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

int readPositiveInt();
float readPositiveFloat();
void readTriangleData(float *base, float *height);
float triangleArea(float base, float height);
float rectangleArea(float width, float height);
float squareArea(float side);
float circleArea(float radius);
char menu(int numTri, int numRect, int numSquares, int numCircles);

int main(void)
{
    char option;
    int numTri = 0, numRect = 0, numSquares = 0, numCircles = 0;
    float area, base, height, width, side, radius;

    do
    {
        option = menu(numTri, numRect, numSquares, numCircles);

        switch(option)
        {
        case 't':
            printf("Base: ");
            base = readPositiveFloat();
            printf("Height: ");
            height = readPositiveFloat();
            //readTriangleData(&base, &height);
            area = triangleArea(base, height);
            printf("\nTriangle area: %.2f.\n", area);
            printf("Press a key...\n");
            getchar();
            numTri++;
            break;
        case 'r':
            printf("Width: ");
            width = readPositiveFloat();
            printf("Height: ");
            height = readPositiveFloat();
            area = rectangleArea(width, height);
            printf("\nRectangle area: %.2f.\n", area);
            printf("Press a key...\n");
            getchar();
            numRect++;
            break;
        case 's':
            printf("Side: ");
            side = readPositiveFloat();
            area = squareArea(side);
            printf("\nSquare area: %.2f.\n", area);
            printf("Press a key...\n");
            getchar();
            numSquares++;
            break;
        case 'c':
            printf("Radius: ");
            radius = readPositiveFloat();
            area = circleArea(radius);
            printf("\nCircle area: %.2f.\n", area);
            printf("Press a key...\n");
            getchar();
            numCircles++;
            break;
        case 'e':
            printf("\nBon voyage!\n");
        }
    }
    while(option != 'e');

    return 0;
}

int readPositiveInt()
{
    int n, r;

    do
    {
        r = scanf("%d", &n);
        while(getchar() != '\n');
    }
    while(r != 1 || n <= 0);

    return n;
}

float readPositiveFloat()
{
    float n;
    int r;

    do
    {
        r = scanf("%f", &n);
        while(getchar() != '\n');
    }
    while(r != 1 || n <= 0);

    return n;
}

void readTriangleData(float *base, float *height)
{
    printf("Base: ");
    (*base) = readPositiveFloat();
    printf("Height: ");
    (*height) = readPositiveFloat();
}

float triangleArea(float base, float height)
{
    return base * height / 2;
}

float rectangleArea(float width, float height)
{
    return width * height;
}

float squareArea(float side)
{
    return side * side;
}

float circleArea(float radius)
{
    return M_PI * radius * radius;
}

char menu(int numTri, int numRect, int numSquares, int numCircles)
{
    char option;

    do
    {
        char a = 248;
        printf("\t\t\tAreas computation\n\n");
        printf("Triangle (N%c): %d\t\t\t\tRetangulo (N%c): %d\n", a, numTri, a, numRect);
        printf("Circle (N%c): %d\t\t\t\t\tSquare (N%c): %d\n", a, numCircles, a, numSquares);
        printf("\n\tOPTIONS\n");
        printf("\t(T)riangle\n");
        printf("\t(R)ectangle\n");
        printf("\t(S)quare\n");
        printf("\t(C)ircle\n");
        printf("\t(E)xit\n");
        printf("OPTION -> ");
        scanf(" %c", &option);
        while(getchar() != '\n');
        option = tolower(option);

        if(option != 't' && option != 'r' && option != 's' && option != 'c' && option != 'e')
        {
            printf("\n\nInvalid option!\n\n");
            printf("Press a key...\n");
            getchar();
        }
    }
    while(option != 't' && option != 'r' && option != 's' && option != 'c' && option != 'e');

    return option;
}