#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>

#define streq(a,b) (strcmp((a),(b))==0)

static void usage(void) {
    printf("
Usage: scsh [meta-arg] [vm-option+] [end-option scheme-args]

meta-arg: \\ <script-file-name>

switch:	-e <entry-point>	Specify top-level entry point.
	-o <structure>		Open structure in current package.
	-m <package>		Switch to package.
	-n <new-package>	Switch to new package.


	-lm <module-file-name>	Load module into config package.
        -le <exec-file-name>    Load file into exec package.
	-l  <file-name>		Load file into current package.

	-ll <module-file-name>  As in -lm, but search the library path list.
	+lp  <dir>		Add <dir> to front of library path list.
	lp+  <dir>		Add <dir> to end of library path list.
	+lpe <dir>		+lp, with env var and ~user expansion.
	lpe+ <dir>		lp+, with env var and ~user expansion.
	+lpsd			Add script-file's dir to front of path list.
	lpsd+			Add script-file's dir to end of path list.
	-lp-clear		Clear library path list to ().
	-lp-default		Reset library path list to system default.

	-ds 			Do script.
	-dm			Do script module.
	-de			Do script exec.

        -h <cells>              Set heap size.
        -i <file>               Specify image.
        -stacksize <cells>      Set stack size

end-option:	-s <script>	Specify script.
		-sfd <num>	Script is on file descriptor <num>.
		-c <exp>	Evaluate expression.
		--		Interactive session.
");
}

static void bad_args(char* msg, char* arg) {

  printf ("Error:\n");
  printf (msg,arg);
  printf ("\n");
  usage();
  exit(1); 
}


void    process_args(char **argv,
                     long *pheap_size,
                     long *pstack_size,
                     char **pobject_file,
                     char **pimage_name) {
    extern char **process_meta_arg(char **);

    /* Handle an initial \ <fname> meta-arg expansion. */
    while ( *argv && streq(*argv, "\\") ) {
        argv++;
        if( !*argv ) bad_args("No arguments after meta-arg %s","\\");	/* die */
        argv = process_meta_arg(argv);
        if( !argv ) {
            fprintf(stderr, "scsh: \\ <fname> expansion failed.\n");
            exit(1);}}


    for (; *argv; argv++){
        
      char *arg = argv[0];
#define S48_ARGCMP(s) (streq(arg,s))
      
      if (S48_ARGCMP ("-h")) { /* heapsize */
	argv++;
	if( !*argv ) bad_args("Option %s requires an argument", arg); /* die */
	*pheap_size = atoi(*argv);
	if( *pheap_size <= 0 ) bad_args("Invalid argument to %s", arg);
      }
      else if (S48_ARGCMP ("-stacksize")) { /* stacksize */
	argv++;
	if( !*argv ) bad_args("Option %s requires an argument", arg); /* die */
	*pstack_size = atoi(*argv);
	if( *pstack_size <= 0 ) bad_args("Invalid argument to %s", arg);
      }
      else if (S48_ARGCMP ("-i")) { /* image */
	argv++;
	if( !*argv ) bad_args("Option %s requires an argument", arg); /* die */
	*pimage_name = *argv;
      }

      else if (S48_ARGCMP ("+lpsd") ||
	       S48_ARGCMP ("lpsd+") ||
	       S48_ARGCMP ("-lp-clear") ||
	       S48_ARGCMP ("-lp-default") ||
	       S48_ARGCMP ("-ds") ||
	       S48_ARGCMP ("-dm") ||
	       S48_ARGCMP ("-de")){
	;
      }
      else if (S48_ARGCMP ("-e") ||
	       S48_ARGCMP ("-o") ||
	       S48_ARGCMP ("-m") ||
	       S48_ARGCMP ("-lm") ||
	       S48_ARGCMP ("-le") ||
	       S48_ARGCMP ("-l") ||
	       S48_ARGCMP ("-ll") ||
	       S48_ARGCMP ("+lp") ||
	       S48_ARGCMP ("lp+") ||
	       S48_ARGCMP ("+lpe") ||
	       S48_ARGCMP ("lpe+")){
	argv++;
	if( !*argv ) bad_args("Option %s requires an argument", arg);
      }
      
      /* These switches terminate arg scanning. */
      else if (S48_ARGCMP ("-s") ||
	       S48_ARGCMP ("-sdf") ||
	       S48_ARGCMP ("-c")){
	argv++;
	if( !*argv ){
	  bad_args("Option %s requires an argument", arg);
	}
	return;
      }
      else if (S48_ARGCMP ("--")) {
	return;
      }
      else{
	bad_args("Unknown switch %s", arg);
      }
    }
		
#undef S48_ARGCMP

    return;
}