/*******************************************************************************
 * Copyright (c) 2005 BEA Systems, Inc.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 * rfrost@bea.com - initial API and implementation
 *******************************************************************************/

package org.eclipse.jst.j2ee.refactor.listeners;

import java.util.HashMap;
import java.util.Map;

import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IResourceChangeEvent;
import org.eclipse.core.resources.IResourceChangeListener;
import org.eclipse.core.resources.IResourceDelta;
import org.eclipse.core.resources.IResourceDeltaVisitor;
import org.eclipse.core.resources.IWorkspaceRoot;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.resources.WorkspaceJob;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.jem.util.logger.proxy.Logger;
import org.eclipse.jst.j2ee.internal.plugin.J2EEPlugin;
import org.eclipse.jst.j2ee.refactor.RefactorResourceHandler;
import org.eclipse.jst.j2ee.refactor.operations.ProjectDeleteDataModelProvider;
import org.eclipse.jst.j2ee.refactor.operations.ProjectRefactorMetadata;
import org.eclipse.jst.j2ee.refactor.operations.ProjectRefactoringDataModelProvider;
import org.eclipse.jst.j2ee.refactor.operations.ProjectRenameDataModelProvider;
import org.eclipse.wst.common.componentcore.ModuleCoreNature;
import org.eclipse.wst.common.componentcore.internal.builder.DependencyGraphManager;
import org.eclipse.wst.common.frameworks.datamodel.DataModelFactory;
import org.eclipse.wst.common.frameworks.datamodel.IDataModel;

/**
 * Listens for project rename/delete events and, if the project had the
 * ModuleCore nature, executes the appropriate logic to update
 * project references.
  */
public final class ProjectRefactoringListener implements IResourceChangeListener, IResourceDeltaVisitor {
	
	/*
	 * Map from name of deleted project to ProjectRefactorMetadata instances.
	 */
	private final Map deletedProjectMetadata = new HashMap();
	
	/**
	 * Maintains a cache of project depencencies;
	 */
	//private final ProjectDependencyCache cache;
	
	//private boolean hasProcessedSavedState = false;
	
	public ProjectRefactoringListener() {//final ProjectDependencyCache dependencyCache) {
		//cache = dependencyCache;
		// force a refresh of the DependencyGraphManager; was hitting an NPE
		// in StructureEdit when the DGM was getting constructed during the receipt of the
		// first pre-delete event
		DependencyGraphManager.getInstance();
	}
	
	// XXX not very feasible to make workspace save participation work given the need to process the
	// pre-delete events
	/*private synchronized void processPendingEvents() {
		if (hasProcessedSavedState) {
			return;
		}
		hasProcessedSavedState = true;
		//process any project rename/delete events that have occurred prior to our activation 
		try {
			ISavedState lastState =	ResourcesPlugin.getWorkspace().addSaveParticipant(J2EEPlugin.getDefault(), this);
			if (lastState != null) {
				lastState.processResourceChangeEvents(this);
			}
		} catch (CoreException ce) {
			Logger.getLogger().logError(ce);
		}
	}*/
	
	/* (non-Javadoc)
	 * @see org.eclipse.core.resources.IResourceChangeListener#resourceChanged(org.eclipse.core.resources.IResourceChangeEvent)
	 */
	public void resourceChanged(final IResourceChangeEvent event) {
		// if we haven't already processed the pending resource change events, process them 
		//processPendingEvents();
		
		// need to capture PRE_DELETE events so that metadata about the
		// deleted project can be collected and cached
		try {
			/*if (event.getType() == IResourceChangeEvent.POST_BUILD) {
				// we get this event type when processing pending events
				IResource resource = event.getResource();
				IResourceDelta delta = event.getDelta();
				if (resource instanceof IProject && delta.getKind() == IResourceDelta.REMOVED) {
					cacheDeletedProjectMetadata((IProject)resource);
				} else {
					delta.accept(this);
				}
			} else */
			if (event.getType() == IResourceChangeEvent.PRE_DELETE) {
				// for now, only dependencies on ModuleCoreNature projects
				final IProject project = (IProject) event.getResource();
				if (ModuleCoreNature.getModuleCoreNature(project) != null) {
					cacheDeletedProjectMetadata(project);
				}
			} else {
				event.getDelta().accept(this);
			}
		} catch (CoreException ce) {
			Logger.getLogger().logError(ce);
		}
	}
	
	private synchronized void cacheDeletedProjectMetadata(final IProject project) {
		final ProjectRefactorMetadata metadata = new ProjectRefactorMetadata(project, ProjectRefactorMetadata.REFERER_CACHING);
		// precompute the metadata while the project still exists
		metadata.computeMetadata();
		metadata.computeServers();
		metadata.computeDependentMetadata(ProjectRefactorMetadata.REF_CACHING,
				DependencyGraphManager.getInstance().getDependencyGraph().getReferencingComponents(project));
		//, cache.getDependentProjects(project));
		deletedProjectMetadata.put(project.getName(), metadata); 		
	}
	
	/* (non-Javadoc)
	 * @see org.eclipse.core.resources.IResourceDeltaVisitor#visit(org.eclipse.core.resources.IResourceDelta)
	 */
	public boolean visit(final IResourceDelta delta) throws CoreException {
		final IResource resource = delta.getResource();
		if (resource instanceof IWorkspaceRoot) {
			// delta is at the workspace root so keep going
			return true;
		} else if (resource instanceof IProject) {
			processProjectDelta((IProject) resource, delta);
		}
		return false;
	}

	/*
	 * Process the project delta in a sync block.
	 */
	private synchronized void processProjectDelta(final IProject project, final IResourceDelta delta) throws CoreException {
		final int kind = delta.getKind();
		final int flags = delta.getFlags();

		if (kind == IResourceDelta.REMOVED) {
			if (flags == 0) {
				// Remove all entries int the project dependency cache
				//cache.removeProject(project);
				// if the kind is REMOVED and there are no special flags, the project was deleted
				ProjectRefactorMetadata metadata = (ProjectRefactorMetadata) deletedProjectMetadata.remove(project.getName()); 
				// note: only projects with ModuleCoreNature will have cached metadata
				if (metadata != null) {
					processDelete(metadata);
				} else {
					// likely due to missing the pre-delete event, ignore for now
					//Logger.getLogger().logWarning(RefactorResourceHandler.getString("pre_delete_not_received_for_removed",  
					//new Object[]{project.getName()}));
				}
			} 
		} else if (kind == IResourceDelta.ADDED && wasRenamed(flags)) { // was renamed
			// get the original name
			final String originalName = delta.getMovedFromPath().lastSegment();
			//Logger.getLogger().logInfo("Added event for " + originalName + " with flags " + flags);
			// we get PRE_DELETE events on rename so retrieve this
			ProjectRefactorMetadata originalMetadata = (ProjectRefactorMetadata) deletedProjectMetadata.remove(originalName);
			// get the metadata for the new project
			final ProjectRefactorMetadata newMetadata = new ProjectRefactorMetadata(project);
			// note: only projects with ModuleCoreNature will have cached metadata
			if (originalMetadata != null) {
				newMetadata.computeMetadata();
				processRename(originalMetadata, newMetadata);
				// Rename all entries in the project dependency cache
				//cache.replaceProject(originalProject, project);
			} else {
				// likely due to missing the pre-delete event, so set the original to a metadata based on new project
				// and reset project to one based on original name
				//Logger.getLogger().logWarning(RefactorResourceHandler.getString("pre_delete_not_received_for_renamed", new Object[]{originalName + " " + flags}));
			}
		} 
		//else if (kind == IResourceDelta.CHANGED || kind == IResourceDelta.ADDED) { 
		// (re)compute the dependencies
		//cache.refreshDependencies(project);
		//}		
	}
	
	/*
	 * Determines if the project was renamed based on the IResourceDelta flags 
	 */
	private boolean wasRenamed(final int flags) {
		if ((flags & IResourceDelta.DESCRIPTION) > 0
			&& (flags & IResourceDelta.MOVED_FROM) > 0) {
			return true;
		}
		return false;
	}
	
	/*
	 * Processes the renaming of a project.
	 */
	private void processRename(final ProjectRefactorMetadata originalMetadata, final ProjectRefactorMetadata newMetadata ) {
		WorkspaceJob job = new WorkspaceJob("J2EEProjectRenameJob") {
			public IStatus runInWorkspace(IProgressMonitor monitor) throws CoreException {
				final IDataModel dataModel = DataModelFactory.createDataModel(new ProjectRenameDataModelProvider());
				dataModel.setProperty(ProjectRefactoringDataModelProvider.PROJECT_METADATA, newMetadata);
				dataModel.setProperty(ProjectRenameDataModelProvider.ORIGINAL_PROJECT_METADATA, originalMetadata);
				try {
					dataModel.getDefaultOperation().execute(monitor, null);
				} catch (Exception e) {
					final String msg = RefactorResourceHandler.getString("error_updating_project_on_rename", new Object[]{originalMetadata.getProjectName()});
					Logger.getLogger().logError(msg);
					Logger.getLogger().logError(e);
					return new Status(Status.ERROR, J2EEPlugin.PLUGIN_ID, 0, msg, e);
				}				
				return Status.OK_STATUS;
			}
		};
		// XXX note: might want to consider switching to a MultiRule for optimization
		job.setRule(ResourcesPlugin.getWorkspace().getRoot());
		job.schedule();
	}
	
	/*
	 * Processes the deletion of a project.
	 */
	private void processDelete(final ProjectRefactorMetadata metadata) {
		WorkspaceJob job = new WorkspaceJob("J2EEProjectDeleteJob") {
			public IStatus runInWorkspace(IProgressMonitor monitor) throws CoreException {
				final IDataModel dataModel = DataModelFactory.createDataModel(new ProjectDeleteDataModelProvider());
				dataModel.setProperty(ProjectRefactoringDataModelProvider.PROJECT_METADATA, metadata);
				try {
					dataModel.getDefaultOperation().execute(monitor, null);
				} catch (Exception e) {
					final String msg = RefactorResourceHandler.getString("error_updating_project_on_delete", new Object[]{metadata.getProjectName()});
					Logger.getLogger().logError(msg);
					Logger.getLogger().logError(e);
					return new Status(Status.ERROR, J2EEPlugin.PLUGIN_ID, 0, msg, e);
				}
				return Status.OK_STATUS;
			}
		};
		// XXX note: might want to consider switching to a MultiRule for optimization
		job.setRule(ResourcesPlugin.getWorkspace().getRoot());
		job.schedule();
	}

	/* (non-Javadoc)
	 * @see org.eclipse.core.resources.ISaveParticipant#doneSaving(org.eclipse.core.resources.ISaveContext)
	 */
//	public void doneSaving(ISaveContext context) {
//	}

	/* (non-Javadoc)
	 * @see org.eclipse.core.resources.ISaveParticipant#prepareToSave(org.eclipse.core.resources.ISaveContext)
	 */
//	public void prepareToSave(ISaveContext context) throws CoreException {
//	}

	/* (non-Javadoc)
	 * @see org.eclipse.core.resources.ISaveParticipant#rollback(org.eclipse.core.resources.ISaveContext)
	 */
//	public void rollback(ISaveContext context) {
//	}

	/* (non-Javadoc)
	 * @see org.eclipse.core.resources.ISaveParticipant#saving(org.eclipse.core.resources.ISaveContext)
	 */
//	public void saving(ISaveContext context) throws CoreException {
//		// no state to be saved by the plug-in, but request a
//		// resource delta to be used on next activation.
//	    context.needDelta();
//	}

}