#include <stdio.h>
#include <locale.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#define INPUT_FILE  "data.txt"
#define OUTPUT_FILE "rezult.txt"

int CorrectCoefficients(char* buffer) {
    int count = 1, correct = 1;
    FILE* data_rezult = fopen(OUTPUT_FILE, "w+");
    
    for (int i = 0; i < strlen(buffer); i++) {
        if (buffer[i] == ' ') {
            count++;
        }
    }

    for (int i = 0; i < strlen(buffer); i++) {
        if (((buffer[i] < '0') || (buffer[i] > '9')) && (buffer[i] != ' ') && (buffer[i] != '.')) {
            fprintf(data_rezult, "coefficients can't be a symbol");
            printf("coefficients can't be a symbol");
            correct = 0;
        }
    }

    if ((count < 3)&&(correct==1)) {
        fprintf(data_rezult, "not enough coefficients");
        printf("not enough coefficients");
        correct = 0;
    }
    else if ((count > 3) && (correct == 1)) {
        fprintf(data_rezult, "too many coefficients");
        printf("too many coefficients");
        correct = 0;
    }
    return correct;
}


int x(double k[3]) {
    FILE* data_rezult = fopen(OUTPUT_FILE, "w+");
    printf("%.3f*x^2+(%.3f*x)+(%.3f)", k[0], k[1], k[2]);
    double d = pow(k[1], 2) - 4. * k[0] * k[2];
    printf("\nD = %.3f", d);
    fprintf(data_rezult, "D: %f", d);
    if (d < 0) {
        printf("\nvalid roots don't exist");
        fprintf(data_rezult, "\nvalid roots don't exist");
        return 1;
    }
    double x1 = (-k[1] + sqrt(d)) / (2 * k[0]);
    double x2 = (-k[1] - sqrt(d)) / (2 * k[0]);
    if (x1 == x2) {
        printf("\nx = %.3f", x1);
        fprintf(data_rezult, "\nx = %f", x1);
        return 0;
    }
    printf("\nx1 = %.3f\nx2 = %.3f", x1, x2);
    fprintf(data_rezult, "\nx1 = %f\nx2 = %f", x1, x2);
}

int main()
{
    char buffer[128];
    double k[3];

    FILE* data_open = fopen(INPUT_FILE, "r");
    FILE* data_rezult = fopen(OUTPUT_FILE, "w+");
    if (data_open == 0) {
        printf("Can't open file");
        return 1;
    }
    fgets(buffer, 127, data_open);
    if (CorrectCoefficients(buffer)) {
        k[0] = atof(strtok(buffer, " "));
        for (int i = 1; i < 3; i++) {
            k[i] = atof(strtok(NULL, " "));
        }

        int count = 0;
        for (int i = 0; i < 3; i++) {
            if (k[i] == 0) {
                count++;
            }
        }
        if (count == 3) {
            fprintf(data_rezult, "all coefficients can't be null");
            printf("all coefficients can't be null");
            return 1;
        }
        x(k);
    }
}