/////////////////////////////////////////////////////////////////////////
// fileio.cpp - demonstrate basic file reading and writing
//              and command line argument handling 
//
// Jim Fawcett, ELE591/791 - Intelligent Systems, Summer 2000
//
/////////////////////////////////////////////////////////////////////////
// Demo Program: Reads first few lines of a file as directed by
//               command line inputs
//
//               Expects a command line of the form:
//                   /17 file1.txt file2.cpp *.h ...
//
//               Demonstrates basic I/O, file I/O, and in memory I/O 
/////////////////////////////////////////////////////////////////////////

#include <sstream>    // string stream module
#include <fstream>    // file stream module
#include <iostream>   // basic I/O module
#include <iomanip>    // manipulators module
#include <string>     // standard strings module

using namespace std;

//----< show command line arguments >--------------------------

void displayCommandLine(int argc, char *argv[],ostream &out) {

  int i;

  // first argument is name of executing image

  out << "\n  command line arguments are:\n    " 
      << argv[0] << "\n    ";
  
  // arguments to the executing image

  for(i=1; i<argc; i++)
    out << argv[i] << ' ';
  out << '\n';
}

//----< does this string represent a command line command? >---

bool isCommand(const char *s) {

  if(s[0] == '/' || s[0] == '-')
    return true;
  return false;
}

//----< does this string contain a wild card? >----------------
//
//  uses standard string find() member function

bool isUnexpandedArgument(const string &s) {

  if(s.find("*") < s.size())
    return true;
  if(s.find("?") < s.size())
    return true;
  return false;
}

//

//----< extract integer value after '/' or '-' >---------------

int getCommand(const char *s) {

  istringstream temp(&s[1]);
  int value;
  temp >> value;    // convert string to integer
  if(temp.good())   // succeeded ?
    return value;
  if(temp.eof())    // succeeded and exhausted string
    return value;
  return 0;         // could not read integer
}

//----< display first maxLines of file text >------------------
//
//  uses global function getline(istream, string)
//  defined in string module <string>

void processFile(istream &in, ostream &out, int maxLines) {

  string line;
  int lineCount = 0;
  while(in.good() && lineCount < maxLines) {
    getline(in,line);
    out << "\n" << setw(4) << ++lineCount << " " << line;
  }
  out << "\n\n";
}

//----< display file tops >------------------------------------
//
//  Accept directions from command line or user, then display
//  file data accordingly.

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

  cout << "\n  Display Top Few Lines of File "
       << "\n ===============================\n";

  displayCommandLine(argc,argv,cout);

  int maxLines = 10;
  ifstream in;

  if(argc == 1) {
    
  // no command line arguments

    string s;
    cout << "\n  please enter the name of a data file to read: ";
    cin  >> s;

    in.open(s.c_str());
    processFile(in,cout,maxLines);
    in.close();
  }

//

  else {

  // found command line arguments

    int i;
    for(i=1; i<argc; i++) {

      if(isCommand(argv[i]))
        maxLines = getCommand(argv[i]);

      else if(isUnexpandedArgument(argv[i])) {

      // Visual C++ command line processing expands
      // wild cards if there are matches, but leaves
      // argument with wild card if there are no matches

        cout << "\n  unexpanded argument \"" << argv[i] << '\n';
      }

      else {

      // attempt to open file with command line argument as name

        in.open(argv[i]);
        if(in.good()) {

        // open succeeded

          processFile(in,cout,maxLines);
        }
        else {

        // no file name matching this argument

          cout << "\n  can't interpret argument \"" 
               << argv[i] << "\"" << "\n";
        }

      // streams go bad once we read end of file marker
      // they can't be used again until error is cleared

        in.close();  // quirk of VC++ iostreams implementation
        in.clear();  // requires close() to come first
      }
    }
  }
}