/******************************************************************************* 
 * Copyright (c) 2009 Red Hat, Inc. 
 * Distributed under license by Red Hat, Inc. All rights reserved. 
 * This program is 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: 
 * Red Hat, Inc. - initial API and implementation 
 ******************************************************************************/
package org.jboss.tools.common.model.filesystems.impl;

import java.io.File;
import java.util.ArrayList;
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.resources.IProject;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.Path;
import org.eclipse.jdt.core.ElementChangedEvent;
import org.eclipse.jdt.core.IClasspathEntry;
import org.eclipse.jdt.core.IElementChangedListener;
import org.eclipse.jdt.core.IJavaElementDelta;
import org.eclipse.jdt.core.IJavaProject;
import org.eclipse.jdt.core.JavaCore;
import org.eclipse.jdt.core.JavaModelException;
import org.jboss.tools.common.model.XModelObject;
import org.jboss.tools.common.model.XModelObjectConstants;
import org.jboss.tools.common.model.plugin.ModelPlugin;
import org.jboss.tools.common.model.util.EclipseResourceUtil;
import org.jboss.tools.common.model.util.XModelObjectUtil;
import org.jboss.tools.common.util.UniquePaths;

/**
 * 
 * @author Viacheslav Kabanovich
 *
 */
public class Libs implements IElementChangedListener {
	protected FileSystemsImpl object;
	protected List<String> paths = null;
	Map<IPath, String> paths2 = new HashMap<IPath, String>();
	Set<String> projects = new HashSet<String>();

	LibraryNames libraryNames = new LibraryNames();
	int excudedState = 0;

	List<LibsListener> listeners = new ArrayList<LibsListener>();
	
	public Libs(FileSystemsImpl object) {
		this.object = object;
	}

	public void init() {
		JavaCore.addElementChangedListener(this);
	}

	private IProject getProjectResource() {
		return EclipseResourceUtil.getProject(object);
	}

	public XModelObject getLibrary(String path) {
		String libName = libraryNames.getName(path);
		if(libName == null) {
			//compatibility to old code.
			libName = LIB_PREFIX + new File(path).getName();
		}
		return object.getChildByPath(libName);
	}

	public XModelObject getLibrary(File f) {
		XModelObject result = null;
		if(f.exists()) {
			String path = f.getAbsolutePath().replace('\\', '/');
			result = getLibrary(path);
		}
		return result;
	}

	public boolean update() {
		boolean result = false;
		int cpv = classpathVersion;
		if(hasToUpdatePaths()) {
			result = updatePaths(getNewPaths(), cpv);
			if(isExcludedStateChanged()) {
				result = true;
			}
			if(paths == null && result) {
				fire();
				return true;
			}
		}	
	
		if(paths != null && fsVersion < pathsVersion) {
			updateFileSystems(paths, 0);
		}
		fsVersion = pathsVersion;

		if(result) {
			fire();
		}
		return result;
	}

	public void requestForUpdate() {
		classpathVersion++;
	}

	synchronized boolean hasToUpdatePaths() {
		return (classpathVersion > pathsVersion);
	}

	private List<String> getNewPaths() {
		List<String> result = null;
		try {
			result = EclipseResourceUtil.getAllVisibleLibraries(getProjectResource());
			List<String> jre = EclipseResourceUtil.getJREClassPath(getProjectResource());
			if(jre != null) result.removeAll(jre);
			if(result != null) {
				Iterator<String> it = result.iterator();
				while(it.hasNext()) {
					String path = it.next();
					String fileName = new File(path).getName();
					if(EclipseResourceUtil.isJar(path) && EclipseResourceUtil.SYSTEM_JAR_SET.contains(fileName)) {
						it.remove();
					}
				}
			}
			updateProjects();
		} catch (CoreException e) {
			ModelPlugin.getDefault().logError(e);
		}
		return result;
	}

	private void updateProjects() throws JavaModelException {
		Set<String> result = new HashSet<String>();
		IJavaProject javaProject = EclipseResourceUtil.getJavaProject(getProjectResource());
		if(javaProject != null) {
			result.add(getProjectResource().getName());
			IClasspathEntry[] es = javaProject.getResolvedClasspath(true);
			for (int i = 0; i < es.length; i++) {
				if(es[i].getEntryKind() == IClasspathEntry.CPE_PROJECT) {
					IProject p = ResourcesPlugin.getWorkspace().getRoot().getProject(es[i].getPath().lastSegment());
					if(p == null || !p.isAccessible()) continue;
					result.add(p.getName());
				}
			}
		}
		projects = result;
	}

	private boolean isExcludedStateChanged() {
		try {
			int es = computeExcludedState();
			if(es != excudedState) {
				excudedState = es;
				return true;
			}
		} catch (JavaModelException e) {
			ModelPlugin.getDefault().logError(e);
		}
		return false;
	}

	private int computeExcludedState() throws JavaModelException {
		int result = 0;
		IJavaProject javaProject = EclipseResourceUtil.getJavaProject(getProjectResource());
		if(javaProject != null) {
			IClasspathEntry[] es = javaProject.getResolvedClasspath(true);
			for (int i = 0; i < es.length; i++) {
				IPath p = es[i].getPath();
				IPath[] ps = es[i].getExclusionPatterns();
				if(ps != null && ps.length > 0) {
					for (int j = 0; j < ps.length; j++) {
						String key = p.toString() + "/" + ps[j].toString(); //$NON-NLS-1$
						result += key.hashCode();
					}
				}
			}
		}
		return result;
	}

	private synchronized boolean updatePaths(List<String> newPaths, int cpv) {
		if(cpv <= pathsVersion) {
			return false;
		}
		pathsVersion = cpv;
		if(paths == null && newPaths == null) return false;
		if((newPaths != null && paths != null) && (paths.size() == newPaths.size())) {
			boolean b = false;
			for (int i = 0; i < paths.size() && !b; i++) {
				if(!paths.get(i).equals(newPaths.get(i))) b = true;
			}
			if(!b) return false;
		}
		paths = newPaths;
		createMap();
		return true;
	}
	
	public static String LIB_PREFIX = "lib-"; //$NON-NLS-1$

	/**
	 * This method is designed to run safe when invoked by several concurrent threads.
	 * Each thread requesting file systems needs them up-to-date when this method returns.
	 * If thread 1 is already running update, and thread 2 is going to request file systems,
	 * it has to start this method independently, because it cannot rely on the other thread
	 * completing before the file systems are obtained.
	 * Synchronizing this method would involve high risk of a deadlock, 
	 * concurrent modification is a better solution if implemented safely.
	 * 
	 * @param paths
	 * @param iteration
	 */
	private void updateFileSystems(List<String> paths, int iteration) {
		Set<String> oldPaths = libraryNames.getPaths();
		for (String p: oldPaths) {
			if(!paths.contains(p)) {
				String n = libraryNames.getName(p);
				if(n != null) {
					XModelObject o = object.getChildByPath(n);
					if(o != null) {
						o.removeFromParent();
					}
				}
				libraryNames.removePath(p);
			}
		}
		
		XModelObject[] fs = object.getChildren();
		Set<XModelObject> fss = new HashSet<XModelObject>();
		for (int i = 0; i < fs.length; i++) {
			if(fs[i].getAttributeValue(XModelObjectConstants.ATTR_NAME).startsWith(LIB_PREFIX)) {
				fss.add(fs[i]);
			}
		}
		
		if(paths != null) for (int i = 0; i < paths.size(); i++) {
			String path = paths.get(i);
			boolean isJar = EclipseResourceUtil.isJar(path);
			String libEntity = isJar ? "FileSystemJar" : "FileSystemFolder"; //$NON-NLS-1$ //$NON-NLS-2$
			String fileName = new File(path).getName();
			String jsname = libraryNames.getExistingOrNewName(path, fileName);
			XModelObject o = object.getChildByPath(jsname);
			if(o != null) {
				fss.remove(o);
				if(o instanceof JarSystemImpl) {
					((JarSystemImpl)o).update();
				}
			} else {
				o = object.getModel().createModelObject(libEntity, null);
				o.setAttributeValue(XModelObjectConstants.ATTR_NAME, jsname); 
				o.setAttributeValue(XModelObjectConstants.ATTR_NAME_LOCATION, path);
				o.set(FileSystemsLoader.IS_ADDED_TO_CLASSPATH, XModelObjectConstants.TRUE);
				object.addChild(o);
//				object.setModified(true);
			}
			libraryNames.put(path, jsname);
		}
		
		for (XModelObject o: fss) {
			String path = XModelObjectUtil.expand(o.getAttributeValue(XModelObjectConstants.ATTR_NAME_LOCATION), o.getModel(), null);
			if(XModelObjectConstants.TRUE.equals(o.get(FileSystemsLoader.IS_ADDED_TO_CLASSPATH))) {
				o.removeFromParent(); 
			} else if(!new File(path).exists()) {
				o.removeFromParent();
			}			
		}

		List<String> newPaths = this.paths;
		if(newPaths != null && (paths != newPaths || !libraryNames.isValidList(newPaths))) {
			if(iteration == 5) {
				ModelPlugin.getDefault().logWarning("Iterative update of file systems for project " //$NON-NLS-1$
					+ EclipseResourceUtil.getProject(object)
					+ " is interrupted to prevent deadlock."); //$NON-NLS-1$
			} else {
				updateFileSystems(newPaths, iteration + 1);
			}
		}
	}

	public List<String> getPaths() {
		return paths;
	}

	public Map<IPath, String> getPathsAsMap() {
		return paths2;
	}
	
	private void createMap() {
		paths2.clear();
		if(paths != null) {
			for (String p : paths) {
				paths2.put(UniquePaths.getInstance().intern(new Path(p)), p);
			}
		}
	}

	public synchronized void addListener(LibsListener listener) {
		listeners.add(listener);
	}

	public synchronized void removeListener(LibsListener listener) {
		listeners.remove(listener);
	}

	void fire() {
		for (LibsListener listener: getListeners()) {
			listener.pathsChanged(paths);
		}
	}

	private synchronized LibsListener[] getListeners() {
		return listeners.toArray(new LibsListener[0]);
	}

	int classpathVersion = 0;
	int pathsVersion = -1;
	int fsVersion = -1;

	public void elementChanged(ElementChangedEvent event) {
		IProject project = getProjectResource();
		if(project == null || !project.exists()) {
			JavaCore.removeElementChangedListener(this);
			return;
		}

		for (IJavaElementDelta dc: event.getDelta().getAffectedChildren()) {
			if(dc.getElement() instanceof IJavaProject && (isReleventProject(((IJavaProject)dc.getElement()).getProject()))) {
				int f = dc.getFlags();
				if((f & (IJavaElementDelta.F_CLASSPATH_CHANGED 
					| IJavaElementDelta.F_RESOLVED_CLASSPATH_CHANGED)) != 0) {
					requestForUpdate();
					return;
				} else {
					for (IJavaElementDelta d1: dc.getAffectedChildren()) {
//						IJavaElement e = d1.getElement();
						if(d1.getKind() == IJavaElementDelta.ADDED || d1.getKind() == IJavaElementDelta.REMOVED) {
							requestForUpdate();
							return;
						}
					}
				}
			}
		}
	}

	private boolean isReleventProject(IProject p) {
		return projects.contains(p.getName());
	}

	public void libraryChanged(JarSystemImpl jar) {
		for (LibsListener listener: getListeners()) {
			listener.libraryChanged(jar.getLocation());
		}
	}

}

class LibraryNames {
	private Map<String, String> pathToName = new HashMap<String, String>();
	private Map<String, String> nameToPath = new HashMap<String, String>();

	public synchronized void put(String path, String name) {
		pathToName.put(path, name);
		nameToPath.put(name, path);
	}

	public synchronized void removePath(String path) {
		String name = pathToName.remove(path);
		if(name != null) {
			nameToPath.remove(name);
		}
	}

	public String getName(String path) {
		return pathToName.get(path);
	}

	public synchronized String getExistingOrNewName(String path, String fileName) {
		String jsname = getName(path);
		if(jsname == null) {
			jsname = Libs.LIB_PREFIX + fileName;
			int q = 0;
			while(hasName(jsname)) {
				jsname = Libs.LIB_PREFIX + fileName + "-" + (++q); //$NON-NLS-1$
			}				
		}
		return jsname;
	}

	public String getPath(String name) {
		return nameToPath.get(name);
	}

	public boolean hasName(String name) {
		return nameToPath.containsKey(name);
	}

	public synchronized Set<String> getPaths() {
		return new HashSet<String>(pathToName.keySet());
	}

	public synchronized boolean isValidList(List<String> paths) {
		if(pathToName.size() != paths.size()) {
			return false;
		}
		for (String p: paths) {
			if(!pathToName.containsKey(p)) {
				return false;
			}
		}
		return true;
	}
}
