#include <stdio.h>
#include <stdlib.h>
#include "tgafiles.h"

FILE * newTGA (const char *fileName, short width, short height, origin_t origin) {
	int i;
	
	FILE *filePtr;
	
	if ((filePtr  = fopen (fileName, "wb")) == NULL)
		return NULL;
	
	fputc(0, filePtr);
	fputc(0, filePtr);
	fputc(2, filePtr); /* image type; 2=RGB, 9=RLE compressed RGB */
	
	for (i = 9; i; --i)
		fputc (0, filePtr);
	
	fputc (width & 0xFF, filePtr);
	fputc (width >> 8, filePtr);
	fputc (height & 0xFF, filePtr);
	fputc (height >> 8, filePtr);
	
	fputc (24, filePtr); /* pixel size - 24 bit */
	
	/* descriptor byte
	 * bits	description
	 * 3-0	0
	 * 4		must be 0
	 * 5		screen origin (0=bottom left, 1=top left)
	 * 7-6	00=non-interleaved, 01=two-way interleaved,
	 *		10=four-way interleaved, 11=reserved
	 */
	fputc (origin == TGA_ORIGIN_TOP?1<<5:0, filePtr); /* descriptor */
	
	return filePtr;
}

FILE * openTGA (const char *fileName, short *widthPtr, short *heightPtr) {
	char compressionFlag;
	char junk;
	int i;
	
	FILE *filePtr;
	
	if ((filePtr  = fopen (fileName, "rb")) == NULL)
		return NULL;
	
	fscanf (filePtr, "%c%c%c", &junk, &junk, &compressionFlag);
	
	if (compressionFlag != 2) {
		fclose (filePtr);
		return NULL;
	}
	
	for (i = 9; i; --i)
		fgetc (filePtr);
	
	fread (widthPtr, 2, 1, filePtr);
	fread (heightPtr, 2, 1, filePtr);
	fread (&junk, 2, 1, filePtr);
	
	return filePtr;
}

int writeTGA (FILE *filePtr, BYTE red, BYTE green, BYTE blue) {
	return fprintf (filePtr, "%c%c%c", blue, green, red);
}

int readTGA (FILE *filePtr, BYTE *redPtr, BYTE *greenPtr, BYTE *bluePtr) {
	*bluePtr = fgetc (filePtr);
	
	if (feof (filePtr))
		return -1;
	
	*greenPtr = fgetc (filePtr);
	
	if (feof (filePtr))
		return -1;
	
	*redPtr = fgetc (filePtr);
	
	if (feof (filePtr))
		return -1;
	
	return 1;
}

int closeTGA (FILE *filePtr) {
	return fclose (filePtr);
}