/* 
 * Program that, given a set of ranges and an input file of integers,
 * says how many items in the input file are in each range.
 *
 * Command-line arguments:
 * input file
 * ranges in the form N,M
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>

typedef struct {
	int start;
	int end;
	int count;
} range_counter_t;

int rcount_compar(const void *e1, const void *e2);

int main(int argc, char *argv[]) {

	/* check for errors in command-line arguments */

	if (argc < 3) {
		printf("usage %s input file ranges .... (in form N,M)\n", 
			argv[0]);
		return 1;
	}

	char *filename = argv[1];

	int num_rcounts = argc-2;
	range_counter_t rcounts[num_rcounts];
	/* rather than this, could also use malloc to make array */

	char *endptr;
	for (int i = 0; i < num_rcounts; ++i) {
		rcounts[i].start = strtol(argv[2+i], &endptr, 10);
		if (*endptr != ',') {
			puts("ranges must be in the form N,M");
			return 1;
		}
		rcounts[i].end = strtol(endptr+1, &endptr, 10);
		if (*endptr != '\0') {
			puts("ranges must be in the form N,M");
			return 1;
		}
		rcounts[i].count = 0;
		if (rcounts[i].start > rcounts[i].end) {
			printf("warning:  N > M for range %s\n", argv[2+i]);
			/* FIXME might be better to skip? */
		}
	}

	/* 
	 * sort ranges and check for overlap
	 */

	qsort(rcounts, num_rcounts, sizeof rcounts[0], rcount_compar);
	for (int i = 0; i < num_rcounts-1; ++i) {
		if (rcounts[i].end >= rcounts[i+1].start) {
			printf("warning:  overlapping ranges %d,%d and %d,%d\n",
				rcounts[i].start, rcounts[i].end,
				rcounts[i+1].start, rcounts[i+1].end);
		}
	}

	/*
	 * process input file and print result
	 */

	FILE * infile = fopen(filename, "r");
	if (infile == NULL) {
		printf("cannot open input file %s\n", filename);
		return 1;
	}

	int input;
	int not_in_a_range = 0;
	while (fscanf(infile, "%d", &input) == 1) {
		bool found = false;
		for (int i = 0; i < num_rcounts; ++i) {
			if ((input >= rcounts[i].start) && 
					(input <= rcounts[i].end)) 
			{
				rcounts[i].count += 1;
				found = true;
			}
		}
		if (!found) {
			not_in_a_range += 1;
		}
	}
	if (!feof(infile)) {
		puts("invalid data in input file");
		/* FIXME or return 1 here? */
	}

	for (int i = 0; i < num_rcounts; ++i) {
		printf("[%d,%d]: %d\n", 
			rcounts[i].start, rcounts[i].end, rcounts[i].count);
	}
	printf("%d input values not in a range\n", not_in_a_range);

	return 0;
}

/*
 * comparison function for ranges (to pass to qsort)
 * sorts by start value, then by end value
 */
int rcount_compar(const void *e1, const void *e2) {
	const range_counter_t *r1 = e1;
	const range_counter_t *r2 = e2;
	if (r1->start < r2->start) {
		return -1;
	} 
	else if (r1->start > r2->start) {
		return 1;
	}
	else if (r1->end < r2->end) {
		return -1;
	}
	else if (r1->end > r2->end) {
		return -1;
	}
	else {
		return 0;
	}


}