/* args.c : parses argc,argv arguments
 * PUBLIC DOMAIN - March 31, 2009 - Jon Mayo
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "args.h"

/* default function that displays the usage */
static void fallback_usage(const char *program_name, const struct arginfo *ai, size_t nr_args) {
	/* TODO: process args */
	size_t i;
	fprintf(stderr, "usage: %s\n", program_name);
	for(i=0;i<nr_args;i++) {
		if(ai[i].name) {
			fprintf(stderr, "  %-13s %s\n", ai[i].name, ai[i].description?ai[i].description:"");
		}
	}
}

/* processes an arginfo list.
 * ai, nr_args - the arginfo list and its length
 * usage - function to override fallback_usage(), NULL to use fallback
 * q - pointer that is passed to all the function callbacks in the arginfo list
 * argc,argv - program arguments
 */
int args_parser(const struct arginfo *ai, size_t nr_args, void (*usage)(const char *program_name, const struct arginfo *ai, size_t nr_args), void *q, int argc, char **argv) {
	int i;
	size_t j;
	const char *opt;
	const char *program_name;

	/* set program_name to something without paths */
	if(!(program_name=strrchr(argv[0], '/'))) program_name=argv[0]; else program_name++;

	/* use a fallback usage if one was not supplied */
	if(!usage) usage=fallback_usage;

	for(i=1;i<argc;i++) {
		/* DEBUG: fprintf(stderr, "argv[%d]=\"%s\"\n", i, argv[i]); */
		for(j=0;j<nr_args;j++) {
			if(!strcasecmp(argv[i], ai[j].name)) {
				if(ai[j].has_parameter && i+1>=argc) {
						fprintf(stderr, "Error: option '%s' takes an argument.\n", ai[j].name);
						goto usage;
				}
				opt=ai[j].has_parameter?argv[++i]:NULL;
				if(ai[j].func_cb) {
					if(!ai[j].func_cb(ai[j].name, opt, ai[j].p, q)) {
						fprintf(stderr, "Error: failed with option '%s'.\n", ai[j].name);
						goto usage;
					}
				}
				goto success; /* we processed a parameter successfully */
			}
		}
		/* display an error message if we got here when the option wasn't -help */
		if(strcasecmp(argv[i], "-help")) {
			fprintf(stderr, "Error: unknown command-line option '%s'.\n", argv[i]);
		}
usage:
		usage(program_name, ai, nr_args);
		exit(EXIT_FAILURE);
success:
		;
	}
	return 1; /* success */
}

/* use the void *p to set an int through (int*) */
int args_cbset_intptr(const char *name, const char *param, void *p, void *q) {
	char *endptr;
	int *intp=p;
	if(intp) {
		*intp=strtol(param, &endptr, 0);
		if(endptr!=param && !*endptr) {
			return 1; /* success */
		}
	}

	return 0; /* failure */
}

/* use the void *p to set a long through (long*) */
int args_cbset_longptr(const char *name, const char *param, void *p, void *q) {
	char *endptr;
	long *longp=p;
	if(longp) {
		*longp=strtol(param, &endptr, 0);
		if(endptr!=param && !*endptr) {
			return 1; /* success */
		}
	}

	return 0; /* failure */
}

/* use the void *p to set a string through (const char**) */
int args_cbset_charptrptr(const char *name, const char *param, void *p, void *q) {
	const char **strptr=p;
	if(strptr) {
		*strptr=param;
		return 1; /* success */
	}

	return 0; /* empty */
}