const [password, setPassword] = useState('');
  const [confirmPassword, setConfirmPassword] = useState('');
  const [errors, setErrors] = useState<Record<string, string>>({});
  const [showPassword, setShowPassword] = useState(false);
  const [showConfirmPassword, setShowConfirmPassword] = useState(false);
  const [isEmailSent, setIsEmailSent] = useState(false);
  const [passwordStrength, setPasswordStrength] = useState(0);
  const [isTokenValid, setIsTokenValid] = useState<boolean | null>(null);
  
  const emailInputRef = useRef<HTMLInputElement>(null);
  const passwordInputRef = useRef<HTMLInputElement>(null);

  // Password reset mutation hooks
  const { mutateAsync: resetPasswordMutation, isPending: isResetting } = useResetPassword();
  const isLoading = isResetting;
  const error = null;
  

  const isResetMode = Boolean(token) || mode === 'reset';

  // Auto-focus on appropriate field when component mounts
  useEffect(() => {
    if (autoFocus) {
      if (isResetMode && passwordInputRef.current) {
        passwordInputRef.current.focus();
      } else if (!isResetMode && emailInputRef.current) {
        emailInputRef.current.focus();
      }
    }
  }, [autoFocus, isResetMode]);

  // Token validation effect
  useEffect(() => {
    if (token) {
      // Simple token format validation (you might want to add actual API validation)
      const isValidFormat = /^[A-Za-z0-9+/=_-]+$/.test(token) && token.length > 20;
      setIsTokenValid(isValidFormat);
      
      if (!isValidFormat) {
      showToast.error('El enlace de restablecimiento no es válido o ha expirado', {
        title: 'Token inválido'
      });
      }
    }
  }, [token, showToast]);

  // Calculate password strength
  const calculatePasswordStrength = (password: string): number => {
    let strength = 0;
    if (password.length >= 8) strength += 25;
    if (/[a-z]/.test(password)) strength += 25;
    if (/[A-Z]/.test(password)) strength += 25;
    if (/[0-9]/.test(password)) strength += 15;
    if (/[^A-Za-z0-9]/.test(password)) strength += 10;
    return Math.min(strength, 100);
  };

  const getPasswordStrengthLabel = (strength: number): string => {
    if (strength < 25) return 'Muy débil';
    if (strength < 50) return 'Débil';
    if (strength < 75) return 'Media';
    return 'Fuerte';
  };

  const getPasswordStrengthColor = (strength: number): string => {
    if (strength < 25) return 'bg-color-error';
    if (strength < 50) return 'bg-yellow-500';
    if (strength < 75) return 'bg-blue-500';
    return 'bg-color-success';
  };

  const validateEmail = (): boolean => {
    const newErrors: Record<string, string> = {};
    
    if (!email.trim()) {
      newErrors.email = 'El email es requerido';
    } else if (!/^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/.test(email)) {
      newErrors.email = 'Por favor, ingrese un email válido';
    }
    
    setErrors(newErrors);
    return Object.keys(newErrors).length === 0;
  };

  const validatePasswords = (): boolean => {
    const newErrors: Record<string, string> = {};
    
    if (!password) {
      newErrors.password = 'La contraseña es requerida';
    } else {
      const passwordErrors = getPasswordErrors(password);
      if (passwordErrors.length > 0) {
        newErrors.password = passwordErrors[0]; // Show first error
      }
    }
    
    if (!confirmPassword) {
      newErrors.confirmPassword = 'Confirma tu nueva contraseña';
    } else if (password !== confirmPassword) {
      newErrors.confirmPassword = 'Las contraseñas no coinciden';
    }
    
    setErrors(newErrors);
    return Object.keys(newErrors).length === 0;
  };

  // Handle password change to update strength
  const handlePasswordChange = (e: React.ChangeEvent<HTMLInputElement>) => {
    const value = e.target.value;
    setPassword(value);
    setPasswordStrength(calculatePasswordStrength(value));
    clearError('password');
  };

  const handleRequestReset = async (e: React.FormEvent) => {
    e.preventDefault();
    
    if (!validateEmail()) {
      // Focus on email field if validation fails
      if (emailInputRef.current) {
        emailInputRef.current.focus();
      }
      return;
    }

    try {
      // Note: Password reset request functionality needs to be implemented in backend
      // For now, show a message that the feature is coming soon
      setIsEmailSent(true);
      showToast.info('La solicitud de restablecimiento de contraseña estará disponible próximamente. Por favor, contacta al administrador.', {
        title: 'Función en desarrollo'
      });
    } catch (err) {
      showToast.error('No se pudo conectar con el servidor. Verifica tu conexión a internet.', {
        title: 'Error de conexión'
      });
    }
  };

  const handleResetPassword = async (e: React.FormEvent) => {
    e.preventDefault();
    
    if (!validatePasswords()) {
      // Focus on password field if validation fails
      if (passwordInputRef.current) {
        passwordInputRef.current.focus();
      }
      return;
    }

    if (!token || isTokenValid === false) {
      showToast.error('El enlace de restablecimiento no es válido. Solicita uno nuevo.', {
        title: 'Token inválido'
      });
      return;
    }

    try {
      // Call the reset password API
      await resetPasswordMutation({
        token: token,
        new_password: password
      });

      showToast.success('¡Tu contraseña ha sido restablecida exitosamente! Ya puedes iniciar sesión.', {
        title: 'Contraseña actualizada'
      });
      onSuccess?.();
    } catch (err: any) {
      const errorMessage = err?.response?.data?.detail || err?.message || 'El enlace ha expirado o no es válido. Solicita un nuevo restablecimiento.';
      showToast.error(errorMessage, {
        title: 'Error al restablecer contraseña'
      });
    }
  };

  const clearError = (field: string) => {
    if (errors[field]) {
      setErrors(prev => ({ ...prev, [field]: undefined }));
    }
  };

  // Handle Enter key submission
  const handleKeyDown = (e: React.KeyboardEvent) => {
    if (e.key === 'Enter' && !isLoading) {
      if (isResetMode) {
        handleResetPassword(e as any);
      } else {
        handleRequestReset(e as any);
      }
    }
  };

  // Success screen for email sent
  if (isEmailSent && !isResetMode) {
    return (
      <Card className={`p-8 w-full max-w-md text-center ${className || ''}`} role="main">
        <div className="mb-8">
          <div className="w-20 h-20 bg-color-success/10 rounded-full flex items-center justify-center mx-auto mb-6">
            <svg 
              className="w-10 h-10 text-color-success" 
              fill="none" 
              stroke="currentColor" 
              viewBox="0 0 24 24"
              aria-hidden="true"
            >
              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M3 8l7.89 4.26a2 2 0 002.22 0L21 8M5 19h14a2 2 0 002-2V7a2 2 0 00-2-2H5a2 2 0 00-2 2v10a2 2 0 002 2z" />
            </svg>
          </div>
          <h1 className="text-2xl font-bold text-text-primary mb-4">
            ¡Email enviado correctamente!
          </h1>
          <div className="bg-background-secondary rounded-lg p-6 mb-6">
            <p className="text-text-secondary mb-2">
              Hemos enviado las instrucciones de restablecimiento a:
            </p>
            <p className="text-text-primary font-semibold text-lg mb-4">
              {email}
            </p>
            <p className="text-text-secondary text-sm">
              Revisa tu bandeja de entrada (y la carpeta de spam). El enlace es válido por 24 horas.
            </p>
          </div>
        </div>

        <div className="space-y-4">
          <Button
            variant="primary"
            onClick={() => {
              setIsEmailSent(false);
              setEmail('');
              setErrors({});
              if (emailInputRef.current) {
                emailInputRef.current.focus();
              }
            }}
            className="w-full"
          >
            Enviar a Otra Dirección
          </Button>
          
          {onBackClick && (
            <Button
              variant="outline"
              onClick={onBackClick}
              className="w-full"
            >
              Volver al Login
            </Button>
          )}
        </div>
      </Card>
    );
  }

  // Show token validation error
  if (isResetMode && isTokenValid === false) {
    return (
      <Card className={`p-8 w-full max-w-md text-center ${className || ''}`} role="main">
        <div className="mb-8">
          <div className="w-20 h-20 bg-color-error/10 rounded-full flex items-center justify-center mx-auto mb-6">
            <svg 
              className="w-10 h-10 text-color-error" 
              fill="none" 
              stroke="currentColor" 
              viewBox="0 0 24 24"
              aria-hidden="true"
            >
              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 9v2m0 4h.01m-6.938 4h13.856c1.54 0 2.502-1.667 1.732-2.5L13.732 4c-.77-.833-1.732-.833-2.464 0L3.34 16.5c-.77.833.192 2.5 1.732 2.5z" />
            </svg>
          </div>
          <h1 className="text-2xl font-bold text-text-primary mb-4">
            Enlace No Válido
          </h1>
          <p className="text-text-secondary mb-6">
            El enlace de restablecimiento no es válido o ha expirado. 
            Solicita un nuevo enlace para restablecer tu contraseña.
          </p>
        </div>

        {onBackClick && (
          <Button
            variant="primary"
            onClick={onBackClick}
            className="w-full"
          >
            Volver al Login
          </Button>
        )}
      </Card>
    );
  }

  return (
    <Card className={`p-8 w-full max-w-md ${className || ''}`} role="main">
      <div className="text-center mb-8">
        <h1 className="text-2xl font-bold text-text-primary mb-2">
          {isResetMode ? 'Crear Nueva Contraseña' : 'Restablecer Contraseña'}
        </h1>
        <p className="text-text-secondary">
          {isResetMode 
            ? 'Crea una contraseña segura para acceder a tu cuenta'
            : 'Te enviaremos un enlace seguro para restablecer tu contraseña'
          }
        </p>
      </div>

      <form 
        onSubmit={isResetMode ? handleResetPassword : handleRequestReset} 
        className="space-y-6"
        noValidate
        onKeyDown={handleKeyDown}
        aria-label={isResetMode ? 'Formulario de nueva contraseña' : 'Formulario de solicitud de restablecimiento'}
      >
        {!isResetMode && (
          <div>
            <Input
              ref={emailInputRef}
              type="email"
              label="Correo Electrónico"
              placeholder="tu.email@panaderia.com"
              value={email}
              onChange={(e) => {
                setEmail(e.target.value);
                clearError('email');
              }}
              error={errors.email}
              disabled={isLoading}
              autoComplete="email"
              required
              aria-describedby={errors.email ? 'email-error' : undefined}
              leftIcon={
                <svg 
                  className="w-5 h-5" 
                  fill="none" 
                  stroke="currentColor" 
                  viewBox="0 0 24 24"
                  aria-hidden="true"
                >
                  <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M16 12a4 4 0 10-8 0 4 4 0 008 0zm0 0v1.5a2.5 2.5 0 005 0V12a9 9 0 10-9 9m4.5-1.206a8.959 8.959 0 01-4.5 1.207" />
                </svg>
              }
            />
            {errors.email && (
              <p id="email-error" className="text-color-error text-sm mt-1" role="alert">
                {errors.email}
              </p>
            )}
          </div>
        )}

        {isResetMode && (
          <>
            <div>
              <Input
                ref={passwordInputRef}
                type={showPassword ? 'text' : 'password'}
                label="Nueva Contraseña"
                placeholder="Contraseña segura"
                value={password}
                onChange={handlePasswordChange}
                error={errors.password}
                disabled={isLoading}
                autoComplete="new-password"
                required
                aria-describedby={`${errors.password ? 'password-error' : ''} password-strength`}
                leftIcon={
                  <svg 
                    className="w-5 h-5" 
                    fill="none" 
                    stroke="currentColor" 
                    viewBox="0 0 24 24"
                    aria-hidden="true"
                  >
                    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 15v2m-6 4h12a2 2 0 002-2v-6a2 2 0 00-2-2H6a2 2 0 00-2 2v6a2 2 0 002 2zm10-10V7a4 4 0 00-8 0v4h8z" />
                  </svg>
                }
                rightIcon={
                  <button
                    type="button"
                    onClick={() => setShowPassword(!showPassword)}
                    className="text-text-secondary hover:text-text-primary transition-colors"
                    aria-label={showPassword ? 'Ocultar contraseña' : 'Mostrar contraseña'}
                    tabIndex={0}
                  >
                    {showPassword ? (
                      <svg 
                        className="w-5 h-5" 
                        fill="none" 
                        stroke="currentColor" 
                        viewBox="0 0 24 24"
                        aria-hidden="true"
                      >
                        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M13.875 18.825A10.05 10.05 0 0112 19c-4.478 0-8.268-2.943-9.543-7a9.97 9.97 0 011.563-3.029m5.858.908a3 3 0 114.243 4.243M9.878 9.878l4.242 4.242M9.878 9.878L3 3m6.878 6.878L21 21" />
                      </svg>
                    ) : (
                      <svg 
                        className="w-5 h-5" 
                        fill="none" 
                        stroke="currentColor" 
                        viewBox="0 0 24 24"
                        aria-hidden="true"
                      >
                        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M15 12a3 3 0 11-6 0 3 3 0 016 0z" />
                        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M2.458 12C3.732 7.943 7.523 5 12 5c4.478 0 8.268 2.943 9.542 7-1.274 4.057-5.064 7-9.542 7-4.477 0-8.268-2.943-9.542-7z" />
                      </svg>
                    )}
                  </button>
                }
              />
              
              {/* Password Strength Indicator */}
              {password && (
                <div className="mt-2">
                  <div className="flex justify-between text-xs mb-1">
                    <span className="text-text-secondary">Seguridad:</span>
                    <span className={`font-medium ${passwordStrength < 50 ? 'text-color-error' : passwordStrength < 75 ? 'text-yellow-600' : 'text-color-success'}`}>
                      {getPasswordStrengthLabel(passwordStrength)}
                    </span>
                  </div>
                  <div className="w-full bg-background-secondary rounded-full h-2">
                    <div 
                      className={`h-2 rounded-full transition-all duration-300 ${getPasswordStrengthColor(passwordStrength)}`}
                      style={{ width: `${passwordStrength}%` }}
                      role="progressbar"
                      aria-valuenow={passwordStrength}
                      aria-valuemin={0}
                      aria-valuemax={100}
                      aria-label={`Fuerza de la contraseña: ${getPasswordStrengthLabel(passwordStrength)}`}
                    />
                  </div>
                </div>
              )}
              
              {errors.password && (
                <p id="password-error" className="text-color-error text-sm mt-1" role="alert">
                  {errors.password}
                </p>
              )}
            </div>

            <div>
              <Input
                type={showConfirmPassword ? 'text' : 'password'}
                label="Confirmar Nueva Contraseña"
                placeholder="Repite tu nueva contraseña"
                value={confirmPassword}
                onChange={(e) => {
                  setConfirmPassword(e.target.value);
                  clearError('confirmPassword');
                }}
                error={errors.confirmPassword}
                disabled={isLoading}
                autoComplete="new-password"
                required
                aria-describedby={errors.confirmPassword ? 'confirm-password-error' : undefined}
                leftIcon={
                  <svg 
                    className="w-5 h-5" 
                    fill="none" 
                    stroke="currentColor" 
                    viewBox="0 0 24 24"
                    aria-hidden="true"
                  >
                    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M9 12l2 2 4-4m6 2a9 9 0 11-18 0 9 9 0 0118 0z" />
                  </svg>
                }
                rightIcon={
                  <button
                    type="button"
                    onClick={() => setShowConfirmPassword(!showConfirmPassword)}
                    className="text-text-secondary hover:text-text-primary transition-colors"
                    aria-label={showConfirmPassword ? 'Ocultar contraseña' : 'Mostrar contraseña'}
                    tabIndex={0}
                  >
                    {showConfirmPassword ? (
                      <svg 
                        className="w-5 h-5" 
                        fill="none" 
                        stroke="currentColor" 
                        viewBox="0 0 24 24"
                        aria-hidden="true"
                      >
                        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M13.875 18.825A10.05 10.05 0 0112 19c-4.478 0-8.268-2.943-9.543-7a9.97 9.97 0 011.563-3.029m5.858.908a3 3 0 114.243 4.243M9.878 9.878l4.242 4.242M9.878 9.878L3 3m6.878 6.878L21 21" />
                      </svg>
                    ) : (
                      <svg 
                        className="w-5 h-5" 
                        fill="none" 
                        stroke="currentColor" 
                        viewBox="0 0 24 24"
                        aria-hidden="true"
                      >
                        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M15 12a3 3 0 11-6 0 3 3 0 016 0z" />
                        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M2.458 12C3.732 7.943 7.523 5 12 5c4.478 0 8.268 2.943 9.542 7-1.274 4.057-5.064 7-9.542 7-4.477 0-8.268-2.943-9.542-7z" />
                      </svg>
                    )}
                  </button>
                }
              />
              {errors.confirmPassword && (
                <p id="confirm-password-error" className="text-color-error text-sm mt-1" role="alert">
                  {errors.confirmPassword}
                </p>
              )}
            </div>
          </>
        )}

        {error && (
          <div 
            className="bg-color-error/10 border border-color-error/20 text-color-error px-4 py-3 rounded-lg text-sm flex items-start space-x-3"
            role="alert"
            aria-live="polite"
          >
            <svg 
              className="w-5 h-5 mt-0.5 flex-shrink-0" 
              fill="currentColor" 
              viewBox="0 0 20 20"
              aria-hidden="true"
            >
              <path fillRule="evenodd" d="M18 10a8 8 0 11-16 0 8 8 0 0116 0zm-7 4a1 1 0 11-2 0 1 1 0 012 0zm-1-9a1 1 0 00-1 1v4a1 1 0 102 0V6a1 1 0 00-1-1z" clipRule="evenodd" />
            </svg>
            <span>{error}</span>
          </div>
        )}

        <Button
          type="submit"
          variant="primary"
          size="lg"
          isFullWidth
          isLoading={isLoading}
          loadingText={isResetMode ? 'Restableciendo contraseña...' : 'Enviando enlace...'}
          disabled={isLoading || (isResetMode && isTokenValid === false)}
          aria-describedby={isResetMode ? 'reset-button-description' : 'request-button-description'}
        >
          {isResetMode ? 'Actualizar Contraseña' : 'Enviar Enlace de Restablecimiento'}
        </Button>

        <div id={isResetMode ? 'reset-button-description' : 'request-button-description'} className="sr-only">
          {isResetMode 
            ? 'Presiona Enter o haz clic para actualizar tu contraseña'
            : 'Presiona Enter o haz clic para enviar el enlace de restablecimiento'
          }
        </div>
      </form>

      {onBackClick && (
        <div className="mt-8 text-center border-t border-border-primary pt-6">
          <Button
            variant="outline"
            onClick={onBackClick}
            disabled={isLoading}
            className="w-full focus:outline-none focus:ring-2 focus:ring-color-primary focus:ring-offset-2"
          >
            Volver al Inicio de Sesión
          </Button>
        </div>
      )}
    </Card>
  );
};

export default PasswordResetForm;
