package org.eclipse.swt.snippets;

import org.eclipse.core.databinding.Binding;
import org.eclipse.core.databinding.observable.Realm;
import org.eclipse.core.databinding.validation.IValidator;
import org.eclipse.core.runtime.IStatus;

/**
 * 
 * @author sylvere richard
 *
 */
public abstract class ValidatorRoundtrip implements IValidator {

	private final Binding b;
	private final Realm realm;

	public ValidatorRoundtrip(Realm realm, Binding b) {
		this.realm = realm;
		this.b = b;
	}

	/**
	 * Method declared final. Validation logic must be put in method 
	 * ValidatorRoundtrip.doValidation
	 * 
	 * 
	 * Will call doValidation. 
	 * 
	 * If the IStatus returned by doValidation is an error
	 * or a cancel, it will force a refresh of the target by calling updateModelToTarget()
	 * to restore the previous value on screen.
	 * Otherwise, the process flow is unchanged.
	 */
	@Override
	public final IStatus validate(Object value) {
		final IStatus res = doValidation(value);
		if (res.matches(IStatus.INFO | IStatus.WARNING) || res.isOK()) {
			return res;
		}

		realm.asyncExec(new Runnable() {

			@Override
			public void run() {
				b.updateModelToTarget();
			}
		});
		return res;
	}

	/**
	 * Puts validation logic here
	 * @param value
	 * @return 
	 */
	public abstract IStatus doValidation(Object value);
}