//
// Created by Lennart on 02/12/2023.
//

#include <stdio.h>
#include "main.h"

int read_line(FILE *f);

int day_1() {
    FILE *f = fopen("day_1.txt", "r");
    if(f == NULL) {
        printf("Error! Missing input file!");
        return -1;
    }

    int sum = 0;
    while(!feof(f)) {
        sum += read_line(f);
    }

    fclose(f);
    printf("Result: %i\n", sum);
    return 0;
}

// Read all digits form the next line in a file
int read_line(FILE *f) {
    int first = -1, last = 10; // Use first=-1 to detect unset value and last=10 to return 0 (-10 + 10) when no values are set
    char buffer[16];
    int digit;
    do {
        fgets(&buffer[0], 16, f);
        for(int i = 0; i < 16; i++) {
            if(buffer[i] == '\n') {
                goto result;
            } else if(buffer[i] == 0) {
                break; // End of buffer
            }
            if(sscanf(&buffer[i], "%1d", &digit) == 1) { // NOLINT(*-err34-c)
                if(first == -1) {
                    first = digit;
                }
                last = digit;
            }
        }
    } while(!feof(f));

    result:
    return first * 10 + last;
}