/***************************************************************************
 *   Copyright (C) 2009 	by Kashyap R Puranik, kashthealien@gmail.com   *
 *                                                                         *
 *   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.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.         *
 ***************************************************************************/

#include "gasCalculator.h"
#include "prefs.h"

using namespace KUnitConversion;

gasCalculator::gasCalculator(QWidget * parent)
        : QWidget(parent)
{
    ui.setupUi(this);

    setupUnitComboboxes();

    init();

    connect(ui.temp , SIGNAL(valueChanged(double)),
            this, SLOT(tempChanged()));
    connect(ui.temp_unit , SIGNAL(activated(int)),
            this, SLOT(tempChanged()));
    connect(ui.volume , SIGNAL(valueChanged(double)),
            this, SLOT(volChanged()));
    connect(ui.volume_unit , SIGNAL(activated(int)),
            this, SLOT(volChanged()));
    connect(ui.pressure , SIGNAL(valueChanged(double)),
            this, SLOT(pressureChanged()));
    connect(ui.pressure_unit , SIGNAL(activated(int)),
            this, SLOT(pressureChanged()));
    connect(ui.mass ,  SIGNAL(valueChanged(double)),
            this, SLOT(massChanged()));
    connect(ui.mass_unit , SIGNAL(activated(int)),
            this, SLOT(massChanged()));
    connect(ui.moles , SIGNAL(valueChanged(double)),
            this, SLOT(molesChanged(double)));
    connect(ui.molarMass, SIGNAL(valueChanged(double)),
            this, SLOT(molarMassChanged(double)));
    connect(ui.a , SIGNAL(valueChanged(double)),
            this, SLOT(Vand_aChanged()));
    connect(ui.b ,  SIGNAL(valueChanged(double)),
            this, SLOT(Vand_bChanged()));
    connect(ui.b_unit , SIGNAL(activated(int)),
            this, SLOT(Vand_bChanged()));
    connect(ui.mode, SIGNAL(activated(int)),
            this, SLOT(setMode(int)));
    connect(ui.reset, SIGNAL(clicked()),
            this, SLOT(init()));
}

gasCalculator:: ~gasCalculator()
{
}

void gasCalculator::init()
{
    error(RESET_GAS_MESSAGE);

    ui.molarMass-> setValue(2.008);
    ui.temp     -> setValue(273.0);
    ui.volume   -> setValue(22.400);
    ui.pressure -> setValue(1.0);
    ui.a        -> setValue(0.0);
    ui.b        -> setValue(0.0);
    ui.mass     -> setValue(2.016);
    ui.moles    -> setValue(1.0);

    ui.mass_unit->setCurrentIndex(0);
    ui.pressure_unit->setCurrentIndex(0);
    ui.temp_unit->setCurrentIndex(0);
    ui.volume_unit->setCurrentIndex(0);
    ui.b_unit->setCurrentIndex(0);

    m_temp = Value(273.0, KUnitConversion::Kelvin);
    m_molarMass = 2.016;
    m_pressure = Value(1.0, KUnitConversion::Atmosphere);
    m_mass = Value(2.016, KUnitConversion::Gram);
    m_moles = 1.0;
    m_Vand_a = 0.0;
    m_Vand_b = Value(0.0, KUnitConversion::Liter);
    m_vol = Value(22.4, KUnitConversion::Liter);

    if (Prefs::ideal()) {
        ui.non_ideal->hide();
    }

    setMode(VOLUME);
}

void gasCalculator::setupUnitComboboxes()
{
    QList<int> units;
    units << Gram << Milligram << Kilogram << Ton;
    populateUnitCombobox( ui.mass_unit, units );

    units.clear();
    units << Atmosphere << Pascal << Bar << Millibar << Torr;
    populateUnitCombobox( ui.pressure_unit, units );

    units.clear();
    units << Kelvin << Celsius << Fahrenheit;
    populateUnitCombobox( ui.temp_unit, units );

    units.clear();
    units << Liter << Milliliter << CubicMeter << KUnitConversion::GallonUS;
    populateUnitCombobox( ui.volume_unit, units );

    units.clear();
    units << Liter << Milliliter << CubicMeter << KUnitConversion::GallonUS;
    populateUnitCombobox( ui.b_unit, units );
}

void gasCalculator::populateUnitCombobox(QComboBox *comboBox, const QList< int > &unitList)
{
    comboBox->clear();

    foreach( int unit, unitList) {
        comboBox->addItem( KUnitConversion::Converter().unit(unit).data()->description(), unit);
    }
}

int gasCalculator::getCurrentUnitId(QComboBox* comboBox)
{
    return comboBox->itemData( comboBox->currentIndex() ).toInt();
}

void gasCalculator::calculatePressure()
{
    double volume = m_vol.convertTo( KUnitConversion::Liter ).number();
    double temp = m_temp.convertTo( KUnitConversion::Kelvin ).number();
    double b = m_Vand_b.convertTo( KUnitConversion::Liter ).number();

    double pressure = m_moles * R * temp / (volume - m_moles * b) - m_moles * m_moles * m_Vand_a / volume / volume;

    m_pressure = Value(pressure, KUnitConversion::Atmosphere );
    m_pressure = m_pressure.convertTo(getCurrentUnitId(ui.pressure_unit));
    ui.pressure->setValue(m_pressure.number());
}

void gasCalculator::calculateMolarMass()
{
    double mass = m_mass.convertTo(KUnitConversion::Gram).number();
    double volume = m_vol.convertTo(KUnitConversion::Liter).number();
    double pressure = m_pressure.convertTo(KUnitConversion::Atmosphere).number();
    double temp = m_temp.convertTo(KUnitConversion::Kelvin).number();
    double b = m_Vand_b.convertTo(KUnitConversion::Liter).number();

    m_molarMass = mass * R * temp / (pressure + m_moles * m_moles * m_Vand_a / volume / volume)\
                  / (volume - m_moles * b);
    ui.molarMass->setValue(m_molarMass);
}

void gasCalculator::calculateVol()
{
    double pressure = m_pressure.convertTo(KUnitConversion::Atmosphere).number();
    double temp = m_temp.convertTo(KUnitConversion::Kelvin).number();
    double b = m_Vand_b.convertTo(KUnitConversion::Liter).number();

    double volume = m_moles * R * temp / pressure + (m_moles * b);
    m_vol = Value(volume, KUnitConversion::Liter);
    m_vol = m_vol.convertTo( getCurrentUnitId(ui.volume_unit) );
    ui.volume->setValue(m_vol.number());
}

void gasCalculator::calculateTemp()
{
    double volume = m_vol.convertTo(KUnitConversion::Liter).number();
    double pressure = m_pressure.convertTo(KUnitConversion::Atmosphere).number();
    double b = m_Vand_b.convertTo(KUnitConversion::Liter).number();

    double temp = (pressure + (m_moles * m_moles * m_Vand_a / volume / volume))\
                  * (volume - m_moles * b) / m_moles / R;
    m_temp = Value(temp, KUnitConversion::Kelvin);
    m_temp = m_temp.convertTo( getCurrentUnitId( ui.temp_unit ) );
    ui.temp->setValue(m_temp.number());
}

void gasCalculator::calculateMoles()
{
    double volume = m_vol.convertTo(KUnitConversion::Liter).number();
    double pressure = m_pressure.convertTo(KUnitConversion::Atmosphere).number();
    double temp = m_temp.convertTo(KUnitConversion::Kelvin).number();
    double b = m_Vand_b.convertTo(KUnitConversion::Liter).number();

    m_moles = (pressure + m_moles * m_moles * m_Vand_a / volume / volume)\
              * (volume - m_moles * b) / R / temp;
    ui.moles->setValue(m_moles);
}

void gasCalculator::calculateMass()
{
    double volume = m_vol.convertTo(KUnitConversion::Liter).number();
    double pressure = m_pressure.convertTo(KUnitConversion::Atmosphere).number();
    double temp = m_temp.convertTo(KUnitConversion::Kelvin).number();
    double b = m_Vand_b.convertTo(KUnitConversion::Liter).number();

    double mass = (pressure + m_moles * m_moles * m_Vand_a / volume / volume)\
                  * (volume - m_moles * b) * m_molarMass / R / temp;
    m_mass = Value(mass, KUnitConversion::Gram);
    m_mass = m_mass.convertTo( getCurrentUnitId( ui.mass_unit ) );
    ui.mass->setValue(m_mass.number());
}


void gasCalculator::volChanged()
{
    m_vol = Value(ui.volume->value(), getCurrentUnitId( ui.volume_unit ) );
    calculate();
}

void gasCalculator::tempChanged()
{
    m_temp = Value(ui.temp->value(), getCurrentUnitId( ui.temp_unit ) );
    calculate();
}

void gasCalculator::pressureChanged()
{
    m_pressure = Value(ui.pressure->value(), getCurrentUnitId( ui.pressure_unit ) );
    calculate();
}

void gasCalculator::massChanged()
{
    m_mass = Value(ui.mass->value(), getCurrentUnitId( ui.mass_unit ) );
    m_moles = m_mass.convertTo(KUnitConversion::Gram).number() / m_molarMass;
    ui.moles->setValue(m_moles);
    calculate();
}

void gasCalculator::molesChanged(double value)
{
    m_moles = value;
    m_mass = Value(m_moles * m_molarMass, KUnitConversion::Gram);
    m_mass = m_mass.convertTo( getCurrentUnitId( ui.mass_unit ) );
    ui.mass->setValue(m_mass.number());
    calculate();
}

void gasCalculator::molarMassChanged(double value)
{
    if (value == 0.0) {
        error(GAS_MOLAR_MASS_ZERO);
        return;
    }
    m_molarMass = value;
    m_mass = Value(m_molarMass * m_moles, KUnitConversion::Gram);
    m_mass = m_mass.convertTo( getCurrentUnitId( ui.mass_unit ) );
    ui.mass->setValue(m_mass.number());
    calculate();
}

void gasCalculator::Vand_aChanged()
{
    m_Vand_a = ui.a->value();
    calculate();
}

void gasCalculator::Vand_bChanged()
{
    m_Vand_b = Value(ui.b->value(), getCurrentUnitId( ui.b_unit ) );
    calculate();
}

void gasCalculator::setMode(int mode)
{
    m_mode = mode;

    ui.moles->setReadOnly(false);
    ui.mass->setReadOnly(false);
    ui.pressure->setReadOnly(false);
    ui.temp->setReadOnly(false);
    ui.volume->setReadOnly(false);

    switch (mode)
    {
    case MOLES:
        ui.moles->setReadOnly(true);
        ui.mass->setReadOnly(true);
        break;
    case PRESSURE:
        ui.pressure->setReadOnly(true);
        break;
    case TEMPERATURE:
        ui.temp->setReadOnly(true);
        break;
    case VOLUME:
        ui.volume->setReadOnly(true);
        break;
    }

    calculate();
}

void gasCalculator::calculate()
{
    error(RESET_GAS_MESSAGE);

    switch (m_mode)
    {
    case MOLES:
        calculateMoles();
        break;
    case PRESSURE:
        calculatePressure();
        break;
    case TEMPERATURE:
        calculateTemp();
        break;
    case VOLUME:
        calculateVol();
        break;
    }
}

void gasCalculator::error(int mode)
{
    switch (mode) { // Depending on the mode, set the error messages.
    case RESET_GAS_MESSAGE:
        ui.error->setText("");
        break;
    case VOL_ZERO :
        ui.error->setText(i18n("Volume cannot be zero, please enter a valid value."));
        break;
    case GAS_MOLAR_MASS_ZERO:
        ui.error->setText(i18n("Molar mass cannot be zero, please enter a non-zero value."));
    default:
        break;
    }
}

#include "gasCalculator.moc"
