/* command shell */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

/*
  <shell program> ::= { <line> }
  <line> ::=
*/

#define LINELEN 4096
#define MAXARGS 64

void process_line() {
	char buffer[LINELEN];
	char * argv[MAXARGS];
	int argc;
	int pos;

	fgets( buffer, LINELEN-1, stdin );
	buffer[ LINELEN-1 ] = '\n';

	/* FIX THIS LATER - no code to detect end of file */

	/* note that the following logic is really stupid */
	/* FIX THIS LATER - argument parsing should be a subroutine */

	/* pick apart the line into argv, argc */
	argc = 0;
	pos = 0;
	for (;;) {
		while (buffer[pos] == ' ') pos++;
		if (buffer[pos] == '\n') break;

		/* we have start of parameter */
		argv[ argc ] = &buffer[pos];
		argc = argc + 1;
		if ( argc >= (MAXARGS - 1) ) break;
		while (buffer[pos] > ' ') pos++;
	}

	/* null terminate all arguments */
	argv[ argc ] = NULL;
	for (argc = 0; argv[ argc ] != NULL; argc++) {
		char * pos = argv[ argc ];
		while (*pos > ' ') pos++;
		*pos = '\0';
	}

	/* FIX THIS LATER - no code to detect and ignore comments */

	/* launch application */
	/* FIX THIS LATER - it ought to check for the right event */
	/* FIX THIS LATER - applications launch ought to be a subroutine */
	if ( fork() ) { /* parent */
		wait();
	} else { /* child */
		/* FIX THIS LATER - Pass on caller's environment */
		/* FIX THIS LATER - Use a search path to find application */
		execve( argv[0], argv, NULL );
		fprintf( stderr, "%s: command not found\n", argv[0] );
		exit( EXIT_FAILURE );
	}
}

int main() {
	for (;;) process_line();
}