/* Gales Scheme executable entry point and option parser
 * J. Welsh, 2017
 */

#include "gscm.h"

#ifndef GSCM_DEF_HEAP
#define GSCM_DEF_HEAP 128
#endif

#define STR_(token) #token
#define STR(token_or_macro) STR_(token_or_macro)

static const char usage[] =
"Usage: gscm [-Hcgh] [-m SIZE] [--] [FILE [ARG ...]]"
"\n"
"\nExecute Scheme source FILE (- for standard input, unless -- is used), with FILE and any ARGs stored in the global list *ARGS*. If no FILE is given, start a read-eval-print loop."
"\n"
"\n-H: Use huge pages if supported"
"\n-c: Load saved core instead of source (TODO)"
"\n-g: Print memory stats to standard error on garbage collection"
"\n-h: Print this help message"
"\n-m: Heap size in MiB. Twice this is fully allocated at startup from the OS kernel's point of view (half reserved for garbage collection). A larger heap reduces GC frequency but may increase virtual memory overhead (TLB thrashing)."
"\n"
"\nBuild configuration:"
"\n Word size (bytes): " STR(__SIZEOF_POINTER__)
"\n Default heap (-m): " STR(GSCM_DEF_HEAP)
"\n Library path: " GSCMLIB
"\n";

/* Strictly parse non-negative decimal integer in null-terminated string src. On success, return true and store the result in dst. On failure (empty string, non-digit or overflow), return false. */
static int parse_ulong_dec(unsigned long *dst, const char *src) {
	unsigned long acc = 0;
	if (!*src) return 0;
	do {
		unsigned char digit = ((unsigned char)(*src)) - '0';
		if (digit > 9) return 0;
		if (acc > (-1UL)/10) return 0;
		acc *= 10;
		if (acc + digit < acc) return 0;
		acc += digit;
	} while (*++src);
	*dst = acc;
	return 1;
}

int main(int argc, char **argv) {
	sc_value heap_mb = GSCM_DEF_HEAP, heap_alloc;
#define SHIFT (++argv, --argc)
	if (argc) SHIFT;
	while (argc) {
		char *arg = *argv;
		if (arg[0] != '-' || !arg[1] || (arg[1] == '-' && !arg[2])) break;
		while (*++arg) switch (*arg) {
			case 'H':
				sc_hugepages = 1; break;
			/* case 'c': break; */
			case 'g':
				sc_gc_verbose = 1; break;
			case 'h':
				sc_write_error(usage); return 0;
			case 'm':
				if (!*++arg) {
					SHIFT;
					if (!argc) {
						sc_write_error("gscm: -m missing argument\n");
						goto err;
					}
					arg = *argv;
				}
				if (!(parse_ulong_dec(&heap_mb, arg) && heap_mb)) {
					sc_write_error("gscm: bad -m argument\n");
					goto err;
				}
				goto next_arg;
			default:
				{
					char tail[] = {*arg, '\n', 0};
					sc_write_error("gscm: bad option: ");
					sc_write_error(tail);
					goto err;
				}
		}
next_arg:
		SHIFT;
	}
	heap_alloc = heap_mb<<21;
	if (heap_alloc>>21 != heap_mb) {
		sc_write_error("gscm: heap size too big (integer overflow)\n");
		return 1;
	}
	sc_init(heap_alloc);
	return sc_toplevel(argc, argv);
err:
	sc_write_error(usage);
	return 1;
}