package org.simantics.district.selection.ui.parts;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

import javax.annotation.PostConstruct;
import javax.inject.Inject;

import org.eclipse.e4.core.services.events.IEventBroker;
import org.eclipse.e4.ui.di.Focus;
import org.eclipse.e4.ui.model.application.MApplication;
import org.eclipse.e4.ui.model.application.ui.basic.MPart;
import org.eclipse.e4.ui.model.application.ui.menu.MHandledToolItem;
import org.eclipse.e4.ui.model.application.ui.menu.MMenuContribution;
import org.eclipse.e4.ui.model.application.ui.menu.MMenuFactory;
import org.eclipse.e4.ui.model.application.ui.menu.MPopupMenu;
import org.eclipse.e4.ui.model.application.ui.menu.MToolBar;
import org.eclipse.e4.ui.model.application.ui.menu.MToolBarElement;
import org.eclipse.e4.ui.services.EMenuService;
import org.eclipse.e4.ui.workbench.modeling.ESelectionService;
import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.jface.viewers.StructuredSelection;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.simantics.Simantics;
import org.simantics.browsing.ui.common.AdaptableHintContext;
import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.layer0.SelectionHints;
import org.simantics.db.layer0.request.ActiveModels;
import org.simantics.db.request.Read;
import org.simantics.district.network.ui.DistrictNetworkUIUtil;
import org.simantics.district.selection.ElementSelector;
import org.simantics.district.selection.ElementSelector.DiagramGenerator;
import org.simantics.district.selection.ElementSelector.ExplicitGenerator;
import org.simantics.district.selection.ElementSelector.PropertySelector;
import org.simantics.district.selection.ElementSelector.SelectionResult;
import org.simantics.district.selection.ui.ElementSelectionTools;
import org.simantics.district.selection.ui.ElementSelectorTableUI;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class ElementSelectionView {
	private static final String CONTEXT_MENU_ID = "org.simantics.district.selection.ui.contextMenu";
	private static final String POPUP_ID = "org.simantics.district.selection.ui.selectiontable.popup";
	private static final String CREATE_NEW_ID = "org.simantics.district.selection.ui.command.createNewSelection";
	private static final String CREATE_NEW_LABEL = "Create New Element Selection Query";
	private static final String CREATE_NEW_ICON = "platform:/plugin/com.famfamfam.silk/icons/add.png";
	private static final String EDIT_ID = "org.simantics.district.selection.ui.command.editElementSelector";
	private static final String EDIT_LABEL = "Edit Element Selection Query";
	private static final String EDIT_ICON = "platform:/plugin/com.famfamfam.silk/icons/pencil.png";
	private static final String DELETE_ID = "org.simantics.district.selection.ui.command.deleteElementSelector";
	private static final String DELETE_LABEL = "Delete Element Selection Query";
	private static final String DELETE_ICON = "platform:/plugin/com.famfamfam.silk/icons/cross.png";

	/**
	 * Name of an event that is posted to IEventBroker when a selection is made. The data value is
	 * an instance of Collection<Resource>.
	 */
	public static final String SELECTION_EVENT_ID = "org/simantics/district/selection/elementQuerySelection";
	
	private static final Logger LOGGER = LoggerFactory.getLogger(ElementSelectionView.class);

	private ElementSelectorTableUI table;

	@Inject
	private ESelectionService selectionService;
	
	@Inject
	private IEventBroker eventBroker;
	
	@Inject
	public void init(MPart part, MApplication app) {
		// Command is contributed via fragment
		MHandledToolItem createItem = MMenuFactory.INSTANCE.createHandledToolItem();
		createItem.setCommand(app.getCommand(CREATE_NEW_ID));
		createItem.setLabel(CREATE_NEW_LABEL);
		createItem.setIconURI(CREATE_NEW_ICON);
		MHandledToolItem editItem = MMenuFactory.INSTANCE.createHandledToolItem();
		editItem.setCommand(app.getCommand(EDIT_ID));
		editItem.setLabel(EDIT_LABEL);
		editItem.setIconURI(EDIT_ICON);
		MHandledToolItem deleteItem = MMenuFactory.INSTANCE.createHandledToolItem();
		deleteItem.setCommand(app.getCommand(DELETE_ID));
		deleteItem.setLabel(DELETE_LABEL);
		deleteItem.setIconURI(DELETE_ICON);
		
		MToolBar toolBar = MMenuFactory.INSTANCE.createToolBar();
		toolBar.setToBeRendered(true);
		
		List<MToolBarElement> children = toolBar.getChildren();
		children.add(createItem);
		children.add(editItem);
		children.add(deleteItem);
		
		part.setToolbar(toolBar);

		MPopupMenu popupMenu = MMenuFactory.INSTANCE.createPopupMenu();
		popupMenu.setElementId(POPUP_ID);

		List<MMenuContribution> menuContributions = app.getMenuContributions();
		for (MMenuContribution menuContribution : menuContributions) {
			if (CONTEXT_MENU_ID.equals(menuContribution.getParentId())) {
				popupMenu.getChildren().addAll(menuContribution.getChildren());
			}
		}

		part.getMenus().add(popupMenu);
	}

	@PostConstruct
	public void createPartControl(Composite parent, EMenuService menuService) {
		table = new ElementSelectorTableUI(parent, SWT.BORDER, this);
		if (!(menuService.registerContextMenu(this.table.getTable(), POPUP_ID)))
			LOGGER.warn("Could not register context menu {}", POPUP_ID);
	}

	@Focus
	public void setFocus() {
		table.setFocus();
	}

	public ElementSelector getSelectedItem() {
		return table.getSelectedItem();
	}

	public void performSelection(Display display, ElementSelector query) {
		try {
			Collection<Resource> models = Simantics.getSession().syncRequest(new ActiveModels(Simantics.getProjectResource()));
			final Resource model = models.isEmpty() ? null : models.iterator().next();
			
			SelectionResult result = performQuery(query, model);
			
			if (result.tailCount != result.tailSize) {
				showArbitraryResultWarning(query, result);
			}
			
			if (query.getGenerator() instanceof DiagramGenerator || query.getGenerator() instanceof ExplicitGenerator) {
				openDiagramWithSelection(display, result);
			}
			
			StructuredSelection selection = makeSelection(model, result);
			selectionService.setPostSelection(selection);
			sendSelectionEvent(selection);
		} catch (DatabaseException e) {
			LOGGER.error("Element selection query failed", e);
		}
	}

	private StructuredSelection makeSelection(final Resource model, SelectionResult result) {
		return new StructuredSelection(result.elements.stream()
				.map(p0 -> {
					AdaptableHintContext selectionElement = new ElementSelectionTools.SelectionElement(SelectionHints.STD_KEYS);
					selectionElement.setHint(SelectionHints.KEY_MAIN, p0);
					selectionElement.setHint(SelectionHints.KEY_MODEL, model);
					return selectionElement;
				})
				.toArray());
	}

	private void openDiagramWithSelection(Display display, SelectionResult result) throws DatabaseException {
		DistrictNetworkUIUtil.openDNDiagramWithSelection(display, new ArrayList<>(result.elements));
	}

	private void sendSelectionEvent(Object selection) {
		eventBroker.send(SELECTION_EVENT_ID, selection);
	}

	private void showArbitraryResultWarning(ElementSelector query, SelectionResult result) {
		String name = query.getSelector() != null && query.getSelector() instanceof PropertySelector ? ((PropertySelector)query.getSelector()).propertyName : null;
		String msg = "Last " + result.tailCount + " of the " + result.elements.size() + " selected elements are an arbitraty subset of " + result.tailSize + " elements with equal values" +
				(name != null ? " for " + name : "");
		MessageDialog.openInformation(Display.getDefault().getActiveShell(), "Note", msg);
	}

	private SelectionResult performQuery(ElementSelector query, final Resource model) throws DatabaseException {
		SelectionResult result = Simantics.getSession().syncRequest(new Read<SelectionResult>() {
			@Override
			public SelectionResult perform(ReadGraph graph) throws DatabaseException {
				if (model == null) {
					LOGGER.warn("No active model");
					return new SelectionResult(Collections.emptyList(), 0, 0);
				}
				
				return query.selectElementsFrom(graph, model);
			}
		});
		return result;
	}
}