// Jeremy Lipschutz
// Program that will print all the nested contents of a given file.

// Note: This program works so well recursively because it takes 
// advantage of the fact that files are "recursive" structures.
// "Files" are either "normal files" or "directories" which 
// contain "files".

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

public class Crawler {
   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("Does not exist");
      } else {
         print(f);
      }
   }
   
   // Prints the file name, and if it is a directory, it will print out
   // all the nested contents with indentation
   public static void print(File file) {
      print(file, 0);
   }  
   
   // file: either a simple file OR they are directories that contain other files
   // Print the file name, and if it is a directory, it will print out 
   // ALL of the nested contents with indentation. Level reperesents
   // how much space to print before the file name
   private static void print(File file, int indent) {
      for(int i = 0; i < indent; i++) {
         System.out.print("    ");
      }
      System.out.println(file.getName());
      if(file.isDirectory()) {
         File[] subFiles = file.listFiles();
         for(File subFile : subFiles) {
            // leap of faith
            print(subFile, indent + 1);
         }
      }
   }
   
   // DO NOT TRY TO UNDERSTAND THIS CODE. This is the iterative, ugly, and hacky
   // way to iteratively approach this problem.
   public static void printIterative(File f) {
      Stack<File> files = new Stack<File>();
      files.push(f);
      int level = 0;
      
      while(!files.isEmpty()) {         
         File file = files.pop();
         if (file != null) {
            for (int i = 0; i < level; i++) {
               System.out.print("    ");
            }
            System.out.println(file.getName());
            if (file.isDirectory()) {
               files.push(null);
               File[] subFiles = file.listFiles();
               for (int i = subFiles.length - 1; i >= 0; i--) {
                  files.push(subFiles[i]);
               }
               level++;
            }
         } else {
             level--;
         }
      }
   }
}