#include <float.h>

#include <math.h>

#include "proj.h"

#include "proj_internal.h"

#include <math.h>

PROJ_HEAD(merc, "Mercator") "\n\tCyl, Sph&Ell\n\tlat_ts=";

PROJ_HEAD(webmerc, "Web Mercator / Pseudo Mercator") "\n\tCyl, Ell\n\t";

static PJ_XY merc_e_forward(PJ_LP lp, PJ *P) { /* Ellipsoidal, forward */

    PJ_XY xy = {0.0, 0.0};

    xy.x = P->k0 * lp.lam;

    // Instead of calling tan and sin, call sin and cos which the compiler

    // optimizes to a single call to sincos.

    double sphi = sin(lp.phi);

    double cphi = cos(lp.phi);

    xy.y = P->k0 * (asinh(sphi / cphi) - P->e * atanh(P->e * sphi));

    return xy;

}

static PJ_XY merc_s_forward(PJ_LP lp, PJ *P) { /* Spheroidal, forward */

    PJ_XY xy = {0.0, 0.0};

    xy.x = P->k0 * lp.lam;

    xy.y = P->k0 * asinh(tan(lp.phi));

    return xy;

}

static PJ_LP merc_e_inverse(PJ_XY xy, PJ *P) { /* Ellipsoidal, inverse */

    PJ_LP lp = {0.0, 0.0};

    lp.phi = atan(pj_sinhpsi2tanphi(P->ctx, sinh(xy.y / P->k0), P->e));

    lp.lam = xy.x / P->k0;

    return lp;

}

static PJ_LP merc_s_inverse(PJ_XY xy, PJ *P) { /* Spheroidal, inverse */

    PJ_LP lp = {0.0, 0.0};

    lp.phi = atan(sinh(xy.y / P->k0));

    lp.lam = xy.x / P->k0;

    return lp;

}

PJ *PJ_PROJECTION(merc) {

    double phits = 0.0;

    int is_phits;

    if ((is_phits = pj_param(P->ctx, P->params, "tlat_ts").i)) {

        phits = fabs(pj_param(P->ctx, P->params, "rlat_ts").f);

        if (phits >= M_HALFPI) {

            proj_log_error(

                P, _("Invalid value for lat_ts: |lat_ts| should be <= 90°"));

            return pj_default_destructor(P,

                                         PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);

        }

    }

    if (P->es != 0.0) { /* ellipsoid */

        if (is_phits)

            P->k0 = pj_msfn(sin(phits), cos(phits), P->es);

        P->inv = merc_e_inverse;

        P->fwd = merc_e_forward;

    }

    else { /* sphere */

        if (is_phits)

            P->k0 = cos(phits);

        P->inv = merc_s_inverse;

        P->fwd = merc_s_forward;

    }

    return P;

}

PJ *PJ_PROJECTION(webmerc) {

    /* Overriding k_0 with fixed parameter */

    P->k0 = 1.0;

    P->inv = merc_s_inverse;

    P->fwd = merc_s_forward;

    return P;

}