//See if semaphor will work

//Include files
#include <string.h>
#include <fstream.h>
#include <iomanip.h>
#include <unistd.h>

//Constant definitions
const char LOW_MENU  = '1';
const char HIGH_MENU = '5';
const char* const CHECKED_OUT_FILENAME = "check.out";  //Check this
const char* const SEMAPHOR = "LOCK";
const int STRING_LENGTH = 20;
const int MAX_FILES = 100;

//Typedefs
typedef char str[STRING_LENGTH];

//Global variables
char id[80];  //The current user

//Prototypes
void Clear_Screen();
void Pause();
void Menu();
char Get_Choice();
bool Process_Choice(char);
void Check_Out();
void Check_In();
void View_Checked_Out();
void Dir();
bool End();
int Read_File(ifstream&, str[], str[]);
bool Get_Semaphor();
void Release_Semaphor();

int main () {
   char choice;
   bool DONE = false;
   Clear_Screen();
   cout << "Enter your user id : ";
   cin >> id;

   while (!DONE) {
      Menu();
      choice = Get_Choice();
      DONE = Process_Choice(choice);
      if (DONE)
         DONE = End();
      if (!DONE)
         Pause();
   } //End of while
}

//--------------------------Function Definitions-------------------------


void Clear_Screen() {
cout << "\033[;H\033[2J" << flush;
}

void Pause() {
   char junk[80];
   cout << "Press <RETURN> to continue.";
   cin.ignore(80,'\n');
   cin.getline(junk, 80, '\n');
}

void Menu() {
   Clear_Screen();
   cout << "        *************\n"
        << "        * Main Menu *\n"
        << "        *************\n"
        << "    1. Check out a file\n"
        << "    2. Check in a file\n"
        << "    3. View checked out files\n"
        << "    4. Directory\n"
        << "    5. End session/Check in files\n\n"
        << " ID : " << id << "\n\n";
   }

char Get_Choice() {
   char choice;
   bool VALID = false;

   while (!VALID) {
      cout << "Choice (V to view menu) :";
      cin >> choice;
      if (choice == 'V' || choice == 'v')
         Menu();
      else if (choice >= LOW_MENU && choice <= HIGH_MENU)
              VALID = true;
           else
              cout << "Invalid choice...Re-enter.\n";
      } //End of while
   return choice;
}

bool Process_Choice(char choice) {
   bool DONE = false;
   switch (choice) {
      case HIGH_MENU : DONE = true; break;
      case '4': Dir(); break;
      case '3': View_Checked_Out(); break;
      case '2': Check_In(); break;
      case '1': Check_Out(); break;
      default : cerr << "Error in code in function Process_Choice\n";
                DONE = true; break;
      }
   return DONE;
}

void View_Checked_Out() {
ifstream fin(CHECKED_OUT_FILENAME);
char file[STRING_LENGTH];
char name[STRING_LENGTH];
if (! (fin >> file)) {
   cout << "No files checked out.\n\n\n";
   fin.close();
   return;
   }
fin.close();
fin.open(CHECKED_OUT_FILENAME);
cout << "File                                Owner\n"
     << "----------------------------------------------\n";
while (fin >> file) {
   fin >> name;
   cout << setiosflags(ios::left) << setw(STRING_LENGTH) << file
        << resetiosflags(ios::left) << setiosflags(ios::right)
        << setw(STRING_LENGTH) << name << resetiosflags(ios::right)
        << endl;
   } //End of while
cout << "\n\n";
}

void Check_Out() {
if (!Get_Semaphor())
   return;   
str file; 
str file2;
str name;
cout << "Enter file to check out :";
cin >> file;
ifstream fin(CHECKED_OUT_FILENAME);
if (fin) {
   bool FOUND = false;
   while (fin >> file2 && !FOUND) {
      fin >> name;
      if (strcmp(file2,file) == 0)
         FOUND = true;
      }
   fin.close();
   if (FOUND)
      cout << file << " is already checked out by " << name << "\n\n\n";
   else {
      ofstream fout(CHECKED_OUT_FILENAME,ios::app);
      fout << file << endl << id << endl;
      fout.close();
      cout << "You have checked out " << file << ".\n\n\n";
      }
   }
else {
   fin.close();
   ofstream fout(CHECKED_OUT_FILENAME);
   fout << file << endl << id << endl;
   fout.close();
   cout << "You have checked out " << file << ".\n\n\n";
   }
Release_Semaphor();
} //End of Check_Out

int Read_File(ifstream& fin, str names[], str files[])
{
int count = 0;
while (fin >> files[count]) {
   fin >> names[count];
   count++;
   } //End of while
return count;
}

void Release_Semaphor()
{
str junk = "";
ofstream fout(SEMAPHOR);
fout << junk;
fout.close();
}

bool Get_Semaphor()
{
str junk = "";
ifstream fin(SEMAPHOR);
fin >> junk; 
fin.close();
if (strcmp(junk,SEMAPHOR) == 0) {
   cout << "File being updated...try later.\n\n\n";
   return false;
   }
ofstream fout(SEMAPHOR);
fout << SEMAPHOR;
fout.close();
return true;
}

void Check_In()
{
if (!Get_Semaphor())
   return;
str names[MAX_FILES];
str files[MAX_FILES];
str filename;

int count = 0;
ifstream fin(CHECKED_OUT_FILENAME);
count = Read_File(fin, names, files);
fin.close();
if (count == 0) {
   cout << "No files to check in.\n\n\n";
   return;
   }
cout << "Name of file to check in : ";
cin >> filename;

//Search for filename
int i;
for (i=0; i < count; i++) 
  if (strcmp(filename, files[i]) == 0)
     break;

if (strcmp(names[i],id) != 0)
   cout << "You don't own that file!\n\n\n";
else {
   int x;
   ofstream fout(CHECKED_OUT_FILENAME);
   for (x=0; x<i; x++) 
      fout << files[x] << endl << names[x] << endl;
   for (x=i+1; x < count; x++)
      fout << files[x] << endl << names[x] << endl;
   fout.close();
   cout << filename << " checked in.\n\n\n";
   } //End of else
Release_Semaphor();
} // End of Check_In

void Dir()
{
str command;
cout << "Enter an additional parameter (optional) : ";
cin.ignore(80,'\n');
cin.getline (command, STRING_LENGTH, '\n');
if (fork() == 0)
   execlp ("ls","ls", command, NULL);
sleep(2);
cin.putback('\n');
}

bool End()
{
if (!Get_Semaphor())
   return false;
str names[MAX_FILES];
str files[MAX_FILES];
str filename;
int x;
int count = 0;

ifstream fin(CHECKED_OUT_FILENAME);
if (!fin) {
   cout << "No files checked out.\n\n\n";
   return true;
   }
count = Read_File(fin, names, files);
fin.close();
ofstream fout(CHECKED_OUT_FILENAME);
for (x-0; x<count; x++)
   if (strcmp(names[x],id) !=0)
      fout << files[x] << endl << names[x];
   else 
      cout << "Checking in " << files[x] <<"...\n";
fout.close();
Release_Semaphor();
return true;
}