/***************************************************************************
                          ksmoon.cpp  -  K Desktop Planetarium
                             -------------------
    begin                : Sun Aug 26 2001
    copyright            : (C) 2001 by Jason Harris
    email                : kstars@30doradus.org
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#include "ksmoon.h"

#include <stdlib.h>
#include <math.h>

#include <QFile>
#include <QTextStream>

#include "ksnumbers.h"
#include "ksutils.h"
#include "kssun.h"
#include "kstarsdata.h"
#include "kspopupmenu.h"
#include "skycomponents/skymapcomposite.h"

namespace {
    // Convert degrees to radians and put it into [0,2*pi] range
    double degToRad(double x) {
        return dms::DegToRad * KSUtils::reduceAngle(x, 0.0, 360.0);
    }

    /*
     * Data used to calculate moon magnitude. 
     *
     * Formula and data were obtained from SkyChart v3.x Beta
     *
     */
    // intensities in Table 1 of M. Minnaert (1961),
    // Phase  Frac.            Phase  Frac.            Phase  Frac.
    // angle  ill.   Mag       angle  ill.   Mag       angle  ill.   Mag
    //  0    1.00  -12.7        60   0.75  -11.0       120   0.25  -8.7
    // 10    0.99  -12.4        70   0.67  -10.8       130   0.18  -8.2
    // 20    0.97  -12.1        80   0.59  -10.4       140   0.12  -7.6
    // 30    0.93  -11.8        90   0.50  -10.0       150   0.07  -6.7
    // 40    0.88  -11.5       100   0.41   -9.6       160   0.03  -3.4
    // 50    0.82  -11.2       110   0.33   -9.2
    static const double MagArray[19] = {
        -12.7, -12.4, -12.1, -11.8, -11.5, -11.2, -11.0, -10.8, -10.4, -10.0,
        -9.6,  -9.2,  -8.7,  -8.2,  -7.6,  -6.7,  -3.4,  0, 0};
}

KSMoon::KSMoon()
        : KSPlanetBase( I18N_NOOP( "Moon" ), QString(), QColor("white"), 3474.8 /*diameter in km*/ )
{
    instance_count++;
    //Reset object type
    setType( SkyObject::MOON );
}

KSMoon::KSMoon(const KSMoon& o) :
    KSPlanetBase(o)
{
    instance_count++;
}

KSMoon* KSMoon::clone() const
{
    return new KSMoon(*this);
}

KSMoon::~KSMoon() {
    instance_count--;
    if(instance_count <= 0) {
        LRData.clear();
        BData.clear();
        data_loaded = false;
    }
}

bool KSMoon::data_loaded = false;
int KSMoon::instance_count = 0;
QList<KSMoon::MoonLRData> KSMoon::LRData;
QList<KSMoon::MoonBData> KSMoon::BData;


bool KSMoon::loadData() {
    if (data_loaded)
        return true;

    QStringList fields;
    QFile f;

    if ( KSUtils::openDataFile( f, "moonLR.dat" ) ) {
        QTextStream stream( &f );
        while ( !stream.atEnd() ) {
            fields = stream.readLine().split( ' ', QString::SkipEmptyParts );

            if ( fields.size() == 6 ) {
                LRData.append( MoonLRData() );
                LRData.last().nd  = fields[0].toInt();
                LRData.last().nm  = fields[1].toInt();
                LRData.last().nm1 = fields[2].toInt();
                LRData.last().nf  = fields[3].toInt();
                LRData.last().Li  = fields[4].toDouble();
                LRData.last().Ri  = fields[5].toDouble();
            }
        }
        f.close();
    } else
        return false;


    if ( KSUtils::openDataFile( f, "moonB.dat" ) ) {
        QTextStream stream( &f );
        while ( !stream.atEnd() ) {
            fields = stream.readLine().split( ' ', QString::SkipEmptyParts );
            
            if ( fields.size() == 5 ) {
                BData.append( MoonBData() );
                BData.last().nd  = fields[0].toInt();
                BData.last().nm  = fields[1].toInt();
                BData.last().nm1 = fields[2].toInt();
                BData.last().nf  = fields[3].toInt();
                BData.last().Bi  = fields[4].toDouble();
            }
        }
        f.close();
    }

    data_loaded = true;
    return true;
}

bool KSMoon::findGeocentricPosition( const KSNumbers *num, const KSPlanetBase* ) {
    //Algorithms in this subroutine are taken from Chapter 45 of "Astronomical Algorithms"
    //by Jean Meeus (1991, Willmann-Bell, Inc. ISBN 0-943396-35-2.  http://www.willbell.com/math/mc1.htm)
    QString fname, snum, line;
    QFile f;

    double T, L, D, M, M1, F, A1, A2, A3;
    double sumL, sumR, sumB;

    //Julian centuries since J2000
    T = num->julianCenturies();

    double Et = 1.0 - 0.002516*T - 0.0000074*T*T;

    //Moon's mean longitude
    L = degToRad( 218.3164591 + 481267.88134236*T - 0.0013268*T*T + T*T*T/538841.0 - T*T*T*T/65194000.0 );
    //Moon's mean elongation
    D = degToRad( 297.8502042 + 445267.1115168*T - 0.0016300*T*T + T*T*T/545868.0 - T*T*T*T/113065000.0 );
    //Sun's mean anomaly
    M = degToRad( 357.5291092 + 35999.0502909*T - 0.0001536*T*T + T*T*T/24490000.0 );
    //Moon's mean anomaly
    M1= degToRad( 134.9634114 + 477198.8676313*T + 0.0089970*T*T + T*T*T/69699.0 - T*T*T*T/14712000.0 );
    //Moon's argument of latitude (angle from ascending node)
    F = degToRad( 93.2720993 + 483202.0175273*T - 0.0034029*T*T - T*T*T/3526000.0 + T*T*T*T/863310000.0 );

    A1 = degToRad( 119.75 +    131.849*T );
    A2 = degToRad(  53.09 + 479264.290*T );
    A3 = degToRad( 313.45 + 481226.484*T );

    //Calculate the series expansions stored in moonLR.txt and moonB.txt.
    //
    sumL = 0.0;
    sumR = 0.0;

    if (!loadData()) return false;

    for ( int i=0; i < LRData.size(); ++i ) {
        const MoonLRData& mlrd = LRData[i];

        double E = 1.0;
        if ( mlrd.nm ) { //if M != 0, include changing eccentricity of Earth's orbit
            E = Et;
            if ( abs( mlrd.nm )==2 ) E = E*E; //use E^2
        }
        sumL += E*mlrd.Li*sin( mlrd.nd*D + mlrd.nm*M + mlrd.nm1*M1 + mlrd.nf*F );
        sumR += E*mlrd.Ri*cos( mlrd.nd*D + mlrd.nm*M + mlrd.nm1*M1 + mlrd.nf*F );
    }

    sumB = 0.0;
    for ( int i=0; i < BData.size(); ++i ) {
        const MoonBData& mbd = BData[i];

        double E = 1.0;
        if ( mbd.nm ) { //if M != 0, include changing eccentricity of Earth's orbit
            E = Et;
            if ( abs( mbd.nm )==2 ) E = E*E; //use E^2
        }
        sumB += E*mbd.Bi*sin( mbd.nd*D + mbd.nm*M + mbd.nm1*M1 + mbd.nf*F );
    }

    //Additive terms for sumL and sumB
    sumL += ( 3958.0*sin( A1 ) + 1962.0*sin( L-F ) + 318.0*sin( A2 ) );
    sumB += ( -2235.0*sin( L ) + 382.0*sin( A3 ) + 175.0*sin( A1-F ) + 175.0*sin( A1+F ) + 127.0*sin( L-M1 ) - 115.0*sin( L+M1 ) );

    //Geocentric coordinates
    setEcLong( sumL/1000000.0 + L * 180.0 / dms::PI ); //convert radians to degrees
    setEcLat(  sumB/1000000.0 );
    Rearth = ( 385000.56 + sumR/1000.0 )/AU_KM; //distance from Earth, in AU

    EclipticToEquatorial( num->obliquity() );

    //Determine position angle
    findPA( num );

    return true;
}

void KSMoon::findMagnitude(const KSNumbers*)
{
    // This block of code to compute Moon magnitude (and the
    // relevant data put into ksplanetbase.h) was taken from
    // SkyChart v3 Beta
    int p = floor( phase().Degrees() );
    if( p > 180 )
        p = p - 360;
    int i = p / 10;
    int k = p % 10;
    int j = (i + 1 > 18) ? 18 : i + 1;
    i = 18 - abs(i);
    j = 18 - abs(j);
    setMag( MagArray[i] + (MagArray[j] - MagArray[i]) * k / 10 );
}

void KSMoon::findPhase() {
    KSSun *Sun = (KSSun*)KStarsData::Instance()->skyComposite()->findByName( "Sun" );
    Phase = ecLong()->Degrees() - Sun->ecLong()->Degrees(); // Phase is obviously in degrees
    double DegPhase = dms( Phase ).reduce().Degrees();
    int iPhase = int( 0.1*DegPhase+0.5 ) % 36; // iPhase must be in [0,36) range
    QString imName = QString().sprintf("moon%02d.png", iPhase);

    QFile imFile;
    if ( KSUtils::openDataFile( imFile, imName ) ) {
        imFile.close();
        image0()->load( imFile.fileName() );
        image()->load( imFile.fileName() );
    }
}

QString KSMoon::phaseName() const {
    double f = illum();
    double p = Phase;

    //First, handle the major phases
    if ( f > 0.99 ) return i18nc( "moon phase, 100 percent illuminated", "Full moon" );
    if ( f < 0.01 ) return i18nc( "moon phase, 0 percent illuminated", "New moon" );
    if ( fabs( f - 0.50 ) < 0.01 ) {
        if ( p < 180.0 ) return i18nc( "moon phase, half-illuminated and growing", "First quarter" );
        else return i18nc( "moon phase, half-illuminated and shrinking", "Third quarter" );
    }

    //Next, handle the more general cases
    if ( p < 90.0 ) return i18nc( "moon phase between new moon and 1st quarter", "Waxing crescent" );
    else if ( p < 180.0 ) return i18nc( "moon phase between 1st quarter and full moon", "Waxing gibbous" );
    else if ( p < 270.0 ) return i18nc( "moon phase between full moon and 3rd quarter", "Waning gibbous" );
    else if ( p < 360.0 ) return i18nc( "moon phase between 3rd quarter and new moon", "Waning crescent" );

    else return i18n( "unknown" );
}

void KSMoon::initPopupMenu( KSPopupMenu* pmenu ) {
    pmenu->createMoonMenu( this );
}

SkyObject::UID KSMoon::getUID() const
{
   return solarsysUID(UID_SOL_BIGOBJ) | 10;
}
