using System;
using System.IO;
using System.Security;

class MyExplorer
{
  public static void Main(string[] args)    
  {
    MyExplorer oExplorer=new MyExplorer();
    String Command;
    String[] CommandLineArgs;
    int ArgumentLength;

    bool CanExit=false;

    Console.WriteLine("Welcome to the MyExplorer Dos Utility");
    do
    {
      Console.Write("MyExplorer>");
      Command=Console.ReadLine();
      Command=ToSingleSpace(Command.Trim().ToLower());
      CommandLineArgs=oExplorer.ParseCommand(Command.ToLower(),out ArgumentLength);
      switch(CommandLineArgs[0])
      {
        case "cpy":
          if(ArgumentLength!=2)
          {
            ShowError("Usage cpy <source> <dest>");
          }
          else
          {
            oExplorer.Copy(CommandLineArgs[1],CommandLineArgs[2]);
          }
          break;
        case "rem":
          if(ArgumentLength!=1)
          {
            ShowError("Usage rem <filename>");            
          }
          else
          {
            oExplorer.Remove(CommandLineArgs[1]);
          }
          break;
        case "dir":
        case "ls":
          switch(ArgumentLength)
          {
            case 0:
              oExplorer.ListFiles(".");
              break;
            case 1:
              oExplorer.ListFiles(CommandLineArgs[1]);
              break;
            default:
              ShowError("Usage dir [<Path>]");
          }
          break;
        case "help":
        case "h":
          oExplorer.ShowHelp();
          break;
        case "quit":
        case "exit":
        case "bye":
          CanExit=true;
          break;
        default:
          ShowError("Invalid Command");
      }
    }while(!CanExit);
  }

  public static void ShowError(string StrError)
  {
    Console.WriteLine(StrError);
  }

  public static String ToSingleSpace(string StrToReplace)
  {
    int Position;
    Position=StrToReplace.IndexOf("  ");

    if(Position==-1)
      return StrToReplace;
    else
      return ToSingleSpace(StrToReplace.Substring(0,Position) + StrToReplace.Substring(Position+1));
  }

  public string[] ParseCommand(String Command,out int ArgumentLength)
  {
    string[] CommandLineArgs=Command.Split(new char[]{' '});
    ArgumentLength=CommandLineArgs.Length-1;
    return CommandLineArgs;
  }


  /* Function to the Usage of MyExplorer */
  public void ShowHelp()
  {
    Console.WriteLine("MyExplorer Help Contents");
    Console.WriteLine("=========================");
    Console.WriteLine("cpy <source> <dest> - Copies the content of source to dest");
    Console.WriteLine("rem <filename>      - Filename to be deleted");
    Console.WriteLine("dir/ls [<path>]     - Directory Listing");
    Console.WriteLine("h/help              - Help for using MyExplorer");
    Console.WriteLine("quit/exit/bye       - Exit MyExplorer");
  }

  /*
    Method to perform File Copy operation
  */
  public void Copy(string SourceFile,string DestinationFile)
  {
    try
    {
     File.Copy(SourceFile,DestinationFile,true);
     Console.WriteLine("File Copied Successfully");
    }
    catch(FileNotFoundException)
    {
      Console.WriteLine("Source File does not Exists");
    }
    catch(ArgumentException)
    {
      Console.WriteLine("Invalid Argument for cpy");
    }
    catch(SecurityException)
    {
      Console.WriteLine("Write Access is Denied");
    }
    catch(Exception)
    {
      Console.WriteLine("UnKnown Exception");
    }
  }

  /*
    Function to Delete the Specified File
  */
  public void Remove(string FileToRemove)
  {
    try
    {
      File.Delete(FileToRemove);
      Console.WriteLine("File Removed Successfully");
    }
    catch(DirectoryNotFoundException)
    {
      Console.WriteLine("File does not exists");
    }
    catch(SecurityException)
    {
      Console.WriteLine("Delete Permission Denied");
    }
    catch(AccessException)
    {
      Console.WriteLine("Directory name is specified where file is required");
    }
    catch(Exception)
    {
      Console.WriteLine("Unknown Exception");
    }    
  }

  /*
    Directory Listing
  */

  public void ListFiles(string StrDirectoryToList)
  {
    Directory oDir;
    FileSystemEntry[] oFiles;
    try
    {
      oDir=new Directory(StrDirectoryToList);
      oFiles=oDir.GetFileSystemEntries();
      bool IsFileFound=true;
      foreach(FileSystemEntry f in oFiles)
      {
        if(IsFileFound)
        {
          Console.WriteLine("{0,-32}{1,-8}{2}","Name","Size","Diretory/File");
          Console.WriteLine(new string('=',80));
          IsFileFound=false;
        }
        if(f.IsFile)
        {
          Console.WriteLine("{0,-32}{1,-8}{2}",f.Name,((File)f).Length,"F");
        }
        else
        {
          Console.WriteLine("{0,-32}{1,-8}{2}",f.Name,"0","D");          
        }
      }
    }
    catch(DirectoryNotFoundException)
    {
      Console.WriteLine("Directory Not Found");
    }
    catch(Exception)
    {
    }
  }

}