import javax.inject.Inject;
import javax.inject.Named;

import org.eclipse.e4.core.di.annotations.CanExecute;
import org.eclipse.e4.core.di.annotations.Execute;
import org.eclipse.e4.core.services.adapter.Adapter;
import org.eclipse.e4.ui.model.application.ui.basic.MPart;
import org.eclipse.e4.ui.services.IServiceConstants;
import org.eclipse.jface.text.ITextOperationTarget;

public class UndoHandler {
	
	@Inject
	private Adapter _adapter;

	@Execute
	public void execute(@Named(IServiceConstants.ACTIVE_PART) final MPart part) {
		final ITextOperationTarget opTarget = _adapter.adapt(part.getObject(),
				ITextOperationTarget.class);

		opTarget.doOperation(ITextOperationTarget.UNDO);
	}

	@CanExecute
	public boolean canExecute(@Named(IServiceConstants.ACTIVE_PART) final MPart part) {
		final ITextOperationTarget opTarget = _adapter.adapt(part.getObject(),
				ITextOperationTarget.class);
		if (opTarget == null)
			return false;
		boolean canDoOperation = opTarget.canDoOperation(ITextOperationTarget.UNDO);
		return canDoOperation;
	}
}