/************************************
 *    Data Structures & Algotihms   *
 *    Project 1                     *
 *    Levent Kaya                   *
 *    1800003183                    *   
 ************************************/
#include <iostream>
#include <string>
#include "myStack.h"
#include "stackADT.h"

using namespace std;

class infixToPostfix{
    public:
        void convertToPostfix();
        bool precedence(char opr1, char opr2);
        void getInfix(string);
        void showInfix();
        void showPostfix();
        infixToPostfix(string);
        string getPfx();
        int evaluatePostfix(char* exp);

    private:
        string infx;
        string postfx;
};

bool infixToPostfix::precedence(char opr1, char opr2){
   char c1 = opr1, c2 = opr2;
   int flag1 = 0, flag2 = 0;
   
   if(c1 == '(' || c1 == ')'){
       flag1 = 0;
   }
   else if(c2 == '(' || c2 == ')'){
       flag2 = 0;
   }
   else if(c1 == '+' || c1 == '-'){
       flag1 = 1;
   }
   else if(c1 == '*' || c1 == '/'){
       flag1 = 2;
   }
   else if(c2 == '+' || c2 == '-'){
       flag2 = 1;
   }
   else if(c2 == '*' || c2 == '/'){
       flag2 = 2;
   }

   if(flag1 >= flag2){
       return true;
   }
   else
    return false;
}

string infixToPostfix::getPfx(){
    return postfx;
}

void infixToPostfix::showPostfix(){
    cout << getPfx() << endl;
}

void infixToPostfix::getInfix(string inputInfix){
    infx = inputInfix;
}

void infixToPostfix::showInfix(){
    cout << infx << endl;
}

int checkSymOperator(char symbol){
    if(symbol == '+' || symbol == '-' || symbol == '*' || symbol == '/'){
        return 1;
    }
    else
    {
        return 0;
    }
    
}
int checkSymOperand(char symbol){
    if(isalpha(symbol) || isdigit(symbol)){
        return 1;
    }
    else{
        return 0;
    }
}

void infixToPostfix::convertToPostfix(){

    stackType<char> stack;
    postfx = "";

    infx.append(")");
    stack.push('(');

    for (int i = 0; i < infx.length(); i++){
        if(checkSymOperator(infx[i])){
            if(checkSymOperator(stack.top())){
                if(precedence(infx[i], stack.top()) == 0){
                    postfx = postfx + stack.top();
                    stack.pop();
                }
                else if(precedence(infx[i], stack.top()) == 1){
                    stack.push(infx[i]);
                }
                else{
                    postfx = postfx + stack.top();
                    stack.pop();                    
                }                
            }
            else{
                stack.push(infx[i]);
            }            
        }
        else{
            if(infx[i] = ')'){
                while (stack.top() != '('){
                    postfx = postfx + stack.top();
                    stack.pop();
                }
                stack.pop();                
            }
            else{
                postfx = postfx + infx[i];
            }          
            
        }
        
    }
      
   
}

infixToPostfix::infixToPostfix(string pref){
    pref = "";
}


int main(){
    string input;
    infixToPostfix inf2post;
    
    cout << "Infix Expression: ";
    cin >> input;
    
    inf2post.getInfix(input);
    inf2post.convertToPostfix();

    cout << "Postfix Expression: ";
    inf2post.showPostfix();
    cout << endl;

    return 0;
}