/*
 * Program to read file of grades and summarize.
 *
 * Name of file is from command-line argument.
 *
 * File consists of one or more lines containing an assignment name
 * (text, no spaces) and two scores (floating-point numbers), a "your
 * score" and a "perfect score".
 *
 * Output is a formatted list of input, sorted by assignment, plus an
 * average (computed as sum of your scores divided by sum of perfect scores).
 */

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

/* somewhat arbitrary sizes of things */

#define LINESIZE 200

#define MAX_ASSIGNMENTS 100

#define NAMESIZE 20
#define FMT_NAME "%20s" /* for reading assignment name */
#define PFMT_NAME "%-20s" /* for printing assignment name */
/* struct for individual grade */
typedef struct {
	char name[NAMESIZE+1];
	double score;
	double perfect_score;
} assignment_t;

/* parse one line, returning true if okay or false if invalid */
bool parse_line(char *line, assignment_t *a);

/* compare for qsort */
int compare_assignments(const void *e1, const void *e2);

/* main program */
int main(int argc, char *argv[]) {
	if (argc != 2) {
		printf("usage:  %s infile\n", argv[0]);
		return 1;
	}
	FILE * infile = fopen(argv[1], "r");
	if (infile == NULL) {
		printf("cannot open input file %s\n", argv[1]);
		return 1;
	}

	assignment_t assignments[MAX_ASSIGNMENTS];

	int num_assignments = 0;

	char line[LINESIZE+1];

	/* 
	 * read in lines of input to EOF or error, putting each line into
	 * an element of "assignments" 
	 */
	while (fgets(line, sizeof line, infile) != NULL) {
		if (strchr(line, '\n') == NULL) {
			printf("line %d too long (max length %d) \n", 
					num_assignments + 1, LINESIZE);
			fclose(infile);
			return 1;
		}
		if (num_assignments == MAX_ASSIGNMENTS) {
			printf("too many assignments (max %d)\n", MAX_ASSIGNMENTS);
			fclose(infile);
			return 1;
		}
		if (!parse_line(line, &assignments[num_assignments])) {
			printf("invalid line %d\n", num_assignments+1);
			fclose(infile);
			return 1;
		}
		num_assignments += 1;
	}
	fclose(infile);

	/* sort array of assignments by "name" field */
	qsort(assignments, num_assignments, sizeof(assignments[0]), 
			compare_assignments);

	/*
	 * go through list of assignments, printing "nicely" and keeping track
	 * of point totals.
	 */
	double total_points = 0.0;
	double total_perfect_points = 0.0;
	for (int i = 0; i < num_assignments; ++i) {
		printf(PFMT_NAME"%10.2f %10.2f\n", assignments[i].name, 
				assignments[i].score, assignments[i].perfect_score);
		total_points += assignments[i].score;
		total_perfect_points += assignments[i].perfect_score;
	}
	printf("\n%d assignments in all, %.2f total points, %.2f perfect score\n",
			num_assignments, total_points, total_perfect_points);
	printf("average %.2f\n", 100 * total_points / total_perfect_points);

	return 0;
}

bool parse_line(char *line, assignment_t *a) {
	/* 
	 * I could have written "%20s %lf %lf" for the format string,
	 * but then I'd have to remember that if I changed the size of
	 * the field in the struct I'd need to change it here too.
	 */
	if (sscanf(line, FMT_NAME"%lf %lf", 
				a->name, &a->score, &a->perfect_score) == 3)
		return true;
	else
		return false;
}

int compare_assignments(const void *e1, const void *e2) {
	/* compare names in *e1, *e2 */
	assignment_t *a1 = (assignment_t *) e1;
	assignment_t *a2 = (assignment_t *) e2;
	return strcmp(a1->name, a2->name);
}