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//=============================================================================
// Copyright 2006-2010 Daniel W. Dyer
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//=============================================================================
package org.uncommons.watchmaker.swing;

import java.awt.BorderLayout;
import java.text.DecimalFormat;
import javax.swing.JComponent;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import org.uncommons.maths.Maths;
import org.uncommons.maths.number.AdjustableNumberGenerator;
import org.uncommons.maths.number.NumberGenerator;
import org.uncommons.maths.random.Probability;

/**
 * A GUI control that allows the user to set/update the value of a
 * {@link Probability} parameter.
 * @author Daniel Dyer
 */
public class ProbabilityParameterControl implements EvolutionControl
{
    private final Probability defaultValue;
    private final int range;
    private final JComponent control;
    private final JSlider probabilitySlider;
    private final JLabel valueLabel = new JLabel();
    private final AdjustableNumberGenerator numberGenerator;
    private final DecimalFormat format;


    /**
     * Creates a control with a default range of 0..1 and a default granularity
     * of 2 decimal places.
     * @param defaultValue The default probability value.
     */
    public ProbabilityParameterControl(Probability defaultValue)
    {
        this(Probability.ZERO, Probability.ONE, 2, defaultValue);
    }


    /**
     * @param minimum The minimum probability that this control will permit.
     * @param maximum The maximum probability that this control will permit.
     * @param decimalPlaces The granularity of the control.
     * @param initialValue The default probability.
     */
    public ProbabilityParameterControl(Probability minimum,
                                       Probability maximum,
                                       int decimalPlaces,
                                       Probability initialValue)
    {
        if (initialValue.compareTo(minimum) < 0 || initialValue.compareTo(maximum) > 0)
        {
            throw new IllegalArgumentException("Initial value must respect minimum and maximum.");
        }
        if (decimalPlaces < 1)
        {
            throw new IllegalArgumentException("Number of decimal places must be >= 1.");
        }
        this.format = createFormat(decimalPlaces);
        this.defaultValue = initialValue;
        this.numberGenerator = new AdjustableNumberGenerator(this.defaultValue);
        this.range = (int) Maths.raiseToPower(10, decimalPlaces);
        this.probabilitySlider = createSlider(initialValue, minimum, maximum);
        probabilitySlider.setName("Slider"); // For easy look-up in unit tests.
        this.control = new JPanel(new BorderLayout());
        control.add(probabilitySlider, BorderLayout.CENTER);
        valueLabel.setText(format.format(defaultValue));
        control.add(valueLabel, BorderLayout.WEST);
    }


    private DecimalFormat createFormat(int decimalPlaces)
    {
        StringBuilder formatString = new StringBuilder("0.");
        for (int i = 0; i < decimalPlaces; i++)
        {
            formatString.append('0');
        }
        return new DecimalFormat(formatString.toString());
    }

    
    private JSlider createSlider(Probability initialValue,
                                 Probability minimum,
                                 Probability maximum)
    {
        int value = (int) Math.round(range * initialValue.doubleValue());
        int min = (int) Math.round(range * minimum.doubleValue());
        int max = (int) Math.round(range * maximum.doubleValue());
        final JSlider slider = new JSlider(min, max, value);
        slider.addChangeListener(new ChangeListener()
        {
            public void stateChanged(ChangeEvent changeEvent)
            {
                Probability probability = new Probability((double) slider.getValue() / range);
                numberGenerator.setValue(probability);
                valueLabel.setText(format.format(probability));
            }
        });
        slider.setMajorTickSpacing(10);
        slider.setMinorTickSpacing(5);
        slider.setPaintTicks(true);
        return slider;
    }


    /**
     * {@inheritDoc}
     */
    public JComponent getControl()
    {
        return control;
    }


    /**
     * {@inheritDoc}
     */
    public void reset()
    {
        int value = (int) Math.round(range * defaultValue.doubleValue());
        probabilitySlider.setValue(value);
        valueLabel.setText(format.format(defaultValue));
        numberGenerator.setValue(defaultValue);
    }


    /**
     * Returns a number generator that simply returns the current probability value
     * represented by the position of the slider control.
     * @return A number generator that can be used to control an evolutionary program.
     */
    public NumberGenerator getNumberGenerator()
    {
        return numberGenerator;
    }


    /**
     * {@inheritDoc}
     */
    public void setDescription(String description)
    {
        probabilitySlider.setToolTipText(description);
        valueLabel.setToolTipText(description);
    }
}