namespace MindBox.Lib;

public class Triangle : FlatShape
{
	private readonly double[] _sides;

	public Triangle(double a, double b, double c)
	{
		_sides = new[] { a, b, c };
		if (_sides.Any(side => side <= 0))
		{
			throw new ArgumentException($"Side(s) cannot be non-positive: {string.Join(" ;", _sides.Where(side => side <= 0))}");
		}
		if (a >= b + c || b >= c + a || c >= a + b)
		{
			throw new ArgumentException($"Sides lengths are not valid: {a}, {b}, {c}");
		}
	}
	public override double GetArea()
	{
		if (_area != null)
		{
			return _area.Value;
		}
		else
		{
			double semiPerimeter = _sides.Sum() / 2;
			_area = Math.Sqrt(semiPerimeter *
				(semiPerimeter - _sides[0]) *
				(semiPerimeter - _sides[1]) *
				(semiPerimeter - _sides[2]));
			return _area.Value;
		}
	}
	public bool IsRight()
	{
		var sorted = _sides.OrderByDescending(x => x);

		double hypotenuse = sorted.First();
		var catheti = sorted.Skip(1);

		return hypotenuse * hypotenuse == catheti.Sum(x => x * x);
	}
}