//------------------------------------------
// Proj3-4.C - advanced solution to project 3
//
//  Dennis L. Frey  CMSC 202  Fall 2002
//
// This program uses an advanced coding technique
// known as a jump table.  this table contains
// the addresses of the functions to be called.
// This eliminates the need for the switch statement
// in Proj3-3.C
//  To use this technique, all functions must have
// the same prototype, so the functions Books()
// and Patrons() take an ifstream as a new parameter
// even though they are not used.
//-------------------------------------------------
//
// If a new command is added, just add the command
// string to the array of commands, the name of 
// the function to the array of function pointers
// and write the function
//
//----------------------------------------------
// With this many functions, it's probably a good idea
// to create an auxiliary .C and .H file.

//-----------------------------------------------
#include <iostream>
#include <fstream>
#include <string>

#include "library.H"
using namespace std;

// function prototypes for functions
// in this file. Note all command related
// functions need the  same prototype
// to be used in the jump table
void AddBook      (ifstream& in, Library& lib);
void AddPatron    (ifstream& in, Library& lib);
void Books        (ifstream& in, Library& lib);
void CheckIn      (ifstream& in, Library& lib);
void CheckOut     (ifstream& in, Library& lib);
void Patrons      (ifstream& in, Library& lib);
void PatronsBooks (ifstream& in, Library& lib);
bool ReadLine  (ifstream& in, string& s);

// array of command strings
// same order as const ints above
const int NRCOMMANDS   = 7;
const string commands[NRCOMMANDS] =
{"ADDBOOK", "ADDPATRON", "BOOKS", "PATRONS",
 "CHECKIN", "CHECKOUT",  "PATRONSBOOKS"
};

// an array of pointers to void functions
// this array must be in the same order as the 
// the list of commands above
void (*funcs[NRCOMMANDS])(ifstream& in, Library& lib) =
{ AddBook, AddPatron, Books, Patrons,
  CheckIn, CheckOut, PatronsBooks
};

int main (int argc, char *argv[] )
{
   // check number of command line args
   if (argc != 2)
   {
      cerr << "Usage: Proj2 <filename>" << endl;
      exit (-1);
   }
   
   // instantiate and open the file
   ifstream infile (argv[1]);
   if (!infile)
   {
      cerr << "Unable to open file: " << argv[1] << endl;
      exit (-2);
   }

   // a-ok, instantiate library
   Library library;
   string command;

      
   // loop until no more commands
   while (ReadLine (infile, command))
   {
      // switch to function for the command
      // 'while' uses short-circuit evaluation
      int i = 0;   
      while ((i < NRCOMMANDS) && (commands[i] != command))
	 i++;

      if (i < NRCOMMANDS)
	 // call function associated with the command
	 (*funcs[i]) (infile, library);
      else
	 cerr << "Invalid command: " << command << endl;
   }
   return 0;
}

//-----------------------------------------------
// AddBook
//  Reads title and author from file, echos command
// and adds the book to the library
//-----------------------------------------------
void AddBook (ifstream& infile, Library& library)
{
   string title, author;

   ReadLine (infile, title);
   ReadLine (infile, author);
   cout << "ADDBOOK: " << title << ", " << author << endl;
   library.AddBook (title, author);
}

//--------------------------------------------
// AddPatron
//   reads patron info from the file
//   echos command and adds patron to library
//--------------------------------------------
void AddPatron (ifstream& infile, Library& library)
{
    string name;
    ReadLine (infile, name);
    cout << "COMMAND:ADDPATRON, "<< name << endl;
    library.AddPatron (name);
}

//--------------------------------------------
// Books
//   Prints all books in the library 
//-------------------------------------------
void Books ( ifstream& in,  Library& library)
{
   cout << "COMMAND:BOOKS" << endl;	 
   library.ListBooks( );

}

//----------------------------------------------
// CheckIn
//  reads title from input file, echos
// command and checks in book 
//----------------------------------------------
void CheckIn (ifstream &infile, Library& library)
{
    string title;
    ReadLine (infile, title);
    cout << "COMMAND:CHECKIN, " << title << endl;
    library.CheckIn (title);
}


//-------------------------------------------------
// CheckOut
//  Reads title and patron from file, echos command
// checks out book if no errors detected
//-------------------------------------------------
void CheckOut (ifstream& infile, Library& library)
{
   string title, patron;

   ReadLine (infile, title);
   ReadLine (infile, patron);
   cout << "CHECKOUT: " << title << ", " << patron << endl;
   library.CheckOut (title, patron);
}


//---------------------------------------
// Patrons
//   Lists all patrons in the library
//-----------------------------------------
void Patrons ( ifstream& in,  Library& library)
{
    cout << "COMMAND:PATRONS" << endl;	 
    library.ListPatrons( );
}

//------------------------------------------------
// PatronsBooks
//    Reads patron's name from file and lists
// books he has checkedout of library
//------------------------------------------------
void PatronsBooks (ifstream& infile,  Library& library)
{
    string name;
    ReadLine (infile, name);
    cout << "COMMAND:PATRONSBOOKS, " << name << endl;
    library.ListPatronsBooks (name);
}

//------------------------------------------------
// ReadLine
// skips blank lines in the file
// returns true if non-blank line read (and s = "")
// returns false on eof (and s contains string read)
//-------------------------------------------------
bool ReadLine (ifstream& in, string& s)
{
   s = "";  // empty string with length==0

   // loop until eof or non-blank string read
   while (!in.eof( ) && s.length() == 0)
   {
      getline (in, s);
      if (s.length() != 0)
	 return true;
   }

   // eof
   return false;
}