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// Metawidget
//
// This file is dual licensed under both the LGPL
// (http://www.gnu.org/licenses/lgpl-2.1.html) and the EPL
// (http://www.eclipse.org/org/documents/epl-v10.php). As a
// recipient of Metawidget, you may choose to receive it under either
// the LGPL or the EPL.
//
// Commercial licenses are also available. See http://metawidget.org
// for details.

package org.metawidget.gwt.client.widgetbuilder;

import static org.metawidget.inspector.InspectionResultConstants.*;

import java.util.Date;
import java.util.List;
import java.util.Map;

import org.metawidget.gwt.client.ui.GwtMetawidget;
import org.metawidget.gwt.client.ui.GwtUtils;
import org.metawidget.gwt.client.ui.GwtValueAccessor;
import org.metawidget.gwt.client.ui.Stub;
import org.metawidget.util.simple.StringUtils;
import org.metawidget.widgetbuilder.iface.WidgetBuilder;

import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.CheckBox;
import com.google.gwt.user.client.ui.HasText;
import com.google.gwt.user.client.ui.ListBox;
import com.google.gwt.user.client.ui.PasswordTextBox;
import com.google.gwt.user.client.ui.TextArea;
import com.google.gwt.user.client.ui.TextBox;
import com.google.gwt.user.client.ui.Widget;

/**
 * WidgetBuilder for GWT environments.
 * 
 * Creates native GWT Widgets, such as TextBox and ListBox, to suit the
 * inspected fields.
 *
 * @author Richard Kennard
 */

public class GwtWidgetBuilder
	implements WidgetBuilder, GwtValueAccessor {

	//
	// Public methods
	//

	public Object getValue( Widget widget ) {

		// CheckBox (must come before HasText, because CheckBox extends
		// ButtonBase which implements HasHTML which extends HasText)

		if ( widget instanceof CheckBox ) {
			return ( (CheckBox) widget ).getValue();
		}

		// HasText

		if ( widget instanceof HasText ) {
			return ( (HasText) widget ).getText();
		}

		// ListBox

		if ( widget instanceof ListBox ) {
			ListBox listBox = (ListBox) widget;
			return listBox.getValue( listBox.getSelectedIndex() );
		}

		return null;
	}

	public boolean setValue( Widget widget, Object value ) {

		// CheckBox (must come before HasText, because CheckBox extends
		// ButtonBase which implements HasHTML which extends HasText)

		if ( widget instanceof CheckBox ) {
			( (CheckBox) widget ).setValue( (Boolean) value );
			return true;
		}

		// HasText

		if ( widget instanceof HasText ) {
			( (HasText) widget ).setText( StringUtils.quietValueOf( value ) );
			return true;
		}

		// ListBox

		if ( widget instanceof ListBox ) {
			GwtUtils.setListBoxSelectedItem( (ListBox) widget, StringUtils.quietValueOf( value ) );
			return true;
		}

		// Not for us

		return false;
	}

	public Widget buildWidget( String elementName, Map attributes, GwtMetawidget metawidget ) {

		// Hidden

		if ( TRUE.equals( attributes.get( HIDDEN ) ) ) {
			return new Stub();
		}

		// Action

		if ( ACTION.equals( elementName ) ) {
			return new Button( metawidget.getLabelString( attributes ) );
		}

		String type = GwtUtils.getActualClassOrType( attributes );

		// If no type, assume a String

		if ( type == null ) {
			type = String.class.getName();
		}

		// Support mandatory Booleans (can be rendered as a checkbox, even though they have a
		// Lookup)

		if ( "Boolean".equals( type ) && TRUE.equals( attributes.get( REQUIRED ) ) ) {
			return new CheckBox();
		}

		// Lookups

		String lookup = attributes.get( LOOKUP );

		if ( lookup != null && !"".equals( lookup ) ) {
			ListBox listBox = new ListBox();
			listBox.setVisibleItemCount( 1 );

			addListBoxItems( listBox, GwtUtils.fromString( lookup, StringUtils.SEPARATOR_COMMA_CHAR ), GwtUtils.fromString( attributes.get( LOOKUP_LABELS ), StringUtils.SEPARATOR_COMMA_CHAR ), attributes );
			return listBox;
		}

		if ( GwtUtils.isPrimitive( type ) ) {
			// booleans

			if ( "boolean".equals( type ) ) {
				return new CheckBox();
			}

			// chars

			if ( "char".equals( type ) ) {
				TextBox textbox = new TextBox();
				textbox.setMaxLength( 1 );

				return textbox;
			}

			// Everything else

			return new TextBox();
		}

		// Strings

		if ( String.class.getName().equals( type ) ) {
			if ( TRUE.equals( attributes.get( MASKED ) ) ) {
				return new PasswordTextBox();
			}

			if ( TRUE.equals( attributes.get( LARGE ) ) ) {
				return new TextArea();
			}

			TextBox textBox = new TextBox();

			String maximumLength = attributes.get( MAXIMUM_LENGTH );

			if ( maximumLength != null && !"".equals( maximumLength ) ) {
				textBox.setMaxLength( Integer.parseInt( maximumLength ) );
			}

			return textBox;
		}

		// Dates

		if ( Date.class.getName().equals( type ) ) {
			return new TextBox();
		}

		if ( GwtUtils.isPrimitiveWrapper( type ) ) {
			// Characters

			if ( Character.class.getName().equals( type ) ) {
				TextBox textbox = new TextBox();
				textbox.setMaxLength( 1 );

				return textbox;
			}

			// Numbers

			return new TextBox();
		}

		// Collections

		if ( GwtUtils.isCollection( type ) ) {
			return new Stub();
		}

		// Not simple, but don't expand

		if ( TRUE.equals( attributes.get( DONT_EXPAND ) ) ) {
			return new TextBox();
		}

		// Nested Metawidget

		return null;
	}

	//
	// Private methods
	//

	private void addListBoxItems( ListBox listBox, List values, List labels, Map attributes ) {

		if ( values == null ) {
			return;
		}

		// Empty option
		//
		// Note: GWT doesn't seem to be able to set null for the
		// value. It always comes back as String "null"

		if ( GwtUtils.needsEmptyLookupItem( attributes ) ) {
			addListBoxItem( listBox, "", null );
		}

		// See if we're using labels

		if ( labels != null && !labels.isEmpty() && labels.size() != values.size() ) {
			throw new RuntimeException( "Labels list must be same size as values list" );
		}

		// Add the select items

		for ( int loop = 0, length = values.size(); loop < length; loop++ ) {
			String value = values.get( loop );
			String label = null;

			if ( labels != null && !labels.isEmpty() ) {
				label = labels.get( loop );
			}

			addListBoxItem( listBox, value, label );
		}
	}

	private void addListBoxItem( ListBox listBox, String value, String label ) {

		if ( label != null ) {
			listBox.addItem( label, value );
			return;
		}

		listBox.addItem( value );
	}
}