#include<iostream>
#include"stack2.h"
#include"polynomial.h"

using namespace std;

int main()
{
  Stack s;
  char c;
  Polynomial * v1, * v2, * v3;
  float coeff;
  int degree;
  bool done=false;
  bool ret;

  // The loop below reads the input, one operator at a time,
  // and carries out the operation depending on the operator.
  // It stops upon receiving 'q' or if the read fails.
  while (!done) {

    if (!(cin >> c)) {
      cout << "Error: cannot read input\n";
      break;
    }

    switch (c) {
    case '?':
      if (!(cin >> coeff)) { // Read the float input
        cout << "Error: cannot read float coeff\n"; // cin failed to read the float
        done = true;                          // so we stop
      }
      else if (!(cin >> degree)) { // Read the int input
        cout << "Error: cannot read int degree\n"; // cin failed to read the float
        done = true;                          // so we stop
      }
      else if((v1=new Polynomial)==NULL || !v1->AddMonomial(degree, coeff) || !s.Push(v1)) {
	  cout<<"Error!\n";
          if (v1!=NULL) delete v1;
      }
      break;

    case '+':     // Handle all the arithmetic operators similarly
    case '-':
    case '*':
      if(!s.Pop(v1)) {
        cout<<"Stack Empty!\n";
	break;
      }
      if(!s.Pop(v2)) {
        cout<<"Stack Has Only One Entry!\n";
        delete v1;
	break;
      }
      if ((v3=new Polynomial)==NULL) {
        cout<<"Out of memory!\n";
        delete v1;
        delete v2;
        break;
      }

      // We already know c is an arithmetic operator;
      // v1 and v2 are the operands
      // now perform the operation and put the result in v3
      switch (c) {
      case '+':
        ret=v3->EqualToSum(v2,v1);
        break;
      case '-':
        ret=v3->EqualToDiff(v2,v1);
        break;
      case '*':
        ret= v3->EqualToProd(v2,v1);
        break;
      }
      if (!ret)
        cout<<"Arithmetic error!\n";
      else if (!s.Push(v3)) {
	  cout<<"Stack Overlow!\n";
          delete v3;
      }
      delete v1;
      delete v2;
      break;

    case '=':     // Print the top of the stack by pop-print-push
      if(!s.Pop(v1)) {
        cout<<"Stack Empty!\n";
	break;
      }
      v1->Print();
      if(!s.Push(v1)) {
	  cout<<"Stack Overlow!\n";
          delete v1;
     }
     break;

    case 'p':     // Pop the top
      if(!s.Pop(v1))
        cout<<"Stack Empty!\n";
      else delete v1;
      break;

    case 'q':     // Quit
      done=true;
      break;

    default:
      cout<<"Invalid Entry!\n";
      break;
    }
  }

  // Free up memory by popping everything and deleting it
  while (s.Pop(v1)) 
    delete v1;

  return 0;
}