package dexterJuni;

import java.io.File;
import java.io.FilenameFilter;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.util.Random;

public class PickRandomFile {

    public static File pickRandomFile(File folder, String ext) {
        File[] files = folder.listFiles(new FilenameFilter() {
            @Override
            public boolean accept(File dir, String name) {
                if(name.endsWith(ext))
                    return true;
                return false;
            }
        });
        Random r = new Random();
        int random = r.nextInt(files.length);
        return files[random];
    }

    public static void zapishi(File file, File folder) throws IOException {
        File to = new File(folder,file.getName());
        if(!to.exists())
            to.createNewFile();
        RandomAccessFile reader = null;
        RandomAccessFile writer = null;
        try {
            reader = new RandomAccessFile(file, "r");
            writer = new RandomAccessFile(to, "rw");
            reader.seek(reader.length()-5);
            int n;
            while((n = reader.read()) != -1) {
                writer.write(n);
            }
        }catch (Exception e) {}
        finally {
            if(reader != null)
                reader.close();
            if(writer != null)
                writer.close();
        }
    }

    public static void doSth(String from, String to) throws IOException {
        File fromFile = new File(from);
        File toFile = new File(to);
        if(fromFile.exists()) {
            if(fromFile.isDirectory()) {
                if(!toFile.exists()) {
                    toFile.mkdir();
                }
                else {
                    if(toFile.isFile()) {
                        System.out.println("Izlezniot ne e folder");
                        return;
                    }
                }
                File randomFile = pickRandomFile(fromFile, ".txt");
                zapishi(randomFile, toFile);
            }
            else {
                System.out.println("Vlezniot ne e folder");
            }
        }
        else {
            System.out.println("Vlezniot ne postoi");
        }
    }

    public static void main(String[] args) throws IOException {
        doSth("from", "to");
    }

}