GeezerVison

.example {
    colr: red;           /* Typo - silently accepted */
    color: 10px;         /* Wrong value type - accepted */
    background: inherit inherit;  /* Duplicate values - accepted */
    widht: 100%;         /* Typo - accepted */
}

package org.htmlunit.cssparser.parser.validator;

import java.util.*;
import org.htmlunit.cssparser.parser.*;

/**
 * Validates CSS properties and values for semantic correctness.
 * Provides suggestions for common mistakes and typos.
 */
public class CSSValidator {
    
    private final Set<String> knownProperties;
    private final Map<String, Set<ValueType>> propertyValueTypes;
    private final boolean strict;
    
    public enum ValueType {
        COLOR,
        LENGTH,
        PERCENTAGE,
        NUMBER,
        INTEGER,
        URL,
        STRING,
        IDENTIFIER,
        TIME,
        ANGLE,
        FREQUENCY,
        RESOLUTION,
        FUNCTION,
        KEYWORD
    }
    
    public CSSValidator() {
        this(false);
    }
    
    public CSSValidator(boolean strict) {
        this.strict = strict;
        this.knownProperties = loadKnownProperties();
        this.propertyValueTypes = loadPropertyValueTypes();
    }
    
    /**
     * Validates a CSS property declaration.
     * 
     * @param property The property name
     * @param value The lexical unit value
     * @param locator The locator for error reporting
     * @throws CSSParseException if validation fails in strict mode
     * @return List of validation warnings (empty if valid)
     */
    public List<ValidationWarning> validateProperty(String property, LexicalUnit value, Locator locator) {
        List<ValidationWarning> warnings = new ArrayList<>();
        
        // Validate property name
        if (!isKnownProperty(property)) {
            String suggestion = findClosestPropertyMatch(property);
            String message = "Unknown CSS property '" + property + "'.";
            if (suggestion != null) {
                message += " Did you mean '" + suggestion + "'?";
            }
            
            ValidationWarning warning = new ValidationWarning(
                message, 
                locator, 
                ValidationWarning.Level.ERROR
            );
            warnings.add(warning);
            
            if (strict) {
                throw new CSSParseException(message, locator);
            }
            return warnings; // Don't validate value if property is unknown
        }
        
        // Validate value type
        if (value != null && !isValidValueForProperty(property, value)) {
            Set<ValueType> expectedTypes = propertyValueTypes.get(property.toLowerCase(Locale.ROOT));
            String message = "Invalid value type for property '" + property + "'. " +
                           "Expected: " + formatExpectedTypes(expectedTypes) +
                           ", got: " + getValueType(value);
            
            ValidationWarning warning = new ValidationWarning(
                message,
                locator,
                ValidationWarning.Level.WARNING
            );
            warnings.add(warning);
        }
        
        // Validate specific property rules
        warnings.addAll(validatePropertySpecificRules(property, value, locator));
        
        return warnings;
    }
    
    /**
     * Checks if a property name is a known CSS property.
     */
    public boolean isKnownProperty(String property) {
        if (property == null) {
            return false;
        }
        
        // Custom properties (CSS variables) are always valid
        if (property.startsWith("--")) {
            return true;
        }
        
        // Vendor prefixes are allowed
        if (property.startsWith("-webkit-") || 
            property.startsWith("-moz-") || 
            property.startsWith("-ms-") || 
            property.startsWith("-o-")) {
            return true;
        }
        
        return knownProperties.contains(property.toLowerCase(Locale.ROOT));...

</details>



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