//This program compiled and ran until I put /*******/ on top of some words
// Helps administrator by deleting a select id and password from passwd file
#include <stdexcept>
#include <typeinfo>
#include <iostream>
#include <fstream>
#include <cstdlib>
#include "SecureBuffer.h"

using namespace std;


int main(int argc, char * argv[])
{
 try{

  if(argc !=2 )
  {
	cerr <<"Usage: del name\n";
	exit(1);
  }

  Buffer id(argv[1]);

  fstream passwd("passwd", ios::in | ios::out);
  const int record_size= sizeof(Buffer)+sizeof(SecureBuffer);
  // format described in list.cpp. file = record[*] blank[*].

  if(!passwd)
  {
    throw runtime_error("File passwd can not be opened\n");
  }
  int number_of_recs;
  passwd.seekp(0, ios::end);
  number_of_recs=passwd.tellp()/record_size ;

  SecureBuffer blank_passwd;
  Buffer blank_id;

  // find id in file if possible
  Buffer file_id;
  int record_number;
  for(record_number=0; record_number<number_of_recs; record_number++)
  {
	  passwd.seekg(record_size*record_number);
	  passwd.read( (char*)&file_id, sizeof(id));
	  if( file_id==id)
	  {
		cout << record_number <<" : "<< file_id << endl;
		break;
          } else if(file_id == blank_id)
	  {
		break;
	  }
  }//end for

  // if id in file overwrite the whole record with the last in the file
  if(file_id==id)
  {
	SecureBuffer last_passwd;
	Buffer last_id;
	streampos last_nonblank;
	passwd.seekg(-record_size, ios::end);
	last_nonblank=passwd.tellg();
	passwd.read( (char*)&last_id, sizeof(last_id));
	while( last_id == blank_id )// stops because first_id== id != blank
	{
		passwd.seekg( - record_size, ios::cur);
		last_nonblank=passwd.tellg();
		passwd.read( (char*)&last_id, sizeof(last_id));
	}//end while
	//last_id is not blank

	passwd.read( (char*)&/*******/, sizeof(last_passwd));

	if(record_size*record_number < last_nonblank)
        {
	   //put a copy of the last_nonblank on top of record_number
		passwd./*******/(record_size*record_number);
		passwd.write( (char*)&last_id, sizeof(last_id));
		passwd.write( (char*)&last_passwd, sizeof(last_passwd));
	}
        //hide the old id and password at the end
        passwd./*******/(last_nonblank);
        passwd.write( (char*)&blank_id, sizeof(blank_id));
        passwd.write( (char*)&blank_passwd, sizeof(blank_passwd));
  }else // id not in file
  if( record_number ==0 )
  {
	cerr << "File is empty, " << id << " not found\n";
  }else //id in file with records
  {
	cerr << id << " not found\n";
  }

  passwd.close();

 }
 catch(exception &e)
 {
    cerr<< "Exception thrown: "<< e.what()<<endl;
 } 

}