#include "proj.h"

#include "proj_internal.h"

#include <errno.h>

#include <math.h>

PROJ_HEAD(lcc, "Lambert Conformal Conic")

"\n\tConic, Sph&Ell\n\tlat_1= and lat_2= or lat_0, k_0=";

#define EPS10 1.e-10

namespace { // anonymous namespace

struct pj_lcc_data {

    double phi1;

    double phi2;

    double n;

    double rho0;

    double c;

};

} // anonymous namespace

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

    PJ_XY xy = {0., 0.};

    struct pj_lcc_data *Q = static_cast<struct pj_lcc_data *>(P->opaque);

    double rho;

    if (fabs(fabs(lp.phi) - M_HALFPI) < EPS10) {

        if ((lp.phi * Q->n) <= 0.) {

            proj_errno_set(P, PROJ_ERR_COORD_TRANSFM_OUTSIDE_PROJECTION_DOMAIN);

            return xy;

        }

        rho = 0.;

    } else {

        rho =

            Q->c * (P->es != 0. ? pow(pj_tsfn(lp.phi, sin(lp.phi), P->e), Q->n)

                                : pow(tan(M_FORTPI + .5 * lp.phi), -Q->n));

    }

    lp.lam *= Q->n;

    xy.x = P->k0 * (rho * sin(lp.lam));

    xy.y = P->k0 * (Q->rho0 - rho * cos(lp.lam));

    return xy;

}

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

    PJ_LP lp = {0., 0.};

    struct pj_lcc_data *Q = static_cast<struct pj_lcc_data *>(P->opaque);

    double rho;

    xy.x /= P->k0;

    xy.y /= P->k0;

    xy.y = Q->rho0 - xy.y;

    rho = hypot(xy.x, xy.y);

    if (rho != 0.) {

        if (Q->n < 0.) {

            rho = -rho;

            xy.x = -xy.x;

            xy.y = -xy.y;

        }

        if (P->es != 0.) {

            lp.phi = pj_phi2(P->ctx, pow(rho / Q->c, 1. / Q->n), P->e);

            if (lp.phi == HUGE_VAL) {

                proj_errno_set(

                    P, PROJ_ERR_COORD_TRANSFM_OUTSIDE_PROJECTION_DOMAIN);

                return lp;

            }

        } else

            lp.phi = 2. * atan(pow(Q->c / rho, 1. / Q->n)) - M_HALFPI;

        lp.lam = atan2(xy.x, xy.y) / Q->n;

    } else {

        lp.lam = 0.;

        lp.phi = Q->n > 0. ? M_HALFPI : -M_HALFPI;

    }

    return lp;

}

PJ *PJ_PROJECTION(lcc) {

    double cosphi, sinphi;

    int secant;

    struct pj_lcc_data *Q = static_cast<struct pj_lcc_data *>(

        calloc(1, sizeof(struct pj_lcc_data)));

    if (nullptr == Q)

        return pj_default_destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);

    P->opaque = Q;

    Q->phi1 = pj_param(P->ctx, P->params, "rlat_1").f;

    if (pj_param(P->ctx, P->params, "tlat_2").i)

        Q->phi2 = pj_param(P->ctx, P->params, "rlat_2").f;

    else {

        Q->phi2 = Q->phi1;

        if (!pj_param(P->ctx, P->params, "tlat_0").i)

            P->phi0 = Q->phi1;

    }

    if (fabs(Q->phi1 + Q->phi2) < EPS10) {

        proj_log_error(P, _("Invalid value for lat_1 and lat_2: |lat_1 + "

                            "lat_2| should be > 0"));

        return pj_default_destructor(P, PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);

    }

    Q->n = sinphi = sin(Q->phi1);

    cosphi = cos(Q->phi1);

    if (fabs(cosphi) < EPS10 || fabs(Q->phi1) >= M_PI_2) {

        proj_log_error(P,

                       _("Invalid value for lat_1: |lat_1| should be < 90°"));

        return pj_default_destructor(P, PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);

    }

    if (fabs(cos(Q->phi2)) < EPS10 || fabs(Q->phi2) >= M_PI_2) {

        proj_log_error(P,

                       _("Invalid value for lat_2: |lat_2| should be < 90°"));

        return pj_default_destructor(P, PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);

    }

    secant = fabs(Q->phi1 - Q->phi2) >= EPS10;

    if (P->es != 0.) {

        double ml1, m1;

        m1 = pj_msfn(sinphi, cosphi, P->es);

        ml1 = pj_tsfn(Q->phi1, sinphi, P->e);

        if (secant) { /* secant cone */

            sinphi = sin(Q->phi2);

            Q->n = log(m1 / pj_msfn(sinphi, cos(Q->phi2), P->es));

            if (Q->n == 0) {

                // Not quite, but es is very close to 1...

                proj_log_error(P, _("Invalid value for eccentricity"));

                return pj_default_destructor(

                    P, PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);

            }

            const double ml2 = pj_tsfn(Q->phi2, sinphi, P->e);

            const double denom = log(ml1 / ml2);

            if (denom == 0) {

                // Not quite, but es is very close to 1...

                proj_log_error(P, _("Invalid value for eccentricity"));

                return pj_default_destructor(

                    P, PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);

            }

            Q->n /= denom;

        }

        Q->rho0 = m1 * pow(ml1, -Q->n) / Q->n;

        Q->c = Q->rho0;

        Q->rho0 *= (fabs(fabs(P->phi0) - M_HALFPI) < EPS10)

                       ? 0.

                       : pow(pj_tsfn(P->phi0, sin(P->phi0), P->e), Q->n);

    } else {

        if (secant)

            Q->n =

                log(cosphi / cos(Q->phi2)) / log(tan(M_FORTPI + .5 * Q->phi2) /

                                                 tan(M_FORTPI + .5 * Q->phi1));

        if (Q->n == 0) {

            // Likely reason is that phi1 / phi2 are too close to zero.

            // Can be reproduced with +proj=lcc +a=1 +lat_2=.0000001

            proj_log_error(

                P, _("Invalid value for lat_1 and lat_2: |lat_1 + lat_2| "

                     "should be > 0"));

            return pj_default_destructor(P,

                                         PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);

        }

        Q->c = cosphi * pow(tan(M_FORTPI + .5 * Q->phi1), Q->n) / Q->n;

        Q->rho0 = (fabs(fabs(P->phi0) - M_HALFPI) < EPS10)

                      ? 0.

                      : Q->c * pow(tan(M_FORTPI + .5 * P->phi0), -Q->n);

    }

    P->inv = lcc_e_inverse;

    P->fwd = lcc_e_forward;

    return P;

}

#undef EPS10