/*******************************************************************************
 * Copyright (c) 2000, 2007 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
 *
 
 *******************************************************************************/
package org.eclipse.dltk.internal.core.util;

import java.util.HashMap;
import java.util.HashSet;

import org.eclipse.core.resources.IFile;
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.dltk.compiler.CharOperation;
import org.eclipse.dltk.compiler.env.lookup.Scope;
import org.eclipse.dltk.core.DLTKCore;
import org.eclipse.dltk.core.DLTKLanguageManager;
import org.eclipse.dltk.core.IBuildpathEntry;
import org.eclipse.dltk.core.IScriptProject;
import org.eclipse.dltk.core.IModelElement;
import org.eclipse.dltk.core.IProjectFragment;
import org.eclipse.dltk.core.IScriptFolder;
import org.eclipse.dltk.core.ISourceModule;
import org.eclipse.dltk.core.ModelException;
import org.eclipse.dltk.core.search.IDLTKSearchScope;
import org.eclipse.dltk.internal.compiler.lookup.TypeScope;
import org.eclipse.dltk.internal.core.ScriptProject;
import org.eclipse.dltk.internal.core.Model;
import org.eclipse.dltk.internal.core.ModelManager;
import org.eclipse.dltk.internal.core.Openable;
import org.eclipse.dltk.internal.core.ProjectFragment;


/**
 * Creates script element handles.
 */
public class HandleFactory {

	/**
	 * Cache package fragment root information to optimize speed performance.
	 */
	private String lastPkgFragmentRootPath;
	private IProjectFragment lastPkgFragmentRoot;

	/**
	 * Cache package handles to optimize memory.
	 */
	private HashtableOfArrayToObject packageHandles;

	private Model model;

	public HandleFactory() {
		this.model = ModelManager.getModelManager().getModel();
	}
	

	/**
	 * Creates an Openable handle from the given resource path.
	 * 
	 * If not null, uses the given scope as a hint for getting DLTK project handles.
	 */
	public Openable createOpenable(String resourcePath, IDLTKSearchScope scope) {
		int separatorIndex;
		if ((separatorIndex= resourcePath.indexOf(IDLTKSearchScope.FILE_ENTRY_SEPARATOR)) > -1) {
			// path to a class file inside a archive
			// Optimization: cache package fragment root handle and package handles
			int rootPathLength;
			if (this.lastPkgFragmentRootPath == null 
					|| (rootPathLength = this.lastPkgFragmentRootPath.length()) != resourcePath.length()
					|| !resourcePath.regionMatches(0, this.lastPkgFragmentRootPath, 0, rootPathLength)) {
				String archivePath= resourcePath.substring(0, separatorIndex);
				IProjectFragment root= this.getArchiveProjectFragment(archivePath, scope);
				if (root == null)
					return null; // match is outside classpath
				this.lastPkgFragmentRootPath= archivePath;
				this.lastPkgFragmentRoot= root;
				this.packageHandles= new HashtableOfArrayToObject(5);
			}
			// create handle
			String classFilePath= resourcePath.substring(separatorIndex + 1);
			String[] simpleNames = new Path(classFilePath).segments();
			String[] pkgName;
			int length = simpleNames.length-1;
			if (length > 0) {
				pkgName = new String[length];
				System.arraycopy(simpleNames, 0, pkgName, 0, length);
			} else {
				pkgName = CharOperation.NO_STRINGS;
			}
			IScriptFolder pkgFragment= (IScriptFolder) this.packageHandles.get(pkgName);
			if (pkgFragment == null) {				
				pkgFragment= ((ProjectFragment) this.lastPkgFragmentRoot).getScriptFolder(toPath(pkgName));
				this.packageHandles.put(pkgName, pkgFragment);
			}
			ISourceModule classFile= pkgFragment.getSourceModule(simpleNames[length]);
			return (Openable) classFile;
		} else {
			// path to a file in a directory
			// Optimization: cache package fragment root handle and package handles
			int rootPathLength = -1;
			if (this.lastPkgFragmentRootPath == null 
				|| !(resourcePath.startsWith(this.lastPkgFragmentRootPath) 
					&& (rootPathLength = this.lastPkgFragmentRootPath.length()) > 0
					&& resourcePath.charAt(rootPathLength) == '/')) {
				IProjectFragment root= this.getProjectFragment(resourcePath, scope);
				if (root == null)
					return null; // match is outside classpath
				this.lastPkgFragmentRoot = root;
				this.lastPkgFragmentRootPath = this.lastPkgFragmentRoot.getPath().toString();
				this.packageHandles = new HashtableOfArrayToObject(5);
			}
			// create handle
			resourcePath = resourcePath.substring(this.lastPkgFragmentRootPath.length() + 1);
			String[] simpleNames = new Path(resourcePath).segments();
			String[] pkgName;
			int length = simpleNames.length-1;
			if (length > 0) {
				pkgName = new String[length];
				System.arraycopy(simpleNames, 0, pkgName, 0, length);
			} else {
				pkgName = CharOperation.NO_STRINGS;
			}
			IScriptFolder pkgFragment= (IScriptFolder) this.packageHandles.get(pkgName);
			if (pkgFragment == null) {
				pkgFragment= ((ProjectFragment) this.lastPkgFragmentRoot).getScriptFolder(toPath(pkgName));
				this.packageHandles.put(pkgName, pkgFragment);
			}
			String simpleName= simpleNames[length];			
			ISourceModule unit= pkgFragment.getSourceModule(simpleName);
			return (Openable) unit;			
		}
	}	
	
	private IPath toPath(String[] pkgName) {
		IPath path = new Path("");
		for( int i = 0; i < pkgName.length; ++i ) {
			path = path.append(pkgName[i]);
		}
		return path;
	}


	/**
	 * Returns a handle denoting the class member identified by its scope.
	 */
	public IModelElement createElement(TypeScope scope, ISourceModule unit, HashSet existingElements, HashMap knownScopes) {
		return createElement(scope, scope.referenceContext.sourceStart(), unit, existingElements, knownScopes);
	}
	/**
	 * Create handle by adding child to parent obtained by recursing into parent scopes.
	 */
	private IModelElement createElement(Scope scope, int elementPosition, ISourceModule unit, HashSet existingElements, HashMap knownScopes) {
		if (DLTKCore.DEBUG) {
			System.err.println("TODO: HandleFactory: Add implementation...");
		}
		return null;
	}
	/**
	 * Returns the package fragment root that corresponds to the given jar path.
	 * See createOpenable(...) for the format of the jar path string.
	 * If not null, uses the given scope as a hint for getting script project handles.
	 */
	private IProjectFragment getArchiveProjectFragment(String archivePathString, IDLTKSearchScope scope) {

		IPath archivePath= new Path(archivePathString);
		
		Object target = Model.getTarget(ResourcesPlugin.getWorkspace().getRoot(), archivePath, false);
		if (target instanceof IFile) {
			// internal jar: is it on the classpath of its project?
			//  e.g. org.eclipse.swt.win32/ws/win32/swt.jar 
			//        is NOT on the classpath of org.eclipse.swt.win32
			IFile archiveFile = (IFile)target;
			ScriptProject scriptProject = (ScriptProject) this.model.getScriptProject(archiveFile);
			IBuildpathEntry[] classpathEntries;
			try {
				classpathEntries = scriptProject.getResolvedBuildpath();
				for (int j= 0, entryCount= classpathEntries.length; j < entryCount; j++) {
					if (classpathEntries[j].getPath().equals(archivePath)) {
						return scriptProject.getProjectFragment(archiveFile);
					}
				}
			} catch (ModelException e) {
				// ignore and try to find another project
			}
		}
		
		// walk projects in the scope and find the first one that has the given archive path in its classpath
		IScriptProject[] projects;
		if (scope != null) {
			IPath[] enclosingProjectsAndArchives = scope.enclosingProjectsAndZips();
			int length = enclosingProjectsAndArchives.length;
			projects = new IScriptProject[length];
			int index = 0;
			for (int i = 0; i < length; i++) {
				IPath path = enclosingProjectsAndArchives[i];
				if (!org.eclipse.dltk.compiler.util.Util.isArchiveFileName(path.lastSegment())) {
					projects[index++] = this.model.getScriptProject(path.segment(0));
				}
			}
			if (index < length) {
				System.arraycopy(projects, 0, projects = new IScriptProject[index], 0, index);
			}
			IProjectFragment root = getArchiveFolder(archivePath, target, projects);
			if (root != null) {
				return root;
			}
		} 
		
		// not found in the scope, walk all projects
		try {
			projects = this.model.getScriptProjects();
		} catch (ModelException e) {
			// script model is not accessible
			return null;
		}
		return getArchiveFolder(archivePath, target, projects);
	}
	
	private IProjectFragment getArchiveFolder(
		IPath archivePath,
		Object target,
		IScriptProject[] projects) {
		for (int i= 0, projectCount= projects.length; i < projectCount; i++) {
			try {
				ScriptProject scriptProject= (ScriptProject)projects[i];
				IBuildpathEntry[] classpathEntries= scriptProject.getResolvedBuildpath(true/*ignoreUnresolvedEntry*/, false/*don't generateMarkerOnError*/, false/*don't returnResolutionInProgress*/);
				for (int j= 0, entryCount= classpathEntries.length; j < entryCount; j++) {
					if (classpathEntries[j].getPath().equals(archivePath)) {
						if (target instanceof IFile) {
							// internal jar
							return scriptProject.getProjectFragment((IFile)target);
						} else {
							// external jar
							return scriptProject.getProjectFragment0(archivePath);
						}
					}
				}
			} catch (ModelException e) {
				// ModelException from getResolvedClasspath - a problem occured while accessing project: nothing we can do, ignore
			}
		}
		return null;
	}
	
	/**
	 * Returns the package fragment root that contains the given resource path.
	 * @param scope 
	 */
	private IProjectFragment getProjectFragment(String pathString, IDLTKSearchScope scope) {

		IPath path= new Path(pathString);
		IProject[] projects= ResourcesPlugin.getWorkspace().getRoot().getProjects();
		IPath[] enclosingProjectsAndZips = scope.enclosingProjectsAndZips();
		for (int i= 0, max= projects.length; i < max; i++) {
			try {
				IProject project = projects[i];
				IPath location = project.getFullPath();
				boolean found = false;
				for (int j = 0; j < enclosingProjectsAndZips.length; j++) {
					if(enclosingProjectsAndZips[j].equals(location) ) {
						found = true;
						break;
					}
				}
				if(!found) {
					continue;
				}
				if (!project.isAccessible() 
					|| !DLTKLanguageManager.hasScriptNature(project)) continue;
				IScriptProject scriptProject= this.model.getScriptProject(project);
				IProjectFragment[] roots= scriptProject.getProjectFragments();
				for (int j= 0, rootCount= roots.length; j < rootCount; j++) {
					ProjectFragment root= (ProjectFragment)roots[j];
					if (root.getPath().isPrefixOf(path) && !Util.isExcluded(path, root.fullInclusionPatternChars(), root.fullExclusionPatternChars(), false)) {
						return root;
					}
				}
			} catch (CoreException e) {
				// CoreException from hasNature - should not happen since we check that the project is accessible
				// ModelException from getProjectFragments - a problem occured while accessing project: nothing we can do, ignore
			}
		}
		return null;
	}
	
}
