package chapter01;

import java.util.*;

/**
 * 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;

	/** Scanner to read from input console. */
	private Scanner scIn = null;

	// Constructor
	/** Default constructor. */
	public PDConsoleUI() {
		scIn = new Scanner(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;
		do {
			for (int i = 0; i < commands.length; i++) {
				System.out.println("Select " + i + ": " + commands[i]);
			}
			try {
				choice = scIn.nextInt(); // Read the next choice.
				scIn.nextLine(); // Skip trailing newline.
				switch (choice) {
				case 0:
					doAddChangeEntry();
					break;
				case 1:
					doLookupEntry();
					break;
				case 2:
					doRemoveEntry();
					break;
				case 3:
				case 4:
					doSave();
					break;
				default:
					System.out.println("*** Invalid choice " + choice
							+ " - try again!");
				}
			} catch (InputMismatchException ex) {
				System.out.println("*** Incorrect data entry - "
						+ "enter an integer between 0 and "
						+ (commands.length - 1));
				scIn.nextLine(); // Discard bad input.
				choice = -1;
			}
		} while (choice != commands.length - 1);
		System.exit(0);
	}

	/**
	 * 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.
	 */
	private void doAddChangeEntry() {
		// Request the name.
		System.out.println("Enter name");
		String newName = scIn.nextLine();
		if (newName.equals("")) {
			return;
		}
		// Request the number.
		System.out.println("Enter number");
		String newNumber = scIn.nextLine();
		if (newNumber.equals("")) {
			return;
		}
		// Insert/change name-number.
		String oldNumber = theDirectory.addOrChangeEntry(newName, newNumber);
		String message;
		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.
	 */
	private void doLookupEntry() {
		// Request the name.
		System.out.println("Enter name");
		String theName = scIn.nextLine();
		if (theName.equals("")) {
			return; // Dialog was cancelled.
		}
		// Look up the name.
		String theNumber = theDirectory.lookupEntry(theName);
		String message;
		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 true
	 */
	private void doRemoveEntry() {
		/** ** BEGIN EXERCISE *** */
		// Request the name
		String theName = scIn.nextLine();
		if (theName.equals("")) {
			return;
		}
		// Remove the entry
		theDirectory.removeEntry(theName);
		// Display confirmaion message
		System.out.println(theName + " has been removed from"
				+ " the directory");
		/** ** 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();
	}
}