/*
 *  JFLAP - Formal Languages and Automata Package
 * 
 * 
 *  Susan H. Rodger
 *  Computer Science Department
 *  Duke University
 *  August 27, 2009

 *  Copyright (c) 2002-2009
 *  All rights reserved.

 *  JFLAP is open source software. Please see the LICENSE for terms.
 *
 */





package gui.grammar.parse;

import grammar.Grammar;
import gui.environment.Universe;

import java.util.*;
import javax.swing.table.*;

/**
 * This is a table model for user definition of the first and follow sets for a
 * grammar. The first column are the variable names. The second column are the
 * first sets, the third column the follow sets.
 * 
 * @author Thomas Finley
 */

public class FirstFollowModel extends AbstractTableModel {
	/**
	 * Instantiates a new <CODE>FirstFollowModel</CODE>.
	 * 
	 * @param grammar
	 *            the grammar for the first follow model, from which the
	 *            variables are extracted for the first column
	 */
	public FirstFollowModel(Grammar grammar) {
		variables = grammar.getVariables();
		Arrays.sort(variables);
		terminals = grammar.getTerminals();

		firstSets = new String[variables.length];
		followSets = new String[variables.length];
		Arrays.fill(firstSets, "");
		Arrays.fill(followSets, "");
	}

	/**
	 * Retrives the first sets as shown in the table.
	 * 
	 * @return the first sets, a map from all single symbols A in the grammar to
	 *         the set of symbols that represent FIRST(A)
	 */
	public Map getFirst() {
		return null;
	}

	/**
	 * Retrieves the follow sets as shown in the table.
	 * 
	 * @return the follow sets, a map from all single variables A in the grammar
	 *         to the set of symbols that represent FOLLOW(A)
	 */
	public Map getFollow() {
		return null;
	}

	/**
	 * Set if the user can edit the first sets at this time.
	 * 
	 * @param canEdit
	 *            <CODE>true</CODE> if editing is allowed
	 */
	public void setCanEditFirst(boolean canEdit) {
		canEditColumn[1] = canEdit;
	}

	/**
	 * Set if the user can edit the follow sets at this time.
	 * 
	 * @param canEdit
	 *            <CODE>true</CODE> if editing is allowed
	 */
	public void setCanEditFollow(boolean canEdit) {
		canEditColumn[2] = canEdit;
	}

	/**
	 * There are as many rows as there are variables.
	 * 
	 * @return the number of variables
	 */
	public int getRowCount() {
		return variables.length;
	}

	/**
	 * There are always three columns for the variables, the first sets, and the
	 * follow sets.
	 * 
	 * @return 3
	 */
	public int getColumnCount() {
		return 3;
	}

	/**
	 * Returns the name of a particular column.
	 * 
	 * @param column
	 *            the index of a column to get the name for
	 */
	public String getColumnName(int column) {
		return COLUMN_NAMES[column];
	}

	/**
	 * Returns the value at each column.
	 * 
	 * @param row
	 *            the row to get data for
	 * @param column
	 *            the column to get data for
	 * @return the data for this column
	 */
	public Object getValueAt(int row, int column) {
		switch (column) {
		case 0:
			return variables[row];
		case 1:
			return firstSets[row];
		case 2:
			return followSets[row];
		}
		return null;
	}

	/**
	 * Returns if a table cell can be edited.
	 * 
	 * @param row
	 *            the row of the cell
	 * @param column
	 *            the column of the cell
	 */
	public boolean isCellEditable(int row, int column) {
		return canEditColumn[column];
	}

	/**
	 * Returns the character set at a particular location.
	 * 
	 * @param row
	 *            the row to get the set for; this will be a set for the
	 *            variable at this row
	 * @param column
	 *            the column to get the set for, which will be 1 for first and 2
	 *            for follow
	 */
	public Set getSet(int row, int column) {
		String s = (String) getValueAt(row, column);
		Set set = new TreeSet();
		for (int i = 0; i < s.length(); i++) {
			if (s.charAt(i) == '!') {
				set.add("");
				continue;
			}
			set.add(s.substring(i, i + 1));
		}
		return set;
	}

	/**
	 * When a string value is used to define a set, it's possible that the
	 * string value will contain multiple characters. This will take a string,
	 * and return a string with not duplicate characters. Only the first
	 * instance of a character is preserved, and others are discarded. So, if
	 * one were to pass in <I>abaacb</I>, this would return the string <I>abc</I>.
	 * 
	 * @param s
	 *            the string to process
	 * @return the same string as was passed in but with duplicate characters
	 *         removed
	 */
	private String removeDuplicateCharacters(String s) {
		Set characters = new HashSet();
		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < s.length(); i++) {
			Character c = new Character(s.charAt(i));
			if (characters.add(c))
				sb.append(c.charValue());
		}
		return sb.toString();
	}

	/**
	 * Sets the value at each column.
	 * 
	 * @param value
	 *            the new value
	 * @param row
	 *            the row to change
	 * @param column
	 *            the column to change
	 */
	public void setValueAt(Object value, int row, int column) {
		switch (column) {
		case 0:
			variables[row] = (String) value;
			break;
		case 1:
			firstSets[row] = removeDuplicateCharacters((String) value);
			break;
		case 2:
			followSets[row] = removeDuplicateCharacters((String) value);
			break;
		}
	}

	/**
	 * Sets the set at a particular cell.
	 * 
	 * @param set
	 *            the set for the cell
	 * @param row
	 *            the row index of the cell to set the set for
	 * @param column
	 *            the column index of the cell to set the set for
	 */
	public void setSet(Set set, int row, int column) {
		StringBuffer sb = new StringBuffer();
		Iterator it = set.iterator();
		while (it.hasNext()) {
			String element = (String) it.next();
			if (element.length() == 0)
				element = "!";
			sb.append(element);
		}
		setValueAt(sb.toString(), row, column);
	}

	/** The variables. */
	private String[] variables;

	/** The terminals. */
	private String[] terminals;

	/** The user defined first sets strings. */
	private String[] firstSets;

	/** The user defined follow sets strings. */
	private String[] followSets;

	/** The permissions to edit each column. */
	private boolean[] canEditColumn = new boolean[] { false, false, false };

	/** The lambda string. */
	public static String LAMBDA = Universe.curProfile.getEmptyString();

	/** The names of columns. */
	public static String[] COLUMN_NAMES = { " ", "FIRST", "FOLLOW" };
}