#include "poisson_law.h"
  #include <assert.h>
  #include <cmath>
  #include <ion.h>
  
  namespace Probability {
  
  PoissonLaw::PoissonLaw() :
    OneParameterLaw(4.0f)
  {
  }
  
  I18n::Message PoissonLaw::title() {
    return I18n::Message::PoissonLaw;
  }
  
  Law::Type PoissonLaw::type() const {
    return Type::Poisson;
  }
  
  bool PoissonLaw::isContinuous() const {
    return false;
  }
  
  I18n::Message PoissonLaw::parameterNameAtIndex(int index) {
    assert(index == 0);
    return I18n::Message::Lambda;
  }
  
  I18n::Message PoissonLaw::parameterDefinitionAtIndex(int index) {
    assert(index == 0);
    return I18n::Message::LambdaPoissonDefinition;
  }
  
  float PoissonLaw::xMin() {
    return -k_displayLeftMarginRatio*xMax();
  }
  
  float PoissonLaw::xMax() {
    assert(m_parameter1 != 0);
    return (m_parameter1 + 5.0f*std::sqrt(m_parameter1))*(1.0f+k_displayRightMarginRatio);
  }
  
  float PoissonLaw::yMin() {
    return - k_displayBottomMarginRatio * yMax();
  }
  
  float PoissonLaw::yMax() {
    int maxAbscissa = (int)m_parameter1;
    assert(maxAbscissa >= 0.0f);
    float result = evaluateAtAbscissa(maxAbscissa);
    if (result <= 0.0f) {
      result = 1.0f;
    }
    return result*(1.0f+ k_displayTopMarginRatio);
  }
  
  bool PoissonLaw::authorizedValueAtIndex(float x, int index) const {
    if (x <= 0.0f || x > 999.0f) {
      return false;
    }
    return true;
  }
  
  template<typename T>
  T PoissonLaw::templatedApproximateAtAbscissa(T x) const {
    if (x < 0) {
      return NAN;
    }
    T lResult = -(T)m_parameter1+std::floor(x)*std::log((T)m_parameter1)-std::lgamma(std::floor(x)+1);
    return std::exp(lResult);
  }
  
  }
  
  template float Probability::PoissonLaw::templatedApproximateAtAbscissa(float x) const;
  template double Probability::PoissonLaw::templatedApproximateAtAbscissa(double x) const;