/* common.c
 *
 * Created by Rory Healy (healyr@student.unimelb.edu.au)
 * Created on 25th August 2021
 * Last modified 25th August 2021
 *
 * Contains functions for general use throughout other files.
 *
 */

#ifndef COMMON_HEADER
#include "common.h"
#endif

#define ARGC_CORRECT_LEN 4
#define MEMORY_ALLOCATION_ERROR "Error: Cannot allocate memory.\n"
#define OPEN_FILE_ERROR "Error: Unable to open file %s\n"
#define NUM_FILE_ERROR "Error: Incorrect number of inputs (3 required).\n"

/* Checks if a given pointer is null. Used for malloc() and realloc(). */
void checkNullPointer(void *ptr) {
	if (!ptr) {
		fputs(MEMORY_ALLOCATION_ERROR, stderr);
		exit(EXIT_FAILURE);
	}
}

/* Checks the validity of the command line input arguments */
void checkInputArgs(int argc, char **argv, FILE **datasetFile, \
    FILE **polygonFile, FILE **outputFile) {
    if (argc != ARGC_CORRECT_LEN) {
        fputs(NUM_FILE_ERROR, stderr);
        exit(EXIT_FAILURE);
    }

    *datasetFile = fopen(argv[1], "r");
    if (*datasetFile == NULL) {
        fprintf(stderr, OPEN_FILE_ERROR, argv[1]);
        exit(EXIT_FAILURE);
    }
    
    *polygonFile = fopen(argv[2], "r");
    if (*polygonFile == NULL) {
        fprintf(stderr, OPEN_FILE_ERROR, argv[2]);
        exit(EXIT_FAILURE);
    }

    *outputFile = fopen(argv[3], "w");
    if (*outputFile == NULL) {
        fprintf(stderr, OPEN_FILE_ERROR, argv[3]);
        exit(EXIT_FAILURE);
    }
}