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

//written by moparisthebest, do whatever the hell you want with it ;)
public class RandomizeM3U {

public static final String newLine = "\n";

    public static void main(String[] args) throws Exception {
	//check args
	if(args.length != 2){
		System.out.println("Usage: RandomizeM3U INPUT_FILE OUTPUT_FILE");
		return;
	}

	//read M3U file in
	FileInputStream fis = new FileInputStream(args[0]);
        Scanner scan = new Scanner(fis);
	String firstLine = scan.nextLine()+newLine;
	//1814 is simply the number of songs I have, can be changed but doesn't need to be
	ArrayList<String> list = new ArrayList<String>(1814);
	//reads 2 lines at once because that is how M3U files are formatted
	while(scan.hasNext())
		list.add(scan.nextLine()+newLine+scan.nextLine()+newLine);
	fis.close();

	//randomize list ordering by swapping random indexes
	String temp;
	int i1, i2, lSize = list.size();
	Random r = new Random();
	//higher x goes up to the more random the list becomes, I think the length is sufficient
	for(int x = 0; x < lSize; ++x){
		i1 = r.nextInt(lSize);
		i2 = r.nextInt(lSize);
		temp = list.get(i1);
		list.set(i1, list.get(i2));
		list.set(i2, temp);
	}

	//write newly randomized list out to file
	BufferedWriter out = new BufferedWriter(new FileWriter(args[1]));
	out.write(firstLine);
	for(String s : list)
        	out.write(s);
	out.close();
    }

}