//Author: ^-^Veerle^-^
public class calc2Engine
{

	private calculatorCalculations ALU = new calculatorCalculations();
	protected String strDisplay = "0.";
	private String strCurrentNumber = "";
	private double memory = 0D;
	private double doubleOperationNum = 0D;
	private char currentOperation = '+';
	private char previousOperation = '+';
	private char doubleOperation = '='; //Used for double operations, e.g. ++, **
	private boolean equalsButtonPressed = false; //When true, if next button pressed is a number, everything is reset and treated as a new sum
	private boolean zeroNumPressed = false; //When true the chop method will not remove trailing 0's

	public void objCalculator ()
	{
	}
	
	public void setCurrentNum (String strNum)
	{
		
		strCurrentNumber = strNum;
		updateDisplayString();
		
	}
	
	public String getCurrentNum ()
	{
		return strCurrentNumber;
	}
	
	private double getCurrentNumber ()
	{
		
		if (strCurrentNumber.equals(""))
		{
			return 0;
		}

		return Double.parseDouble(strCurrentNumber);
		
	}
	
	protected void handleMemory (String strMemoryAction)
	{

		if (strMemoryAction.equalsIgnoreCase("MS")) //Memory save
		{			
			memory = getCurrentNumber();
		}
		else if (strMemoryAction.equalsIgnoreCase("MR")) //Memory call
		{
			
			strCurrentNumber = Double.toString(memory);
			updateDisplayString();
			
		}
		else if (strMemoryAction.equalsIgnoreCase("M+")) //Memory add
		{
			
			if (memory == 0)
			{
				memory = getCurrentNumber();
			}
			else
			{
				memory += getCurrentNumber();
			}
			
		}
		else //Memory clear
		{
			memory = 0d;
		}
		
	}

	protected void processNumber (char enteredNumber)
	{

		if (equalsButtonPressed) //If equals button was last pressed, treat this as a new calculation
		{
			resetEverything();
		}

		if (!(enteredNumber == '0' && strCurrentNumber.equals(""))) //Do not allow 0 as the first number
		{

			strCurrentNumber += enteredNumber;

			if (enteredNumber == '0')
			{
				zeroNumPressed = true; //Stops the chop method removing the current 0 from the display
			}

			updateDisplayString();

		}

	}

	protected void processOperation (char operation)
	{

		equalsButtonPressed = false;
		doubleOperation = '='; //Resets double operation
		
		previousOperation = currentOperation;
		currentOperation = operation;

		switch (operation)
		{

			case '+':
			case '-':
			case '*':
			case '/':	processNormalOperation();
						break;
			case '^':
			case 'v':	processSpecialOperation();
						break;
			case '%':	processPercentOperation();
						break;

		}

		strCurrentNumber = ALU.toString(); //Put total answer in strCurrentNumber so it can be displayed
		updateDisplayString();
		strCurrentNumber = ""; //Reset strCurrentNumber so a new number can be entered

	}

	private void processNormalOperation ()
	{

		if (!(strCurrentNumber.equals("") && ALU.isBlank()))
		{

			if (strCurrentNumber.equals("") && previousOperation != currentOperation)
			{
				previousOperation = currentOperation; //Allow operation changing
			}
			else if (strCurrentNumber.equals("") && currentOperation == previousOperation)
			{
				
				doubleOperation = currentOperation; //Allow the ++, -- etc
				doubleOperationNum = ALU.getTotalNum();
				
			}
			else
			{
				ALU.performNormalCalculation(getCurrentNumber(), previousOperation);
			}

		}

	}

	private void processSpecialOperation ()
	{

		if (!strCurrentNumber.equals(""))
		{
			ALU.performSpecialCalculation(getCurrentNumber(), currentOperation);
		}
		
		currentOperation = '=';

	}

	private void processPercentOperation ()
	{

		if (!strCurrentNumber.equals(""))
		{
			ALU.performNormalCalculation(getCurrentNumber(), currentOperation);
		}

	}

	protected void processDecimalPlace ()
	{

		if (equalsButtonPressed)
		{
			resetEverything();
		}

		if (strCurrentNumber.indexOf('.') == -1)
		{

			if (getCurrentNumber() == 0D) //Imitate window's calculator with 0. if the number is empty
			{
				strCurrentNumber += "0.";
			}
			else
			{
				strCurrentNumber += ".";
			}

			updateDisplayString();

		}

	}

	protected void processEqualsOperation ()
	{

		if (!ALU.isBlank() && (currentOperation != '=' || doubleOperation != '='))
		{

			if (currentOperation == '%')
			{
				ALU.performPercentCalculation(previousOperation);
			}
			else if (doubleOperation != '=')
			{
				ALU.performNormalCalculation(doubleOperationNum, doubleOperation);
			}
			else if (!strCurrentNumber.equals(""))
			{
				ALU.performNormalCalculation(getCurrentNumber(), currentOperation);
			}

			strCurrentNumber = ALU.toString();
			equalsButtonPressed = true;
			currentOperation = '='; //Prevents error if you pressed the (+) next, it would count as a double operation
			updateDisplayString();

		}

	}

	protected void resetEverything ()
	{

		ALU.reset();

		doubleOperationNum = 0D;
		equalsButtonPressed = zeroNumPressed = false;
		currentOperation = previousOperation = '+';
		strCurrentNumber = "";
		doubleOperation = '=';

		updateDisplayString();

	}

	protected void deleteLastChar ()
	{

		if (!(strCurrentNumber.equals("") || equalsButtonPressed))
		{

			strCurrentNumber = strCurrentNumber.substring(0, strCurrentNumber.length() - 1);
			updateDisplayString();

		}

	}

	private void updateDisplayString ()
	{

		strDisplay = strCurrentNumber;

		if (strDisplay.equals(""))
		{
			strDisplay = "0.";
		}
		else if (strDisplay.indexOf('.') == -1) //If the number doesn't have a decimal place in it
		{
			strDisplay += ".";
		}

		chopDisplayString();

	}

	private void chopDisplayString ()
	{

		if (!zeroNumPressed)
		{

			//Removes trailing 0 padding
			for (int i = strDisplay.length(); i != 0; i--)
			{

				if (strDisplay.charAt(i - 1) == '0')
				{
					strDisplay = strDisplay.substring(0, (i - 1));
				}
				else
				{
					break;
				}

			}

		}

		zeroNumPressed = false;

		if (strDisplay.length() >= 15)
		{
			strDisplay.substring(0, 14);
		}

	}

}