using MathConsoleApplication;
using org.mariuszgromada.math.mxparser;

public class Bisection
{
    private static float EPSILON = (float)0.01;

    // An example function whose
    // solution is determined using
    // Bisection Method. The function
    // is x^3 - x^2 + 2
    private static double func(string expression, double x)
    {
        expression = SobstitutionClass.replaceX(expression, x);
        Expression e = new Expression(expression);
        return e.calculate();
    }

    public static void bisection(string expression,
                          double a,
                          double b)
    {
        if (func(expression, a) * func(expression, b) >= 0)
        {
            Console.WriteLine("a e b non sono corretti");
            return;
        }

        double c = a;
        while ((b - a) >= EPSILON)
        {
            // Find middle point
            c = (a + b) / 2;

            // Check if middle
            // point is root
            if (func(expression, c) == 0.0)
                break;

            // Decide the side
            // to repeat the steps
            else if (func(expression, c) * func(expression, a) < 0)
                b = c;
            else
                a = c;
        }
        Console.WriteLine($"la radice equivale a {Math.Round(c, 15)}");
    }
}


namespace MathConsoleApplication
{
    public class SobstitutionClass
    {
        public static string replaceX(string expression, double x)
        {
            for (int i = 0; i < expression.Length; i++)
            {
                if (expression[i] == 'x')
                {
                    if (i - 1 >= 0)
                    {
                        if (expression[i - 1] == '(' || expression[i - 1] == '+' || expression[i - 1] == '-' || expression[i - 1] == '*' || expression[i - 1] == '/')
                        {
                            expression = expression.Remove(i, "x".Length - 1);
                            expression = expression.Insert(i, x.ToString());
                        }
                        else
                        {
                            string tmpRepace = $"*{x.ToString()}";
                            expression = expression.Remove(i, "x".Length);
                            expression = expression.Insert(i, tmpRepace);
                        }
                    }
                    else
                    {
                        expression = expression.Remove(i, "x".Length - 1).Insert(i, x.ToString());
                    }
                    {
                    }
                }
            }
            return expression;
        }
    }
}