/*******************************************************************************
 * Copyright (c) 2016 Chalmers | University of Gothenburg, rt-labs 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:
 * 	   Chalmers | University of Gothenburg and rt-labs - initial API and implementation and/or initial documentation
 *******************************************************************************/

package org.eclipse.capra.ui.office.views;

import java.awt.Desktop;
import java.io.File;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import org.apache.poi.hssf.OldExcelFormatException;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xwpf.usermodel.XWPFParagraph;
import org.apache.xmlbeans.SchemaTypeLoaderException;
import org.eclipse.capra.ui.office.Activator;
import org.eclipse.capra.ui.office.exceptions.CapraOfficeFileNotSupportedException;
import org.eclipse.capra.ui.office.exceptions.CapraOfficeObjectNotFound;
import org.eclipse.capra.ui.office.model.CapraExcelRow;
import org.eclipse.capra.ui.office.model.CapraGoogleSheetsRow;
import org.eclipse.capra.ui.office.model.CapraOfficeObject;
import org.eclipse.capra.ui.office.model.CapraWordRequirement;
import org.eclipse.capra.ui.office.preferences.OfficePreferences;
import org.eclipse.capra.ui.office.utils.CapraOfficeUtils;
import org.eclipse.capra.ui.office.utils.OfficeSourceProvider;
import org.eclipse.capra.ui.office.utils.OfficeTransferType;
import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.emf.edit.ui.dnd.ViewerDragAdapter;
import org.eclipse.jface.action.IMenuListener;
import org.eclipse.jface.action.IMenuManager;
import org.eclipse.jface.action.MenuManager;
import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.jface.viewers.DoubleClickEvent;
import org.eclipse.jface.viewers.IDoubleClickListener;
import org.eclipse.jface.viewers.IStructuredContentProvider;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.ITableLabelProvider;
import org.eclipse.jface.viewers.LabelProvider;
import org.eclipse.jface.viewers.TableViewer;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.jface.viewers.ViewerDropAdapter;
import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DragSourceEvent;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.dnd.TransferData;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.FileDialog;
import org.eclipse.swt.widgets.Link;
import org.eclipse.swt.widgets.Menu;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.TableItem;
import org.eclipse.ui.ISharedImages;
import org.eclipse.ui.PartInitException;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.handlers.HandlerUtil;
import org.eclipse.ui.part.ViewPart;
import org.eclipse.ui.services.ISourceProviderService;

import com.google.common.io.Files;

/**
 * Provides a Capra perspective view for displaying the contents of Excel and
 * Word documents. The view displays the contents if the user drags an Excel or
 * a Word document into the surface.
 *
 * @author Dusan Kalanj
 *
 */
public class OfficeView extends ViewPart {

	/**
	 * The ID of the view as specified by the extension.
	 */
	public static final String ID = "org.eclipse.capra.ui.views.OfficeView";

	/**
	 * The caption that is shown when a message dialog appears describing an
	 * error.
	 */
	private static final String ERROR_TITLE = "Error";

	/**
	 * The URL for the Bugzilla Office handler page
	 */
	private static final String BUGZILLA_OFFICE_URL = "https://bugs.eclipse.org/bugs/show_bug.cgi?id=503313#add_comment";

	/**
	 * The actual view that contains the contents of the documents.
	 */
	private TableViewer viewer;

	/**
	 * The collection that contains the Excel/Word contents.
	 */
	private List<CapraOfficeObject> selection = new ArrayList<CapraOfficeObject>();

	/**
	 * The names (String) of all the sheets, contained in the selected workbook
	 * and information about whether they are empty or not (Boolean).
	 */
	private HashMap<String, Boolean> isSheetEmptyMap;

	/**
	 * The name of the sheet that is currently displayed in the Office view.
	 */
	private String selectedSheetName;

	/**
	 * The file that is currently displayed in the view.
	 */
	private File selectedFile;

	/**
	 * The ID of the file that is currently displayed in the view (non-null only
	 * if acquired from Google Drive).
	 */
	private String selectedFileId;

	/**
	 * Instance of OfficeSourceProvider (used for hiding context menu options)
	 */
	private OfficeSourceProvider provider = (OfficeSourceProvider) ((ISourceProviderService) PlatformUI.getWorkbench()
			.getService(ISourceProviderService.class)).getSourceProvider(OfficeSourceProvider.CAPRA_OFFICE_OBJECT);

	/**
	 * The content provider class used by the view.
	 */
	class ViewContentProvider implements IStructuredContentProvider {
		@Override
		public void inputChanged(Viewer v, Object oldInput, Object newInput) {
		}

		@Override
		public void dispose() {
		}

		@Override
		public Object[] getElements(Object parent) {
			return selection.toArray();
		}
	}

	/**
	 * The label provider class used by the view.
	 */
	class ViewLabelProvider extends LabelProvider implements ITableLabelProvider {

		@Override
		public String getText(Object obj) {
			int minAllowed = Activator.getDefault().getPreferenceStore().getInt(OfficePreferences.CHAR_COUNT);
			String text = obj.toString();
			int textLength = Math.min(text.length(), minAllowed);
			if (textLength == minAllowed)
				text = text.substring(0, textLength) + "...";
			return text;
		};

		@Override
		public String getColumnText(Object obj, int index) {
			return getText(obj);
		}

		@Override
		public Image getColumnImage(Object obj, int index) {
			return getImage(obj);
		}

		@Override
		public Image getImage(Object obj) {
			return PlatformUI.getWorkbench().getSharedImages().getImage(ISharedImages.IMG_OBJ_ELEMENT);
		}
	}

	/**
	 * Adapter used by the view to handle drop events.
	 */
	class SelectionDropAdapter extends ViewerDropAdapter {

		public SelectionDropAdapter(TableViewer viewer) {
			super(viewer);
		}

		@Override
		public boolean performDrop(Object data) {
			try {
				if (data instanceof String[]) {
					File file = new File(((String[]) data)[0]);
					if (file != null && file.exists())
						parseGenericFile(file);
				}
			} catch (CapraOfficeFileNotSupportedException e) {
				e.printStackTrace();
				showErrorMessage(ERROR_TITLE, e.getMessage(), null);
				return false;
			}
			return true;
		}

		@Override
		public boolean validateDrop(Object target, int operation, TransferData transferType) {
			return true;
		}
	}

	/**
	 * Adapter used by the view to handle drag events.
	 */
	class SelectionDragAdapter extends ViewerDragAdapter {

		TableViewer viewer;

		public SelectionDragAdapter(TableViewer viewer) {
			super(viewer);
			this.viewer = viewer;
		}

		@Override
		public void dragSetData(DragSourceEvent event) {

			if (OfficeTransferType.getInstance().isSupportedType(event.dataType)) {
				TableItem[] items = viewer.getTable().getSelection();
				ArrayList<CapraOfficeObject> officeObjects = new ArrayList<CapraOfficeObject>();

				for (int i = 0; i < items.length; i++)
					officeObjects.add((CapraOfficeObject) items[i].getData());

				event.data = officeObjects;
			}
		}
	}

	@Override
	public void setFocus() {
		viewer.getControl().setFocus();
	}

	@Override
	public void createPartControl(Composite parent) {

		viewer = new TableViewer(parent);
		viewer.setContentProvider(new ViewContentProvider());
		viewer.setLabelProvider(new ViewLabelProvider());
		viewer.setInput(getViewSite());

		getSite().setSelectionProvider(viewer);
		hookContextMenu();

		int ops = DND.DROP_COPY | DND.DROP_MOVE;
		Transfer[] transfersIn = new Transfer[] { org.eclipse.swt.dnd.FileTransfer.getInstance() };
		Transfer[] transfersOut = new Transfer[] { org.eclipse.capra.ui.office.utils.OfficeTransferType.getInstance() };

		viewer.addDropSupport(ops, transfersIn, new SelectionDropAdapter(viewer));
		viewer.addDragSupport(ops, transfersOut, new SelectionDragAdapter(viewer));
		viewer.addDoubleClickListener(new IDoubleClickListener() {

			@Override
			public void doubleClick(DoubleClickEvent event) {
				showObjectDetails(event, parent.getShell());
			}
		});
	}

	/**
	 * A method that is called when the user drags file (word or excel) into the
	 * OfficeView. Its main task is to parse the dragged file and display its
	 * contents in the OfficeView. It only parses the file if it is of type
	 * xlsx, xls, or docx.
	 *
	 * @param data
	 *            the object that was dragged into the view
	 * @throws CapraOfficeFileNotSupportedException
	 */
	private void parseGenericFile(File file) throws CapraOfficeFileNotSupportedException {
		String fileExtension = Files.getFileExtension(file.getName());

		if (fileExtension.equals(CapraOfficeObject.XLSX) || fileExtension.equals(CapraOfficeObject.XLS))
			parseExcelDocument(file, null, null);
		else if (fileExtension.equals(CapraOfficeObject.DOCX))
			parseWordDocument(file);
		else
			throw new CapraOfficeFileNotSupportedException(fileExtension);
	}

	/**
	 * Extracts the data from the Excel document and adds it to the view.
	 *
	 * @param officeFile
	 *            the File object pointing to the Excel document that was
	 *            dragged into the view
	 * @param googleDriveFileId
	 *            the id of the file from Google drive (shown in the URL when a
	 *            user opens a file inside Google Drive). If provided it will be
	 *            used when creating the URI of the objects, otherwise (if null)
	 *            the path of the containing file will be used instead. That
	 *            also means that, if googleDriveFileId is provided, the Objects
	 *            in the OfficeView will be of type CapraGoogleSheetsRow,
	 *            otherwise of type CapraExcelRow.
	 * @param sheetName
	 *            the name of the sheet that should be displayed in the Office
	 *            view. If null, the currently active sheet will be displayed.
	 */
	public void parseExcelDocument(File officeFile, String googleDriveFileId, String sheetName) {

		// Get Excel Workbook
		Workbook workBook;
		try {
			workBook = CapraOfficeUtils.getExcelWorkbook(officeFile);
		} catch (OldExcelFormatException e) {
			showErrorMessage(ERROR_TITLE, e.getMessage(), null);
			return;
		} catch (IOException e) {
			e.printStackTrace();
			return;
		}

		// Get Excel sheet with provided sheetName from provided workBook
		Sheet sheet = CapraOfficeUtils.getSheet(workBook, sheetName);
		if (sheet == null) {
			// In theory, this could only happen if someone uses the selectSheet
			// (public) method and provides a non-valid sheetName. The method is
			// currently only used for changing the displayed sheet through the
			// tool-bar menu, where all the names are valid. TODO The best way
			// to tackle this would probably be to introduce a new exception
			// (CapraOfficeSheetNotFoundException?), but to do that, a bit of
			// reordering and partitioning of the methods would be required -
			// ideally, the selectSheet (public) method would throw the
			// exception, not this one.
			String hyperlinkMessage = "It appears that the file doesn't contain any sheets. If that is not true, please report the issue to our <a href=\""
					+ BUGZILLA_OFFICE_URL + "\"> Bugzilla project page </a> and we will do our best to resolve it.";
			showErrorMessage(ERROR_TITLE, hyperlinkMessage, BUGZILLA_OFFICE_URL);
			return;
		}

		// Check if the whole workbook (all of the sheets) is empty.
		HashMap<String, Boolean> isSheetEmptyMap = CapraOfficeUtils.getSheetsEmptinessInfo(workBook);
		if (!isSheetEmptyMap.values().contains(false)) {
			showErrorMessage(ERROR_TITLE, "There are no rows to display in any of the sheets.", null);
			clearSelection();
			return;
		}

		// Clear the Office view and all static variables
		clearSelection();

		// Save new values to properties
		this.selectedSheetName = sheet.getSheetName();
		this.selectedFile = officeFile;
		this.selectedFileId = googleDriveFileId;
		this.isSheetEmptyMap = isSheetEmptyMap;

		// Populate the view with Excel rows
		String idColumn = Activator.getDefault().getPreferenceStore().getString(OfficePreferences.EXCEL_COLUMN_VALUE);
		boolean isGoogleSheet = googleDriveFileId != null;
		for (int i = 0; i <= sheet.getLastRowNum(); i++) {
			Row row = sheet.getRow(i);
			if (row != null) {
				CapraOfficeObject cRow;
				// If the file is in the java's "temporary-file" folder, it was
				// obtained from Google drive
				if (isGoogleSheet)
					cRow = new CapraGoogleSheetsRow(officeFile, row, idColumn, googleDriveFileId);
				else
					cRow = new CapraExcelRow(officeFile, row, idColumn);

				if (!cRow.getData().isEmpty())
					selection.add(cRow);
			}
		}

		// Save info about the type of the data displayed in the Office view.
		if (!selection.isEmpty())
			provider.setResource(selection.get(0));

		viewer.refresh();
	}

	/**
	 * Extracts the data from the Word document and adds it to the view.
	 *
	 * @param officeFile
	 *            the File object pointing of the Word document that was dragged
	 *            into the view.
	 */
	private void parseWordDocument(File officeFile) {

		List<XWPFParagraph> paragraphs;
		try {
			paragraphs = CapraOfficeUtils.getWordParagraphs(officeFile);
		} catch (IOException e) {
			e.printStackTrace();
			showErrorMessage(ERROR_TITLE, e.getMessage(), null);
			return;
		} catch (SchemaTypeLoaderException e) {
			e.printStackTrace();
			showErrorMessage(ERROR_TITLE, e.getMessage(), null);
			return;
		}

		if (paragraphs.isEmpty())
			return;

		// Clear the Office view and all static variables
		clearSelection();

		// Save new values to properties
		this.selectedFile = officeFile;

		// Populate the view with Word requirements
		String fieldName = Activator.getDefault().getPreferenceStore().getString(OfficePreferences.WORD_FIELD_NAME);
		for (int i = 0; i < paragraphs.size(); i++) {
			XWPFParagraph paragraph = paragraphs.get(i);
			if (paragraph != null) {
				CapraWordRequirement cRequirement = new CapraWordRequirement(officeFile, paragraph, fieldName);
				if (!cRequirement.getData().isEmpty())
					selection.add(cRequirement);
			}
		}

		if (!selection.isEmpty())
			provider.setResource(selection.get(0));
		else {
			showErrorMessage(ERROR_TITLE, "There are no fields with the specified field name in this document.", null);
			clearSelection();
			return;
		}

		viewer.refresh();
	}

	/**
	 * Shows the details of the object in its native environment (MS Word, MS
	 * Excel or Google Drive (sheets)).
	 * 
	 * @param event
	 *            Should be of type DoubleClickEvent or ExecutionEvent, hold the
	 *            event that triggered the request for details.
	 * @param parentShell
	 *            Shell which will be the parent of the dialog window.
	 */
	public void showObjectDetails(Object event, Shell parentShell) {
		CapraOfficeObject officeObject;

		if (event instanceof DoubleClickEvent) { // If called with double click
			IStructuredSelection selection = (IStructuredSelection) ((DoubleClickEvent) event).getSelection();
			officeObject = (CapraOfficeObject) selection.getFirstElement();

		} else if (event instanceof ExecutionEvent) { // If called from menu
			IStructuredSelection selection;

			try {
				selection = (IStructuredSelection) HandlerUtil.getCurrentSelectionChecked((ExecutionEvent) event);
				officeObject = (CapraOfficeObject) selection.getFirstElement();
			} catch (ExecutionException e) {
				e.printStackTrace();
				return;
			}
		} else {
			return;
		}

		try {
			officeObject.showOfficeObjectInNativeEnvironment();
		} catch (CapraOfficeObjectNotFound e) {
			e.printStackTrace();
			showErrorMessage(ERROR_TITLE, e.getMessage(), null);
		}

	}

	/**
	 * Clears the OfficeView as well as all the static variables.
	 */
	public void clearSelection() {
		selection.clear();
		viewer.refresh();
		provider.setResource(null);
		selectedSheetName = null;
		selectedFile = null;
		selectedFileId = null;
		isSheetEmptyMap = null;
	}

	/**
	 * Opens a file-chooser dialog and calls the parseOfficeFile method, which
	 * displays the contents of the selected file in the TableViewer (if the
	 * file is of type xlsx, xls or docx).
	 */
	public void openFile() {

		FileDialog fd = new FileDialog(viewer.getControl().getShell(), SWT.OK);
		String filePath = fd.open();

		if (filePath != null && !filePath.isEmpty()) {
			File file = new File(filePath);
			if (file != null && file.exists()) {
				try {
					parseGenericFile(file);
				} catch (CapraOfficeFileNotSupportedException e) {
					e.printStackTrace();
					showErrorMessage(ERROR_TITLE, e.getMessage(), null);
				}
			}
		}
	}

	/**
	 * Displays the provided sheet from the current workbook.
	 * 
	 * @param sheetName
	 *            the name of the sheet to be displayed in the Office view.
	 */
	public void displaySheet(String sheetName) {
		if (selection.isEmpty())
			return;
		else if (selection.get(0) instanceof CapraExcelRow)
			parseExcelDocument(selectedFile, selectedFileId, sheetName);
	}

	/**
	 * Getter method for the HashMap that contains the sheet names and
	 * information about whether they are empty or not
	 * 
	 * @return names and information about "emptiness" of all the sheets
	 *         contained in the current workbook or null if a workbook isn't
	 *         opened.
	 */
	public HashMap<String, Boolean> getIsSheetEmptyMap() {

		// isSheetEmptyMap is used by the SelectSheetDynamicMenu class.
		if (isSheetEmptyMap == null) {
			try {
				isSheetEmptyMap = CapraOfficeUtils.getSheetsEmptinessInfo(
						CapraOfficeUtils.getExcelWorkbook(((CapraExcelRow) (selection.get(0))).getFile()));
			} catch (OldExcelFormatException | IOException e) {
				e.printStackTrace();
			}
		}

		return isSheetEmptyMap;
	}

	/**
	 * Getter method for the name of currently displayed sheet.
	 * 
	 * @return name of currently displayed sheet or null if none is displayed.
	 */
	public String getSelectedSheetName() {
		return selectedSheetName;
	}

	/**
	 * Provides the instance of the view.
	 * 
	 * @return instance of the view.
	 */
	public static OfficeView getOpenedView() {
		try {
			return (OfficeView) PlatformUI.getWorkbench().getActiveWorkbenchWindow().getActivePage().showView(ID);
		} catch (PartInitException e) {
			e.printStackTrace();
		}

		return null;
	}

	/**
	 * Refreshes the Office view.
	 */
	public void refreshView() {

		if (selection.isEmpty())
			return;

		if (selection.get(0) instanceof CapraExcelRow)
			parseExcelDocument(selectedFile, selectedFileId, selectedSheetName);
		else if (selection.get(0) instanceof CapraWordRequirement)
			parseWordDocument(selectedFile);
	}

	/**
	 * Enable context menu for this view.
	 */
	private void hookContextMenu() {
		MenuManager menuMgr = new MenuManager("#PopupMenu");
		menuMgr.setRemoveAllWhenShown(true);
		menuMgr.addMenuListener(new IMenuListener() {
			public void menuAboutToShow(IMenuManager manager) {
			}
		});
		Menu menu = menuMgr.createContextMenu(viewer.getControl());
		viewer.getControl().setMenu(menu);
		getSite().registerContextMenu(menuMgr, viewer);
	}

	private void showErrorMessage(String caption, String message, String url) {
		new HyperlinkDialog(viewer.getControl().getShell(), ERROR_TITLE, null, MessageDialog.ERROR,
				new String[] { "OK" }, 0, message, url).open();
	}

	/**
	 * A pop-up dialog that can contain a hyperlink that, on click, opens a
	 * browser window at the provided url.
	 */
	class HyperlinkDialog extends MessageDialog {

		private String hyperlinkMessage;
		private String url;

		/**
		 * A constructor that creates the dialog with the provided parameters.
		 * Call open() in order to display the dialog.
		 * 
		 * @param parentShell
		 *            the parent shell
		 * @param dialogTitle
		 *            the title of the dialog
		 * @param dialogTitleImage
		 *            the dialog title image, or null if none
		 * @param dialogImageType
		 *            one of the static values from MessageDialog class (NONE,
		 *            ERROR, INFORMATION, QUESTION, WARNING)
		 * @param dialogButtonLabels
		 *            varargs of Strings for the button labels in the button bar
		 * @param defaultIndex
		 *            the index in the button label array of the default button
		 * @param hyperlinkMessage
		 *            a String that will be shown to the user and can contain a
		 *            hyperlink, that will, on click, open a browser window at
		 *            the provided url
		 * @param url
		 *            the hyperlink to the web page, or null, if not required
		 */
		public HyperlinkDialog(Shell parentShell, String dialogTitle, Image dialogTitleImage, int dialogImageType,
				String[] dialogButtonLabels, int defaultIndex, String hyperlinkMessage, String url) {
			super(parentShell, dialogTitle, dialogTitleImage, null, dialogImageType, dialogButtonLabels, defaultIndex);
			this.hyperlinkMessage = hyperlinkMessage;
			this.url = url;
		}

		protected Control createCustomArea(Composite parent) {
			Link link = new Link(parent, SWT.None);
			link.setText(hyperlinkMessage);
			GridData gd = new GridData();
			gd.widthHint = 300;
			link.setLayoutData(gd);
			if (url != null && !url.contentEquals("")) {
				link.setToolTipText(url);
				link.addSelectionListener(new SelectionAdapter() {
					public void widgetSelected(SelectionEvent e) {
						try {
							Desktop.getDesktop().browse(new URI(url));
							HyperlinkDialog.this.okPressed();
						} catch (IOException e1) {
							e1.printStackTrace();
						} catch (URISyntaxException e1) {
							e1.printStackTrace();
						}
					}
				});
			}
			return link;
		}
	}
}