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

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

PROJ_HEAD(igh_o, "Interrupted Goode Homolosine Oceanic View") "\n\tPCyl, Sph";

/*
This projection is a variant of the Interrupted Goode Homolosine
projection that emphasizes ocean areas. The projection is a
compilation of 12 separate sub-projections. Sinusoidal projections
are found near the equator and Mollweide projections are found at
higher latitudes. The transition between the two occurs at 40 degrees
latitude and is represented by `igh_o_phi_boundary`.

Each sub-projection is assigned an integer label
numbered 1 through 12. Most of this code contains logic to assign
the labels based on latitude (phi) and longitude (lam) regions.

Original Reference:
J. Paul Goode (1925) THE HOMOLOSINE PROJECTION: A NEW DEVICE FOR
    PORTRAYING THE EARTH'S SURFACE ENTIRE, Annals of the Association of
    American Geographers, 15:3, 119-125, DOI: 10.1080/00045602509356949
*/

C_NAMESPACE PJ *pj_sinu(PJ *), *pj_moll(PJ *);

/*
Transition from sinusoidal to Mollweide projection
Latitude (phi): 40deg 44' 11.8"
*/

constexpr double igh_o_phi_boundary =
    (40 + 44 / 60. + 11.8 / 3600.) * DEG_TO_RAD;

namespace pj_igh_o_ns {
struct pj_igh_o_data {
    struct PJconsts *pj[12];
    double dy0;
};

constexpr double d10 = 10 * DEG_TO_RAD;
constexpr double d20 = 20 * DEG_TO_RAD;
constexpr double d40 = 40 * DEG_TO_RAD;
constexpr double d50 = 50 * DEG_TO_RAD;
constexpr double d60 = 60 * DEG_TO_RAD;
constexpr double d90 = 90 * DEG_TO_RAD;
constexpr double d100 = 100 * DEG_TO_RAD;
constexpr double d110 = 110 * DEG_TO_RAD;
constexpr double d140 = 140 * DEG_TO_RAD;
constexpr double d150 = 150 * DEG_TO_RAD;
constexpr double d160 = 160 * DEG_TO_RAD;
constexpr double d130 = 130 * DEG_TO_RAD;
constexpr double d180 = 180 * DEG_TO_RAD;

constexpr double EPSLN =
    1.e-10; /* allow a little 'slack' on zone edge positions */

} // namespace pj_igh_o_ns

/*
Assign an integer index representing each of the 12
sub-projection zones based on latitude (phi) and
longitude (lam) ranges.
*/

static PJ_XY igh_o_s_forward(PJ_LP lp, PJ *P) { /* Spheroidal, forward */
    using namespace pj_igh_o_ns;

    PJ_XY xy;
    struct pj_igh_o_data *Q = static_cast<struct pj_igh_o_data *>(P->opaque);
    int z;

    if (lp.phi >= igh_o_phi_boundary) {
        if (lp.lam <= -d90)
            z = 1;
        else if (lp.lam >= d60)
            z = 3;
        else
            z = 2;
    } else if (lp.phi >= 0) {
        if (lp.lam <= -d90)
            z = 4;
        else if (lp.lam >= d60)
            z = 6;
        else
            z = 5;
    } else if (lp.phi >= -igh_o_phi_boundary) {
        if (lp.lam <= -d60)
            z = 7;
        else if (lp.lam >= d90)
            z = 9;
        else
            z = 8;
    } else {
        if (lp.lam <= -d60)
            z = 10;
        else if (lp.lam >= d90)
            z = 12;
        else
            z = 11;
    }

    lp.lam -= Q->pj[z - 1]->lam0;
    xy = Q->pj[z - 1]->fwd(lp, Q->pj[z - 1]);
    xy.x += Q->pj[z - 1]->x0;
    xy.y += Q->pj[z - 1]->y0;

    return xy;
}

static PJ_LP igh_o_s_inverse(PJ_XY xy, PJ *P) { /* Spheroidal, inverse */
    using namespace pj_igh_o_ns;

    PJ_LP lp = {0.0, 0.0};
    struct pj_igh_o_data *Q = static_cast<struct pj_igh_o_data *>(P->opaque);
    const double y90 =
        Q->dy0 + sqrt(2.0); /* lt=90 corresponds to y=y0+sqrt(2) */

    int z = 0;
    if (xy.y > y90 + EPSLN || xy.y < -y90 + EPSLN) /* 0 */
        z = 0;
    else if (xy.y >= igh_o_phi_boundary)
        if (xy.x <= -d90)
            z = 1;
        else if (xy.x >= d60)
            z = 3;
        else
            z = 2;
    else if (xy.y >= 0)
        if (xy.x <= -d90)
            z = 4;
        else if (xy.x >= d60)
            z = 6;
        else
            z = 5;
    else if (xy.y >= -igh_o_phi_boundary) {
        if (xy.x <= -d60)
            z = 7;
        else if (xy.x >= d90)
            z = 9;
        else
            z = 8;
    } else {
        if (xy.x <= -d60)
            z = 10;
        else if (xy.x >= d90)
            z = 12;
        else
            z = 11;
    }

    if (z) {
        bool ok = false;

        xy.x -= Q->pj[z - 1]->x0;
        xy.y -= Q->pj[z - 1]->y0;
        lp = Q->pj[z - 1]->inv(xy, Q->pj[z - 1]);
        lp.lam += Q->pj[z - 1]->lam0;

        switch (z) {
        /* Plot projectable ranges with exetension lobes in zones 1 & 3 */
        case 1:
            ok = (lp.lam >= -d180 - EPSLN && lp.lam <= -d90 + EPSLN) ||
                 ((lp.lam >= d160 - EPSLN && lp.lam <= d180 + EPSLN) &&
                  (lp.phi >= d50 - EPSLN && lp.phi <= d90 + EPSLN));
            break;
        case 2:
            ok = (lp.lam >= -d90 - EPSLN && lp.lam <= d60 + EPSLN);
            break;
        case 3:
            ok = (lp.lam >= d60 - EPSLN && lp.lam <= d180 + EPSLN) ||
                 ((lp.lam >= -d180 - EPSLN && lp.lam <= -d160 + EPSLN) &&
                  (lp.phi >= d50 - EPSLN && lp.phi <= d90 + EPSLN));
            break;
        case 4:
            ok = (lp.lam >= -d180 - EPSLN && lp.lam <= -d90 + EPSLN);
            break;
        case 5:
            ok = (lp.lam >= -d90 - EPSLN && lp.lam <= d60 + EPSLN);
            break;
        case 6:
            ok = (lp.lam >= d60 - EPSLN && lp.lam <= d180 + EPSLN);
            break;
        case 7:
            ok = (lp.lam >= -d180 - EPSLN && lp.lam <= -d60 + EPSLN);
            break;
        case 8:
            ok = (lp.lam >= -d60 - EPSLN && lp.lam <= d90 + EPSLN);
            break;
        case 9:
            ok = (lp.lam >= d90 - EPSLN && lp.lam <= d180 + EPSLN);
            break;
        case 10:
            ok = (lp.lam >= -d180 - EPSLN && lp.lam <= -d60 + EPSLN);
            break;
        case 11:
            ok = (lp.lam >= -d60 - EPSLN && lp.lam <= d90 + EPSLN) ||
                 ((lp.lam >= d90 - EPSLN && lp.lam <= d100 + EPSLN) &&
                  (lp.phi >= -d90 - EPSLN && lp.phi <= -d40 + EPSLN));
            break;
        case 12:
            ok = (lp.lam >= d90 - EPSLN && lp.lam <= d180 + EPSLN);
            break;
        }
        z = (!ok ? 0 : z); /* projectable? */
    }

    if (!z)
        lp.lam = HUGE_VAL;
    if (!z)
        lp.phi = HUGE_VAL;

    return lp;
}

static PJ *pj_igh_o_destructor(PJ *P, int errlev) {
    using namespace pj_igh_o_ns;

    int i;
    if (nullptr == P)
        return nullptr;

    if (nullptr == P->opaque)
        return pj_default_destructor(P, errlev);

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

    for (i = 0; i < 12; ++i) {
        if (Q->pj[i])
            Q->pj[i]->destructor(Q->pj[i], errlev);
    }

    return pj_default_destructor(P, errlev);
}

/*
  Zones:

    -180       -90               60           180
      +---------+----------------+-------------+    Zones 1,2,3,10,11 & 12:
      |1        |2               |3            |    Mollweide projection
      |         |                |             |
      +---------+----------------+-------------+    Zones 4,5,6,7,8 & 9:
      |4        |5               |6            |    Sinusoidal projection
      |         |                |             |
    0 +---------+--+-------------+--+----------+
      |7           |8               |9         |
      |            |                |          |
      +------------+----------------+----------+
      |10          |11              |12        |
      |            |                |          |
      +------------+----------------+----------+
    -180          -60               90        180
*/

static bool pj_igh_o_setup_zone(PJ *P, struct pj_igh_o_ns::pj_igh_o_data *Q,
                                int n, PJ *(*proj_ptr)(PJ *), double x_0,
                                double y_0, double lon_0) {
    if (!(Q->pj[n - 1] = proj_ptr(nullptr)))
        return false;
    if (!(Q->pj[n - 1] = proj_ptr(Q->pj[n - 1])))
        return false;
    Q->pj[n - 1]->ctx = P->ctx;
    Q->pj[n - 1]->x0 = x_0;
    Q->pj[n - 1]->y0 = y_0;
    Q->pj[n - 1]->lam0 = lon_0;
    return true;
}

PJ *PJ_PROJECTION(igh_o) {
    using namespace pj_igh_o_ns;

    PJ_XY xy1, xy4;
    PJ_LP lp = {0, igh_o_phi_boundary};
    struct pj_igh_o_data *Q = static_cast<struct pj_igh_o_data *>(
        calloc(1, sizeof(struct pj_igh_o_data)));
    if (nullptr == Q)
        return pj_default_destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
    P->opaque = Q;

    /* sinusoidal zones */
    if (!pj_igh_o_setup_zone(P, Q, 4, pj_sinu, -d140, 0, -d140) ||
        !pj_igh_o_setup_zone(P, Q, 5, pj_sinu, -d10, 0, -d10) ||
        !pj_igh_o_setup_zone(P, Q, 6, pj_sinu, d130, 0, d130) ||
        !pj_igh_o_setup_zone(P, Q, 7, pj_sinu, -d110, 0, -d110) ||
        !pj_igh_o_setup_zone(P, Q, 8, pj_sinu, d20, 0, d20) ||
        !pj_igh_o_setup_zone(P, Q, 9, pj_sinu, d150, 0, d150)) {
        return pj_igh_o_destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
    }

    /* mollweide zones */
    if (!pj_igh_o_setup_zone(P, Q, 1, pj_moll, -d140, 0, -d140)) {
        return pj_igh_o_destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
    }

    /* y0 ? */
    xy1 = Q->pj[0]->fwd(lp, Q->pj[0]); /* zone 1 */
    xy4 = Q->pj[3]->fwd(lp, Q->pj[3]); /* zone 4 */
    /* y0 + xy1.y = xy4.y for lt = 40d44'11.8" */
    Q->dy0 = xy4.y - xy1.y;

    Q->pj[0]->y0 = Q->dy0;

    /* mollweide zones (cont'd) */
    if (!pj_igh_o_setup_zone(P, Q, 2, pj_moll, -d10, Q->dy0, -d10) ||
        !pj_igh_o_setup_zone(P, Q, 3, pj_moll, d130, Q->dy0, d130) ||
        !pj_igh_o_setup_zone(P, Q, 10, pj_moll, -d110, -Q->dy0, -d110) ||
        !pj_igh_o_setup_zone(P, Q, 11, pj_moll, d20, -Q->dy0, d20) ||
        !pj_igh_o_setup_zone(P, Q, 12, pj_moll, d150, -Q->dy0, d150)) {
        return pj_igh_o_destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
    }

    P->inv = igh_o_s_inverse;
    P->fwd = igh_o_s_forward;
    P->destructor = pj_igh_o_destructor;
    P->es = 0.;

    return P;
}