/*
 * [ColourScheme.java]
 *
 * Summary: Generate a series of colour swatches to display a colour scheme.
 *
 * Copyright: (c) 2008-2017 Roedy Green, Canadian Mind Products, http://mindprod.com
 *
 * Licence: This software may be copied and used freely for any purpose but military.
 *          http://mindprod.com/contact/nonmil.html
 *
 * Requires: JDK 1.8+
 *
 * Created with: JetBrains IntelliJ IDEA IDE http://www.jetbrains.com/idea/
 *
 * Version History:
 *  1.8 2009-02-06 include go package in ZIP bundle.
 */
package com.mindprod.htmlmacros.macro;

import com.mindprod.common18.Misc;
import com.mindprod.fastcat.FastCat;

import java.awt.Color;
import java.util.Arrays;
import java.util.Comparator;

import static java.lang.System.*;

/**
 * Generate a series of colour swatches to display a colour scheme.
 *
 * @author Roedy Green, Canadian Mind Products
 * @version 1.8 2009-02-06 include go package in ZIP bundle.
 * @since 2008-09-14
 */
public final class ColourScheme extends Macro
    {
    /**
     * how to use the macro
     */
    private static final String USAGE = "\nColourScheme macro needs a list of colours of the form #rrggbb in hex";

    /**
     * expandNoRef each colour into a td cell
     *
     * @param colors array of colours to use in creating the swatches.
     *
     * @return expansion row of colour swatches as a table row <td>..<td>
     */
    private static String expand( Color[] colors )
        {
        final FastCat sb = new FastCat( colors.length * 7 );
        for ( Color color : colors )
            {
            final int r = color.getRed();
            final int g = color.getGreen();
            final int b = color.getBlue();
            final String contrast;
            if ( r + g + b > 0x80 * 3 )
                {
                contrast = "black";
                }
            else
                {
                contrast = "white";
                }
            sb.append( "<td style=\"background-color:" );
            sb.append( getRGBHexString( color ) );
            sb.append( ";color:" );
            sb.append( contrast );
            sb.append( "\">" );
            sb.append( getRGBHexString( color ) );
            sb.append( "</td>\n" );
            }
        return sb.toString();
        }

    /**
     * get #rrggbb value of a colour
     *
     * @param color colour you want to get hex name of
     *
     * @return #rrggbb
     */
    private static String getRGBHexString( Color color )
        {
        String g = Integer.toString( color.getRGB() & 0xffffff, 16/* radix */ );
        // pad out to 6 chars with lead zeros.
        if ( g.length() < 6 )
            {
            g = "0000000".substring( 0, 6 - g.length() ) + g;
            }
        return '#' + g;
        }

    /**
     * typical use: <!-- macro ColourScheme #00000 #808080 #ffffff -->
     *
     * @param parms   RFC# as a string
     * @param quiet   true if want output suppressed.
     * @param verbose @return expanded macro HTML
     */
    public String expandMacro( String[] parms,
                               final boolean quiet, final boolean verbose )
        {
        if ( !quiet )
            {
            out.print( "C" );
            }
        if ( parms.length < 1 )
            {
            throw new IllegalArgumentException( USAGE );
            }
        Color[] colors = new Color[ parms.length ];
        int i = 0;
        for ( String parm : parms )
            {
            if ( !( parm.length() == 7 && parm.charAt( 0 ) == '#' ) )
                {
                throw new IllegalArgumentException( USAGE );
                }
            try
                {
                colors[ i++ ] = new Color( Integer.parseInt( parm.substring( 1 ), 16 ) );
                }
            catch ( NumberFormatException e )
                {
                throw new IllegalArgumentException( USAGE );
                }
            } // end for
        // sort colours darkest first, brightest last
        Arrays.sort( colors, new ColourScheme.ByWhiteness() );
        return ( expand( colors ) );
        }

    /**
     * Sort by whiteness.
     * <p/>
     * Defines an alternate sort order for Color.
     *
     * @version 1.0 2009-05-22 - initial release
     * @since 2009-05-22
     */
    static class ByWhiteness implements Comparator<Color>
        {
        /**
         * needed to hold return values
         */
        private static final float[] hsbvals = new float[ 3 ];

        /**
         * Sort by whiteness.
         * Defines an alternate sort order for Color.
         * Compare two Color Objects.
         * Compares whiteness.
         * Informally, returns (a-b), or +ve if a is more positive than b.
         *
         * @param a first Color to compare
         * @param b second Color to compare
         *
         * @return +ve if a&gt;b, 0 if a==b, -ve if a&lt;b
         */
        public final int compare( Color a, Color b )
            {
            final float[] aHSB = Color.RGBtoHSB(
                    a.getRed(),
                    a.getGreen(),
                    a.getBlue(),
                    hsbvals );
            final float aSat = aHSB[ 1 ];
            final float aBright = aHSB[ 2 ];
            final float aWhiteness = aBright - aSat * .1f;
            final float[] bHSB = Color.RGBtoHSB(
                    b.getRed(),
                    b.getGreen(),
                    b.getBlue(),
                    hsbvals );
            final float bSat = bHSB[ 1 ];
            final float bBright = bHSB[ 2 ];
            final float bWhiteness = bBright - bSat * .1f;
            return Misc.signum( aWhiteness - bWhiteness );
            }
        }
    }