#!/usr/bin/env slsh

% This is a simple-minded implementation of a highlighting grep program
% designed to test the pcre module.
import ("pcre");

static define usage ()
{
   ()=fprintf(stderr, "Usage: %s [-inl] pattern [files...]\n", __argv[0]);
   exit (1);
}

static variable MATCH = 1;
static variable LINENUM = 2;
static variable FILENAME = 4;
static variable Output_Format = 0;

static define grep (file, p)
{
   variable fp;
   
   if (file == NULL)
     fp = stdin;
   else
     fp = fopen (file, "r");
   
   if (fp == NULL)
     {
	fprintf (stderr, "*** Unable to open %s\n", file);
	return;
     }

   variable linenum = 0;
   foreach (fp) using ("line")
     {
	variable str = ();
	linenum++;

	if (pcre_exec (p, str, 0))
	  {
	     variable i0, i1, i;

	     switch (Output_Format)
	       {
		case FILENAME:
		  () = fprintf (stdout, "%s\n", file);
		  return;
	       }
	       {
		case LINENUM:
		  () = fprintf (stdout, "%d\n", linenum);
		  continue;
	       }
	       {
		case (MATCH|LINENUM):
		  
		  () = fprintf (stdout, "%d:", linenum);
	       }
	       {
		case (LINENUM|FILENAME):
		  () = fprintf (stdout, "%s:%d\n", file, linenum);
		  continue;
	       }
	       {
		case (LINENUM|FILENAME|MATCH):
		  () = fprintf (stdout, "%s:%d:", file, linenum);
	       }
	       {
		case (FILENAME|MATCH):
		  () = fprintf (stdout, "%s:", file);
	       }
	       
	     do
	       {
		  i = pcre_nth_match (p, 0);
		  i0 = i[0];
		  i1 = i[1];
		  if (i1 <= i0)
		    break;
		  if (i0 > 0)
		    () = fprintf (stdout, "%s", str[[0:i0-1]]);
		  () = fprintf (stdout, "\e[7m%s\e[m", str[[i0:i1-1]]);
		  str = str[[i1:]];
	       }
	     while (pcre_exec (p, str, 0));
	     () = fprintf (stdout, "%s", str);
	  }
     }
}

static define main (argc, argv)
{
   variable i;
   variable files, pattern;
   variable options;
   
   i = 1;
   files = NULL;
   pattern = NULL;
   options = 0;
   Output_Format = MATCH;

   while (i < argc)
     {
	variable arg = __argv[i];
	i++;

	if (arg[0] == '-')
	  {
	     foreach (arg[[1:]])
	       {
		  variable ch = ();
		  switch (ch)
		    {
		     case 'i':
		       options |= PCRE_CASELESS;
		    }
		    {
		     case 'l':
		       Output_Format &= ~MATCH;
		       Output_Format |= FILENAME;
		    }
		    {
		     case 'n':
		       Output_Format |= LINENUM;
		    }
		    {
		       () = fprintf (stderr, "Unsupported option: '%c'\n", ch);
		       exit (1);
		    }
	       }
	     continue;
	  }
		       
	pattern = arg;
	break;
     }

   if (pattern == NULL)
     usage ();

   variable p = pcre_compile (pattern, options);

   if (i == __argc)
     {
	if (isatty (stdin))
	  usage ();

	Output_Format &= ~FILENAME;
	grep (NULL, p);
	return;
     }
   
   files = argv[[i:]];

   if (length(files) > 1)
     Output_Format |= FILENAME;

   foreach (files)
     {
	variable f = ();
	grep (f, p);
     }
}

public define slsh_main ()
{
   main (__argc, __argv);
   exit (0);   
}