/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   RPN.cpp                                            :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: adjoly <adjoly@student.42angouleme.fr>     +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2025/06/03 12:07:59 by adjoly            #+#    #+#             */
/*   Updated: 2025/07/03 20:15:20 by adjoly           ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include <RPN.hpp>
#include <cctype>
#include <exception>
#include <sstream>
#include <stack>
#include <stdexcept>

int add(int first, int second) { return first + second; }
int subst(int first, int second) { return first - second; }
int mult(int first, int second) { return first * second; }
int div(int first, int second) {
	if (second == 0)
		throw std::invalid_argument("can't divide by 0 sorry D:");
	return first / second;
}

void calc(int (*op)(int, int), std::stack<int> &stack) {
	if (stack.size() < 2)
		throw std::range_error("not enough operands");

	int second = stack.top();
	stack.pop();
	int first = stack.top();
	stack.pop();
	stack.push(op(first, second));
}

void handle(std::string::const_iterator c, std::stack<int> &stack) {
	if (*c == ' ')
		return;
	else if (std::isdigit(*c))
		stack.push(*c - '0');
	else if (*c == '+')
		calc(add, stack);
	else if (*c == '-')
		calc(subst, stack);
	else if (*c == '*')
		calc(mult, stack);
	else if (*c == '/')
		calc(div, stack);
	else
		throw std::invalid_argument("invalid caracter detected");
}

void rpn(char *av) {
	std::string		str(av);
	std::stack<int> stack;

	for (auto it = range(str)) {
		try {
			handle(it, stack);
		} catch (std::exception &e) {
			std::stringstream str;
			str << "Error: " << e.what() << " : " << *it;
			throw std::runtime_error(str.str());
		}
	}
	if (stack.size() != 1)
		throw std::runtime_error("Error: leftover operands in stack");
	std::cout << stack.top() << std::endl;
}