package arraylistplay;
  import java.io.File;
   import java.io.FileNotFoundException;
  import java.util.ArrayList;
   import java.util.Scanner;
   public class WordList
    {
            private static final int LIMIT = 1000;
             private static ArrayList <String> words = new ArrayList<>(LIMIT);
              private static int numberOfWords = 0;
             private static Scanner commandReader = new Scanner(System.in);
             public static void main(String[] args)
             {
                  try
                   {
                     readwords();
                      interpreter();
                  }
                  catch (FileNotFoundException ex)
                  {
                       System.out.println("The file was not found. Please think again.");
                       System.exit(-1);
                   }
               }
               private static Scanner establishScanner(String fn) throws FileNotFoundException
               {
                   String separator = File.separator;
                  String homeDirectory = System.getProperty("user.home");
                  String path =  homeDirectory + separator + "CS1Files" + separator + "data" + separator;
                  String fullFileName = path + fn;
                  return new Scanner(new File(fullFileName));
              }
             private static void readwords() throws FileNotFoundException
              {
                  Scanner scanner = establishScanner("WordSet.txt");
                 while (scanner.hasNext())
                 {
                      words.add(scanner.next());
                      numberOfWords = numberOfWords + 1;
                  }
              }
               private static void displayWords() {
                  for (int x = 0; x < numberOfWords; x = x + 1)
                   {
                      System.out.println(words.get(x));
                   }
              }
               private static void interpreter()
              {
                  System.out.print(">>> ");
                  String command = commandReader.next();
                 if (command.equalsIgnoreCase("DISPLAY"))
                {
                     interpreterDisplayCommand();
                  }
                 else if (command.equalsIgnoreCase("PRINT"))
                  {
                      interpretPrintCommand();
                  }
                  else if (command.equalsIgnoreCase("SWAP"))
                  {
                      interpretSwapCommand();
                  }
                  else if (command.equalsIgnoreCase("ADD"))
                  {
                     interpretAddCommand();
                 }
                   else if (command.equalsIgnoreCase("HELP"))
                   {
                    interpretHelpCommand();
                   }
                else if (command.equalsIgnoreCase("EXIT"))
               {
                     System.exit(0);
               }
               else
                     {
                     System.out.println("### Unrecognizable command: " + command);
                  }
                interpreter();
              }
              private static void interpreterDisplayCommand()
              {
                 displayWords();
              }
               private static void interpretPrintCommand()
              {
                 String operand = commandReader.next();
                   if (operand.equalsIgnoreCase("FIRST"))
                 {
                      System.out.println(words.get(0));
                 }
                 else if (operand.equalsIgnoreCase("LAST"))
                 {
                     System.out.println(words.get(numberOfWords - 1));
                }
               else
                      {
                     int index = Integer.valueOf(operand);
                    System.out.println(words.get(index - 1));
                  }
            }

             private static void interpretHelpCommand()
             {
                  System.out.println("HELP - display a menu of commands");
                  System.out.println("DISPLAY - display the list of numbers");
                System.out.println("PRINT - print a String (FIRST;LAST;nth)");
                 System.out.println("SWAP - exchange two elements (nth;mth)");
                  System.out.println("ADD - add a String to the list (FIRST;LAST)");
                  System.out.println("EXIT - terminate execution of the program");
             }

             private static void interpretSwapCommand() {
                 int position1 = commandReader.nextInt();
                  int position2 = commandReader.nextInt();
                  words.set(position1-1, words.set(position2-1, words.get(position1-1)));
             }

             private static void interpretAddCommand()
             {
                 String position = commandReader.next();
                 if (position.equalsIgnoreCase("LAST"))
                 {
                     addLast();
                }
              else if (position.equalsIgnoreCase("FIRST"))
               {
                      addFirst();
                 }
                 else
                     {
                      System.out.println("### invalid operand for add command");
                 }
                  numberOfWords = numberOfWords + 1;
             }

              private static void addLast()
            {
                  words.add(commandReader.next());
              }

              private static void addFirst()
              {
                  words.add(0,commandReader.next());
              }
          }