#include <stdio.h>
#include <math.h>

typedef struct
{
    double x, y;
}point_t;

point_t readPoint(void);
void printPoint(point_t d);
double lengthSide(point_t a, point_t b);
double trianglePerimeter(double a, double b, double c);
double triangleVolume(double o, double a, double b, double c);
int testPoint(point_t a, point_t b);

int main()
{
    point_t Point[3];
    double L[3], o, v;

    puts("Kolokwium 2 - IN - program testowy\n");
    printf("Podaj nastepujace punkty:\nA: ");
    Point[0] = readPoint();
    printf("B: ");
    Point[1] = readPoint();
    printf("C: ");
    Point[2] = readPoint();

    printf("\nPodano nastepujace punkty:\nA: ");
    printPoint(Point[0]);
    printf("B: ");
    printPoint(Point[1]);
    printf("C: ");
    printPoint(Point[2]);

    if(testPoint(Point[0], Point[1])&&testPoint(Point[1], Point[2])&&testPoint(Point[2], Point[0]))
    {
        L[0] = lengthSide(Point[0], Point[1]);
        L[1] = lengthSide(Point[1], Point[2]);
        L[2] = lengthSide(Point[2], Point[0]);
        o = trianglePerimeter(L[0], L[1], L[2]);
        v = triangleVolume(o, L[0], L[1], L[2]);
        if(v == 0) printf("Punkty leza na prostej - nie ma trojkata!\n");
        else
        {
            printf("\nObwod trojkata: %.2lf\n", o);
            printf("Pole trojkota: %.2lf\n\n",v);
        }
    }else
    {
        puts("\nPodano dwa takie same punkty!");
    }
    return 0;
}

point_t readPoint(void)
{
    point_t d;
    printf("\tpodaj x: ");
    scanf("%lf", &d.x);
    fflush(stdin);

    printf("\tpodaj y: ");
    scanf("%lf", &d.y);
    fflush(stdin);

    return d;
}

int testPoint(point_t a, point_t b)
{
    return (a.x == b.x && a.y == b.y) ? 0 : 1;
}

void printPoint(point_t d)
{
    printf("x=%.2lf, y=%.2lf\n", d.x, d.y);
}

double lengthSide(point_t a, point_t b)
{
    double l, e, f;
    e = b.y - a.y;
    e = pow(e,2);
    f = b.x - a.x;
    f = pow(f,2);
    l = sqrt(e+f);
    return l;
}

double trianglePerimeter(double a, double b, double c)
{
    return a + b + c;
}

double triangleVolume(double p, double a, double b, double c)
{
    double s;
    p /= 2;
    a = p-a;
    b = p-b;
    c = p-c;
    s = p*a*b*c;
    s = sqrt(s);
    return s;
}