/*=========================================================================

   Library: iMSTK

   Copyright (c) Kitware, Inc. & Center for Modeling, Simulation,
   & Imaging in Medicine, Rensselaer Polytechnic Institute.

   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.txt

   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.

=========================================================================*/

#pragma once

#include "imstkMath.h"
#include "imstkColor.h"
#include "imstkSceneEntity.h"

#include <string>

namespace imstk
{
///
/// \class Light
///
/// \brief Abstract base class for lights
///
class Light : public SceneEntity
{
protected:
    Light() = default;

public:
    virtual ~Light() override = default;

public:
    ///
    /// \brief Set the light focal point
    ///
    void setFocalPoint(const Vec3d& p) { m_focalPoint = p; }
    void setFocalPoint(const double x, const double y, const double z) { setFocalPoint(Vec3d(x, y, z)); }
    const Vec3d& getFocalPoint() const { return m_focalPoint; }

    ///
    /// \brief Get the status (On/off) of the light
    ///
    bool isOn() const { return m_switchState; }

    ///
    /// \brief Switch the light On
    ///
    void switchOn() { m_switchState = true; }

    ///
    /// \brief Switch the light Off
    ///
    void switchOff() { m_switchState = false; }

    ///
    /// \brief Get the light color
    ///
    const Color& getColor() const { return m_color; }

    ///
    /// \brief Set the light color
    ///
    void setColor(const Color& c) { m_color = c; }

    ///
    /// \brief Get the light intensity
    ///
    double getIntensity() const { return m_intensity; }

    ///
    /// \brief Set the light intensity. This value is unbounded.
    ///
    void setIntensity(const double intensity) { m_intensity = intensity; }

    ///
    /// \brief Sets the attenuation values. Quadratic, linear, and constant c (ax^2+bx+c)
    /// (a,b,c) = {0,0,1} would be constant lighting, multiplied with intensity
    ///
    void setAttenuationValues(const double a, const double b, const double c)
    {
        m_attenuation[0] = c;
        m_attenuation[1] = b;
        m_attenuation[2] = a;
    }

    const Vec3d& getAttenuationValues() const { return m_attenuation; }

protected:
    // properties with defaults
    double m_intensity   = 1.0;
    Color  m_color       = Color::White;
    bool   m_switchState = true;
    Vec3d  m_focalPoint  = Vec3d::Zero();
    Vec3d  m_attenuation = Vec3d(1.0, 0.0, 0.0); ///> c, b, a (ax^2+bx+c)
};
} // imstk