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

import javax.swing.JFileChooser;

public class Huffman {
	
	String[] myEncodings;
	int[] myFreqs;
	private TreeNode myRoot;
	OutputStream myOut;
	
	protected static JFileChooser ourChooser = new JFileChooser(System
            .getProperties().getProperty("user.dir"));
	
	
	public Huffman() throws FileNotFoundException{
		myEncodings = new String[256];
		myFreqs = new int[256];
		myOut = new FileOutputStream("hopethisworks.txt");
	}

	public void openFile() throws IOException{
		int retval = ourChooser.showOpenDialog(null);
		if (retval == JFileChooser.APPROVE_OPTION) {
			File file = ourChooser.getSelectedFile();
			countChunks(file);
			makeTree();
			makeEncodings(myRoot,"");
			writeCounts();
			doCompress(file);
		}
	}
	
	public void makeEncodings(TreeNode root, String path){
	   if (root == null){
		   
		   return;
	   }
	   if (root.left == null && root.right == null){
		   storeChunk(root.chunk,path);
	   }
	   else {
		   makeEncodings(root.left, path + "0");
		   makeEncodings(root.right, path + "1");
	   }
	}
	
	public void writeCounts() throws IOException{
		for(int k=0; k < myFreqs.length; k++){
			printCount(myFreqs[k]);
		}
	}
	
	private void printCount(int i) throws IOException {
		myOut.write(i);
	}

	public void doCompress(File file) throws IOException{
		InputStream is = new BufferedInputStream(new FileInputStream(file));
		int bits;
		
		while ((bits = is.read()) != -1) {
			String code = myEncodings[bits];
			for(int k=0; k < code.length(); k++){
				if (code.charAt(k) == '0'){
					printCount(0);
				}
				else {
					printCount(1);
				}
			}
		}
	}

	private void storeChunk(int chunk, String path) {
		myEncodings[chunk] = path;
	}

	public void makeTree(){
		PriorityQueue<TreeNode> pq = new PriorityQueue<TreeNode>();
		 for(int k=0; k < myFreqs.length; k++){
			 if (myFreqs[k] != 0){
		       pq.add(new TreeNode(k,myFreqs[k],null,null));
			 }
		 }
		 while (pq.size() > 1){
		    TreeNode left = pq.remove();
		    TreeNode right = pq.remove();
		    pq.add(new TreeNode(0,left.weight+right.weight,
		                        left,right));
		 }
		 myRoot = pq.remove();

	}
	
	private void countChunks(File file) throws IOException {
		InputStream is = new BufferedInputStream(new FileInputStream(file));
		int bits;
		
		while ((bits = is.read()) != -1) {
			myFreqs[bits] += 1;
		}
		int total = 0;
		for(int k=0; k < myFreqs.length; k++){
			if (myFreqs[k] != 0) {
				System.out.printf("%d %d\n",k,myFreqs[k]);
				total += myFreqs[k];
			}
		}
		System.out.printf("\ntotal = %d\n", total);
	}
	public static void main(String[] args) throws IOException{
		Huffman hf = new Huffman();
		hf.openFile();
	}
}