/*******************************************************************************
 * Copyright (c) 2004 IBM Corporation and others.
 * 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:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jst.jsp.core.internal.java.search;

import java.io.File;
import java.util.HashMap;

import org.eclipse.core.resources.IFile;
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.runtime.CoreException;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Platform;
import org.eclipse.core.runtime.Plugin;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.runtime.content.IContentType;
import org.eclipse.core.runtime.jobs.IJobChangeEvent;
import org.eclipse.core.runtime.jobs.Job;
import org.eclipse.core.runtime.jobs.JobChangeAdapter;
import org.eclipse.jdt.internal.core.JavaModelManager;
import org.eclipse.jdt.internal.core.index.Index;
import org.eclipse.jdt.internal.core.search.indexing.IndexManager;
import org.eclipse.jst.jsp.core.internal.JSPCoreMessages;
import org.eclipse.jst.jsp.core.internal.JSPCorePlugin;
import org.eclipse.jst.jsp.core.internal.Logger;
import org.eclipse.jst.jsp.core.internal.provisional.contenttype.ContentTypeIdForJSP;
import org.eclipse.osgi.util.NLS;
import org.osgi.framework.Bundle;

/**
 * Responsible for keeping the JSP index up to date.
 * 
 * @author pavery
 */
public class JSPIndexManager implements IResourceChangeListener {
	
	// for debugging
	static final boolean DEBUG;
	static {
		String value= Platform.getDebugOption("org.eclipse.jst.jsp.core/debug/jspindexmanager"); //$NON-NLS-1$
		DEBUG= value != null && value.equalsIgnoreCase("true"); //$NON-NLS-1$
	}
	
	private static final String PKEY_INDEX_STATE = "jspIndexState"; //$NON-NLS-1$

	
	// set to S_UPDATING once a resource change comes in
	// set to S_STABLE if:
	// - we know we aren't interested in the resource change
	// - or the ProcessFilesJob completes
	// set to S_CANCELED if an indexing job is canceled
	// set to S_REBUILDING if re-indexing the entire workspace

	// the int '0' is reserved for the default value if a preference is not there
	/** index is reliable to use*/
	public static final int S_STABLE = 1;
	/** index is being updated (from a resource delta)*/
	public static final int S_UPDATING = 2;
	/** entire index is being rebuilt */
	public static final int S_REBUILDING = 3;
	/** indexing job was canceled in the middle of it, index needs to be rebuilt */
	public static final int S_CANCELED = 4;
	
	/** symbolic name for OSGI framework */
	private final String OSGI_FRAMEWORK_ID = "org.eclipse.osgi"; //$NON-NLS-1$
	
	/**
	 * Collects JSP files from a resource delta.
	 */
	private class JSPResourceVisitor implements IResourceDeltaVisitor {
		// using hash map ensures only one of each file
		// must be reset before every use
		private HashMap jspFiles = null;
		
		public JSPResourceVisitor() {
			this.jspFiles = new HashMap();
		}
		
		public boolean visit(IResourceDelta delta) throws CoreException {
			
			// in case JSP search was canceled (eg. when closing the editor)
			if(JSPSearchSupport.getInstance().isCanceled() || frameworkIsShuttingDown()) {
				setCanceledState();
				return false;
			}
			
			try {
				if(!isHiddenResource(delta.getFullPath())) {
					
					int kind = delta.getKind();
					boolean added = (kind & IResourceDelta.ADDED) == IResourceDelta.ADDED;
					boolean isInterestingChange = false;
					if((kind & IResourceDelta.CHANGED) == IResourceDelta.CHANGED) {
						int flags = delta.getFlags();
						// ignore things like marker changes
						isInterestingChange = (flags & IResourceDelta.CONTENT) == IResourceDelta.CONTENT || (flags & IResourceDelta.REPLACED) == IResourceDelta.REPLACED;
					}
					boolean removed = (kind & IResourceDelta.REMOVED) == IResourceDelta.REMOVED;
					if(added || isInterestingChange) {
						
						// https://w3.opensource.ibm.com/bugzilla/show_bug.cgi?id=3553
						// quick check if it's even JSP related to improve performance
						// checking name from the delta before getting resource because it's lighter
						int numSegments = delta.getFullPath().segmentCount();
						String filename = delta.getFullPath().segment(numSegments-1);
						if (getJspContentType().isAssociatedWith(filename)) {
							IResource r = delta.getResource();
							if (r != null && r.exists() && r.getType() == IResource.FILE) {
								this.jspFiles.put(r.getFullPath(), r);
							}
						}
					}
					else if(removed) {
						// handle cleanup 
						if(delta.getResource() != null) {
							IResource r = delta.getResource();
							if(r.getType() == IResource.FOLDER && r.exists()) {
								deleteIndex((IFile)r);
							}
						}
					}
				}
			}
			catch (Exception e){
				// need to set state here somehow, and reindex
				// otherwise index will be unreliable
				if(DEBUG)
					Logger.logException("Delta analysis may not be complete",  e); //$NON-NLS-1$
			}
			// if the delta has children, continue to add/remove files
			return true;
		}
		// https://bugs.eclipse.org/bugs/show_bug.cgi?id=93463
		private boolean isHiddenResource(IPath p) {
			String[] segments = p.segments();
			for (int i = 0; i < segments.length; i++) {
				if(segments[i].startsWith("."))	//$NON-NLS-1$
					return true;
			}
			return false;
		}
		
		private void deleteIndex(IFile folder) {
			// cleanup index
			IndexManager im = JavaModelManager.getJavaModelManager().getIndexManager();
			IPath folderPath = folder.getFullPath();
			IPath indexLocation = JSPSearchSupport.getInstance().computeIndexLocation(folderPath);
			im.removeIndex(indexLocation);
//			im.indexLocations.removeKey(folderPath);
//			im.indexLocations.removeValue(indexLocation);
			File f = indexLocation.toFile();
			f.delete();
		}
		
		public IFile[] getFiles() {
			return (IFile[])this.jspFiles.values().toArray(new IFile[this.jspFiles.size()]);
		}
		
		public void reset() {
			this.jspFiles.clear();
		}
	}
	// end class JSPResourceVisitor
	
	/**
	 * schedules JSP files for indexing by Java core
	 */
	private class ProcessFilesJob extends Job { 
		IFile[] jspFiles =  null;
		ProcessFilesJob(String taskName, IFile[] files) {
			super(taskName);
			this.jspFiles = files;
		}
		
		protected IStatus run(IProgressMonitor monitor) {
			
			if(isCanceled(monitor) || frameworkIsShuttingDown()) {
				setCanceledState();
				return Status.CANCEL_STATUS;
			}
			
			long start = System.currentTimeMillis();
			
			try {
				// API indicates that monitor is never null
				monitor.beginTask("", this.jspFiles .length); //$NON-NLS-1$
				JSPSearchSupport ss = JSPSearchSupport.getInstance();
				String processingNFiles = ""; //$NON-NLS-1$

				
				for(int i = 0; i<this.jspFiles.length; i++) {

					if(isCanceled(monitor) || frameworkIsShuttingDown()) {
						setCanceledState();
						return Status.CANCEL_STATUS;
					}
					try {
						ss.addJspFile(this.jspFiles [i]);
						// JSP Indexer processing n files
						processingNFiles = NLS.bind(JSPCoreMessages.JSPIndexManager_2, new String[]{Integer.toString((this.jspFiles .length -i))});
						monitor.subTask(processingNFiles + " - " + this.jspFiles [i].getName()); //$NON-NLS-1$
						monitor.worked(1);
						
						if(DEBUG) {
							System.out.println("JSPIndexManager Job added file: " + this.jspFiles [i].getName()); //$NON-NLS-1$
						}
					}
					catch (Exception e){
					    // RATLC00284776
					    // ISSUE: we probably shouldn't be catching EVERY exception, but
					    // the framework only allows to return IStatus in order to communicate
					    // that something went wrong, which means the loop
					    // won't complete, and we would hit the same problem the next time.
					    // 
					    // a possible solution is to keep track of the exceptions logged
					    // and only log a certain amt of the same one, otherwise skip it.
						if(!frameworkIsShuttingDown()) {
						    String filename = this.jspFiles[i] != null ? this.jspFiles[i].getFullPath().toString() : ""; //$NON-NLS-1$
						    Logger.logException("JSPIndexer problem indexing:" + filename,  e); //$NON-NLS-1$
						}
					}
				} // end for
			}
			finally {
				// just in case something didn't follow API (monitor is null)
				if(monitor != null)
					monitor.done();
			}
			
			long finish = System.currentTimeMillis();
			long diff = finish - start;
			if(DEBUG) {
				fTotalTime += diff;
				System.out.println("============================================================================"); //$NON-NLS-1$
				System.out.println("this time: " + diff +" cumulative time for resource changed: " + fTotalTime); //$NON-NLS-1$ //$NON-NLS-2$
				System.out.println("============================================================================"); //$NON-NLS-1$
			}	
			return Status.OK_STATUS;
		}
		
		private boolean isCanceled(IProgressMonitor runMonitor) {
			
			boolean canceled = false;
			// check specific monitor passed into run method (the progress group in this case)
			// check main search support canceled
			if(runMonitor != null && runMonitor.isCanceled())
				canceled = true;
			else if(JSPSearchSupport.getInstance().isCanceled())
				canceled = true;
			return canceled;
		}
	}
	// end class ProcessFilesJob
	
	private static JSPIndexManager fSingleton = null;
	private JSPResourceVisitor fVisitor = null;
	private IContentType fContentTypeJSP = null;
		
	static long fTotalTime = 0;
	
	private JSPIndexManager(){
		// only one instance
	}
	
	public synchronized static JSPIndexManager getInstance() {
		
		if(fSingleton == null)
			fSingleton = new JSPIndexManager();
		return fSingleton;
	}
	
	/**
	 * @see org.eclipse.core.resources.IResourceChangeListener#resourceChanged(org.eclipse.core.resources.IResourceChangeEvent)
	 */
	public void resourceChanged(IResourceChangeEvent event) {
		
		// ignore resource changes if already rebuilding
		if(getIndexState() == S_REBUILDING)
			return;
		// previously canceled, needs entire index rebuild
		if(getIndexState() == S_CANCELED) {
			rebuildIndex();
			return;
		}
		
		// set flag, so we know if a job is going to be started
		// and the state will eventually be set back to S_STABLE
		boolean beganProcess = false;
		setUpdatingState();
		
		IResourceDelta delta = event.getDelta();
		if(delta != null) {
			// only care about adds or changes right now...
			int kind = delta.getKind();
			boolean added = (kind & IResourceDelta.ADDED) == IResourceDelta.ADDED;
			boolean changed = (kind & IResourceDelta.CHANGED) == IResourceDelta.CHANGED;
			if(added || changed) {
				
				// only analyze the full (starting at root) delta hierarchy
				if(delta.getFullPath().toString().equals("/")) { //$NON-NLS-1$
					try {
						JSPResourceVisitor v = getVisitor();
						// clear from last run
						v.reset();
						// count files, possibly do this in a job too...
						// don't include PHANTOM resources
						delta.accept(v, false);
						
						// process files from this delta
						IFile[] files = v.getFiles();
						if(files.length > 0) {	
							//processFiles(files);
							indexFiles(files);
							beganProcess = true;
						}
					}
					catch (CoreException e) {
						// need to set state here somehow, and reindex
						// otherwise index will be unreliable
						if(DEBUG)
							Logger.logException(e);
					}
					catch (Exception e) {
						// need to set state here somehow, and reindex
						// otherwise index will be unreliable
						if(DEBUG)
							Logger.logException(e);
					}
				}
			}

		}
		// if we never kicked off process, job won't set back to stable
		// so we set it here
		if(!beganProcess) {
			setStableState();
		}
	}
	
	public synchronized void setIndexState(int state) {
		if(DEBUG) {
			System.out.println("JSPIndexManager setting index state to: " + state2String(state)); //$NON-NLS-1$
		}
		Plugin jspModelPlugin = JSPCorePlugin.getDefault();
		jspModelPlugin.getPluginPreferences().setValue(PKEY_INDEX_STATE, state);
		jspModelPlugin.savePluginPreferences();
		
	}
	private String state2String(int state) {
		String s = "UNKNOWN";	//$NON-NLS-1$
		switch(state) {
			case(S_STABLE):
				s = "S_STABLE";	//$NON-NLS-1$
				break;
			case(S_UPDATING):
				s = "S_UPDATING";	//$NON-NLS-1$
				break;
			case(S_CANCELED):
				s = "S_CANCELED";	//$NON-NLS-1$
				break;
			case(S_REBUILDING):
				s = "S_REBUILDING";	//$NON-NLS-1$
				break;
		}
		return s;
	}
	public int getIndexState() {
		return JSPCorePlugin.getDefault().getPluginPreferences().getInt(PKEY_INDEX_STATE); 
	}
	public void setUpdatingState() {
		if(getIndexState() != S_CANCELED)
			setIndexState(S_UPDATING);
	}
	public void setCanceledState() {
		setIndexState(JSPIndexManager.S_CANCELED);
	}
	// ca
	public void setStableState() {
		if(getIndexState() != S_CANCELED)
			setIndexState(S_STABLE);
	}
	public void setRebuildingState() {
		setIndexState(S_REBUILDING);
	}
	public synchronized void rebuildIndexIfNeeded() {
		if(getIndexState() != S_STABLE) {
			rebuildIndex();
		}
	}
	
	private void rebuildIndex() {
		
		if(DEBUG) 
			System.out.println("*** JSP Index unstable, requesting re-indexing"); //$NON-NLS-1$

		final IndexWorkspaceJob indexingJob = new IndexWorkspaceJob();
		
		indexingJob.addJobChangeListener(new JobChangeAdapter() {
			public void aboutToRun(IJobChangeEvent event) {
				super.aboutToRun(event);
				setRebuildingState();
			}
			public void done(IJobChangeEvent event) {
				super.done(event);
				setStableState();
				indexingJob.removeJobChangeListener(this);
			}
		});
		indexingJob.schedule();
		
	}
	
	/**
	 * Creates and schedules a Job to process collected files.
	 * All JSP indexing should be done through this method or processFiles(IFile file)
	 * @param files
	 */
	public final void indexFiles(IFile[] files) {
		// updating JSP Index
		String taskName = JSPCoreMessages.JSPIndexManager_0;
		
		// Processing resource delta
		final Job processFiles = new ProcessFilesJob(taskName, files);

		// only show in verbose mode
		processFiles.setSystem(true);
		
		// don't use this rule
		// https://w3.opensource.ibm.com/bugzilla/show_bug.cgi?id=4931
		//processFiles.setRule(new IndexFileRule());
		
		processFiles.setPriority(Job.LONG);
		processFiles.addJobChangeListener(new JobChangeAdapter() {
			public void done(IJobChangeEvent event) {
				super.done(event);
				setStableState();
			}
		});
		processFiles.schedule();
	}
	
	
	/**
	 * Package protected for access by inner Job class in resourceChanged(...)
	 * @return
	 */
	JSPResourceVisitor getVisitor()  {
		
		if(this.fVisitor == null) {
			this.fVisitor = new JSPResourceVisitor();
		}
		return this.fVisitor;
	}
	
	// https://w3.opensource.ibm.com/bugzilla/show_bug.cgi?id=5091
	// makes sure IndexManager is aware of our indexes
	public void saveIndexes() {
		IndexManager indexManager = JavaModelManager.getJavaModelManager().getIndexManager();
		IPath jspModelWorkingLocation = JSPSearchSupport.getInstance().getModelJspPluginWorkingLocation();
		
		File folder = new File(jspModelWorkingLocation.toOSString());
		String[] files = folder.list();
		String locay = ""; //$NON-NLS-1$
		Index index = null;
		try {
			for(int i=0; i<files.length; i++) {
				if(files[i].toLowerCase().endsWith(".index")) { //$NON-NLS-1$
					locay = jspModelWorkingLocation.toString() +"/" + files[i]; //$NON-NLS-1$
					index = new Index(locay, "Index for " + locay, true /*reuse index file*/); //$NON-NLS-1$
					indexManager.saveIndex(index);
				}
			}
		}
		catch (Exception e) {
			// we should be shutting down, want to shut down quietly
			if(DEBUG)
				e.printStackTrace();
		}
	}
	
	IContentType getJspContentType() {
		if(this.fContentTypeJSP == null)
			this.fContentTypeJSP = Platform.getContentTypeManager().getContentType(ContentTypeIdForJSP.ContentTypeID_JSP);
		return this.fContentTypeJSP;
	}
	
	/**
	 * A check to see if the OSGI framework is shutting down.
	 * @return true if the System Bundle is stopped (ie. the framework is shutting down)
	 */
	boolean frameworkIsShuttingDown() {
		// in the Framework class there's a note:
		// set the state of the System Bundle to STOPPING.
		// this must be done first according to section 4.19.2 from the OSGi R3 spec.  
		boolean shuttingDown = Platform.getBundle(OSGI_FRAMEWORK_ID).getState() == Bundle.STOPPING;
		if (DEBUG && shuttingDown) {
			System.out.println("JSPIndexManager: system is shutting down!"); //$NON-NLS-1$
		}
		return shuttingDown;
	}
}