/* 
@ITMillApache2LicenseForJavaFiles@
 */

package com.itmill.toolkit.data;

import java.util.Collection;

/**
 * <p>
 * Interface for validatable objects. Defines methods to verify if the object's
 * value is valid or not, and to add, remove and list registered validators of
 * the object.
 * </p>
 * 
 * @author IT Mill Ltd.
 * @version
 * @VERSION@
 * @since 3.0
 * @see com.itmill.toolkit.data.Validator
 */
public interface Validatable {

    /**
     * <p>
     * Adds a new validator for this object. The validator's
     * {@link Validator#validate(Object)} method is activated every time the
     * object's value needs to be verified, that is, when the {@link #isValid()}
     * method is called. This usually happens when the object's value changes.
     * </p>
     * 
     * @param validator
     *                the new validator
     */
    void addValidator(Validator validator);

    /**
     * <p>
     * Removes a previously registered validator from the object. The specified
     * validator is removed from the object and its <code>validate</code>
     * method is no longer called in {@link #isValid()}.
     * </p>
     * 
     * @param validator
     *                the validator to remove
     */
    void removeValidator(Validator validator);

    /**
     * <p>
     * Lists all validators currently registered for the object. If no
     * validators are registered, returns <code>null</code>.
     * </p>
     * 
     * @return collection of validators or <code>null</code>
     */
    public Collection getValidators();

    /**
     * <p>
     * Tests the current value of the object against all registered validators.
     * The registered validators are iterated and for each the
     * {@link Validator#validate(Object)} method is called. If any validator
     * throws the {@link Validator.InvalidValueException} this method returns
     * <code>false</code>.
     * </p>
     * 
     * @return <code>true</code> if the registered validators concur that the
     *         value is valid, <code>false</code> otherwise
     */
    public boolean isValid();

    /**
     * <p>
     * Checks the validity of the validatable. If the validatable is valid this
     * method should do nothing, and if it's not valid, it should throw
     * <code>Validator.InvalidValueException</code>
     * </p>
     * 
     * @throws Validator.InvalidValueException
     *                 if the value is not valid
     */
    public void validate() throws Validator.InvalidValueException;

    /**
     * <p>
     * Checks the validabtable object accept invalid values.The default value is
     * <code>true</code>.
     * </p>
     * 
     */
    public boolean isInvalidAllowed();

    /**
     * <p>
     * Should the validabtable object accept invalid values. Supporting this
     * configuration possibility is optional. By default invalid values are
     * allowed.
     * </p>
     * 
     * @param invalidValueAllowed
     * 
     * @throws UnsupportedOperationException
     *                 if the setInvalidAllowed is not supported.
     */
    public void setInvalidAllowed(boolean invalidValueAllowed)
            throws UnsupportedOperationException;

}