import { useState } from 'react';

export function useFormValidation(rules) {
  const [errors, setErrors] = useState({});
  
  const validate = (data) => {
    const newErrors = {};
    
    Object.entries(rules).forEach(([field, fieldRules]) => {
      for (const rule of fieldRules) {
        const error = rule(data[field], data);
        if (error) {
          newErrors[field] = error;
          break;
        }
      }
    });
    
    setErrors(newErrors);
    return Object.keys(newErrors).length === 0;
  };
  
  const clearError = (field) => {
    setErrors(prev => {
      const next = { ...prev };
      delete next[field];
      return next;
    });
  };
  
  const clearAllErrors = () => setErrors({});
  
  return { errors, validate, clearError, clearAllErrors };
}

export const validators = {
  required: (message = 'Pflichtfeld') => (value) => {
    if (!value || (typeof value === 'string' && !value.trim())) {
      return message;
    }
    return null;
  },
  
  email: (message = 'Ungültige E-Mail-Adresse') => (value) => {
    if (!value) return null;
    const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
    if (!emailRegex.test(value)) {
      return message;
    }
    return null;
  },
  
  url: (message = 'Ungültige URL') => (value) => {
    if (!value) return null;
    try {
      new URL(value);
      return null;
    } catch {
      return message;
    }
  },
  
  minLength: (min, message) => (value) => {
    if (!value || value.length < min) {
      return message || `Mindestens ${min} Zeichen`;
    }
    return null;
  }
};