package com.onaro.util.jfc.mixedvalue;

import static com.onaro.util.jfc.mixedvalue.MixedValueConstants.MIXED_VALUE;

import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.ComboBoxModel;
import javax.swing.DefaultComboBoxModel;
import javax.swing.JComboBox;
import javax.swing.JList;
import javax.swing.ListCellRenderer;
import javax.swing.UIManager;

import org.apache.commons.lang3.StringUtils;

/**
 * An extension to {@link JComboBox} allowing for a special "mixed" valued. Used when editing multiple values which are
 * not the same, though the user can set all of them to the same value selected from the list.
 * <p>
 * Once the user clics on the field, the mixed mode, if set, is reset and the value clears and a value is selected.
 */
public class MixedComboBox extends JComboBox<Object> {

    private static final long serialVersionUID = 1L;

    /**
     * Tells if the current value is this special "mixed".
     */
    private boolean mixed;

    /**
     * Font to use for the special "mixed" value.
     */
    private Font italicFont;

    /**
     * Standard font to use for any value but the special "mixed" value.
     */
    private Font plainFont;

    /**
     * Initializes this mixed-value combo-box field. Records the default fonts. Registers the listeners that will
     * clear the "mixed mode" once the user clicks on the field.
     * @param items the values from which the user can select
     */
    public MixedComboBox(final Object items[]) {
        this(new DefaultComboBoxModel<Object>(items));
    }

    /**
     * Initializes this mixed-value combo-box field. Records the default fonts. Registers the listeners that will
     * clear the "mixed mode" once the user clicks on the field.
     * @param aModel the model for this combo-box
     */
    public MixedComboBox(ComboBoxModel<Object> aModel) {
        super(aModel);

        italicFont = getFont().deriveFont(Font.ITALIC);
        plainFont = getFont().deriveFont(Font.PLAIN);

        addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if (getSelectedIndex() >= 0) {
                    setMixed(false);
                }
            }
        });
    }

    public void reset() {
        // set the current selected item.
        selectedItemReminder = dataModel.getSelectedItem();
    }

    /**
     * Sets the mixed mode of this field. When set to true, the field will show "mixed" in italic, blue font.
     * @param mixed true if the field should enter the "mixed mode"
     */
    public void setMixed(boolean mixed) {
        if (this.mixed != mixed) {
            this.mixed = mixed;
            if (mixed) setSelectedIndex(-1);
        }
    }

    /**
     * Tells if the field is currently in "mixed mode".
     * @return true if the field is in "mixed mode"
     */
    public boolean isMixed() {
        return mixed;
    }

    protected boolean isDontCare(Object value){
        return value == null;
    }

    /**
     * Override the original method to guarantee enough space for all values.
     * @return
     */
    public Dimension getPreferredSize() {
        Dimension size = super.getPreferredSize();
        size.setSize(size.getWidth()+10,size.getHeight());
        return size;
    }

    public void setRenderer(ListCellRenderer<Object> renderer) {
        super.setRenderer(new MixedCellRenderer(renderer));
    }

    private class MixedCellRenderer implements ListCellRenderer<Object> {

        ListCellRenderer<Object> encapsulatedRenderer;

        public MixedCellRenderer(ListCellRenderer<Object> encapsulatedRenderer) {
            this.encapsulatedRenderer = encapsulatedRenderer;
        }

        public Component getListCellRendererComponent(JList<?> list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
            /**
             * Render "DONT_CARE" as blank.
             */
            if (isDontCare(value)) value = StringUtils.EMPTY;

            /**
             * Render "MIXED" as blue italic
             */
            if(isMixed() && index < 0) {
                list.setForeground(UIManager.getColor("mixedValue.color")); //$NON-NLS-1$
                list.setFont(italicFont);
                value = MIXED_VALUE;
            }else{
                list.setForeground(Color.BLACK);
                list.setFont(plainFont);
            }

            return encapsulatedRenderer.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
        }
    }
}