import java.io.*;

public class HuffmanTester
{

	protected BufferedReader fileReader;

	protected PrintWriter fileWriter;

	protected Huffman huffman;

	protected String inFilePath;


	/**
 	 *  Initializes this HuffmanTester object.
 	 *
 	 */
 	public HuffmanTester()
	{
        	huffman = new Huffman();
 	} // default constructor


	/**
     	 *  Reads in file paths and opens the input and output files.     
     	 *
     	 * @return (a reference to) the file writer.
     	 * 
     	 */
	public PrintWriter openFiles()
	{
		final String IN_FILE_PROMPT =
          		"\nPlease enter the path for the input file: ";

      		final String OUT_FILE_PROMPT =
          		"\nPlease enter the path for the output file: ";

      		BufferedReader keyboardReader = new BufferedReader
                                          	(new InputStreamReader (System.in));
      		String outFilePath,
                       line;

      		boolean pathsOK = false;

      		while (!pathsOK)
      		{
          		try
          		{
              			System.out.print (IN_FILE_PROMPT);
              			inFilePath = keyboardReader.readLine();
              			fileReader= new BufferedReader(new FileReader (inFilePath));           		  	
				System.out.print (OUT_FILE_PROMPT);
              			outFilePath = keyboardReader.readLine();
              			fileWriter = new PrintWriter (new FileWriter (outFilePath));
				pathsOK = true;	
          		} // try
          		catch (IOException e)
          		{
              		System.out.println (e);
          		} // catch
        	} // while !pathOK
		return fileWriter;
	} // method openFiles


	/**
 	 *  Creates the Huffman encoding.
 	 *  The worstTime(n) is O(n).
 	 *
 	 */
	public void createEncoding()
	{
     		String line;

        	try
        	{
            		while (true)
            		{
                		line = fileReader.readLine();
                		if (line == null)
                    			break;
                		huffman.updateFrequencies (line);
            		} // while
			fileReader.close(); // re-opened in saveEncodedMessage
            		huffman.createPQ();
            		huffman.createHuffmanTree();
            		huffman.calculateHuffmanCodes();
        	} // try
        	catch (IOException e)
        	{
            		System.out.println (e);
        	} // catch IOException
	} // method createEncoding


	/**
 	 *  Saves the Huffman codes and the encoded message to a file.
 	 *  The worstTime(n) is O(n).
 	 *  
 	 */
	public void saveEncodedMessage()
	{
        	String line;

        	try
        	{
           		fileWriter.print (huffman.getCodes());
            		fileWriter.println ("**"); // to separate codes from encoded message
            		fileReader = new BufferedReader (new FileReader (inFilePath));

            		while (true)
            		{
                		line = fileReader.readLine();
                		if (line == null)
                    			break;
                		fileWriter.println (huffman.getEncodedLine (line));
            		} // while            	
        	} // try
        	catch (IOException e)
        	{
            		System.out.println (e);
        	} // catch IOException
	} // method saveEncodedMessage

} // class HuffmanTester