Copyright (c) 2005, 2015 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) 2005, 2015 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.jdt.internal.launching;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.preferences.IEclipsePreferences;
import org.eclipse.core.runtime.preferences.IPreferenceNodeVisitor;
import org.eclipse.core.runtime.preferences.InstanceScope;
import org.eclipse.core.runtime.preferences.PreferenceModifyListener;
import org.eclipse.jdt.launching.IVMInstall;
import org.eclipse.jdt.launching.JavaRuntime;
import org.eclipse.jdt.launching.VMStandin;
import org.osgi.service.prefs.BackingStoreException;

Manages import of installed JREs. Merges valid imported JREs with existing JREs.
Since:
3.1/**
 * Manages import of installed JREs. Merges valid imported JREs with existing JREs.
 *
 * @since 3.1
 */
public class JREPreferenceModifyListener extends PreferenceModifyListener {

	class Visitor implements IPreferenceNodeVisitor {

		@Override
		public boolean visit(IEclipsePreferences node) throws BackingStoreException {
			if (node.name().equals(LaunchingPlugin.getUniqueIdentifier())) {
				String jresXML = node.get(JavaRuntime.PREF_VM_XML, null);
				if (jresXML != null) {
					VMDefinitionsContainer vms = new VMDefinitionsContainer();
					String pref = InstanceScope.INSTANCE.getNode(LaunchingPlugin.ID_PLUGIN).get(JavaRuntime.PREF_VM_XML, ""); //$NON-NLS-1$
					// names -> existing vm's
					Map<String, IVMInstall> names = new HashMap<>();
					Set<String> ids = new HashSet<>();
					if (pref.length() > 0) {
						try {
							VMDefinitionsContainer container = VMDefinitionsContainer.parseXMLIntoContainer(new ByteArrayInputStream(pref.getBytes("UTF8"))); //$NON-NLS-1$
							List<IVMInstall> validVMList = container.getValidVMList();
							Iterator<IVMInstall> iterator = validVMList.iterator();
							while (iterator.hasNext()) {
								IVMInstall vm = iterator.next();
								names.put(vm.getName(), vm);
								ids.add(vm.getId());
								vms.addVM(vm);
							}
							vms.setDefaultVMInstallCompositeID(container.getDefaultVMInstallCompositeID());
							vms.setDefaultVMInstallConnectorTypeID(container.getDefaultVMInstallConnectorTypeID());
						} catch (IOException e) {
							LaunchingPlugin.log(e);
							return false;
						}
					}
					// merge valid VMs with existing VMs
					try {
						ByteArrayInputStream inputStream = new ByteArrayInputStream(jresXML.getBytes("UTF8")); //$NON-NLS-1$
						VMDefinitionsContainer container = VMDefinitionsContainer.parseXMLIntoContainer(inputStream);
						List<IVMInstall> validVMList = container.getValidVMList();
						Iterator<IVMInstall> iterator = validVMList.iterator();
						while (iterator.hasNext()) {
							IVMInstall vm = iterator.next();
							IVMInstall existing = names.get(vm.getName());
							if (existing != null) {
								// VM with same name already exists - replace with imported VM
								vms.removeVM(existing);
								ids.remove(existing.getId());
							}
							boolean collision = ids.contains(vm.getId());
							if (collision) {
								// conflicting id, create a new one with unique id
								long unique = System.currentTimeMillis();
								while(ids.contains(String.valueOf(unique))){
									unique++;
								}
								vm = new VMStandin(vm, String.valueOf(unique));
								ids.add(vm.getId());
							}
							vms.addVM(vm);
						}
						// update default VM if it exists
						String defaultVMInstallCompositeID = container.getDefaultVMInstallCompositeID();
						validVMList = vms.getValidVMList();
						iterator = validVMList.iterator();
						while (iterator.hasNext()) {
							IVMInstall vm = iterator.next();
							if (JavaRuntime.getCompositeIdFromVM(vm).equals(defaultVMInstallCompositeID)) {
								vms.setDefaultVMInstallCompositeID(defaultVMInstallCompositeID);
								break;
							}
						}
					} catch (IOException e) {
						LaunchingPlugin.log(e);
						return false;
					}
					try {
						String xml = vms.getAsXML();
						node.put(JavaRuntime.PREF_VM_XML, xml);
					}  catch (CoreException e) {
						LaunchingPlugin.log(e);
						return false;
					}
				}
				return false;
			}
			return true;
		}

	}

	@Override
	public IEclipsePreferences preApply(IEclipsePreferences node) {
		try {
			// force VMs to be initialized before we import the new VMs
			JavaRuntime.getVMInstallTypes();
			node.accept(new Visitor());
		} catch (BackingStoreException e) {
            LaunchingPlugin.log(e);
		}
		return node;
	}


}