/*
Shader make_indexed_framebuffers

Define mental ray framebuffers in version 3.6.x using a geometry
shader to modify the options block.  For example:

instance "framebuffer_creation"
    geometry
    "make_indexed_framebuffers" (
        "option_block_name" "options",
        "framebuffers" [
	    { "index" 0,
              "type" "+rgba",
              "filename" "buffer_0.tif" },
            { "index" 1,
              "type" "+rgba",
              "filename" "buffer_1.tif" },
            { "index" 2,
              "type" "+rgba",
              "filename" "buffer_2.tif" }
        ]
    )
end instance
*/

/* For sprintf in Windows: */
#define _CRT_SECURE_NO_WARNINGS

#include <string.h>
#include <stdlib.h>
#include "shader.h"
#include "geoshader.h"


/* Input parameter for each framebuffer is a struct: */

typedef struct {
    miInteger index;
    miTag type;
    miTag filename;
} indexed_framebuffer;


/* Parameter struct for shader function: */

struct make_indexed_framebuffers {
    miTag option_block_name;
    int i_fb;
    int n_fb;
    indexed_framebuffer fb[1];
};


/* Struct to store the arguments resulting from evaluating shader parameters: */

typedef struct {
    int index;
    char* type;
    char* filename;
    char* ext;
    char* name;
} fb_args;


/* Evaluate the parameters for the arguments required to define framebuffers: */

char* tag_to_string(miTag tag, char *default_value)
{
    char *result = default_value;
    if (tag != 0) {
	result = (char*)mi_db_access(tag);
	mi_db_unpin(tag);
    }
    return result;
}

char* get_extension(char *filename)
{
  char* extension = NULL;
  if (filename) {
    extension = strrchr(filename, '.');
    if (extension) extension++;  /* String after "." */
  }
  return extension;
}

/* Get the set of arguments by evaluating parameters: */

void get_indexed_framebuffer_args(
    fb_args args[], int count, miState *state, 
    struct make_indexed_framebuffers *params)
{
    int i_fb = *mi_eval_integer(&params->i_fb), i;
    mi_info("Making %i user framebuffers:", count);

    for (i = 0; i < count; ++i) {
	char name[16];
	indexed_framebuffer fb = params->fb[i + i_fb];
	args[i].index = *mi_eval_integer(&fb.index);
	args[i].type = tag_to_string(*mi_eval_tag(&fb.type), NULL);
	args[i].filename = tag_to_string(*mi_eval_tag(&fb.filename), NULL);
	args[i].ext = get_extension(args[i].filename);
	sprintf(name, "fb%d", args[i].index);
	args[i].name = mi_mem_strdup(name);
	mi_progress("   Buffer %d: filename '%s', type '%s', ext '%s', name '%s'",
		    args[i].index, args[i].filename, args[i].type,
		    args[i].ext, args[i].name);
    }
}


/* Shader functions: */

DLLEXPORT
int make_indexed_framebuffers_version(void) { return 1; }

DLLEXPORT
miBoolean make_indexed_framebuffers (
    miTag *result, miState *state, struct make_indexed_framebuffers *params)
{
    char* option_block_name = 
	tag_to_string(*mi_eval_tag(&params->option_block_name), "opt");
    miOptions* options = (miOptions*)(state->options);

    int count = *mi_eval_integer(&params->n_fb), i;
    fb_args* args = (fb_args*)mi_mem_allocate(count * sizeof(fb_args));
    get_indexed_framebuffer_args(args, count, state, params);

    mi_api_options_begin(mi_mem_strdup(option_block_name));
    for (i = 0; i < count; ++i)
	mi_api_framebuffer(
	    options, args[i].index, mi_mem_strdup(args[i].type));
    mi_api_options_end();

    for (i = 0; i < count; ++i) {
	/* A framebuffer might not be output to file; check for a filename: */
	if (args[i].filename && strlen(args[i].filename) > 0) {
	    mi_api_framebuffer_add(
		state->camera->buffertag, mi_mem_strdup(args[i].name), 
		mi_mem_strdup(args[i].ext), 0, 
		mi_mem_strdup(args[i].filename));
	}
    }
    mi_mem_release(args);
    return miTRUE;
}