#ifndef __MAPNIK_VECTOR_TILE_PROJECTION_H__
#define __MAPNIK_VECTOR_TILE_PROJECTION_H__

#include <mapnik/box2d.hpp>
#include <mapnik/well_known_srs.hpp>
#include <cmath>

#ifndef M_PI
#define M_PI 3.141592653589793238462643
#endif

namespace mapnik { namespace vector_tile_impl {

    class spherical_mercator
    {
    private:
        double tile_size_;
    public:
        spherical_mercator(unsigned tile_size)
          : tile_size_(static_cast<double>(tile_size)) {}

        void from_pixels(double shift, double & x, double & y)
        {
            double b = shift/2.0;
            x = (x - b)/(shift/360.0);
            double g = (y - b)/-(shift/(2 * M_PI));
            y = R2D * (2.0 * std::atan(std::exp(g)) - M_PI_by2);
        }

        void xyz(int x,
                 int y,
                 int z,
                 double & minx,
                 double & miny,
                 double & maxx,
                 double & maxy)
        {
            minx = x * tile_size_;
            miny = (y + 1.0) * tile_size_;
            maxx = (x + 1.0) * tile_size_;
            maxy = y * tile_size_;
            double shift = std::pow(2.0,z) * tile_size_;
            from_pixels(shift,minx,miny);
            from_pixels(shift,maxx,maxy);
            lonlat2merc(&minx,&miny,1);
            lonlat2merc(&maxx,&maxy,1);
        }
    };

    }} // end ns

#endif // __MAPNIK_VECTOR_TILE_PROJECTION_H__
