package Lect27Arrays2D;

public class BulletinBoard {
	static final int MSG_DISPLAY_LEN = 20;   // Standard width of message for displaying
	
	private String[][] board;    // The messages in the bulletin board
	
	/**
	 * Creates an empty bulletin board.
	 * @param maxRows
	 * @param maxCols
	 */
	public BulletinBoard(int maxRows, int maxCols) {
		board = new String[maxRows][];
		for (int row=0; row<board.length; row++) {
			board[row] = new String[maxCols];
		}
	}
	
	/**
	 * Adds the specified posting to the board.  Assumes the board has
	 * already been created.  It will overwrite any existing posting.
	 * It does not check for validity of indices.
	 * @param posting
	 * @param row
	 * @param col
	 */
	public void addPosting(String posting, int row, int col) {
		board[row][col] = posting;
	}

	/**
	 * Create a nice string representation of the board
	 * @return the board string
	 */
	public String toString() {
		String result = "";
		
		for (int row=0; row<board.length; row++) {
			result += "ROW[" + row + "]: ";
			for (int col=0; col<board[row].length; col++) {
				// First determine message
				String msg;
				if (board[row][col] != null) {
					msg = board[row][col];
				} else {
					msg = "EMPTY";
				}
				
				// Create msg display with constant width.  If it is too short,
				// pad the msg on the left with spaces
				if (msg.length() < MSG_DISPLAY_LEN) {
					int padLen = MSG_DISPLAY_LEN - msg.length();
					StringBuffer padding = new StringBuffer();
					for (int i=0; i<padLen; i++) {
						padding.append(' ');
					}
					msg = padding + msg;
				}
				
				// Finally, add message to display string
				result += msg + " | ";
			}
			result += "\n";
		}
		
		return result;
	}

	/**
	 * Removes the posting from the specified bulletin position.
	 * It does not check for validity of indices.
	 * @param row
	 * @param col
	 */
	public void removePosting(int row, int col) {
		board[row][col] = null;
	}
	
	public static void main(String[] args) {
		BulletinBoard bulletinBoard = new BulletinBoard(2, 3);
		System.out.println("Initial Board:");
		System.out.println(bulletinBoard);
		
		bulletinBoard.addPosting("Selling Car", 0, 0);
		bulletinBoard.addPosting("Looking for Dog", 0, 1);
		bulletinBoard.addPosting("Selling old computer", 0, 2);
		bulletinBoard.addPosting("Lost Glasses", 1, 0);
		bulletinBoard.addPosting("Looking Roommate", 1, 2);
		System.out.println("After adding some postings:");
		System.out.println(bulletinBoard);
		
		bulletinBoard.removePosting(0, 2);
		bulletinBoard.removePosting(1, 0);
		System.out.println("After removing some postings:");
		System.out.println(bulletinBoard);
	}
}