/*******************************************************************************
 * Copyright (c) 2010, 2011 Obeo.
 * 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:
 *     Obeo - initial API and implementation
 *******************************************************************************/
package org.eclipse.mylyn.docs.intent.collab.ide.repository;

import com.google.common.base.Predicate;

import org.eclipse.core.resources.IFolder;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IWorkspace;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.Status;
import org.eclipse.emf.common.util.URI;
import org.eclipse.emf.ecore.EClass;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.ecore.EPackage.Registry;
import org.eclipse.emf.ecore.resource.Resource;
import org.eclipse.emf.ecore.resource.ResourceSet;
import org.eclipse.emf.transaction.TransactionalEditingDomain;
import org.eclipse.emf.transaction.impl.InternalTransactionalEditingDomain;
import org.eclipse.mylyn.docs.intent.collab.handlers.RepositoryClient;
import org.eclipse.mylyn.docs.intent.collab.handlers.adapters.RepositoryAdapter;
import org.eclipse.mylyn.docs.intent.collab.handlers.adapters.RepositoryStructurer;
import org.eclipse.mylyn.docs.intent.collab.ide.adapters.WorkspaceAdapter;
import org.eclipse.mylyn.docs.intent.collab.repository.Repository;
import org.eclipse.mylyn.docs.intent.collab.repository.RepositoryConnectionException;

/**
 * Representation of a Workspace as a repository.
 * 
 * @author <a href="mailto:alex.lagarde@obeo.fr">Alex Lagarde</a>
 */
public class WorkspaceRepository implements Repository {

	/**
	 * The default extension for any element stored on the repository.
	 */
	private static final String WORKSPACE_RESOURCE_EXTENSION = "repomodel";

	/**
	 * Represents this repository configuration.
	 */
	private WorkspaceConfig workspaceConfig;

	/**
	 * Session that will notify any listening entities about changes on Workspace resources corresponding to
	 * repository resources.
	 */
	private WorkspaceSession session;

	/**
	 * Indicates if the repository resource set has been initialized.
	 */
	private boolean isResourceSetLoaded;

	/**
	 * The repository editing domain.
	 */
	private TransactionalEditingDomain editingDomain;

	/**
	 * The repository structurer.
	 */
	private RepositoryStructurer repositoryStructurer;

	/**
	 * Used to determine if a resource can be unloaded: if the root has one of this unloadableTypes, then it
	 * will be unloaded.
	 */
	private EClass[] unloadableTypes;

	/**
	 * WorkspaceRepository constructor.
	 * 
	 * @param workspaceConfig
	 *            this repository configuration
	 * @param unloadableTypes
	 *            the list of types which cannot be unloaded
	 */
	public WorkspaceRepository(WorkspaceConfig workspaceConfig, EClass... unloadableTypes) {
		this.unloadableTypes = unloadableTypes;
		this.workspaceConfig = workspaceConfig;
		this.editingDomain = TransactionalEditingDomain.Factory.INSTANCE.createEditingDomain();
		isResourceSetLoaded = false;
	}

	/**
	 * Initializes the resource set using the repository content ; if the repository content is empty, creates
	 * all the declared indexes.
	 * 
	 * @throws CoreException
	 *             it the resourceSet cannot be initialized
	 */
	private void initializeResourceSet() throws CoreException {

		// We first get the project on which the repository is defined
		IProject project = workspaceConfig.getProject();
		if (!project.exists()) {
			project.create(null);
		}
		if (!project.isOpen()) {
			project.open(null);
		}
		IFolder folder = project.getFolder(workspaceConfig.getRepositoryRelativePath());
		// We created a WorkspaceRepositoryLoader using the indexPathList
		WorkspaceRepositoryLoader loader = new WorkspaceRepositoryLoader(this, this.getWorkspaceConfig()
				.getIndexesPathList());
		// If the repository folder exists
		if (folder.exists()) {
			// We load the resourceSet
			loader.loadResourceSet();
		} else {
			// If the repository folder doesn't exist
			// We create it
			folder.create(IResource.NONE, true, null);
			// And use the RepositoryLoader to initialize the resource set with empty content
			// loader.loadResourceSet();
			// loader.createResourceSet();

		}
		isResourceSetLoaded = true;

	}

	/**
	 * {@inheritDoc}
	 * 
	 * @see org.eclipse.mylyn.docs.intent.collab.repository.Repository#register(org.eclipse.mylyn.docs.intent.collab.handlers.RepositoryClient)
	 */
	public void register(RepositoryClient client) {
		// No need to register
	}

	/**
	 * {@inheritDoc}
	 * 
	 * @see org.eclipse.mylyn.docs.intent.collab.repository.Repository#unregister(org.eclipse.mylyn.docs.intent.collab.handlers.RepositoryClient)
	 */
	public void unregister(RepositoryClient client) {
		// No need to unregister

	}

	/**
	 * {@inheritDoc}
	 * 
	 * @see org.eclipse.mylyn.docs.intent.collab.repository.Repository#getOrCreateSession()
	 */
	public synchronized Object getOrCreateSession() throws RepositoryConnectionException {

		// We first initialize the resource set if needed
		if (!isResourceSetLoaded) {
			try {
				initializeResourceSet();
			} catch (CoreException e) {
				throw new RepositoryConnectionException(e.getMessage());
			}
		}
		if (this.session == null) {
			// Creation of a Workspace session that will send notifications when the workspace's resources
			// corresponding to repository resources change
			this.session = new WorkspaceSession(this);
			IWorkspace workspace = ResourcesPlugin.getWorkspace();
			workspace.addResourceChangeListener(session);
		}
		return this.session;
	}

	/**
	 * {@inheritDoc}
	 * 
	 * @see org.eclipse.mylyn.docs.intent.collab.repository.Repository#closeSession()
	 */
	public synchronized void closeSession() throws RepositoryConnectionException {
		if (this.session != null) {
			ResourcesPlugin.getWorkspace().removeResourceChangeListener(session);
			this.session.close();
			this.session = null;
		}

		// If a transaction is being executed, we abort it
		if (((InternalTransactionalEditingDomain)this.editingDomain).getActiveTransaction() != null) {
			((InternalTransactionalEditingDomain)this.editingDomain).getActiveTransaction().abort(
					Status.CANCEL_STATUS);
		}
		this.editingDomain.dispose();
	}

	/**
	 * {@inheritDoc}
	 * 
	 * @see org.eclipse.mylyn.docs.intent.collab.repository.Repository#getPackageRegistry()
	 */
	public Registry getPackageRegistry() throws RepositoryConnectionException {
		// Return the resourceset's package registry
		return getResourceSet().getPackageRegistry();
	}

	// ---- SPECIFIC BEHAVIORS
	/**
	 * Indicates if the given path represents a location in the repository.
	 * 
	 * @param path
	 *            the path to study
	 * @return true if the given path represents a location in the repository, false otherwise
	 */
	public boolean isInRepositoryPath(String path) {
		return path.startsWith(this.workspaceConfig.getRepositoryRelativePath());
	}

	/**
	 * Indicates if the given resource is included in the given path.
	 * 
	 * @param path
	 *            is the path
	 * @param resource
	 *            the resource to determine if it's included in the given path
	 * @return true if the resource's associated path starts with or is equals to the given path, false
	 *         otherwise
	 */
	public boolean isIncludedInPath(String path, Resource resource) {
		// We first get the complete URI of the given path
		URI uriPath = getURIMatchingPath(path);
		// We compare the two URI
		return resource.getURI().toString().startsWith(uriPath.toString());
	}

	/**
	 * Returns the Repository URI corresponding to the given path.
	 * <p>
	 * The complete path is calculated by prefixing the given path by this repository path and postfixing it
	 * by the default file extension.
	 * </p>
	 * 
	 * @param path
	 *            is the path
	 * @return the Repository URI corresponding to the given path
	 */
	public URI getURIMatchingPath(String path) {
		String completePath = this.getWorkspaceConfig().getRepositoryAbsolutePath() + path;
		// If the path don't ends with '/' (i.e isn't a folder), we add the file extension
		if (shouldHaveWorkspaceResourceExtension(completePath)) {
			completePath += "." + WORKSPACE_RESOURCE_EXTENSION;
		}
		completePath = completePath.trim();
		URI uri = URI.createPlatformResourceURI(completePath, false);
		return uri;
	}

	/**
	 * Indicates if the Repository resource located at the given path should be association with the
	 * {@link WorkspaceRepository#WORKSPACE_RESOURCE_EXTENSION} extension.
	 * 
	 * @param path
	 *            the path of the Repository resource
	 * @return true if the Repository resource located at the given path should be association with the
	 *         {@link WorkspaceRepository#WORKSPACE_RESOURCE_EXTENSION} extension, false otherwise
	 */
	public boolean shouldHaveWorkspaceResourceExtension(String path) {
		return !path.endsWith("/");
	}

	/**
	 * Returns the EMF ResourceSet of this Workspace repository.
	 * <p>
	 * It will handle resource creation, package registry management...
	 * </p>
	 * 
	 * @return the resourceSet the EMF ResourceSet of this Workspace repository
	 */
	public ResourceSet getResourceSet() {
		return editingDomain.getResourceSet();
	}

	/**
	 * Returns this repository configuration.
	 * 
	 * @return this repository configuration
	 */
	public WorkspaceConfig getWorkspaceConfig() {
		return workspaceConfig;
	}

	/**
	 * Returns the default extension for any element stored on the repository.
	 * 
	 * @return the default extension for any element stored on the repository
	 */
	public static String getWorkspaceResourceExtension() {
		return WORKSPACE_RESOURCE_EXTENSION;
	}

	public TransactionalEditingDomain getEditingDomain() {
		return editingDomain;
	}

	/**
	 * {@inheritDoc}
	 * 
	 * @see org.eclipse.mylyn.docs.intent.collab.repository.Repository#setRepositoryStructurer(org.eclipse.mylyn.docs.intent.collab.handlers.adapters.RepositoryStructurer)
	 */
	public void setRepositoryStructurer(RepositoryStructurer structurer) {
		this.repositoryStructurer = structurer;

	}

	/**
	 * {@inheritDoc}
	 * 
	 * @see org.eclipse.mylyn.docs.intent.collab.repository.Repository#createRepositoryAdapter()
	 */
	public RepositoryAdapter createRepositoryAdapter() {
		WorkspaceAdapter workspaceAdapter = new WorkspaceAdapter(this);
		if (this.repositoryStructurer != null) {
			workspaceAdapter.attachRepositoryStructurer(this.repositoryStructurer);
		}
		// We set a new unloadable Resource Predicate
		workspaceAdapter.setUnloadableResourcePredicate(new Predicate<Resource>() {

			public boolean apply(Resource resource) {
				// The Intent index should never be unloaded
				if (!resource.getContents().isEmpty()) {
					boolean res = false;
					EObject root = resource.getContents().iterator().next();
					for (EClass unloadableType : unloadableTypes) {
						if (root.eClass().equals(unloadableType)) {
							res = true;
						}
					}
					return res;
				}
				return false;
			}
		});
		return workspaceAdapter;
	}

	/**
	 * {@inheritDoc}
	 * 
	 * @see org.eclipse.mylyn.docs.intent.collab.repository.Repository#getIdentifier()
	 */
	public String getIdentifier() {
		return workspaceConfig.getProject().getName();
	}

	/**
	 * {@inheritDoc}
	 * 
	 * @see org.eclipse.mylyn.docs.intent.collab.repository.Repository#getRepositoryLocation()
	 */
	public String getRepositoryLocation() {
		return ResourcesPlugin.getWorkspace().getRoot().getLocation().toPortableString()
				+ getWorkspaceConfig().getRepositoryAbsolutePath().replace(".repository", "");
	}

	/**
	 * {@inheritDoc}
	 * 
	 * @see org.eclipse.mylyn.docs.intent.collab.repository.Repository#getRepositoryURI()
	 */
	public URI getRepositoryURI() {
		return URI.createPlatformResourceURI(getIdentifier(), true);
	}
}