#include "Stack.h"
#include <iostream>
#include <string>
using namespace std;

// Postfix Calculator
string getNext(string input, int & pos);
int postFixCalculator(string exp);
void postFixTest(string exp);
void postFixExample();

// Stack operation tests
void pushpopTest();
void copyTest();
void assignmentTest();

int main()
{
	//pushpopTest();
	copyTest();
	assignmentTest();
	cout << endl;
	postFixExample();
	return 0;
}

// Postfix Calclator
// Parses a RPN string, returning the next operand or operator from
// the given position
// PRE: input is in the correct format
// PARAM: input - the RPN string
//        pos - the position to start parsing from
// Format: the string should contain a series of integer operands and 
//         the +, - * and / operators separated by spaces
string getNext(string input, int & pos) {
	string result = "";
	int nextSpace = 0;
	// Ignore current space (given by pos)
	if (pos > 0) {
		pos++;
	}
	if (pos < (int)input.size()) {
		// Find next space
		nextSpace = input.find(" ", pos + 1);
		// DEBUG
		// cout << "nextSpace = " << nextSpace << endl;
		// END DEBUG
		result = input.substr(pos, nextSpace - pos);
		pos = nextSpace;
	}
	return result;
}

// Calculates and returns the result of a RPN expression
// PRE: input is in the correct format
// PARAM: exp - the RPN string
int postFixCalculator(string exp) {
	// Initialize variables
	int pos = 0; // For parsing exp
	string next = ""; // Next operand or operator
	Stack st(exp.size());
	int leftOp = 0;
	int rightOp = 0;

	// Process each operator or operand
	while (pos != -1) {
		next = getNext(exp, pos);
		// DEBUG
		// cout << "next op: " << next << endl;
		// END DEBUG

		// Push operand onto stack
		if (next != "+" && next != "-" && next != "/" && next != "*") {
			st.push(atoi(next.c_str()));
		}
		// Or process each operator
		else {
			rightOp = st.pop();
			leftOp = st.pop();
			// DEBUG
			cout << leftOp << " " << next << " " << rightOp << endl;
			// END DEBUG
			if (next == "+") { // +
				st.push(leftOp + rightOp);
			}
			else if (next == "-") { // -
				st.push(leftOp - rightOp);
			}
			else if (next == "*") { // *
				st.push(leftOp * rightOp);
			}
			else if (next == "/") { // /
				st.push(leftOp / rightOp);
			}
		}
	}

	// Return result
	return st.pop();
}

// Test function for the postFixCalculator function
void postFixTest(string exp)
{
	int result = postFixCalculator(exp);
	cout << exp << " = " << result;
}

// Calls postFixTest three times
void postFixExample()
{
	cout << "POSTFIX TEST" << endl << endl;
	postFixTest("5 1 2 + 4 * + 3 -");
	cout << endl << endl;
	postFixTest("9 7 + 5 3 - /");
	cout << endl << endl;
	postFixTest("3 5 2 * 17 7 - + * 11 3 * -");
	cout << endl << "END POSTFIX TEST" << endl << endl;
}

//----------------------
// Stack Operation Tests
// Quick test of push and pop
void pushpopTest()
{
	cout << endl << "Push, Pop Test" << endl << endl;
	// Insert values in stack
	int n = 4;
	Stack st(n);
	for (int i = 0; i < n; i++) {
		st.push(i + 1);
	}

	// Remove and print values in stack
	while (!st.empty()) {
		cout << st.pop() << endl;
	}

	cout << endl << "test complete" << endl;
}

// Quick test of the copy constructor
void copyTest()
{
	cout << endl << "COPY TEST" << endl << endl;
	int n = 4;
	Stack st1(n);
	for (int i = 0; i < n; i++) {
		st1.push(i + 1);
	}

	// Create st2 - a copy of st1
	Stack st2(st1);
	// Change st2
	st2.pop();
	st2.pop(); 
	st2.pop();
	st2.push(21);
	st2.push(22);

	// Demonstrate that st2 and st1 are different
	cout << "ST1" << endl << "---" << endl;
	st1.print();
	cout << endl;
	cout << "ST2" << endl << "---" << endl;
	st2.print();
	
	cout << "END COPY CONSTRUCTOR TEST" << endl;
}

// Quick test of the overloaded assignment operator
void assignmentTest()
{
	cout << endl << "ASSIGNMENT TEST" << endl << endl;
	int n = 4;
	Stack st1(n);
	for (int i = 0; i < n; i++) {
		st1.push(i + 1);
	}

	// Create st2
	n = 8;
	Stack st2(n);
	for (int i = 0; i < n; i++) {
		st2.push(i + 1);
	}

	st2 = st1;
	// Change st2
	st2.pop();
	st2.pop();
	st2.pop();
	st2.push(21);
	st2.push(22);

	// Demonstrate that st2 and st1 are different
	cout << "ST1" << endl << "---" << endl;
	st1.print();
	cout << endl;
	cout << "ST2" << endl << "---" << endl;
	st2.print();

	cout << "END ASSIGNMENT OPERATOR TEST" << endl;
}