#include "gif.h"

/* just a small cleanup routine before we leave */
void cleanup(BYTE *ptr) {
	if (ptr)
		free(ptr);
}

/* Function :	ReadHDF
** Return:		0 on completion without error, -1 on error
** Input:		CHAR *h5_file - HDF file name
**				CHAR *dset_name - Name of the HDF Image dataset
**				CHAR *pal_name - Name of the HDF palette
** Output	:	BYTE** data - the HDF Image to be converted
**				BYTE  palette[256][3] - the corresponding palette
**				hsize_t* image_size - the size of each dimension of the image
**
** Future Notes: 
** The way readHDF works right now is that it expects the user 
** to know the exact path to the HDF image. Thus it does not
** parse the HDF file looking for image datasets and corresponding
** palettes. Also it takes in the default palette for the image 
** specified, if the palette is missing, it makes a default greyscale
** palette and throws it in.
**
*/
int ReadHDF(BYTE** data ,
			BYTE palette[256][3] ,
			hsize_t *image_size ,
			CHAR *h5_file ,
			CHAR *dset_name ,
			CHAR *pal_name) 
{
	hid_t fHfile;	/* H5 file to open */
	herr_t status;	/* status variable */
	hid_t dspace;	/* dataspace identifier for the the dataset */
	hid_t dset;		/* dataset identifier */

	hid_t pal_set;	/* dataset for palette */
	hid_t pal_space;/* dataspace for palette */
	
	hsize_t datasize;	/* size of the image */

	int pal_exist = 0;	/* do we have a palette? */

	/* check stuff */
	if (!h5_file || !dset_name || !image_size) {
		fprintf(stderr , "NULL is not an acceptable input for HDFread. Aborting.\n");
		return -1;
	}

	/* do we have a palette ? */
	if (pal_name) {
		pal_exist = 1;
	}

	/* try opening the file */
	/* H5 file open calls */
	if ((fHfile = H5Fopen(h5_file , H5F_ACC_RDONLY , H5P_DEFAULT)) < 0) {
		fprintf(stderr , "Unable to open HDF file for input. Aborting.\n");
		return -1;
	}

	/* open the dataset for reading */
	if ((dset = H5Dopen(fHfile , dset_name)) < 0) {
		fprintf(stderr , "Unable to open dataset\n");
		return -1;
	}

	/* get the dataspace */
	if ((dspace = H5Dget_space(dset)) < 0) {
		fprintf(stderr , "Unable to get dataspace\n");
		return -1;
	}

	/* get the dimension size of the image */
	if (H5Sget_simple_extent_dims(dspace , image_size , NULL) !=2 ) {
		fprintf(stderr , "Unable to get dimension info\n");
		return -1;
	}

	/* size needed to store the image */
	datasize = image_size[0] * image_size[1];

	/* allocate memory to store the image */
	if ((*data = (BYTE*) malloc((size_t)datasize)) == NULL) {
		fprintf(stderr , "Out of memory, exiting");
		return -1;
	}

	/* get the actual image */
	if ((status = H5Dread(dset , H5Dget_type(dset) , H5S_ALL , H5S_ALL , H5P_DEFAULT , *data)) < 0) {
		fprintf(stderr , "Unable to read data \n");
		cleanup(*data);
		return -1;
	}

	if (pal_exist) {
		hsize_t pal_size[2];
		hsize_t pal_datasize;

		BYTE *temp_buf;
		hsize_t temp_size;

		/* get the palette dataset */
		if ((pal_set = H5Dopen(fHfile , pal_name)) < 0) {
			fprintf(stderr , "Unable to open dataset\n");
			pal_exist = 0;
			return -1;
		}
		
		/* get the dataspace */
		if ((pal_space = H5Dget_space(pal_set)) < 0) {
			fprintf(stderr , "Unable to get dataspace\n");
			pal_exist = 0;
			return -1;
		}
		
		/* get the dimension size of the palette. */
		if (H5Sget_simple_extent_dims(pal_space , pal_size , NULL) !=2 ) {
			fprintf(stderr , "Unable to get dimension info\n");
			pal_exist = 0;
			return -1;
		}
		
		/* size needed to store the image */
		pal_datasize = pal_size[0] * pal_size[1];
		
		/* copy stuff into a temp buffer and then copy 256*3 elements to palette */
		temp_size = H5Dget_storage_size(pal_set);
		
		temp_buf = (BYTE*) malloc ((size_t)temp_size * sizeof(BYTE));

		/* make sure that the palette is actually 256 X 3 so that we don't create overflows */
		if (pal_datasize > 256 * 3)
		{
			fprintf(stderr , "Palette seems to be more than 256X3 bytes\n");
			fprintf(stderr , "Truncating palette to 256 colors. This might cause a problem with the final image\n");
			pal_datasize = 256 * 3;
		}		

		/* get the actual palette */
		if ((status = H5Dread(pal_set , H5Dget_type(pal_set) , H5S_ALL , H5S_ALL , H5P_DEFAULT , temp_buf)) < 0) {
			fprintf(stderr , "Unable to read data \n");
			cleanup(*data);
			cleanup(temp_buf);
			return -1;
		}

		/* copy stuff into the actual palette */
		memcpy(palette , temp_buf , (size_t)pal_datasize);

		/* get rid of the temp memory */
		cleanup(temp_buf);
		/* end of if (pal_exist) */
	
	} else {
		int i;
		/* if palette does not exist we just go ahead and create a uniform greyscale palette */
		for (i = 0 ; i < 256 ; i++) {
			palette[i][0] = 255 - i;
			palette[i][1] = 255 - i;
			palette[i][2] = 255 - i;
		}
	}

	/* close everything */
	status = H5Dclose(dset);
	status = H5Sclose(dspace);
	status = H5Fclose(fHfile);

	return 0;
}