/*******************************************************************************
 * Copyright (c) 2007, 2010 Association for Decentralized Information Management
 * in Industry THTH ry.
 * 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:
 *     VTT Technical Research Centre of Finland - initial API and implementation
 *******************************************************************************/
package org.simantics.selectionview;

import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Set;
import java.util.TreeSet;
import java.util.function.Consumer;

import org.eclipse.jface.viewers.ISelection;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.ui.IWorkbenchPartSite;
import org.simantics.utils.ObjectUtils;

/**
 * <p>
 * See PropertyPage for more information on what can be extended or
 * reimplemented from the superclasses. In addition to those, subclasses may
 * extend or reimplement the following methods:
 * <ul>
 * <li><code>getContexts</code> - reimplement to define what browse contexts
 * this property page should be initialized with. The same result can also be
 * achieved by using the
 * {@link StandardPropertyPage#StandardPropertyPage(IWorkbenchPartSite, Set)}
 * constructor.</li>
 * </ul>
 * </p>
 * 
 * @author Tuukka Lehtonen
 * 
 * @see StandardProperties
 */
public class StandardPropertyPage extends PropertyPage {

    private final Set<String>          contexts;
    private StandardProperties         tabs;

    /**
     * For updating the view title when the active tab changes.
     */
    //private transient ISelection       lastSelection;
    private transient Consumer<String> lastTitleCallback;

    /**
     * Initializes a new standard property page for the specified workbench part
     * without loading the page configuration from any extensible contexts.
     * 
     * @param site the workbench part site that contains this page or
     *        <code>null</code> if there is no site, i.e. the page is within a
     *        dialog or a plain shell.
     */
    public StandardPropertyPage(IWorkbenchPartSite site) {
        this(site, new TreeSet<String>());
    }

    /**
     * Initializes a new standard property page for the specified workbench part
     * and specifies which contexts should be searched for
     * {@link SelectionProcessor} and {@link PropertyTabContributor} bindings to
     * initialize the page.
     * 
     * @param site the workbench part site that contains this page or
     *        <code>null</code> if there is no site, i.e. the page is within a
     *        dialog or a plain shell.
     * @param contexts the contexts to search bindings for to initialize the
     *        property page
     */
    public StandardPropertyPage(IWorkbenchPartSite site, Set<String> contexts) {
        super(site);
        this.contexts = contexts;
    }

    protected SelectionProcessor<?, ?> getSelectionProcessor() {
        return new StandardSelectionProcessor();
    }

    protected Set<String> getContexts() {
        return contexts;
    }

    @SuppressWarnings("unchecked")
    @Override
    protected void createPageControls(Composite parent) {
        SelectionProcessor<?, ?> sp = getSelectionProcessor();
        @SuppressWarnings("rawtypes")
        Collection sps = null;
        if (sp != null)
            sps = Collections.singleton(sp);

        tabs = new StandardProperties(sourceSite, getSite(), parent, SWT.NONE, getContexts(), sps) {
            @Override
            protected void activeTabChanged(TabChangeEvent event) {
                StandardPropertyPage.this.activeTabChanged(event);
            }
            @Override
            protected ComparableTabContributor selectInitialTab(Collection<Object> selectionContents, Collection<ComparableTabContributor> contributions) {
                return StandardPropertyPage.this.selectInitialTab(selectionContents, contributions);
            }
            @Override
            protected int getTabFolderStyle() {
                return StandardPropertyPage.this.getTabFolderStyle();
            }
        };
        tab = tabs;
        tab.createControl(tabs, getSessionContext());
        getSite().setSelectionProvider(tabs.getSelectionProvider());

        fillToolBar(getSite().getActionBars().getToolBarManager());
        fillDropDownMenu(getSite().getActionBars().getMenuManager());
    }

    @Override
    public void updatePartName(ISelection forSelection, Consumer<String> updateCallback) {
    	
    	if(!visible) {
    		updateCallback.accept("Selection");
    		return;
    	}
    	
        //this.lastSelection = forSelection;
        this.lastTitleCallback = updateCallback;
        IPropertyTab tab = tabs.getActiveTab();
        //System.out.println("updatePartName(" + forSelection + ", " + updateCallback + "): " + tab);
        if (tab instanceof IPropertyTab2) {
            //System.out.println("invoking tab.updatePartName for tab " + tab);
        	// TabbedPropertyTable implementation reacts to events with several subsequent runnables.
        	// This causes the part name update to be run before the input is set. Hence we have to set the input here.
        	// TLe: this is broken since there is no guarantee that forSelection
        	// is the proper input for this property tab whose input may well be
        	// a transformed version of the original workbench selection.
        	//((IPropertyTab2) tab).setInput(getSessionContext(), forSelection, false);
            ((IPropertyTab2) tab).updatePartName(updateCallback);
        } else {
            //System.out.println("using default updatePartName for tab " + tab);
            super.updatePartName(forSelection, updateCallback);
        }
    }

    /**
     * @return
     */
    protected int getTabFolderStyle() {
        return SWT.BOTTOM | SWT.FLAT;
    }

    /**
     * A simple tab label based implementation for restoring the last selected
     * tab as the initial tab selection when the property page contents are
     * reset. It statically stores the last selected tab names for
     * {@value #MAX_SELECTED_TABS_REMEMBERED} last different ordered tab name
     * combinations.
     * 
     * @param selectionContents
     * @param contributions
     * @return the previously selected tab contribution for a matching list of tabs
     */
    protected ComparableTabContributor selectInitialTab(Collection<Object> selectionContents, Collection<ComparableTabContributor> contributions) {
        tabSelection = TabSelection.make(contributions);
        for (Iterator<TabSelection> it = previouslySelectedTabs.iterator(); it.hasNext();) {
            TabSelection t = it.next();
            if (t.equals(tabSelection)) {
                tabSelection = t;
                // Move selection to front of list.
                it.remove();
                previouslySelectedTabs.addFirst(t);
                for (ComparableTabContributor contrib : contributions) {
                    if (ObjectUtils.objectEquals(contrib.getLabel(), t.selected)) {
                        return contrib;
                    }
                }
                // selection must have been null, select first tab anyway. 
                return null;
            }
        }
        tabSelection.setSelected(contributions.iterator().next().getLabel());
        previouslySelectedTabs.addFirst(tabSelection);
        while (previouslySelectedTabs.size() > MAX_SELECTED_TABS_REMEMBERED)
            previouslySelectedTabs.removeLast();
        return null;
    }

    protected void activeTabChanged(TabChangeEvent event) {
        //System.out.println("active tab changed: " + event);
        if (tabSelection != null)
            tabSelection.setSelected(event.getNewTabLabel());
        IPropertyTab tab = event.getNewTab();
        if (tab instanceof IPropertyTab2) {
            //System.out.println("invoking tab.updatePartName for tab " + tab);
        	if(lastTitleCallback != null)
        		((IPropertyTab2) tab).updatePartName(lastTitleCallback);
        }
    }

    /**
     * The maximum number of previous initial tab selections to store. See
     * {@link #previouslySelectedTabs} and {@link #tabSelection}.
     */
    private static final int                MAX_SELECTED_TABS_REMEMBERED = 20;

    /**
     * An LRU managed list of previously existing tab selections. The list is
     * static but only used from the SWT display thread so no synchronization is
     * necessary.
     */
    private static LinkedList<TabSelection> previouslySelectedTabs       = new LinkedList<TabSelection>();

    /**
     * The selection of tabs this property page is currently showing. Also
     * contains the currently selected tab name, which is updated by
     * {@link #activeTabChanged(TabChangeEvent)} and
     * {@link #selectInitialTab(Collection, Collection)}.
     */
    private TabSelection                    tabSelection;

    /**
     * A class for representing a set of tabs by their labels and a marking the previously selected one. 
     */
    static class TabSelection {

        private final String[] tabLabels;
        private String         selected;

        public static TabSelection make(Collection<ComparableTabContributor> contribs) {
            String[] labels = new String[contribs.size()];
            int i = 0;
            for (ComparableTabContributor contrib : contribs)
                labels[i++] = contrib.getLabel();
            return new TabSelection(labels);
        }

        public TabSelection(String... tabLabels) {
            this.tabLabels = tabLabels;
        }

        public String getSelected() {
            return selected;
        }

        /**
         * Ensures that the selected tab is among the set of different tab
         * labels. Otherwise the set request is ignored.
         * 
         * @param label
         */
        public void setSelected(String label) {
            for (String l : tabLabels) {
                if (l.equals(label)) {
                    this.selected = label;
                    break;
                }
            }
        }

        @Override
        public int hashCode() {
            return Arrays.hashCode(tabLabels);
        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj)
                return true;
            if (obj == null)
                return false;
            if (getClass() != obj.getClass())
                return false;
            TabSelection other = (TabSelection) obj;
            return Arrays.equals(tabLabels, other.tabLabels);
        }

        @Override
        public String toString() {
            return getClass().getName() + "[" + Arrays.toString(tabLabels) + " - " + selected + "]";
        }

    }

}