#define PJ_LIB_

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

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

PROJ_HEAD(imoll_o, "Interrupted Mollweide Oceanic View") "\n\tPCyl, Sph";

/*
This projection is a variant of the Interrupted Mollweide projection
that emphasizes ocean areas.
This projection is a compilation of 6 separate sub-projections.
It is related to the Interrupted Goode Homolosine projection,
but uses Mollweide at all latitudes.

Each sub-projection is assigned an integer label
numbered 1 through 6. Most of this code contains logic to assign
the labels based on latitude (phi) and longitude (lam) regions.
The code is adapted from igh.cpp.

Original Reference:
J. Paul Goode (1919) STUDIES IN PROJECTIONS: ADAPTING THE
    HOMOLOGRAPHIC PROJECTION TO THE PORTRAYAL OF THE EARTH'S
    ENTIRE SURFACE, Bul. Geog. SOC.Phila., Vol. XWIJNO.3.
    July, 1919, pp. 103-113.
*/

C_NAMESPACE PJ *pj_moll(PJ *);

/* SIMPLIFY THIS */
static const double d10 = 10 * DEG_TO_RAD;
static const double d20 = 20 * DEG_TO_RAD;
static const double d60 = 60 * DEG_TO_RAD;
static const double d90 = 90 * DEG_TO_RAD;
static const double d110 = 110 * DEG_TO_RAD;
static const double d130 = 130 * DEG_TO_RAD;
static const double d140 = 140 * DEG_TO_RAD;
static const double d150 = 150 * DEG_TO_RAD;
static const double d180 = 180 * DEG_TO_RAD;

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

namespace { // anonymous namespace
struct pj_opaque {
    struct PJconsts *pj[6];
};
} // anonymous namespace

/*
Assign an integer index representing each of the 6
sub-projection zones based on latitude (phi) and
longitude (lam) ranges.
*/

static PJ_XY imoll_o_s_forward(PJ_LP lp, PJ *P) { /* Spheroidal, forward */
    PJ_XY xy;
    struct pj_opaque *Q = static_cast<struct pj_opaque *>(P->opaque);
    int z;

    if (lp.phi >= 0) { /* 1|2|3 */
        if (lp.lam <= -d90)
            z = 1;
        else if (lp.lam >= d60)
            z = 3;
        else
            z = 2;
    } else {
        if (lp.lam <= -d60)
            z = 4;
        else if (lp.lam >= d90)
            z = 6;
        else
            z = 5;
    }

    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 imoll_o_s_inverse(PJ_XY xy, PJ *P) { /* Spheroidal, inverse */
    PJ_LP lp = {0.0, 0.0};
    struct pj_opaque *Q = static_cast<struct pj_opaque *>(P->opaque);
    const double y90 = sqrt(2.0); /* lt=90 corresponds to y=sqrt(2) */

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

    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) {
        case 1:
            ok = ((lp.lam >= -d180 - EPSLN && lp.lam <= -d90 + EPSLN) &&
                  (lp.phi >= 0.0 - EPSLN));
            break;
        case 2:
            ok = ((lp.lam >= -d90 - EPSLN && lp.lam <= d60 + EPSLN) &&
                  (lp.phi >= 0.0 - EPSLN));
            break;
        case 3:
            ok = ((lp.lam >= d60 - EPSLN && lp.lam <= d180 + EPSLN) &&
                  (lp.phi >= 0.0 - EPSLN));
            break;
        case 4:
            ok = ((lp.lam >= -d180 - EPSLN && lp.lam <= -d60 + EPSLN) &&
                  (lp.phi <= 0.0 + EPSLN));
            break;
        case 5:
            ok = ((lp.lam >= -d60 - EPSLN && lp.lam <= d90 + EPSLN) &&
                  (lp.phi <= 0.0 + EPSLN));
            break;
        case 6:
            ok = ((lp.lam >= d90 - EPSLN && lp.lam <= d180 + EPSLN) &&
                  (lp.phi <= 0.0 + EPSLN));
            break;
        }
        z = (!ok ? 0 : z); /* projectable? */
    }

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

    return lp;
}

static PJ *destructor(PJ *P, int errlev) {
    int i;
    if (nullptr == P)
        return nullptr;

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

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

    for (i = 0; i < 6; ++i) {
        if (Q->pj[i])
            Q->pj[i]->destructor(Q->pj[i], errlev);
    }

    return pj_default_destructor(P, errlev);
}

/*
  Zones:

    -180       -90               60           180
      +---------+----------------+-------------+
      |1        |2               |3            |
      |         |                |             |
      |         |                |             |
      |         |                |             |
      |         |                |             |
    0 +---------+--+-------------+--+----------+
      |4           |5               |6         |
      |            |                |          |
      |            |                |          |
      |            |                |          |
      |            |                |          |
      +------------+----------------+----------+
    -180          -60               90        180
*/

static bool setup_zone(PJ *P, struct pj_opaque *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;
}

static double compute_zone_offset(struct pj_opaque *Q, int zone1, int zone2,
                                  double lam, double phi1, double phi2) {
    PJ_LP lp1, lp2;
    PJ_XY xy1, xy2;

    lp1.lam = lam - (Q->pj[zone1 - 1]->lam0);
    lp1.phi = phi1;
    lp2.lam = lam - (Q->pj[zone2 - 1]->lam0);
    lp2.phi = phi2;
    xy1 = Q->pj[zone1 - 1]->fwd(lp1, Q->pj[zone1 - 1]);
    xy2 = Q->pj[zone2 - 1]->fwd(lp2, Q->pj[zone2 - 1]);
    return (xy2.x + Q->pj[zone2 - 1]->x0) - (xy1.x + Q->pj[zone1 - 1]->x0);
}

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

    /* Setup zones */
    if (!setup_zone(P, Q, 1, pj_moll, -d140, 0, -d140) ||
        !setup_zone(P, Q, 2, pj_moll, -d10, 0, -d10) ||
        !setup_zone(P, Q, 3, pj_moll, d130, 0, d130) ||
        !setup_zone(P, Q, 4, pj_moll, -d110, 0, -d110) ||
        !setup_zone(P, Q, 5, pj_moll, d20, 0, d20) ||
        !setup_zone(P, Q, 6, pj_moll, d150, 0, d150)) {
        return destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
    }

    /* Adjust zones */

    /* Match 2 (center) to 1 (west) */
    Q->pj[1]->x0 +=
        compute_zone_offset(Q, 2, 1, -d90, 0.0 + EPSLN, 0.0 + EPSLN);

    /* Match 3 (east) to 2 (center) */
    Q->pj[2]->x0 += compute_zone_offset(Q, 3, 2, d60, 0.0 + EPSLN, 0.0 + EPSLN);

    /* Match 4 (south) to 1 (north) */
    Q->pj[3]->x0 +=
        compute_zone_offset(Q, 4, 1, -d180, 0.0 - EPSLN, 0.0 + EPSLN);

    /* Match 5 (south) to 2 (north) */
    Q->pj[4]->x0 +=
        compute_zone_offset(Q, 5, 2, -d60, 0.0 - EPSLN, 0.0 + EPSLN);

    /* Match 6 (south) to 3 (north) */
    Q->pj[5]->x0 += compute_zone_offset(Q, 6, 3, d90, 0.0 - EPSLN, 0.0 + EPSLN);

    P->inv = imoll_o_s_inverse;
    P->fwd = imoll_o_s_forward;
    P->destructor = destructor;
    P->es = 0.;

    return P;
}
