#include <stdexcept>
#include "color.h"

Color::Color(int r, int g, int b, int a)
  : r{r}, g{g}, b{b}, a{a}
{
  if ( out_of_range(r) || out_of_range(g) ||
       out_of_range(b) || out_of_range(a) )
  {
    throw std::range_error{"value out of range"};
  }
}

bool Color::out_of_range(int value) const
{
  return ( value < 0 || value > 255);
}

int average(int a, int b)
{
  return (a + b) / 2;
}

Color Color::operator+(Color const& rhs) const
{
  return Color{ average(r, rhs.r), 
                average(g, rhs.g),
                average(b, rhs.b)
              };
}

Color operator+(int lhs, Color const& rhs)
{
  return Color{lhs} + rhs;
}

Color operator+(Color const& lhs, int rhs)
{
  return lhs + Color{rhs};
}

std::ostream& operator<<(std::ostream& os, Color const& c)
{
  return os << "{" << c.r << ", " << c.g <<  ", " << c.b << "}";
}

#define CATCH_CONFIG_MAIN
#include "catch.hpp"
#include <sstream>
#include "color.h"

std::string str(Color const& c)
{
  std::ostringstream oss;
  oss << c;
  return oss.str();
}

TEST_CASE("construction")
{
  CHECK_NOTHROW( (Color{1,255,0,255}) );
  CHECK_NOTHROW( (Color{100,200,0}) );
  CHECK_NOTHROW( (Color{75,140,60}) );
  CHECK_NOTHROW( (Color{128}) );
  CHECK_THROWS( (Color{256,-1,256,-1}) );
}

TEST_CASE("print")
{
  CHECK( str(Color{50,80,20,128}) == "{50, 80, 20}");
}

TEST_CASE("add color")
{
  Color a{100,200,0};
  Color b{50,80,120};
  Color c{75,140,60};
  
  REQUIRE( str(Color{50,80,20}) == "{50, 80, 20}");
  
  CHECK( str(a+b) == str(c) );
  CHECK( str(a+c) != str(b) );
  CHECK( str(b+c) != str(a) );
}

TEST_CASE("add grayscale")
{
  Color a{100,200,0};
  Color b{100,150,50};
  
  REQUIRE( str(Color{50,80,20}) == "{50, 80, 20}");
  
  CHECK( str(a+100) == str(b) );
  CHECK( str(100+a) == str(b) );
}