#include <errno.h>
#include <math.h>

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

namespace { // anonymous namespace
struct pj_putp5_data {
    double A, B;
};
} // anonymous namespace

PROJ_HEAD(putp5, "Putnins P5") "\n\tPCyl, Sph";
PROJ_HEAD(putp5p, "Putnins P5'") "\n\tPCyl, Sph";

#define C 1.01346
#define D 1.2158542

static PJ_XY putp5_s_forward(PJ_LP lp, PJ *P) { /* Spheroidal, forward */
    PJ_XY xy = {0.0, 0.0};
    struct pj_putp5_data *Q = static_cast<struct pj_putp5_data *>(P->opaque);

    xy.x = C * lp.lam * (Q->A - Q->B * sqrt(1. + D * lp.phi * lp.phi));
    xy.y = C * lp.phi;

    return xy;
}

static PJ_LP putp5_s_inverse(PJ_XY xy, PJ *P) { /* Spheroidal, inverse */
    PJ_LP lp = {0.0, 0.0};
    struct pj_putp5_data *Q = static_cast<struct pj_putp5_data *>(P->opaque);

    lp.phi = xy.y / C;
    lp.lam = xy.x / (C * (Q->A - Q->B * sqrt(1. + D * lp.phi * lp.phi)));

    return lp;
}

PJ *PJ_PROJECTION(putp5) {
    struct pj_putp5_data *Q = static_cast<struct pj_putp5_data *>(
        calloc(1, sizeof(struct pj_putp5_data)));
    if (nullptr == Q)
        return pj_default_destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
    P->opaque = Q;

    Q->A = 2.;
    Q->B = 1.;

    P->es = 0.;
    P->inv = putp5_s_inverse;
    P->fwd = putp5_s_forward;

    return P;
}

PJ *PJ_PROJECTION(putp5p) {
    struct pj_putp5_data *Q = static_cast<struct pj_putp5_data *>(
        calloc(1, sizeof(struct pj_putp5_data)));
    if (nullptr == Q)
        return pj_default_destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
    P->opaque = Q;

    Q->A = 1.5;
    Q->B = 0.5;

    P->es = 0.;
    P->inv = putp5_s_inverse;
    P->fwd = putp5_s_forward;

    return P;
}

#undef C
#undef D