/**
 * Write a description of class Calculator here.
 *
 * @author (your name)
 * @version (a version number or a date)
 */

import java.util.Scanner;
public class Calculator extends BasicCalculations
{
    // instance variables - replace the example below with your own

    /**
     * Constructor for objects of class Calculator
     */
    public Calculator() {
       currentNumber = 0;
       isError = false;
    }

    /**
     * An example of a method - replace this comment with your own
     *
     * @param  y  a sample parameter for a method
     * @return    the sum of x and y
     */

    public void runCommandLoop() 
    {
        Scanner input = new Scanner(System.in);
        Calculator calc = new Calculator();
        while (true) {
            System.out.print("Enter a command: ");
            String command = input.next();
            
            if (!isError) {
            if (command.equalsIgnoreCase("exit"))  {
                System.out.print("Thanks for calculating with us!");
                break;
            }

            if (command.equalsIgnoreCase("clear"))  {
                calc.clear();
            }

            if (command.equalsIgnoreCase("invert"))  {
                calc.invertSign();
            }
            
            if (command.equalsIgnoreCase("inverse"))  {
                calc.inverse(currentNumber);
            }

            if (command.equalsIgnoreCase("save"))  {
                calc.remember();
            }

            if (command.equalsIgnoreCase("recall"))  {
                calc.recall();
            }

            if (command.equalsIgnoreCase("save2"))  {
                calc.addToNumInMemory();
            }
            
            if (command.equalsIgnoreCase("mode")) {
                calc.switchDisplayMode();
            }
            
            if (command.equalsIgnoreCase("units")) {
                calc.switchUnitsMode();
            }

            if (command.equalsIgnoreCase("add"))  {
                if (currentNumber == 0) {
                    firstNumber = input.nextDouble();
                    // read second number
                    secondNumber = input.nextDouble();
                    // call the add method on calc and display
                    calc.add(firstNumber,secondNumber);
                } else {
                    firstNumber = currentNumber;
                    secondNumber = input.nextDouble();
                    calc.add(firstNumber,secondNumber);
                }
            }

            if (command.equalsIgnoreCase("subtract"))  {
                if (currentNumber == 0) {
                    firstNumber = input.nextDouble();
                    // read second number
                    secondNumber = input.nextDouble();
                    // call the add method on calc and display
                    calc.subtract(firstNumber,secondNumber);
                } else {
                    firstNumber = currentNumber;
                    secondNumber = input.nextDouble();
                    calc.subtract(firstNumber,secondNumber);
                }
            }

            if (command.equalsIgnoreCase("multiply"))  {
                if (currentNumber == 0) {
                    firstNumber = input.nextDouble();
                    // read second number
                    secondNumber = input.nextDouble();
                    // call the add method on calc and display
                    calc.multiply(firstNumber,secondNumber);
                } else {
                    firstNumber = currentNumber;
                    secondNumber = input.nextDouble();
                    calc.multiply(firstNumber,secondNumber);
                }
            }

            if (command.equalsIgnoreCase("divide"))  {
                if (currentNumber == 0) {
                    firstNumber = input.nextDouble();
                    // read second number
                    secondNumber = input.nextDouble();
                    // call the add method on calc and display
                    calc.divide(firstNumber,secondNumber);
                } else {
                    firstNumber = currentNumber;
                    secondNumber = input.nextDouble();
                    calc.divide(firstNumber,secondNumber);
                }
            }
            if (command.equalsIgnoreCase("square"))  {
                if (currentNumber == 0) {
                    firstNumber = input.nextDouble();
                    // call the add method on calc and display
                    calc.square(firstNumber);
                } else {
                    firstNumber = currentNumber;
                    calc.square(firstNumber);
                }
            }
            
            if (command.equalsIgnoreCase("round"))  {
                if (currentNumber == 0) {
                    firstNumber = input.nextDouble();
                    // call the add method on calc and display
                    calc.round(firstNumber);
                } else {
                    firstNumber = currentNumber;
                    calc.round(firstNumber);
                }
            }
            
            if (command.equalsIgnoreCase("up"))  {
                if (currentNumber == 0) {
                    firstNumber = input.nextDouble();
                    // call the add method on calc and display
                    calc.roundUp(firstNumber);
                } else {
                    firstNumber = currentNumber;
                    calc.roundUp(firstNumber);
                }
            }
            
            if (command.equalsIgnoreCase("down"))  {
                if (currentNumber == 0) {
                    firstNumber = input.nextDouble();
                    // call the add method on calc and display
                    calc.roundDown(firstNumber);
                } else {
                    firstNumber = currentNumber;
                    calc.roundDown(firstNumber);
                }
            }
            
            if (command.equalsIgnoreCase("log"))  {
                if (currentNumber == 0) {
                    firstNumber = input.nextDouble();
                    // call the add method on calc and display
                    calc.log(firstNumber);
                } else {
                    firstNumber = currentNumber;
                    calc.log(firstNumber);
                }
            }

            if (command.equalsIgnoreCase("power"))  {
                if (currentNumber == 0) {
                    firstNumber = input.nextDouble();
                    // call the add method on calc and display
                    secondNumber = input.nextDouble();
                    calc.power(firstNumber, secondNumber);
                } else {
                    firstNumber = currentNumber;
                    secondNumber = input.nextDouble();
                    calc.power(firstNumber, secondNumber);
                }
            }

            if (command.equalsIgnoreCase("sin"))  {
                if (currentNumber == 0) {
                    firstNumber = input.nextDouble();
                    // call the add method on calc and display
                    calc.sin(firstNumber);
                } else {
                    firstNumber = currentNumber;
                    calc.sin(firstNumber);
                }
            }
            
            if (command.equalsIgnoreCase("invsin"))  {
                if (currentNumber == 0) {
                    firstNumber = input.nextDouble();
                    // call the add method on calc and display
                    calc.asin(firstNumber);
                } else {
                    firstNumber = currentNumber;
                    calc.asin(firstNumber);
                }
            }

            if (command.equalsIgnoreCase("cos"))  {
                if (currentNumber == 0) {
                    firstNumber = input.nextDouble();
                    // call the add method on calc and display
                    calc.cos(firstNumber);
                } else {
                    firstNumber = currentNumber;
                    calc.cos(firstNumber);
                }
            }
            
            if (command.equalsIgnoreCase("invcos"))  {
                if (currentNumber == 0) {
                    firstNumber = input.nextDouble();
                    // call the add method on calc and display
                    calc.acos(firstNumber);
                } else {
                    firstNumber = currentNumber;
                    calc.acos(firstNumber);
                }
            }

            if (command.equalsIgnoreCase("tan"))  {
                if (currentNumber == 0) {
                    firstNumber = input.nextDouble();
                    // call the add method on calc and display
                    calc.tan(firstNumber);
                } else {
                    firstNumber = currentNumber;
                    calc.tan(firstNumber);
                }
                // and on and on
            }
            
            if (command.equalsIgnoreCase("invtan"))  {
                if (currentNumber == 0) {
                    firstNumber = input.nextDouble();
                    // call the add method on calc and display
                    calc.atan(firstNumber);
                } else {
                    firstNumber = currentNumber;
                    calc.atan(firstNumber);
                }
            }
        } else {
         System.out.println("Error! Clear Error!");
         if (command.equalsIgnoreCase("clear")) {
             calc.clear();
            }
        }
        }
    }
}