#include <string.h>
#include <math.h>
#include "shader.h"
#include "geoshader.h"
#include "miaux.h"

struct instanced_object_file {
    miTag name;
    miTag filename;
    miTag material;
    miVector bbox_min;
    miVector bbox_max;
    int i_positions; 
    int n_positions; 
    miVector positions[1];
};

DLLEXPORT
int instanced_object_file_version(void) { return 1; }

DLLEXPORT
miBoolean instanced_object_file (
    miTag *result, miState *state, struct instanced_object_file *params  )
{
    int i;
    static int instance_index;  /* Geometry shaders are single-threaded. */
    char *filename, *name, instance_name[1024];
    miInstance *instance;
    miTag object_tag, instance_tag;
    int position_count = *mi_eval_integer(&params->n_positions);
    miVector *positions = mi_eval_vector(params->positions) + 
        *mi_eval_integer(&params->i_positions);

    if (!(name = miaux_tag_to_string(*mi_eval_tag(&params->name), NULL)) ||
        !(filename = miaux_tag_to_string(*mi_eval_tag(&params->filename), NULL)))
        return miFALSE;

    object_tag = miaux_object_from_file(name, filename, 
                                        *mi_eval_vector(&params->bbox_min),
                                        *mi_eval_vector(&params->bbox_max));

    for (i = 0; i < position_count; i++, positions++) {
        miMatrix matrix;
        miTag material_tag;
        sprintf(instance_name, "%s-%d", name, instance_index++);
        if (!(instance = mi_api_instance_begin(mi_mem_strdup(instance_name))))
            return miFALSE;

        mi_matrix_ident(matrix);
        matrix[12] = positions->x;
        matrix[13] = positions->y;
        matrix[14] = positions->z;
        mi_matrix_copy(instance->tf.local_to_global, matrix);
        mi_matrix_invert(instance->tf.global_to_local,
                         instance->tf.local_to_global);
        
        material_tag = *mi_eval_tag(&params->material);
        if (material_tag)
            instance->material = mi_phen_clone(state, material_tag);

        instance_tag = mi_api_instance_end(0, object_tag, 0);
        if (instance_tag == miNULLTAG || 
            mi_geoshader_add_result(result, instance_tag) == miFALSE)
            return miFALSE;
    }
    return miTRUE;
}