package com.temp.client.foundation.widget.table.cell;

import com.google.gwt.cell.client.*;
import com.google.gwt.dom.client.*;
import com.google.gwt.event.dom.client.*;
import com.google.gwt.safehtml.shared.*;

/**
 * A {@link Cell} used to render a radio button. The value of the radio button
 * may be toggled using the ENTER key as well as via mouse click.
 */
public class RadioButtonCell extends AbstractEditableCell<Boolean, Boolean> {

    private static final String RADIO_INPUT_TEMPLATE_START = "<input type=\"radio\" tabindex=\"-1\" name=\"";
    private static final String RADIO_INPUT_TEMPLATE_END = "/>";
    private static final String RADIO_INPUT_SELECTED_TOKEN = "checked=\"checked\" ";
    private static final String RADIO_INPUT_DISABLED_TOKEN = "disabled";

    private boolean dependsOnSelection, handlesSelection, enabled;
    private String name;

    /**
     * Constructs a new {@link RadioButtonCell} that does not depend on
     * selection and does not handle selection.
     */
    public RadioButtonCell( boolean enabled, String name ) {
        super( "change", "keydown" );
        this.enabled = enabled;
        this.name = name;
    }

    /**
     * Constructs a new {@link RadioButtonCell} that can be configured to depend
     * and/or handle selection
     *
     * @param groupName          HTML name attribute of the radiobutton
     * @param dependsOnSelection true if the cell depends on the selection state
     * @param handlesSelection   true if the cell modifies the selection state
     */
    public RadioButtonCell( boolean dependsOnSelection, boolean handlesSelection, boolean enabled, String name ) {
        this( enabled, name );
        this.dependsOnSelection = dependsOnSelection;
        this.handlesSelection = handlesSelection;
    }

    @Override
    public boolean dependsOnSelection() {
        return dependsOnSelection;
    }

    @Override
    public boolean handlesSelection() {
        return handlesSelection;
    }

    @Override
    public void onBrowserEvent( Context context, Element parent, Boolean value,
                                NativeEvent event, ValueUpdater<Boolean> valueUpdater ) {
        String type = event.getType();

        boolean enterPressed = "keydown".equals( type )
                               && event.getKeyCode() == KeyCodes.KEY_ENTER;
        if ( "change".equals( type ) || enterPressed ) {
            InputElement input = parent.getFirstChild().cast();
            Boolean isChecked = input.isChecked();

            /**
             * Check the radio button if the enter key was pressed and the cell handles
             * selection or doesn't depend on selection. If the cell depends on
             * selection but doesn't handle selection, then ignore the enter key and
             * let the SelectionEventManager determine which keys will trigger a
             * change.
             */
            if ( enterPressed && (handlesSelection() || !dependsOnSelection()) ) {
                isChecked = true;
                input.setChecked( isChecked );
            }

            /**
             * Save the new value. However, if the cell depends on the selection, then
             * do not save the value because we can get into an inconsistent state.
             */
            Object key = context.getKey();
            if ( value != isChecked && !dependsOnSelection() ) {
                setViewData( key, isChecked );
            } else {
                clearViewData( key );
            }

            if ( valueUpdater != null ) {
                valueUpdater.update( isChecked );
            }
        }
    }

    @Override
    public boolean isEditing( com.google.gwt.cell.client.Cell.Context context,
                              Element parent, Boolean value ) {
        // A radio button is never in "edit mode". There is no intermediate state
        // between checked and unchecked.
        return false;
    }

    @Override
    public void render( com.google.gwt.cell.client.Cell.Context context,
                        Boolean value, SafeHtmlBuilder sb ) {
        Object key = context.getKey();
        Boolean viewData = getViewData( key );
        if ( viewData != null && viewData.equals( value ) ) {
            clearViewData( key );
            viewData = null;
        }

        if ( value != null && ((viewData != null) ? viewData : value) ) {
            sb.append( this.getRadioButtonInput( true ) );
        } else {
            sb.append( this.getRadioButtonInput( false ) );
        }
    }

    /**
     * Provides an HTML string representation of a radio button
     *
     * @param selected
     */
    private SafeHtml getRadioButtonInput( boolean selected ) {
        StringBuffer sb = new StringBuffer( RADIO_INPUT_TEMPLATE_START );

        String safeName = SafeHtmlUtils.htmlEscape( this.name );

        sb.append( (null == this.name) ? "" : safeName );
        sb.append( "\" " );

        if ( selected ) {
            sb.append( RADIO_INPUT_SELECTED_TOKEN );
        }

        if ( !this.enabled ) {
            sb.append( RADIO_INPUT_DISABLED_TOKEN );
        }

        sb.append( RADIO_INPUT_TEMPLATE_END );
        return SafeHtmlUtils.fromSafeConstant( sb.toString() );
    }
}