/*******************************************************************************
 * 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.client.ui.utils;

import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.ecore.resource.Resource;
import org.eclipse.mylyn.docs.intent.client.ui.IntentEditorActivator;
import org.eclipse.mylyn.docs.intent.client.ui.editor.IntentEditor;
import org.eclipse.mylyn.docs.intent.client.ui.editor.IntentEditorInput;
import org.eclipse.mylyn.docs.intent.client.ui.logger.IntentUiLogger;
import org.eclipse.mylyn.docs.intent.collab.common.logger.IIntentLogger.LogType;
import org.eclipse.mylyn.docs.intent.collab.common.logger.IntentLogger;
import org.eclipse.mylyn.docs.intent.collab.common.query.IntentDocumentQuery;
import org.eclipse.mylyn.docs.intent.collab.handlers.adapters.ReadOnlyException;
import org.eclipse.mylyn.docs.intent.collab.handlers.adapters.RepositoryAdapter;
import org.eclipse.mylyn.docs.intent.collab.repository.Repository;
import org.eclipse.mylyn.docs.intent.core.document.IntentDocument;
import org.eclipse.mylyn.docs.intent.core.document.IntentGenericElement;
import org.eclipse.mylyn.docs.intent.core.query.IntentHelper;
import org.eclipse.ui.IEditorPart;
import org.eclipse.ui.IEditorReference;
import org.eclipse.ui.IWorkbenchPage;
import org.eclipse.ui.IWorkbenchWindow;
import org.eclipse.ui.PartInitException;
import org.eclipse.ui.PlatformUI;

/**
 * Class used for opening ReStrucutred Models editor.
 * 
 * @author <a href="mailto:alex.lagarde@obeo.fr">Alex Lagarde</a>
 * @author <a href="mailto:william.piers@obeo.fr">William Piers</a>
 */
public final class IntentEditorOpener {

	/**
	 * EditorUtil constructor.
	 */
	private IntentEditorOpener() {

	}

	/**
	 * Opens an editor on the Intent document contained in the given repository.
	 * 
	 * @param repository
	 *            The repository to use for this editor
	 * @param readOnlyMode
	 *            indicates if the editor should be opened in readOnly mode.
	 */
	public static IntentEditor openIntentEditor(final Repository repository, boolean readOnlyMode) {
		try {
			final RepositoryAdapter repositoryAdapter = repository.createRepositoryAdapter();

			openContext(repositoryAdapter, readOnlyMode);
			IntentDocument elementToOpen = new IntentDocumentQuery(repositoryAdapter)
					.getOrCreateIntentDocument();
			return openIntentEditor(repositoryAdapter, elementToOpen, false, elementToOpen, false);
		} catch (PartInitException e) {
			IntentUiLogger.logError(e);
			return null;
		}
	}

	/**
	 * Opens an editor on the element with the given identifier.
	 * 
	 * @param repository
	 *            The repository to use for this editor
	 * @param elementToOpen
	 *            the element to open.
	 * @param readOnlyMode
	 *            indicates if the editor should be opened in readOnly mode.
	 * @param elementToSelectRangeWith
	 *            the element on which the created editor should select its range (can be null).
	 * @param forceNewEditor
	 *            if true, will open in a new editor anyway. If false, will open in a new editor or select
	 *            inside of an already opened editor
	 */
	public static void openIntentEditor(final Repository repository, final EObject elementToOpen,
			boolean readOnlyMode, EObject elementToSelectRangeWith, boolean forceNewEditor) {
		try {
			final RepositoryAdapter repositoryAdapter = repository.createRepositoryAdapter();
			openIntentEditor(repositoryAdapter, elementToOpen, false, elementToSelectRangeWith,
					forceNewEditor);
		} catch (PartInitException e) {
			IntentUiLogger.logError(e);
		}
	}

	/**
	 * Opens an editor on the element with the given identifier.
	 * 
	 * @param repositoryAdapter
	 *            the repository adapter
	 * @param elementToOpen
	 *            the element to open.
	 * @param readOnlyMode
	 *            indicates if the editor should be opened in readOnly mode.
	 * @param elementToSelectRangeWith
	 *            the element on which the created editor should select its range (can be null).
	 * @param forceNewEditor
	 *            if true, will open in a new editor anyway. If false, will open in a new editor or select
	 *            inside of an already opened editor
	 * @return the opened editor
	 * @throws PartInitException
	 *             if the editor cannot be opened.
	 */
	private static IntentEditor openIntentEditor(RepositoryAdapter repositoryAdapter, EObject elementToOpen,
			boolean readOnlyMode, EObject elementToSelectRangeWith, boolean forceNewEditor)
			throws PartInitException {
		IntentEditor openedEditor = null;
		IStatus status = null;
		// We get the element on which open this editor
		openContext(repositoryAdapter, readOnlyMode);

		final EObject elementToOpenLoadedFromAdapter = repositoryAdapter.getElementWithID(repositoryAdapter
				.getIDFromElement(elementToOpen));
		final EObject elementToSelectRangeWithLoadedFromAdapter = repositoryAdapter
				.getElementWithID(repositoryAdapter.getIDFromElement(elementToSelectRangeWith));

		boolean foundInAlreadyExistingEditor = false;
		if (!forceNewEditor) {
			// Step 2 : if an editor containing this element is already opened
			IntentEditor editor = getAlreadyOpenedEditor(elementToOpenLoadedFromAdapter);
			if (editor != null) {
				editor.getEditorSite().getPage().activate(editor);
				openedEditor = editor;
				foundInAlreadyExistingEditor = editor
						.selectRange((IntentGenericElement)elementToSelectRangeWithLoadedFromAdapter);
			}
		}

		if (openedEditor == null || !foundInAlreadyExistingEditor) {

			// Step 3 : we open a new editor.
			IWorkbenchPage page = null;
			try {
				page = PlatformUI.getWorkbench().getActiveWorkbenchWindow().getActivePage();
				openedEditor = IntentEditorOpener.openEditor(repositoryAdapter, page,
						elementToOpenLoadedFromAdapter);
				EObject container = elementToSelectRangeWithLoadedFromAdapter;
				while (container != null && !(container instanceof IntentGenericElement)) {
					container = container.eContainer();
				}
				if (container instanceof IntentGenericElement) {
					openedEditor.selectRange((IntentGenericElement)container);
				} else {
					if (elementToOpenLoadedFromAdapter instanceof IntentGenericElement) {
						openedEditor.selectRange((IntentGenericElement)elementToOpenLoadedFromAdapter);
					}
				}

			} catch (NullPointerException e) {
				status = new Status(IStatus.ERROR, IntentEditorActivator.PLUGIN_ID,
						"An unexpected error has occured");
				throw new PartInitException(status);
			}
		}

		return openedEditor;
	}

	/**
	 * Opens a context through the {@link RepositoryAdapter}, read-only or not according to the given boolean.
	 * 
	 * @param repositoryAdapter
	 *            the {@link RepositoryAdapter} to use
	 * @param readOnlyMode
	 *            indicates whether the context should be opened in read-only mode or node
	 */
	private static void openContext(RepositoryAdapter repositoryAdapter, boolean readOnlyMode) {
		if (repositoryAdapter.getContext() == null) {
			boolean isReadOnly = readOnlyMode;
			if (!readOnlyMode) {
				try {
					repositoryAdapter.openSaveContext();
				} catch (ReadOnlyException e) {
					IntentLogger
							.getInstance()
							.log(LogType.WARNING,
									"The Intent Editor has insufficient rights (read-only) to save modifications on the repository. A read-only context will be used instead.");
					isReadOnly = true;
				}
			}

			if (isReadOnly) {
				repositoryAdapter.openReadOnlyContext();
			}
		}
	}

	/**
	 * If an editor is already opened on the given element, returns it ; returns null otherwise.
	 * 
	 * @param elementToOpen
	 *            the element to search in editors
	 * @return an IntentEditor already opened on the given element, null otherwise.
	 */
	public static IntentEditor getAlreadyOpenedEditor(EObject elementToOpen) {
		IntentEditor alreadyOpenedEditor = null;
		IWorkbenchPage activePage = null;
		IWorkbenchWindow activeWorkbenchWindow = PlatformUI.getWorkbench().getActiveWorkbenchWindow();
		if (activeWorkbenchWindow != null) {
			activePage = activeWorkbenchWindow.getActivePage();
		}

		if (activePage != null) {

			// While no editor containing the given element has been found
			IEditorReference[] editorReferences = activePage.getEditorReferences();
			int editorCount = 0;
			while ((editorCount < editorReferences.length) && alreadyOpenedEditor == null) {
				IEditorReference editorReference = editorReferences[editorCount];
				IEditorPart editor = editorReference.getEditor(false);

				if (editor instanceof IntentEditor) {
					if (((IntentEditor)editor).containsElement((IntentGenericElement)elementToOpen)) {
						alreadyOpenedEditor = (IntentEditor)editor;
						activePage.activate(alreadyOpenedEditor);
					}
				}
				editorCount++;
			}
		}

		return alreadyOpenedEditor;
	}

	/**
	 * Opens an editor on the given IntentModel element.
	 * 
	 * @param repositoryAdapter
	 *            the repository adapter to use for this document
	 * @param page
	 *            the page in which the editor should be opened
	 * @param intentElementToOpen
	 *            the Intent element to open
	 * @return the opened editor
	 * @throws PartInitException
	 *             if the editor cannot be opened.
	 */
	private static IntentEditor openEditor(RepositoryAdapter repositoryAdapter, IWorkbenchPage page,
			Object intentElementToOpen) throws PartInitException {

		// If we can't open a IntentEditor on the given element, we try to get its container until null or an
		// editable intent element is found
		boolean canBeOpenedByIntentEditor = IntentHelper.canBeOpenedByIntentEditor(intentElementToOpen);
		EObject elementToOpen = null;
		if (intentElementToOpen instanceof EObject) {
			elementToOpen = (EObject)intentElementToOpen;
		}
		while (!canBeOpenedByIntentEditor && elementToOpen != null && !(elementToOpen instanceof Resource)) {
			elementToOpen = elementToOpen.eContainer();
			canBeOpenedByIntentEditor = IntentHelper.canBeOpenedByIntentEditor(elementToOpen);
		}

		if (canBeOpenedByIntentEditor) {
			IntentEditorInput input = new IntentEditorInput(elementToOpen, repositoryAdapter);
			IEditorPart part = page.openEditor(input, IntentEditorActivator.EDITOR_ID);
			if (part instanceof IntentEditor) {
				return (IntentEditor)part;
			} else {
				IStatus status = new Status(IStatus.ERROR, IntentEditorActivator.PLUGIN_ID,
						"cannot open the editor");
				throw new PartInitException(status);
			}
		} else {
			IntentUiLogger.logError("this element is not a correct Intent element", new PartInitException(
					"Invalid element : must be a Intent Element"));
			IStatus status = new Status(IStatus.ERROR, IntentEditorActivator.PLUGIN_ID,
					"this element is not a correct Intent element");

			throw new PartInitException(status);
		}

	}
}