/////////////////////////////////////////////////////////////////////////
//                                                                     //
// top.c      -  display first few lines of text file                  //
// ver 1.2                                                             //
//                                                                     //
// Language:     Visual C++, ver 6.0                                   //
// Platform:     Micron dual Pentium Pro 200, Win NT 4.0, SP 3.0       //
// Application:  CSE784 demonstration                                  //
// Author:       Jim Fawcett, CST 2-187, Syracuse University           //
//               (315) 443-3948, fawcett@ecs.syr.edu                   //
//                                                                     //
/////////////////////////////////////////////////////////////////////////
//                                                                     //
//  Program Operations:                                                //
//  ===================                                                //
//  This is a simple demonstration of how modules are constructed      //
//  and used to partition a program.                                   //
//                                                                     //
//  This program displays the first few lines of a text file.  It      //
//  uses the services of module lines for building lines of text from  //
//  files or by copying other lines.  It also uses the services of     //
//  module open to attach files for reading.                           //
//                                                                     //
//  Program will expand wildcards in filenames on command line if      //
//  linked with wildargs.obj (see below).                              //
//                                                                     //
/////////////////////////////////////////////////////////////////////////
//                                                                     //
//  Build Process                                                      //
//                                                                     //
//  Files Required:                                                    //
//    top.c, open.h, open.c, lines.h, lines.c,                         //
//                                                                     //
//  Integrated Environment:                                            //
//  - open project citing all *.c files above                          //
//  - add setargv.obj to Object/Modules: edit box in                   //
//    Project/Settings/Link                                            //
//  - enter *.h *.c* in Program Arguments edit box in                  //
//    Project/Settings/Debug                                           //
//  - compile, link, and run                                           //
//                                                                     //
//  Command Line Environment:                                          //
//    cl /GX top.c open.c lines.c setargv.obj                          //
//                                                                     //
/////////////////////////////////////////////////////////////////////////
/*

   Maintenance History:
     ver 1.2 : 15 Jan 00
       - cosmetic changes to these comments
     ver 1.1 : 31 Mar 97
       - added expand option
     ver 1.0 : 05 Sep 96
       - first release


*/

/**/

///////////////////////////////////////////////////////////////
//                                                           //
//                    definitions                            //
//                                                           //
///////////////////////////////////////////////////////////////

#include <stdlib.h>  /* free()                               */
#include <stdio.h>   /* fprintf()                            */
#include <ctype.h>   /* isalpha()                            */
#include <string.h>  /* strlen()                             */
#include "open.h"    /* getRStream(char*), getWStream(char*) */
#include "lines.h"   /* getLine(fptr)                        */


static int expand = 0;       /* send ff to output? */


/*----< display first few lines of file >----------------------

  Processing:
  - read numLines lines from input stream in
  - display on stdout
  Inputs:
  - numLines is the number of lines to be displayed
  - input FILE stream in
  Outputs:
  - numLines lines sent to stdout
*/

void display(int numLines, FILE *in) {

  int i;
  char *line=0;
  for(i=0; i<numLines; i++) {
    if(!(line = getLine(in)))
      break;
    if(strlen(line) > 75) line[75] = '\0';
    fprintf(stdout, "%s\n", line);
    free(line);
  }
  fprintf(stdout, "\n");
}

/**/

/*----< parse command line, open files, display top lines >----

  Processing:
  - process commands to set number of lines displayed
  - open files cited on command line and display
  Inputs:
  - argc is the number of arguments on command line
  - argv is an array of pointers to command line arguments
  Outputs:
  - displays top lines for each existing file cited on command line
*/

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

  FILE  *in=0;
  int files=0, i;
  int numLines = 10;   /* default display size  */

/* parse command line and open named files */
  for(i=1; i<argc; i++) {
    if(argv[i][0] == '-') {
      if(argv[i][1] == 'e')
      	expand = 1;
      else
	      numLines = atoi(&argv[i][1]);
    }
    if(isalpha(argv[i][0])) {
      files++;
      in  = getRStream(argv[i]);    /* 1st file is input  */
      if(!in)
      	break;
      else {
      	fprintf(stdout,"File: %s\n\n",argv[i]);
      	display(numLines,in);
      	if(expand && i < argc-1) 
	        fprintf(stdout,"\f");
      }
    }
  }

/* didn't find any files on command line */
  if(!files)
    if((in = getRStream(0)) != 0)
      display(numLines,in);
}