// Hunter Schafer, CSE 143
// This program prints out the structure of a given directory or file
import java.io.*;
import java.util.*;

public class DirectoryCrawler {

    public static void main(String[] args) {
        Scanner console = new Scanner(System.in);
        System.out.print("directory or file name? ");
        String name = console.nextLine();
        File f = new File(name);
        if (!f.exists()) {
           System.out.println("That file or directory does not exist");
        } else {
           print(f);
        }
    }

    // prints the name of the file
    // if the file is a directory, prints its children in the same format
    private static void print(File file) {
        if (!file.isDirectory()) {
            System.out.println(file.getName());
        } else {
            System.out.println(file.getName());
            // print all the children of file
            File[] subFiles = file.listFiles();
            for (for int i = 0; i < subFiles.length; i++) {
                print(subFiles[i]);
            }
        }
    }


    /****************************************************************************************
     * Below is an iterative version of this solution (that also adds spacing to output)    *
     * Note how much extra work is necessary in order to not use recursion here!            *
     * You should not try to write code like this!                                          *
     ****************************************************************************************/

     public static void printIterative(File file) {
        System.out.println(file.getName());
        if (file.isDirectory()) {
            Stack<Queue<File>> toProcess = new Stack<>();
            toProcess.push(children(file));

            while (!toProcess.isEmpty()) {
                Queue<File> subFilesQueue = toProcess.peek();
                if (subFilesQueue.isEmpty()) {
                    toProcess.pop();
                } else {
                    File nextFile = subFilesQueue.remove();

                    for (int i = 0; i < toProcess.size(); i++) {
                        System.out.print("    ");
                    }
                    System.out.println(nextFile.getName());

                    if (nextFile.isDirectory()) {
                        toProcess.push(children(nextFile));
                    }
                }
            }
        }
    }

    private static Queue<File> children(File file) {
        File[] subFiles = file.listFiles();
        Queue<File> subFilesQueue = new LinkedList<>();
        for (File subFile : subFiles) {
            subFilesQueue.add(subFile);
        }
        return subFilesQueue;
    }
}