// This Source Code is in the Public Domain per: http://unlicense.org
package org.litesoft.GWT.client.widgets.nonpublic;

import org.litesoft.commonfoundation.html.*;

import com.google.gwt.user.client.*;
import com.google.gwt.user.client.ui.*;

/**
 * Derived from  com.google.gwt.user.client.ui.TabBar
 * because they did not allow direct access to the underlying HorizontalPanel.
 * <p/>
 * A horizontal bar of folder-style tabs, most commonly used as part of a
 * {@link com.google.gwt.user.client.ui.TabPanel}.
 * <p/>
 * <img class='gallery' src='TabBar.png'/>
 * </p>
 * <h3>CSS Style Rules</h3>
 * <ul class='css'>
 * <li>.gwt-TabBar { the tab bar itself }</li>
 * <li>.gwt-TabBar .gwt-TabBarFirst { the left edge of the bar }</li>
 * <li>.gwt-TabBar .gwt-TabBarRest { the right edge of the bar }</li>
 * <li>.gwt-TabBar .gwt-TabBarItem { unselected tabs }</li>
 * <li>.gwt-TabBar .gwt-TabBarItem-selected { additional style for selected
 * tabs } </li>
 * </ul>
 * <p/>
 * </p>
 */
public class WidgetTabBar extends Composite implements SourcesTabEvents,
                                                       ClickListener {

    private HorizontalPanel panel = new HorizontalPanel();
    private Widget selectedTab;
    private TabListenerCollection tabListeners;

    /**
     * Creates an empty tab bar.
     */
    public WidgetTabBar() {
        initWidget( panel );
        sinkEvents( Event.ONCLICK );
        //noinspection GWTStyleCheck
        setStyleName( "gwt-TabBar" );

        panel.setVerticalAlignment( HasVerticalAlignment.ALIGN_BOTTOM );

        HTML first = new HTML( HTMLConstants.NBSP, true ), rest = new HTML( HTMLConstants.NBSP, true );
        //noinspection GWTStyleCheck
        first.setStyleName( "gwt-TabBarFirst" );
        //noinspection GWTStyleCheck
        rest.setStyleName( "gwt-TabBarRest" );
//        first.setHeight( "100%" );
//        rest.setHeight( "100%" );

        panel.add( first );
        panel.add( rest );
//        first.setHeight( "100%" );
        panel.setCellHeight( first, "100%" );
        panel.setCellWidth( rest, "100%" );
    }

    /**
     * Adds a new tab with the specified text.
     *
     * @param text the new tab's text
     */
    public void addTab( String text ) {
        insertTab( text, getTabCount() );
    }

    /**
     * Adds a new tab with the specified text.
     *
     * @param text   the new tab's text
     * @param asHTML <code>true</code> to treat the specified text as html
     */
    public void addTab( String text, boolean asHTML ) {
        insertTab( text, asHTML, getTabCount() );
    }

    @Override
    public void addTabListener( TabListener listener ) {
        if ( tabListeners == null ) {
            tabListeners = new TabListenerCollection();
        }
        tabListeners.add( listener );
    }

    /**
     * Gets the tab that is currently selected.
     *
     * @return the selected tab
     */
    public int getSelectedTab() {
        if ( selectedTab == null ) {
            return -1;
        }
        return panel.getWidgetIndex( selectedTab ) - 1;
    }

    /**
     * Gets the number of tabs present.
     *
     * @return the tab count
     */
    public int getTabCount() {
        return panel.getWidgetCount() - 2;
    }

    /**
     * Gets the specified tab's HTML.
     *
     * @param index the index of the tab whose HTML is to be retrieved
     *
     * @return the tab's HTML
     */
    public String getTabHTML( int index ) {
        if ( index >= getTabCount() ) {
            return null;
        }
        Widget widget = panel.getWidget( index + 1 );
        if ( widget instanceof HTML ) {
            return ((HTML) widget).getHTML();
        } else {
            return ((Label) widget).getText();
        }
    }

    public Widget getWidget( int pIndex ) {
        return panel.getWidget( pIndex + 1 );
    }

    /**
     * Inserts a new tab at the specified index.
     *
     * @param text        the new tab's text
     * @param asHTML      <code>true</code> to treat the specified text as HTML
     * @param beforeIndex the index before which this tab will be inserted
     */
    public void insertTab( String text, boolean asHTML, int beforeIndex ) {
        if ( (beforeIndex < 0) || (beforeIndex > getTabCount()) ) {
            throw new IndexOutOfBoundsException( String.valueOf( beforeIndex ) );
        }

        Label item;
        if ( asHTML ) {
            item = new HTML( text );
        } else {
            item = new Label( text );
        }

        item.setWordWrap( false );
        item.addClickListener( this );
        //noinspection GWTStyleCheck
        item.setStyleName( "gwt-TabBarItem" );
        item.addStyleName( "gwt-TabBarItem-NonError" );
        panel.insert( item, beforeIndex + 1 );
    }

    /**
     * Inserts a new tab at the specified index.
     *
     * @param text        the new tab's text
     * @param beforeIndex the index before which this tab will be inserted
     */
    public void insertTab( String text, int beforeIndex ) {
        insertTab( text, false, beforeIndex );
    }

    @Override
    public void onClick( Widget sender ) {
        for ( int i = 1; i < panel.getWidgetCount() - 1; ++i ) {
            if ( panel.getWidget( i ) == sender ) {
                selectTab( i - 1 );
                return;
            }
        }
    }

    /**
     * Removes the tab at the specified index.
     *
     * @param index the index of the tab to be removed
     */
    public void removeTab( int index ) {
        checkTabIndex( index );

        // (index + 1) to account for 'first' placeholder widget.
        Widget toRemove = panel.getWidget( index + 1 );
        if ( toRemove == selectedTab ) {
            selectedTab = null;
        }
        panel.remove( toRemove );
    }

    @Override
    public void removeTabListener( TabListener listener ) {
        if ( tabListeners != null ) {
            tabListeners.remove( listener );
        }
    }

    /**
     * Programmatically selects the specified tab. Use index -1 to specify that no
     * tab should be selected.
     *
     * @param index the index of the tab to be selected.
     *
     * @return <code>true</code> if successful, <code>false</code> if the
     * change is denied by the {@link TabListener}.
     */
    public boolean selectTab( int index ) {
        checkTabIndex( index );

        if ( tabListeners != null ) {
            if ( !tabListeners.fireBeforeTabSelected( this, index ) ) {
                return false;
            }
        }

        // Check for -1.
        setSelectionStyle( selectedTab, false );
        if ( index == -1 ) {
            selectedTab = null;
            return true;
        }

        selectedTab = panel.getWidget( index + 1 );
        setSelectionStyle( selectedTab, true );

        if ( tabListeners != null ) {
            tabListeners.fireTabSelected( this, index );
        }
        return true;
    }

    private void checkTabIndex( int index ) {
        if ( (index < -1) || (index >= getTabCount()) ) {
            throw new IndexOutOfBoundsException( String.valueOf( index ) );
        }
    }

    private void setSelectionStyle( Widget item, boolean selected ) {
        if ( item != null ) {
            if ( selected ) {
                //noinspection GWTStyleCheck
                item.addStyleName( "gwt-TabBarItem-selected" );
            } else {
                //noinspection GWTStyleCheck
                item.removeStyleName( "gwt-TabBarItem-selected" );
            }
        }
    }
}