#include <errno.h>

#include "proj.h"
#include "proj_internal.h"

namespace { // anonymous namespace
struct pj_putp3_data {
    double A;
};
} // anonymous namespace

PROJ_HEAD(putp3, "Putnins P3") "\n\tPCyl, Sph";
PROJ_HEAD(putp3p, "Putnins P3'") "\n\tPCyl, Sph";

#define C 0.79788456
#define RPISQ 0.1013211836

static PJ_XY putp3_s_forward(PJ_LP lp, PJ *P) { /* Spheroidal, forward */
    PJ_XY xy = {0.0, 0.0};

    xy.x = C * lp.lam *
           (1. - static_cast<struct pj_putp3_data *>(P->opaque)->A * lp.phi *
                     lp.phi);
    xy.y = C * lp.phi;

    return xy;
}

static PJ_LP putp3_s_inverse(PJ_XY xy, PJ *P) { /* Spheroidal, inverse */
    PJ_LP lp = {0.0, 0.0};

    lp.phi = xy.y / C;
    lp.lam =
        xy.x / (C * (1. - static_cast<struct pj_putp3_data *>(P->opaque)->A *
                              lp.phi * lp.phi));

    return lp;
}

PJ *PJ_PROJECTION(putp3) {
    struct pj_putp3_data *Q = static_cast<struct pj_putp3_data *>(
        calloc(1, sizeof(struct pj_putp3_data)));
    if (nullptr == Q)
        return pj_default_destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
    P->opaque = Q;

    Q->A = 4. * RPISQ;

    P->es = 0.;
    P->inv = putp3_s_inverse;
    P->fwd = putp3_s_forward;

    return P;
}

PJ *PJ_PROJECTION(putp3p) {
    struct pj_putp3_data *Q = static_cast<struct pj_putp3_data *>(
        calloc(1, sizeof(struct pj_putp3_data)));
    if (nullptr == Q)
        return pj_default_destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
    P->opaque = Q;

    Q->A = 2. * RPISQ;

    P->es = 0.;
    P->inv = putp3_s_inverse;
    P->fwd = putp3_s_forward;

    return P;
}

#undef C
#undef RPISQ