package msoe.se1021.filereader;
/*
 * Created on Apr 26, 2005
 * Modified Dec 3, 2009
 *
 * FileReader.java
 * @author: hornick
 */

import java.io.*;
import java.text.*;
import java.util.*;

/**
 * A simple data file reader (that hides a lot of file-related I/O from the user of this class)
 * @author hornick
 *
 */
public class FileReader {

    // These are constants values returned by the getStutus method (see below)
    // Note: We're doing something very unusual here, in that we're generating a random
    //  value between 0 and 100 that we're initializing the first constant to, so
    //  that you (the student) cannot assume that these constants have any specific values.
    public static final int NOT_INITIALIZED = (int)( 100*Math.random());  
    public static final int NO_SUCH_FILE = NOT_INITIALIZED+1;
    public static final int BAD_DATA = NOT_INITIALIZED+2;
    public static final int DATA_READ_OK = NOT_INITIALIZED+3;

    private static int status = NOT_INITIALIZED; // the status of the last method called; one of the above constants
    private static int numTokens = 0; // the number of tokens in the file
    
    /**
     * Constructor for a FileReader object
     * The constructor is private, since there is no need to allow instantiation, as all methods are static.
     */
    private FileReader()
    {
        // nothing to do; there are no instance attributes to initialize
    }

    /**
     * Accessor
     * @return the current status of the FileReader, as defined by one of the following:
     * NOT_INITIALIZED - readFileIntoString() has not been called yet
     * NO_SUCH_FILE - invalid file passed to readFileIntoString
     * BAD_DATA - corrupted data in the file
     * DATA_READ_OK - all data read was OK
     */
    public static int getStatus()
    {
        return status;
    }

    /**
     * Accessor
     * @return the number of tokens in read from the input file
     */
    public static int getNumTokens() {
    	return numTokens;
    }
    
    /**
     * Reads the entire contents of the specified file into a String
     * @param filename the file to be read
     * @return a String containing the entire contents of the file, or a null if an error occurred.
     * Check the success or failure of this method by calling the getStatus() method, which
     * will return NOT_INITIALIZED, NO_SUCH_FILE, or BAD_DATA in the case of a failure,
     * and DATA_READ_OK if the file was read successfully.
     */
    public static String readFileIntoString( String filename ) {
        File dataFile = new File( filename );
        if( !dataFile.exists() ) {
            status = NO_SUCH_FILE;
            return null; // return a null string if no such file exists 
        }

        Scanner scanner; // we'll use this Scanner to read the file
        numTokens = 0;   // this counts the number of tokens we'll read from the file

        try {
            scanner = new Scanner(dataFile);
            scanner.useDelimiter("[,;:\\s]+"); // allow commas, semicolons, colons, or any kind of white space for delimiters
        }
        catch( FileNotFoundException e ){ // no such file to scan, or no permission to read it
            status = NO_SUCH_FILE;
            return null;  // return a null string if no such file exists
        }

        String bigString = ""; // the string being created

        try {
            while( scanner.hasNext() ) { // keep reading as long as there is something left to read...
                String data = scanner.next();
                bigString += data;
                if( scanner.hasNext() )
                	bigString += ","; // add a comma as long as there is another token coming
                numTokens++;
            }
            status = DATA_READ_OK;
            return bigString;
        }
        catch( Exception e ) {  // oh no...
            status = BAD_DATA;
            return null;  // on read error, return a null string
        }
    }
}