#include "shader.h"
#include "geoshader.h"
#include "miaux.h"

typedef struct {
    miTag name;
    miInteger count;
    miScalar radius;
    miVector bbox_min;
    miVector bbox_max;
    miScalar y_offset_max;
    miScalar z_offset_max;
    miInteger approximation;
    miInteger degree;
    miInteger random_seed;
} hair_geo_row_t;

DLLEXPORT
int hair_geo_row_version(void) { return 1; }

void hair_geo_row_bbox(miObject *obj, void* params)
{
    hair_geo_row_t *p = (hair_geo_row_t*)params;
    obj->bbox_min = p->bbox_min;
    obj->bbox_max = p->bbox_max;
}

miBoolean hair_geo_row_callback(miTag tag, void *ptr);

DLLEXPORT
miBoolean hair_geo_row (
    miTag *result, miState *state, hair_geo_row_t *params  )
{
    hair_geo_row_t *p = 
        (hair_geo_row_t*) mi_mem_allocate(sizeof(hair_geo_row_t));
    p->name          = *mi_eval_tag(&params->name);
    p->count         = *mi_eval_integer(&params->count);
    p->radius        = *mi_eval_scalar(&params->radius);
    p->bbox_min      = *mi_eval_vector(&params->bbox_min);
    p->bbox_max      = *mi_eval_vector(&params->bbox_max);
    p->y_offset_max  = *mi_eval_scalar(&params->y_offset_max);
    p->z_offset_max  = *mi_eval_scalar(&params->z_offset_max);
    p->approximation = *mi_eval_integer(&params->approximation);
    p->degree        = *mi_eval_integer(&params->degree);
    p->random_seed   = *mi_eval_integer(&params->random_seed);

    miaux_define_hair_object(
        p->name, hair_geo_row_bbox, p, result, hair_geo_row_callback);

    return miTRUE;
}

miBoolean hair_geo_row_callback(miTag tag, void *ptr)
{
    miHair_list *hair_list;
    miGeoIndex *harray;
    miScalar *hair_scalars;
    int i, h, per_hair_data_count, vertex_count, vertex_size,
        per_hair_scalar_count, total_scalar_count;
    hair_geo_row_t *p = (hair_geo_row_t *)ptr;
    miScalar x, y_offset, z_offset,
        yoff_max = p->y_offset_max, zoff_max = p->z_offset_max;

    mi_api_incremental(miTRUE);
    miaux_define_hair_object(p->name, hair_geo_row_bbox, p, NULL, NULL);

    hair_list = mi_api_hair_begin();
    hair_list->approx = p->approximation;
    hair_list->degree = p->degree;
    mi_api_hair_info(0, 'r', 1);
    mi_api_hair_info(0, 't', 1);

    per_hair_data_count = 2;  /* Radius and random value */
    vertex_count = 4;
    vertex_size = 3;
    per_hair_scalar_count = 
        vertex_count * vertex_size + per_hair_data_count;
    total_scalar_count = p->count * per_hair_scalar_count;

    hair_scalars = mi_api_hair_scalars_begin(total_scalar_count);
    mi_srandom(p->random_seed);

    for (i = 0; i < p->count; i++) {
        x = miaux_random_range(p->bbox_min.x, p->bbox_max.x);
        y_offset = miaux_random_range(-yoff_max, yoff_max);
        z_offset = miaux_random_range(-zoff_max, zoff_max);

        *hair_scalars++ = p->radius;             
        *hair_scalars++ = miaux_random_range(0.0, 1.0); 
        *hair_scalars++ = x; 
        *hair_scalars++ = p->bbox_min.y + yoff_max + y_offset;
        *hair_scalars++ = p->bbox_min.z + zoff_max + z_offset;
        *hair_scalars++ = x; 
        *hair_scalars++ = p->bbox_max.y - yoff_max + y_offset;
        *hair_scalars++ = p->bbox_min.z + zoff_max + z_offset;
        *hair_scalars++ = x; 
        *hair_scalars++ = p->bbox_max.y - yoff_max + y_offset;
        *hair_scalars++ = p->bbox_max.z - zoff_max + z_offset;
        *hair_scalars++ = x; 
        *hair_scalars++ = p->bbox_min.y + yoff_max + y_offset;
        *hair_scalars++ = p->bbox_max.z - zoff_max + z_offset;
    }
    mi_api_hair_scalars_end(total_scalar_count);
    
    harray = mi_api_hair_hairs_begin(p->count + 1);
    for (h=0; h < p->count + 1; h++)
        harray[h] = h * per_hair_scalar_count;
    mi_api_hair_hairs_end();

    mi_api_hair_end();
    mi_api_object_end();
    return miTRUE;
}