import java.util.Scanner;
import java.util.Arrays;
/*
Online Java - IDE, Code Editor, Compiler

Online Java is a quick and easy tool that helps you to build, compile, test your programs online.
*/

public class Main
{
       public static void main(String[] args) {
        
        System.out.println("Welcome to Online IDE!! Happy Coding :)");
        
        char[] acceptedNumerals = new char[]{'M','D','C','L','X', 'V','I'};
        //These are all accepted roman numerals
         
        int number; //This is set once end user specifies number numerals in their number to be inputted
     
        boolean noMatch=true;  // this flag is used to check if the numeral entered is a valid one
       
        int j;  //used to increment the character array containing user input of numeral
        int count=0;  // this keeps track number times end user has entered a character. It can be decremented if it fails validation.
        
        //int pos;
        
        Scanner reader=null;
        
        
        // This is used to ascertain how many digits end user wants
        reader = new Scanner(System.in); // Reading from System.in
        System.out.println("Enter number numerals in the number to be converted to decimal:");
        number=reader.nextInt();
        
        char inputtedNumerals[] = new char[number];   // this creates character array with end user specified size
        int [][] posValues = new int [number][2];  // this is used to keep track of:
        
         // this is 2D array. 'number' simply increments with array index of the roman numeral in character array 
        // the multidimensal aspect at 0 index will store:  index of which numeral i.e  M is 0, D is 1
                             //aspect at 1 index will store:  decimal conversion
        // This will support later analysis.
        
        
do
{
reader = new Scanner(System.in); // Reading from System.in
System.out.println("Enter roman numeral " + (count+1) + "of " + number + ":");   // end user prompted to enter roman numeral
inputtedNumerals[count]=reader.next().charAt(0);
count++;

for (j=0; j<inputtedNumerals.length;j++)  // this will check each item in the inputted area against 7 roman numerals.
                                          // the condition could equally be set to count for better loop efficiency if the 
                                          //number entered is long
{

    for (int k=0; k<acceptedNumerals.length;k++)  // this goes through roman numerals
    {
    
    if (inputtedNumerals[j]==acceptedNumerals[k])  // this checks to see if the roman numerals entered are valid
    {
        
        posValues[count-1][0]=k;             
        
        
        // This switch statement now checks 'k'validposition in hierarcy of the 7 numerals.
        //'M','D','C','L','X', 'V','I'
        
        switch(k)
        {
            case 0:
                posValues[count-1][1]=1000;
                break;
            
            case 1:
                posValues[count-1][1]=500;
                break;
                
            case 2:
                posValues[count-1][1]=100;
                break;
                
            case 3:
                posValues[count-1][1]=50;
                break;
                
            case 4:
                posValues[count-1][1]=10;
                break;
                
            case 5:
                posValues[count-1][1]=5;
                break;
                
            case 6:
                posValues[count-1][1]=1;
                break;
        }
        
        //pos=k;
        
        // THIS IS THE AREA WHICH IS VALIDATED BASED ON CORRECT NUMERALS. BUT NOT IF THE SYNTAX IS CORRECT.
        // FOR EXAMPLE VXV IS INCORRECT.
        System.out.println("Successful roman numerals. PLEASE NOTE SYNTAX CAN STILL BE WRONG");
        
        noMatch=false;   // This sets flag stating match has been found.
        k=acceptedNumerals.length-1;
        break;
        
        }
    
}
// This will now give information if the user input is valid for each numeral.
// If found to be incorrect, the count will go back and end user will need to enter it again.

 if (noMatch==true)
    {
       System.out.println("Please input a successful roman numeral:  M  D  C  L  X  V  I");
       count=count-1;
       break;
    }
}

} while (count<inputtedNumerals.length);

String str = String.valueOf(inputtedNumerals);
System.out.println("This will be converted to decimal:" + str);  // This informs end user of the roman numerals to be converted

performConversion pc = new performConversion(acceptedNumerals, inputtedNumerals,posValues); // calls constructor in class to perform conversion
}
}

class performConversion
{
    char[] inputtedNumerals;
    char[] acceptedNumerals;
    int [][] posValues;
    
    public void converter()
    {
        // There will be NO issues in performing conversion of a single roman numeral
        
        if (inputtedNumerals.length==1)    // This functions
        {
                System.out.println("Conversion is:" + posValues[0][1]);
        }
        
        // this is 2D array. count simply increments with array index of the roman numeral in character array 
        // the multidimensal aspect at 0 index will store:  index of which numeral i.e  M is 0, D is 1
                             //aspect at 1 index will store:  decimanl conversion
                             
            
       // ONCE ALL PRINCIPLES ARE UNDERSTOOD FOR A VALID ROMAN NUMERAL, THE CODE WILL BE IMPLEMENTED FURTHER     
            
            if (inputtedNumerals.length==2)
        {
            if (posValues[0][0]==posValues[1][0])
            {
                
            System.out.println("Conversion is:" + (posValues[0][1] + posValues[1][1]));
            }
            
            
            if (posValues[0][0]<posValues[1][0])  // an example would be CV
            {
                
            System.out.println("Incorrect roman numeral entered");
            }
            
            
           
        }
        
    }
    
    // This is the constructor used to call the converter method. 
    public performConversion (char[] aNumerals, char [] inputNumerals, int [][] pValues)
    {
        this.acceptedNumerals=aNumerals;
        this.inputtedNumerals=inputNumerals;
        this.posValues=pValues;
        converter();
    }
}