Copyright (c) 2000, 2009 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2009 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ltk.internal.core.refactoring;

import org.eclipse.core.expressions.EvaluationResult;
import org.eclipse.core.expressions.Expression;
import org.eclipse.core.expressions.ExpressionConverter;
import org.eclipse.core.expressions.ExpressionTagNames;
import org.eclipse.core.expressions.IEvaluationContext;

import org.eclipse.core.runtime.Assert;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;

import org.eclipse.ltk.core.refactoring.RefactoringStatus;
import org.eclipse.ltk.core.refactoring.participants.IParticipantDescriptorFilter;
import org.eclipse.ltk.core.refactoring.participants.RefactoringParticipant;

public class ParticipantDescriptor {

	private IConfigurationElement fConfigurationElement;
	private boolean fEnabled;

	private static final String ID= "id"; //$NON-NLS-1$
	private static final String NAME= "name";  //$NON-NLS-1$
	private static final String CLASS= "class"; //$NON-NLS-1$
	private static final String PROCESS_ON_CANCEL= "processOnCancel";  //$NON-NLS-1$

	public ParticipantDescriptor(IConfigurationElement element) {
		fConfigurationElement= element;
		fEnabled= true;
	}

	public String getId() {
		return fConfigurationElement.getAttribute(ID);
	}

	public String getName() {
		return fConfigurationElement.getAttribute(NAME);
	}

	public IStatus checkSyntax() {
		if (fConfigurationElement.getAttribute(ID) == null) {
			return new Status(IStatus.ERROR, RefactoringCorePlugin.getPluginId(), IStatus.ERROR,
				RefactoringCoreMessages.ParticipantDescriptor_error_id_missing, null);
		}
		if (fConfigurationElement.getAttribute(NAME) == null) {
			return new Status(IStatus.ERROR, RefactoringCorePlugin.getPluginId(), IStatus.ERROR,
				Messages.format( RefactoringCoreMessages.ParticipantDescriptor_error_name_missing, getId()),
				null);
		}
		if (fConfigurationElement.getAttribute(CLASS) == null) {
			return new Status(IStatus.ERROR, RefactoringCorePlugin.getPluginId(), IStatus.ERROR,
				Messages.format( RefactoringCoreMessages.ParticipantDescriptor_error_class_missing, getId()),
				null);
		}
		return Status.OK_STATUS;
	}

	public boolean matches(IEvaluationContext context, IParticipantDescriptorFilter filter, RefactoringStatus status) throws CoreException {
		IConfigurationElement[] elements= fConfigurationElement.getChildren(ExpressionTagNames.ENABLEMENT);
		if (elements.length == 0)
			return false;
		Assert.isTrue(elements.length == 1);
		Expression exp= ExpressionConverter.getDefault().perform(elements[0]);
		if (!convert(exp.evaluate(context)))
			return false;
		if (filter != null && !filter.select(fConfigurationElement, status))
			return false;

		return true;
	}

	public RefactoringParticipant createParticipant() throws CoreException {
		return (RefactoringParticipant)fConfigurationElement.createExecutableExtension(CLASS);
	}

	public boolean isEnabled() {
		return fEnabled;
	}

	public void disable() {
		fEnabled= false;
	}

	public boolean processOnCancel() {
		String attr= fConfigurationElement.getAttribute(PROCESS_ON_CANCEL);
		if (attr == null)
			return false;
		return Boolean.valueOf(attr).booleanValue();
	}

	private boolean convert(EvaluationResult eval) {
		if (eval == EvaluationResult.FALSE)
			return false;
		return true;
	}

	@Override
	public String toString() {
		return "name= " + getName() + (isEnabled() ? " (enabled)" : " (disabled)") + //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
				"\nid= " + getId() + //$NON-NLS-1$
				"\nclass= " + fConfigurationElement.getAttribute(CLASS); //$NON-NLS-1$
	}
}