/*
 * [CalcBiorhythms.java]
 *
 * Summary: Calculates Biorhythm values for any given day.
 *
 * Copyright: (c) 1999-2017 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:
 *  2.6 2009-03-24 fix layout bug, use anti-aliasing.
 */
package com.mindprod.bio;

import com.mindprod.common18.Misc;

import java.awt.Color;

/**
 * Calculates Biorhythm values for any given day.
 *
 * @author Roedy Green, Canadian Mind Products
 * @version 2.6 2009-03-24 fix layout bug, use anti-aliasing.
 * @since 1999
 */
final class CalcBiorhythms
    {
    /**
     * length of combined cycle in days.
     *
     * @noinspection WeakerAccess
     */
    static final int COMBI_PERIOD = 23 * 28 * 33;

    /**
     * length of emotional cycle in days.
     *
     * @noinspection WeakerAccess
     */
    static final int EMOTIONAL_PERIOD = 28;

    /**
     * length of intellectual cycle in days.
     *
     * @noinspection WeakerAccess
     */
    static final int INTELLECTUAL_PERIOD = 33;

    /**
     * length of physical cycle in days.
     *
     * @noinspection WeakerAccess
     */
    static final int PHYSICAL_PERIOD = 23;

    /**
     * colour for combined cycle line.
     */
    static final Color FOREGROUND_FOR_COMBI = new Color( 0xffa500 );/* orange */

    /**
     * colour for emotional cycle line.
     */
    static final Color FOREGROUND_FOR_EMOTIONAL = Color.blue;

    /**
     * colour for intellectual cycle line  dark green.
     */
    static final Color FOREGROUND_FOR_INTELLECTUAL = new Color( 0x008000 );

    /**
     * colour for physical cycle line.
     */
    static final Color FOREGROUND_FOR_PHYSICAL = Color.red;

    /**
     * calculate combined biorhythm.
     *
     * @param daysSinceBirth number of days since birthdate to calculate for.
     *
     * @return weighted average of phys, emot, intel biorhythms -1 .. +1.
     */
    private static double combiLevel( int daysSinceBirth )
        {
        double phys =
                Math.sin( Math.PI * 2 / PHYSICAL_PERIOD * ( daysSinceBirth
                                                            % PHYSICAL_PERIOD ) );
        double emot =
                Math.sin( Math.PI * 2 / EMOTIONAL_PERIOD * ( daysSinceBirth
                                                             % EMOTIONAL_PERIOD ) );
        double intel =
                Math.sin( Math.PI * 2 / INTELLECTUAL_PERIOD * ( daysSinceBirth
                                                                % INTELLECTUAL_PERIOD ) );
        // magic constant are arbitrary fiddled to give more weight to phys
        return phys * 0.37 + emot * 0.34 + intel * 0.29;
        }

    /**
     * calculate biorhythm.
     *
     * @param daysSinceBirth number of days since birthdate to calculate for.
     * @param period         periodicity in days.  Period of that type of biorhythm, 0 for combination.
     *
     * @return phys, emot or intel biorhythms -1.0 .. +1.0
     * @noinspection WeakerAccess
     */
    static double level( int daysSinceBirth, int period )
        {
        if ( period == COMBI_PERIOD )
            {
            return combiLevel( daysSinceBirth );
            }
        else
            {
            return Math.sin( Math.PI * 2 / period * ( daysSinceBirth % period ) );
            }
        }

    /**
     * Calculate a value for today for given biorhythm.
     *
     * @param daysSinceBirth days since the person was born. This lets you calculate the biorythm for any day.
     * @param period         Number of days for the period. 0 means combined.
     *
     * @return String representing how high that type of biorhythm is today e.g. "very high", "high", l"low", "very
     * low", "critical".
     */
    static String levelInWords( int daysSinceBirth, int period )
        {
        // value of sine wave today
        double todayLevel = level( daysSinceBirth, period );
        if ( todayLevel >= +.8 )
            {
            return "very high";
            }
        if ( todayLevel <= -.8 )
            {
            return "very low";
            }
        if ( todayLevel >= +.5 )
            {
            return "high";
            }
        if ( todayLevel <= -.5 )
            {
            return "low";
            }
        if ( todayLevel >= +.1 )
            {
            return "average";
            }
        if ( todayLevel <= -.1 )
            {
            return "below average";
            }
        // it almost critical. To count as "the" critical day you must have:
        // 1. a sign change between today and either yesterday or tomorrow.
        // 2. be closer in absolute value to 0 than yesterday or tomorrow.
        // value of sine wave yesterday
        double yesterdayLevel = level( daysSinceBirth - 1, period );
        // value of sine wave tomorrow
        double tomorrowLevel = level( daysSinceBirth + 1, period );
        if ( ( signDiff( yesterdayLevel, todayLevel ) || signDiff( todayLevel,
                tomorrowLevel ) )
             && ( Math.abs( todayLevel ) <= Math.abs( yesterdayLevel ) )
             && ( Math.abs( todayLevel ) <= Math.abs( tomorrowLevel ) ) )
            {
            return "critical";
            }
        // must be -.1 .. +.1
        return "average";
        }

    /**
     * Returns random string describing luck level.
     *
     * @param daysSinceBirth How many days since birth, not necessarily representing today.
     *
     * @return String, possibly empty, describing luck level.
     */
    static String luckLevelInWords( int daysSinceBirth )
        {
        double luck = level( daysSinceBirth, COMBI_PERIOD );
        double yesterdayLuck = level( daysSinceBirth - 1, COMBI_PERIOD );
        double tomorrowLuck = level( daysSinceBirth + 1, COMBI_PERIOD );
        if ( luck > 0.5 && luck > yesterdayLuck && luck > tomorrowLuck )
            {
            return "Today is your lucky day!";
            }
        else
            {
            return "";
            }
        }

    /**
     * Do a and b differ in sign?.
     *
     * @param a first number to compare.
     * @param b second number to compare.
     *
     * @return true of have different sign.
     */
    private static boolean signDiff( double a, double b )
        {
        return Misc.signum( a ) != Misc.signum( b );
        }
    }