namespace Lunar.Evil_Calculator
{
    internal class ReverseNotationSolver
    {
        List<Token> equation = new List<Token>();

        public string? ToReverseNotation(ref List<Token> equation)
        {
            List<Token> TEMP = new List<Token>();
            Stack<Token> OPERATORS = new Stack<Token>();
            foreach (Token token in equation)
            {
                if (token.tokenType == Token.TokenType.Operand)
                {
                    TEMP.Add(token);
                }
                if (token.tokenType == Token.TokenType.Operator)
                {
                    if (token.value == "(")
                    {
                        OPERATORS.Push(token);
                    }
                    else if (token.value == ")")
                    {
                        while (OPERATORS.Peek().value != "(")
                        {
                            TEMP.Add(OPERATORS.Pop());
                        }
                        OPERATORS.Pop();
                    }
                    else
                    {
                        while (OPERATORS.Count != 0 ? OPERATORS.Peek().priority >= token.priority : false)
                        {
                            TEMP.Add(OPERATORS.Pop());
                        }
                        OPERATORS.Push(token);
                    }
                }
            }
            while (OPERATORS.Count != 0)
            {
                TEMP.Add(OPERATORS.Pop());
            }
            this.equation = TEMP;
            return equationToString();
        }



        public string? Solve(ref List<Token> equation)
        {
            ToReverseNotation(ref equation);
            Stack<Token> stack = new Stack<Token>();
            foreach (Token token in this.equation)
            {
                double result, left, right;
                if (token.tokenType == Token.TokenType.Operand)
                {
                    stack.Push(token);
                }
                if (token.tokenType == Token.TokenType.Operator)
                {
                    switch (token.value)
                    {
                        case "+":
                            right = Convert.ToDouble(stack.Pop().value);
                            left = Convert.ToDouble(stack.Pop().value);
                            result = left + right;
                            stack.Push(new Token(Token.TokenType.Operand, result.ToString()));
                            break;
                        case "-":
                            right = Convert.ToDouble(stack.Pop().value);
                            left = Convert.ToDouble(stack.Pop().value);
                            result = left - right;
                            stack.Push(new Token(Token.TokenType.Operand, result.ToString()));
                            break;
                        case "*":
                            right = Convert.ToDouble(stack.Pop().value);
                            left = Convert.ToDouble(stack.Pop().value);
                            result = left * right;
                            stack.Push(new Token(Token.TokenType.Operand, result.ToString()));
                            break;
                        case "/":
                            right = Convert.ToDouble(stack.Pop().value);
                            left = Convert.ToDouble(stack.Pop().value);
                            result = left / right;
                            stack.Push(new Token(Token.TokenType.Operand, result.ToString()));
                            break;
                        case "^":
                            right = Convert.ToDouble(stack.Pop().value);
                            left = Convert.ToDouble(stack.Pop().value);
                            result = Math.Pow(left, right);
                            stack.Push(new Token(Token.TokenType.Operand, result.ToString()));
                            break;
                    }
                }
            }
            return stack.Pop().value;
        }



        public string equationToString()
        {
            string equationString = "";
            foreach (Token token in this.equation)
            {
                equationString += token.value.ToString() + " ";
            }
            return equationString;
        }


    }
}