#ifndef __SLVS_H
#define __SLVS_H

#ifdef __cplusplus
extern "C" {
#endif

typedef DWORD Slvs_hParam;
typedef DWORD Slvs_hEntity;
typedef DWORD Slvs_hConstraint;
typedef DWORD Slvs_hGroup;

// To obtain the 3d (not projected into a workplane) of a constraint or
// an entity, specify this instead of the workplane.
#define SLVS_FREE_IN_3D         0


typedef struct {
    Slvs_hParam     h;
    Slvs_hGroup     group;
    double          val;
} Slvs_Param;


#define SLVS_E_POINT_IN_3D     50000
#define SLVS_E_POINT_IN_2D     50001

#define SLVS_E_NORMAL_IN_3D    60000
#define SLVS_E_NORMAL_IN_2D    60001

#define SLVS_E_DISTANCE        70000

#define SLVS_E_WORKPLANE       80000
#define SLVS_E_LINE_SEGMENT    80001
#define SLVS_E_CUBIC           80002
#define SLVS_E_CIRCLE          80003
#define SLVS_E_ARC_OF_CIRCLE   80004

typedef struct {
    Slvs_hEntity    h;
    Slvs_hGroup     group;

    int             type;

    Slvs_hEntity    wrkpl;
    Slvs_hEntity    point[4];
    Slvs_hEntity    normal;
    Slvs_hEntity    distance;

    Slvs_hParam     param[4];
} Slvs_Entity;

#define SLVS_C_POINTS_COINCIDENT        100000
#define SLVS_C_PT_PT_DISTANCE           100001
#define SLVS_C_PT_PLANE_DISTANCE        100002
#define SLVS_C_PT_LINE_DISTANCE         100003
#define SLVS_C_PT_FACE_DISTANCE         100004
#define SLVS_C_PT_IN_PLANE              100005
#define SLVS_C_PT_ON_LINE               100006
#define SLVS_C_PT_ON_FACE               100007
#define SLVS_C_EQUAL_LENGTH_LINES       100008
#define SLVS_C_LENGTH_RATIO             100009
#define SLVS_C_EQ_LEN_PT_LINE_D         100010
#define SLVS_C_EQ_PT_LN_DISTANCES       100011
#define SLVS_C_EQUAL_ANGLE              100012
#define SLVS_C_EQUAL_LINE_ARC_LEN       100013
#define SLVS_C_SYMMETRIC                100014
#define SLVS_C_SYMMETRIC_HORIZ          100015
#define SLVS_C_SYMMETRIC_VERT           100016
#define SLVS_C_SYMMETRIC_LINE           100017
#define SLVS_C_AT_MIDPOINT              100018
#define SLVS_C_HORIZONTAL               100019
#define SLVS_C_VERTICAL                 100020
#define SLVS_C_DIAMETER                 100021
#define SLVS_C_PT_ON_CIRCLE             100022
#define SLVS_C_SAME_ORIENTATION         100023
#define SLVS_C_ANGLE                    100024
#define SLVS_C_PARALLEL                 100025
#define SLVS_C_PERPENDICULAR            100026
#define SLVS_C_ARC_LINE_TANGENT         100027
#define SLVS_C_CUBIC_LINE_TANGENT       100028
#define SLVS_C_EQUAL_RADIUS             100029

typedef struct {
    Slvs_hConstraint    h;
    Slvs_hGroup         group;

    int                 type;

    Slvs_hEntity        wrkpl;

    double              valA;
    Slvs_hEntity        ptA;
    Slvs_hEntity        ptB;
    Slvs_hEntity        entityA;
    Slvs_hEntity        entityB;
    Slvs_hEntity        entityC;
    Slvs_hEntity        entityD;

    int                 other;
} Slvs_Constraint;


typedef struct {
    //// INPUT VARIABLES
    //
    // Here, we specify the parameters and their initial values, the entities,
    // and the constraints. For example, param[] points to the array of
    // parameters, which has length params, so that the last valid element
    // is param[params-1].
    //
    // param[] is actually an in/out variable; if the solver is successful,
    // then the new values (that satisfy the constraints) are written to it.
    //
    Slvs_Param          *param;
    int                 params;
    Slvs_Entity         *entity;
    int                 entities;
    Slvs_Constraint     *constraint;
    int                 constraints;

    // If a parameter corresponds to a point (distance, normal, etc.) being
    // dragged, then specify it here. This will cause the solver to favor
    // that parameter, and attempt to change it as little as possible even
    // if that require it to change other parameters more.
    //
    // Unused members of this array should be set to zero.
    Slvs_hParam         dragged[4];

    //// OUTPUT PARAMETERS
    // 
    // If the solver fails, then it can report which constraints are causing
    // the problem. The caller should allocate the array failed[], and pass
    // its size in faileds. 
    //
    // The solver will set faileds equal to the number of problematic
    // constraints, and write their Slvs_hConstraints on 
    Slvs_hConstraint    *failed;
    int                 faileds;

    // The solver indicates the number of unconstrained degrees of freedom.
    int                 dof;

    // The solver indicates whether the solution succeeded.
#define SLVS_RESULT_OKAY                0
#define SLVS_RESULT_INCONSISTENT        1
#define SLVS_RESULT_DIDNT_CONVERGE      2
#define SLVS_RESULT_TOO_MANY_UNKNOWNS   3
    int                 result;
} Slvs_System;

void Slvs_Solve(Slvs_System *sys, Slvs_hGroup hg);


// Our base coordinate system has basis vectors
//     (1, 0, 0)  (0, 1, 0)  (0, 0, 1)
// A unit quaternion defines a rotation to a new coordinate system with
// basis vectors
//         U          V          N
// which these functions compute from the quaternion.
void Slvs_QuaternionU(double qw, double qx, double qy, double qz,
                         double *x, double *y, double *z);
void Slvs_QuaternionV(double qw, double qx, double qy, double qz,
                         double *x, double *y, double *z);
void Slvs_QuaternionN(double qw, double qx, double qy, double qz,
                         double *x, double *y, double *z);

// Similarly, compute a unit quaternion in terms of two basis vectors.
void Slvs_MakeQuaternion(double ux, double uy, double uz,
                         double vx, double vy, double vz,
                         double *qw, double *qx, double *qy, double *qz);


//-------------------------------------
// These are just convenience functions, to save you the trouble of filling
// out the structures by hand. The code is included in the header file to
// let the compiler inline them if possible.

static Slvs_Param Slvs_MakeParam(Slvs_hParam h, Slvs_hGroup group, double val)
{
    Slvs_Param r;
    r.h = h;
    r.group = group;
    r.val = val;
    return r;
}
static Slvs_Entity Slvs_MakePoint2d(Slvs_hEntity h, Slvs_hGroup group,
                                    Slvs_hEntity wrkpl,
                                    Slvs_hParam u, Slvs_hParam v)
{
    Slvs_Entity r;
    memset(&r, 0, sizeof(r));
    r.h = h;
    r.group = group;
    r.type = SLVS_E_POINT_IN_2D;
    r.wrkpl = wrkpl;
    r.param[0] = u;
    r.param[1] = v;
    return r;
}
static Slvs_Entity Slvs_MakePoint3d(Slvs_hEntity h, Slvs_hGroup group,
                               Slvs_hParam x, Slvs_hParam y, Slvs_hParam z)
{
    Slvs_Entity r;
    memset(&r, 0, sizeof(r));
    r.h = h;
    r.group = group;
    r.type = SLVS_E_POINT_IN_3D;
    r.wrkpl = SLVS_FREE_IN_3D;
    r.param[0] = x;
    r.param[1] = y;
    r.param[2] = z;
    return r;
}
static Slvs_Entity Slvs_MakeNormal3d(Slvs_hEntity h, Slvs_hGroup group,
              Slvs_hParam qw, Slvs_hParam qx, Slvs_hParam qy, Slvs_hParam qz)
{
    Slvs_Entity r;
    memset(&r, 0, sizeof(r));
    r.h = h;
    r.group = group;
    r.type = SLVS_E_NORMAL_IN_3D;
    r.wrkpl = SLVS_FREE_IN_3D;
    r.param[0] = qw;
    r.param[1] = qx;
    r.param[2] = qy;
    r.param[3] = qz;
    return r;
}
static Slvs_Entity Slvs_MakeNormal2d(Slvs_hEntity h, Slvs_hGroup group,
                                     Slvs_hEntity wrkpl)
{
    Slvs_Entity r;
    memset(&r, 0, sizeof(r));
    r.h = h;
    r.group = group;
    r.type = SLVS_E_NORMAL_IN_2D;
    r.wrkpl = wrkpl;
    return r;
}
static Slvs_Entity Slvs_MakeDistance(Slvs_hEntity h, Slvs_hGroup group,
                                     Slvs_hEntity wrkpl, Slvs_hParam d)
{
    Slvs_Entity r;
    memset(&r, 0, sizeof(r));
    r.h = h;
    r.group = group;
    r.type = SLVS_E_DISTANCE;
    r.wrkpl = wrkpl;
    r.param[0] = d;
    return r;
}
static Slvs_Entity Slvs_MakeLineSegment(Slvs_hEntity h, Slvs_hGroup group,
                                        Slvs_hEntity wrkpl,
                                        Slvs_hEntity ptA, Slvs_hEntity ptB)
{
    Slvs_Entity r;
    memset(&r, 0, sizeof(r));
    r.h = h;
    r.group = group;
    r.type = SLVS_E_LINE_SEGMENT;
    r.wrkpl = wrkpl;
    r.point[0] = ptA;
    r.point[1] = ptB;
    return r;
}
static Slvs_Entity Slvs_MakeCubic(Slvs_hEntity h, Slvs_hGroup group,
                                  Slvs_hEntity wrkpl,
                                  Slvs_hEntity pt0, Slvs_hEntity pt1,
                                  Slvs_hEntity pt2, Slvs_hEntity pt3)
{
    Slvs_Entity r;
    memset(&r, 0, sizeof(r));
    r.h = h;
    r.group = group;
    r.type = SLVS_E_CUBIC;
    r.wrkpl = wrkpl;
    r.point[0] = pt0;
    r.point[1] = pt1;
    r.point[2] = pt2;
    r.point[3] = pt3;
    return r;
}
static Slvs_Entity Slvs_MakeArcOfCircle(Slvs_hEntity h, Slvs_hGroup group,
                                        Slvs_hEntity wrkpl,
                                        Slvs_hEntity center,
                                        Slvs_hEntity start, Slvs_hEntity end)
{
    Slvs_Entity r;
    memset(&r, 0, sizeof(r));
    r.h = h;
    r.group = group;
    r.type = SLVS_E_ARC_OF_CIRCLE;
    r.wrkpl = wrkpl;
    r.point[0] = center;
    r.point[1] = start;
    r.point[2] = end;
    return r;
}
static Slvs_Entity Slvs_MakeCircle(Slvs_hEntity h, Slvs_hGroup group,
                                   Slvs_hEntity wrkpl,
                                   Slvs_hEntity center,
                                   Slvs_hEntity normal, Slvs_hEntity radius)
{
    Slvs_Entity r;
    memset(&r, 0, sizeof(r));
    r.h = h;
    r.group = group;
    r.type = SLVS_E_CIRCLE;
    r.wrkpl = wrkpl;
    r.point[0] = center;
    r.normal = normal;
    r.distance = radius;
    return r;
}
static Slvs_Entity Slvs_MakeWorkplane(Slvs_hEntity h, Slvs_hGroup group,
                                      Slvs_hEntity origin, Slvs_hEntity normal)
{
    Slvs_Entity r;
    memset(&r, 0, sizeof(r));
    r.h = h;
    r.group = group;
    r.type = SLVS_E_WORKPLANE;
    r.wrkpl = SLVS_FREE_IN_3D;
    r.point[0] = origin;
    r.normal = normal;
    return r;
}

static Slvs_Constraint Slvs_MakeConstraint(Slvs_hConstraint h,
                                           Slvs_hGroup group,
                                           int type,
                                           Slvs_hEntity wrkpl,
                                           double valA,
                                           Slvs_hEntity ptA,
                                           Slvs_hEntity ptB,
                                           Slvs_hEntity entityA,
                                           Slvs_hEntity entityB)
{
    Slvs_Constraint r;
    memset(&r, 0, sizeof(r));
    r.h = h;
    r.group = group;
    r.type = type;
    r.wrkpl = wrkpl;
    r.valA = valA;
    r.ptA = ptA;
    r.ptB = ptB;
    r.entityA = entityA;
    r.entityB = entityB;
    return r;
}

#ifdef __cplusplus
}
#endif

#endif