package graph;
import java.io.IOException;
import java.io.InputStream;
import java.io.StreamTokenizer;

/**
 * Parses an ADJ file and outputs an AdjacencyMatrix.
 * The format of the file is:
 *
 * <PRE>
 *	# This is a comment
 *         Fa.Of   Sc.Of   Sem.R
 *	Fa.Of   2                      Faculty Offices
 *	Sc.Of   2       1              Faculty Secretary Offices
 *	Sem.R   1       1       0      Seminar Room
 *
 * </PRE>
 *
 * The following parsing rules are used:
 * <UL>
 *   <LI>White space can be either tabs or spaces
 *   <LI>Shell-style comments are used (# denotes comment to the end of line)
 *   <LI>Matrix is assumed to be symmetric; the
 *			abbreviations in the margins are for readability only
 *	 <LI>The right-most text is the labels for the rows/columns
 *   <LI>Only elements from the lower-left half of the matrix are used
 *			as input data; the right-most text is assumed to be the first
 *			non-number string past the diagonal.
 *   <LI>The first non-comment line of the file must contain data
 * </UL>
 * 
 * @see AdjacencyMatrix
 * @author Michael Shilman (michaels@eecs.berkeley.edu)
 * @version $Id$
 */
public class AdjacencyParser {
    /**
     * Parse an ADJ file and output an AdjacencyMatrix
     *
     * @param s		The Input stream of the file
     * @return		The
     * @exception IOException	
     *              Thrown if there is any problem with the input stream
     * @exception FileFormatException
     *				Thrown if there is a problem with the format
     *              of contents of the file.
     */
    public static AdjacencyMatrix parse(InputStream s)
    throws IOException, FileFormatException {
		StreamTokenizer st = new StreamTokenizer(s);
		st.commentChar('#');
		st.parseNumbers();
		st.eolIsSignificant(true);
		st.wordChars('(','(');
		st.wordChars(')',')');
		st.wordChars('_','_');
		st.wordChars('\'', '\'');

		int val;

		//Get the number of rows/columns from the first line
		int numCols = 0;
		while((val = st.nextToken()) != StreamTokenizer.TT_EOL) {
			if((val == StreamTokenizer.TT_WORD) ||
				(val == StreamTokenizer.TT_NUMBER)) {
				String cname = ((val == StreamTokenizer.TT_WORD) ? st.sval :
								String.valueOf(st.nval));
//DBG			System.out.println("Column = " + cname);
				numCols++;
			}
			else {
				String err = "Parse error, line " + st.lineno() +
					" : Expected string header for column " + numCols + ".";
				throw (new FileFormatException(err));
			}
		}
//DBG	System.out.println("NumCols = " + numCols);
        AdjacencyMatrix mat = new AdjacencyMatrix(numCols);

		//Fill in the matrix line-by-line
        int y = 0;
        while(y < numCols) {
        	val = st.nextToken();
        	if(val != StreamTokenizer.TT_WORD) {
        		String err = "Parse error, line " + st.lineno() + " : Expected row header.";
        		throw (new FileFormatException(err));
        	}
        	//else ignore it
//DBG      	System.out.println("Row header " + st.sval);

        	//Traverse the row
        	int x = 0;
        	while(x <= y) {
        		val = st.nextToken();
        		if(val != StreamTokenizer.TT_NUMBER) {
	        		String err = "Parse error, line " + st.lineno() +
	        			" : Expected integer edge weight, column " + x + ".";
        			throw (new FileFormatException(err));
        		}
        		else {
        			mat.values[x][y] = mat.values[y][x] = (int)st.nval;
        			x++;
        		}
        	}

        	//Grab the title off the end of the row
        	String label = new String();
        	while((val = st.nextToken()) != StreamTokenizer.TT_EOL) {
        		if(val == StreamTokenizer.TT_WORD) {
        			label = label + " " + st.sval;
        		}
        		else if(val == StreamTokenizer.TT_NUMBER) {
        			label = label + " " + String.valueOf(st.nval);
        		}
        		else if(val == StreamTokenizer.TT_EOF) {
        			//the end of the line was actually EOF
        			if(y == (numCols-1)) {
        				//we are on the last line anyway
        				mat.names[y] = label;
        				return mat;
        			}
        			else {
        				String err = "Parse error, line " + st.lineno() + " : Premature EOF.";
        				throw (new FileFormatException(err));
        			}
        		}
        		else {
        			String err = "Parse error, line " + st.lineno() + " : Expected string label.";
        			throw (new FileFormatException(err));
        		}
        	}
//DBG       System.out.println("Label = " + label);
      		mat.names[y] = label;
        	y++;
        }
        //We are done with all the rows
        if((val = st.nextToken()) != StreamTokenizer.TT_EOF) {
        	String warn = "Warning, line " + st.lineno()
        					+ " : Ignoring extra information at end of file";
        	System.out.println(warn);
        }
        return mat;
    }
}