package com.temp.client.foundation.widget;

import com.google.gwt.event.dom.client.*;
import com.google.gwt.user.client.ui.*;
import com.google.web.bindery.event.shared.*;

import java.util.*;

/**
 * By placing a TabPanelNavPanel widget inside a tabbed panel, it'd render
 * a back and next button that handles switching between tabs within the tab panel
 *
 * @author ngchihou
 */
public class TabPanelNavPanel extends HorizontalPanel {
    private NamedLabel next;
    private NamedLabel back;
    private int tabIndex;
    private TabPanel masterTabPanel;
    private boolean hideNextButton;
    private boolean hideBackButton;
    private HandlerRegistration nextRegistrationHandler;
    private HandlerRegistration backRegistrationHandler;
    private final String BUTTON_STYLE = "tab-nav-button";

    public TabPanelNavPanel() {
        next = new NamedLabel( "Next >>" );
        next.setStyleName( BUTTON_STYLE );
        nextRegistrationHandler = next.addClickHandler( new ClickHandler() {
            @Override
            public void onClick( ClickEvent event ) {
                if ( masterTabPanel != null && tabIndex + 1 < masterTabPanel.getTabBar().getTabCount() ) {
                    masterTabPanel.getTabBar().selectTab( tabIndex + 1 );
                }
            }
        } );

        back = new NamedLabel( "<< Back" );
        back.setStyleName( BUTTON_STYLE );
        backRegistrationHandler = back.addClickHandler( new ClickHandler() {
            @Override
            public void onClick( ClickEvent event ) {
                if ( masterTabPanel != null && tabIndex - 1 >= 0 ) {
                    masterTabPanel.getTabBar().selectTab( tabIndex - 1 );
                }
            }
        } );

        add( back );
        add( new LeftRightSiblings() );
        add( next );
    }

    /**
     * Set a custom click handler for the next button
     *
     * @param handler
     */
    public void addNextClickHandler( ClickHandler handler ) {
        if ( handler != null ) {
            nextRegistrationHandler.removeHandler();
            next.addClickHandler( handler );
        }
    }

    /**
     * Set a custom click handler for the back button
     *
     * @param handler
     */
    public void addBackClickHandler( ClickHandler handler ) {
        if ( handler != null ) {
            backRegistrationHandler.removeHandler();
            back.addClickHandler( handler );
        }
    }

    @Override
    protected void onAttach() {
        super.onAttach();

        // Get the reference to the TabPanel obj as well as the
        // Tab that this TabPanelNavPanel obj resides in
        // With these two pieces of info we can derive the tab
        // index which this nav panel is in
        Widget tab = null;
        Widget parent = getParent();
        while ( parent != null ) {
            if ( parent instanceof TabPanel ) {
                masterTabPanel = (TabPanel) parent;
                break;
            } else if ( parent.getParent() != null && parent.getParent() instanceof DeckPanel ) {
                tab = parent;
            }

            parent = parent.getParent();
        }

        if ( masterTabPanel != null && tab != null ) {
            Iterator<Widget> widgets = masterTabPanel.iterator();
            int wIndex = 0;
            while ( widgets.hasNext() ) {
                Widget w = widgets.next();
                if ( w == tab ) {
                    tabIndex = wIndex;
                    break;
                }
                wIndex++;
            }

            if ( tabIndex == 0 ) {
                back.setVisible( false );
            }
        }

        // Hide the button if necessary
        if ( hideNextButton ) {
            next.setVisible( false );
        }
        if ( hideBackButton ) {
            back.setVisible( false );
        }
    }

    public boolean isHideNextButton() {
        return hideNextButton;
    }

    public void setHideNextButton( boolean hideNextButton ) {
        this.hideNextButton = hideNextButton;
    }

    public boolean isHideBackButton() {
        return hideBackButton;
    }

    public void setHideBackButton( boolean hideBackButton ) {
        this.hideBackButton = hideBackButton;
    }
}