import java.io.*;

/** This class is an implementation of PDUserInterface
    that uses the console to display the menu of command choices.
    @author Koffman & Wolfgang
 */
public class PDConsoleUI
    implements PDUserInterface {

  /** A reference to the PhoneDirectory object to be processed.
        Globally available to the command-processing methods.
   */
  private PhoneDirectory theDirectory = null;
  /** Buffered reader to read from the input console. */
  private BufferedReader in = null;

  // Constructor
  /** Default constructor. */
  public PDConsoleUI() {
    in = new BufferedReader(new InputStreamReader(System.in));
  }

  // Methods

  /** Method to display the command choices and process user
       commands.
      pre:  The directory exists and has been loaded with data.
      post: The directory is updated based on user commands.
      @param thePhoneDirectory A reference to the PhoneDirectory
        to be processed
   */

  public void processCommands(PhoneDirectory thePhoneDirectory) {
    String[] commands = {
        "Add/Change Entry",
        "Look Up Entry",
        "Remove Entry",
        "Save Directory",
        "Exit"};

    theDirectory = thePhoneDirectory;
    int choice;
    try {
      do {
        for (int i = 0; i < commands.length; i++) {
          System.out.println("Select " + i + ": " + commands[i]);
        }
        String line = in.readLine();
        if (line != null)
          choice = Integer.parseInt(line);
        else
          choice = commands.length - 1;
        switch (choice) {
          case 0:
            doAddChangeEntry();
            break;
          case 1:
            doLookupEntry();
            break;
          case 2:
            doRemoveEntry();
            break;
          case 3:
            doSave();
            break;
          case 4:
            doSave();
            break;
        }
      }
      while (choice < commands.length - 1);
      System.exit(0);
    }
    catch (IOException ex) {
      System.err.println
          ("IO Exception while reading from System.in");
      System.exit(1);
    }
  }

  /** Method to add or change an entry.
        pre:  The directory exists and has been loaded with data.
        post: A new name is added, or the value for the name is
              changed, modified is set to true.
        @throws IOException - if an IO error occurs
   */
  private void doAddChangeEntry() throws IOException {
    // Request the name.
    System.out.println("Enter name");
    String newName = null;
    newName = in.readLine();
    if (newName == null) {
      return;
    }
    // Request the number.
    System.out.println("Enter number");
    String newNumber = null;
    newNumber = in.readLine();
    if (newNumber == null) {
      return;
    }
    // Insert/change name-number.
    String oldNumber =
        (theDirectory.addOrChangeEntry(newName, newNumber));
    String message = null;
    if (oldNumber == null) { // New entry.
      message = newName + " was added to the directory"
          + "\nNew number: " + newNumber;
    }
    else { // Changed entry.
      message = "Number for " + newName + " was changed"
          + "\nOld number: " + oldNumber
          + "\nNew number: " + newNumber;
    }
    // Display confirmation message.
    System.out.println(message);
  }

  /** Method to look up an entry.
        pre:  The directory has been loaded with data.
        post: No changes made to the directory.
        @throws IOException - If an IO error occurs
   */
  private void doLookupEntry() throws IOException {
    // Request the name.
    System.out.println("Enter name");
    String theName = null;
    theName = in.readLine();
    if (theName == null) {
      return; // Dialog was cancelled.
    }
    // Look up the name.
    String theNumber = theDirectory.lookupEntry(theName);
    String message = null;
    if (theNumber != null) { // Name was found.
      message = "The number for " + theName + " is " + theNumber;
    }
    else { // Name was not found.
      message = theName + " is not listed in the directory";
    }
    // Display the result.
    System.out.println(message);
  }

  /** Method to remove an entry.
        pre:  The directory has been loaded with data.
        post: The requested name is removed, modifed is set to true.
        @throws IOException - If there is an IO Error
   */
  private void doRemoveEntry() throws IOException {
    /**** BEGIN EXERCISE ****/
    // Request the name.
    System.out.println("Enter name");
    String theName = null;
    theName = in.readLine();
    if (theName == null) {
      return; // Dialog was cancelled.
    }
    // remove the name.
    String theNumber = theDirectory.lookupEntry(theName);
    String message = null;
    if (theNumber != null) { // Name was found.
      theDirectory.removeEntry(theName);
      message = "" + theName + " has been removed.";
    }
    else { // Name was not found.
      message = theName + " is not listed in the directory";
    }
    // Display the result.
    System.out.println(message);

    /**** END EXERCISE ****/
  }

  /** Method to save the directory to the data file.
        pre:  The directory has been loaded with data.
        post: The current contents of the directory have been saved
              to the data file.
   */
  private void doSave() {
    theDirectory.save();
  }
}