package huffman.algorithm;
import javafx.util.Pair;
import javax.swing.*;
import java.awt.*;
import java.io.*;
import java.util.*;

public class Huffman {
    String text = "";
    ArrayList<Pair<String, Integer>> nodeList;
    TreeMap<Character, String> prefixCodes;
    public static void main(String[] args){
        Huffman h = new Huffman();
        h.loadFile();
        h.codingAndDecoding();
    }
    public void loadFile(){
        JFileChooser chooser = new JFileChooser();
        chooser.showOpenDialog(null);
        readFile(chooser.getSelectedFile());
    }
    public void readFile(File file){
        try(BufferedReader in = new BufferedReader(new FileReader(file))){
            TreeMap<Character, Integer> freqTable = new TreeMap<>();
            String line = null;
            while((line = in.readLine()) != null){
                text += line;
                for(int i = 0; i < line.length(); i++)
                    freqTable.put(line.charAt(i),
                            freqTable.containsKey(line.charAt(i)) ? freqTable.get(line.charAt(i)) + 1 : 1 );
            }
            nodeList = new ArrayList<>();
            for(Map.Entry e : freqTable.entrySet())
                nodeList.add(new Pair(e.getKey().toString(), e.getValue()));
            Collections.sort(nodeList, new comparatorList());
            makePrefixCodes(nodeList);
        }catch(IOException ex){
            ex.printStackTrace();
        }
    }
    public void makePrefixCodes(ArrayList<Pair<String, Integer>> list){
        prefixCodes = new TreeMap<>();
        for(Pair<String, Integer> p : list) {
            Character c = p.getKey().charAt(0);
            prefixCodes.put(c, "");
        }
        System.out.println(list);
        while(list.size() > 1){
            String leftSon = list.get(list.size() - 2).getKey();
            String rightSon = list.get(list.size() - 1).getKey();

            Pair<String, Integer> temp;
            temp = new Pair<>(leftSon + rightSon, list.get(list.size() - 2).getValue() + list.get(list.size() - 1).getValue());

            for(int i = 0; i < leftSon.length(); i++)
                prefixCodes.put(leftSon.charAt(i), prefixCodes.get(leftSon.charAt(i)) + "0");
            for(int i = 0; i < rightSon.length(); i++)
                prefixCodes.put(rightSon.charAt(i), prefixCodes.get(rightSon.charAt(i)) + "1");

            list.remove(list.size() - 1);
            list.remove(list.size() - 1);
            list.add(temp);
            Collections.sort(list, new comparatorList());
            System.out.println(list);
        }
//        System.out.println(prefixCodes);
        for(Map.Entry e : prefixCodes.entrySet()){
            StringBuilder newCode = new StringBuilder(e.getValue().toString());
            prefixCodes.put((Character)e.getKey(), newCode.reverse().toString());
        }
        System.out.println(prefixCodes);
    }

    class comparatorList implements Comparator<Pair<String, Integer>>{
        @Override
        public int compare(Pair<String, Integer> one, Pair<String, Integer> two) {
            return one.getValue() > two.getValue() ? -1 : one.getValue() < two.getValue() ? 1 : 0;
        }
    }

    public void codingAndDecoding(){
        JFileChooser chooser = new JFileChooser();
        chooser.showOpenDialog(null);
        write(chooser.getSelectedFile());
        JFileChooser chooser1 = new JFileChooser();
        chooser1.showOpenDialog(null);
        read(chooser1.getSelectedFile());
    }
    public void write(File file) {
        try(FileOutputStream writer = new FileOutputStream(file)) {
            Character temp = null;
            // по строчкам текста
            // по буквам строки
            for (int i = 0; i < text.length(); i++) {
                temp = text.charAt(i);
                int lengthCode = prefixCodes.get(temp).length();
                byte buffer = 0;
                //по коду буквы
                for (int j = 0; j < lengthCode; j++) {
                    if (prefixCodes.get(temp).charAt(j) == '0')
                        buffer |= (0 << j);
                    else
                        buffer |= (1 << j);
                }
                writer.write(buffer);
            }
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }
    public void read(File file){
        TreeMap<String, Character> decodeMap = new TreeMap<>();
        for(Map.Entry e : prefixCodes.entrySet())
            decodeMap.put(e.getValue().toString(), (Character)e.getKey());

        try(FileInputStream input = new FileInputStream(file)) {
            byte b = -1;
            byte[] mass = input.readAllBytes();
            for(int k = 0; k < mass.length; k++){
                b = mass[k];
                String code = "";
                for (int i = 0; i < 8; i++) {
                    if ((b & (1 << i)) != 0)
                        code += "1";
                    else
                        code += "0";
                    if(decodeMap.containsKey(code)){
                        System.out.print((decodeMap.get(code) + ""));
                        break;
                    }
                }
            }
        }catch(IOException ex){
            ex.printStackTrace();
        }
    }
}