wag3

package eg.edu.alexu.csd.oop.calculator.cs37;
import java.awt.EventQueue;

import java.util.EventObject;
import javax.swing.JTextArea;

import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.JLabel;
import java.awt.Font;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.SwingConstants;

import java.io.File;

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.io.BufferedReader;
import java.util.ArrayList;
import javax.management.RuntimeErrorException;
import java.util.Arrays;
import java.util.List;
import java.util.ArrayList;

public class Calc implements Calculator {
	 String operator = null;
	 double [] n = new double[2];
	 double ans = 0;
	 String nums1="" ;
	 String nums2="" ;
    String expression="" ;
    String result="" ;
     int current1 = -1,prev=0,next=0 ;
	 int shift = 0 ;
     String [] process = new String [5];


     File file ;
	public void input(String s) {
		if (!s.matches("^-?\\d+(\\.\\d+)?(\\s+)?[-+*\\/](\\s+)?-?\\d+(\\.\\d+)?(\\s+)?$")) {//^ start of the line , $ end of the line , d digit , [..] any one ,
			operator = "false" ;
			//throw new RuntimeException("you enterd non valid expression");
		}else {
			if (current1 < 4 ) {
				current1 ++ ;
				}else { // shifting
					shift = 1 ;
					current1 = 4 ;
				}
			//remove spaces
			s = s.replaceAll("//s+", "");
			String [] nums = s.split("[-+*\\/]");
			String [] operat = s.split("\\d+(\\.\\d+)?");
			operator = operat[1].charAt(0)+"";
			int i = 0 ;
			for (String number : nums) {
				if (!number.isEmpty()) {
					if (i==0 && s.charAt(0)=='-') { //negative
						number="-"+number ;
						n[i] = Double.parseDouble(number);
					}else if (i == 1 && (nums[1].equals("") || nums.length == 4)) { //negative
	                    number = "-" + number;
	                    n[i] = Double.parseDouble(number);
	                }

			    	else {
					n[i] = Double.parseDouble(number);

				}
				i++;
			}


		}
				}


	}
	/* Return the result of the current operations or throws a runtime
	exception */
	public String getResult() {
		if (operator.equals("false")) {
			throw new RuntimeException ("You Enterd non valid expression");
		}else if (operator.charAt(0) == '+') {
			ans = n[0]+n[1];

		}else if (operator.charAt(0) == '*') {
			ans = n[0]*n[1];
		}else if (operator.charAt(0) == '-') {
			ans = n[0]-n[1];
		}else if (operator.charAt(0) == '/') {
			if (n[1] != 0) {
			ans = n[0]/n[1];
			}else {
				throw new RuntimeException ("You can't divide by 0");
			}

		}
		//answer = String.format("%.16f", result);
		result = String.format("%.16f", ans);
	//	result = Double.toString(ans);
		nums1 = Double.toString(n[0]);
		nums2=Double.toString(n[1]);
		expression=nums1+operator + nums2+"=" +result ;
		if (shift == 0 && current1 > -1) {
			process[current1]=expression;
			}else if (shift == 1){ // shifting
				for (int i=0 ; i<4 ; i++) {
					process[i] =process[i+1];
				}
				process[4] = expression ;
			}
		return result ;
	}
	/* return the current formula */
	public String current () {
	if (current1 < -1 || current1 > 4) {
		return null ;
	}else {
		return process[current1];
	}
		}
	/* return the last operation in String format, or Null if no more history
	available, will update current */
	public String prev() {
		if (current1 == -1 ) {
			throw new RuntimeException ("You Enterd only one");
		}else {
			prev = current1 - 1;
			next = current1 ;
			current1 = prev ;
		}
		return process[current1];
	}
	/* return the next operation in String format, or Null if no more history
	available, will update current */
	public String next() {
		if (current1 == 4) {
			throw new RuntimeException ("there is no next operation of this ");
		}else {
			next = current1 + 1 ;
			prev = current1 ;
			current1 = next ;
		}
		return process[current1];
	}
	/* Save in file the last 5 done Operations */
	public void save() {
		File file = new File ("hendo.txt");
		PrintWriter pw ;
		try {
			pw= new PrintWriter (file);
				for (int i=0 ; i<=current1 ; i++) {
					pw.write(process[i]);
					pw.write("\n");
				}
				pw.close();


		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}


	/* Load from file the saved operations */
	public void load()
	{

		List<String> temp =  Arrays.asList(process);
		 try {
	            FileReader fr = new FileReader("hendo.txt");
	            int i;
	            try {
	                String st = "";
	                String[] s1 = new String[2];
	                temp.clear();
	                current1 = -1;
	                int index=0;
	                while ((i = fr.read()) != -1) {
	                    if(index!=0&&i=='\n') {
	                    	s1[1]= getResult() ;
	                    	}

	                    if (i != '\n') {
	                        st = st + (char) i;
	                    } else {
	                        index++;
	                        input(st);
	                        s1[0] = st;
	                        st = "";
	                    }
	                }
	                prev = temp.size() ;
	            } catch (IOException e) {
	                // TODO Auto-generated catch block
	                e.printStackTrace();
	            }
	        } catch (FileNotFoundException e) {
	            // TODO Auto-generated catch block
	            e.printStackTrace();
	        }

	    }
	}