using System;

namespace ConsoleApp2
{
    public static class Program
    {
        public static void Main(string[] args)
        {
            Console.WriteLine("Hello World!");

            var rectangle = new CRect();
            rectangle.setRect(5, 8);

            var square = new CRect();
            square.setRect(6);

            Console.WriteLine($"Rectangle: {rectangle.ShowRect()}");
            Console.WriteLine($"Square: {square.ShowRect()}");

            var rectanglePerimeter = rectangle.Perimeter();
            var squarePerimeter = square.Perimeter();

            Console.Write($"Rectangle's perimeter: {rectanglePerimeter}, square's perimeter: {squarePerimeter}. ");

            var perimeterComparison = "Perimeters are the same.";
            if (rectanglePerimeter > squarePerimeter)
                perimeterComparison = "Rectangle's perimeter is bigger.";
            else if (squarePerimeter > rectanglePerimeter)
                perimeterComparison = "Square's perimeter is bigger.";

            Console.WriteLine(perimeterComparison);

            var rectangleArea = rectangle.Area();
            var squareArea = square.Area();

            Console.Write($"Rectangle's area: {rectangleArea}, square's area: {squareArea}. ");

            string areaComparison = "Areas are the same.";
            if (rectangleArea > squareArea)
                areaComparison = "Rectangle's area is bigger.";
            else if (squareArea > rectangleArea)
                areaComparison = "Square's area is bigger.";

            Console.WriteLine(areaComparison);

            Console.ReadKey();
        }

        public class CRect
        {
            private float a;
            private float b;

            private bool aIsZero => a == 0;
            private bool bIsZero => b == 0;

            public void setRect(float a)
            {
                if (a <= 0) throw new ArgumentOutOfRangeException(nameof(a));

                this.a = a;
            }

            public void setRect(float a, float b)
            {
                if (a <= 0) throw new ArgumentOutOfRangeException(nameof(a));
                if (b <= 0) throw new ArgumentOutOfRangeException(nameof(b));

                this.a = a;
                this.b = b;
            }

            public float Perimeter()
            {
                if (aIsZero) throw new InvalidOperationException($"Run {nameof(setRect)} method first");

                return bIsZero
                    ? 4 * a
                    : 2 * a + 2 * b;
            }

            public float Area()
            {
                if (aIsZero) throw new InvalidOperationException($"Run {nameof(setRect)} method first");

                return bIsZero
                    ? a * a
                    : a * b;
            }

            public string ShowRect() => $"a={a}, b={b}";
        }
    }
}