/*
 * Copyright © 2021-2022 Nick Bowler
 *
 * Helper functions for formatting --help program output.
 *
 * In order to support localized output, this depends on the Gnulib gettext-h
 * and mbswidth modules.  However, if ENABLE_NLS is not defined (or defined to
 * 0) then these modules are not required.
 *
 * License WTFPL2: Do What The Fuck You Want To Public License, version 2.
 * This is free software: you are free to do what the fuck you want to.
 * There is NO WARRANTY, to the extent permitted by law.
 */

#if HAVE_CONFIG_H
#	include <config.h>
#endif
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <limits.h>
#include <getopt.h>

#include "help.h"

#ifndef ENABLE_NLS
#	define ENABLE_NLS 0
#endif

#if ENABLE_NLS
#	include <locale.h>
#	include <gettext.h>
#	include <mbswidth.h>
#else
#	define gettext(s) (s)
#	define pgettext_expr(c, s) (s)
#	define mbsnwidth(a, b, c) (assert(0), 0)
#endif

#define _(s) gettext(s)

/* Returns a single numeric value depending on the type of option:
 *
 *   6 - if the option has a short option character and an optional argument
 *   5 - if the option has a short option character and a mandatory argument
 *   4 - if the option has a short option charater and no argument
 *   3 - N/A
 *   2 - if the option has no short option character and an optional argument
 *   1 - if the option has no short option character and a mandatory argument
 *   0 - if the option has no short option character and no argument
 */
static int option_type(const struct option *opt)
{
	int ret = opt->has_arg & 3;

	if (!opt->flag)
		ret |= (opt->val <= CHAR_MAX) << 2;

	return ret;
}

enum {
	OPT_SHORT_WITH_OPTIONAL_ARG  = 6,
	OPT_SHORT_WITH_MANDATORY_ARG = 5,
	OPT_SHORT_WITHOUT_ARG        = 4,
	OPT_LONG_WITH_OPTIONAL_ARG   = 2,
	OPT_LONG_WITH_MANDATORY_ARG  = 1,
	OPT_LONG_WITHOUT_ARG         = 0,
};

int help_print_optstring(const struct option *opt, const char *argname, int l)
{
	char optstring[100];
	int w;

	if (!ENABLE_NLS)
		goto no_translate;

	switch (option_type(opt)) {
#if HELP_GETOPT_LONG_ONLY
	case OPT_SHORT_WITH_OPTIONAL_ARG:
	case OPT_LONG_WITH_OPTIONAL_ARG:
		w = snprintf(optstring, sizeof optstring,
		             _("  -%s [%s]"), opt->name,
		             pgettext_expr(opt->name, argname));
		break;
	case OPT_SHORT_WITH_MANDATORY_ARG:
	case OPT_LONG_WITH_MANDATORY_ARG:
		w = snprintf(optstring, sizeof optstring,
		             _("  -%s %s"), opt->name,
		             pgettext_expr(opt->name, argname));
		break;
	case OPT_SHORT_WITHOUT_ARG:
	case OPT_LONG_WITHOUT_ARG:
		w = snprintf(optstring, sizeof optstring,
		             _("  -%s"), opt->name);
		break;
#else
	case OPT_SHORT_WITH_OPTIONAL_ARG:
		w = snprintf(optstring, sizeof optstring,
		             _("  -%c, --%s[=%s]"), opt->val, opt->name,
		             pgettext_expr(opt->name, argname));
		break;
	case OPT_LONG_WITH_OPTIONAL_ARG:
		w = snprintf(optstring, sizeof optstring,
		             _("  --%s[=%s]"), opt->name,
		             pgettext_expr(opt->name, argname));
		break;
	case OPT_SHORT_WITH_MANDATORY_ARG:
		w = snprintf(optstring, sizeof optstring,
		             _("  -%c, --%s=%s"), opt->val, opt->name,
		             pgettext_expr(opt->name, argname));
		break;
	case OPT_LONG_WITH_MANDATORY_ARG:
		w = snprintf(optstring, sizeof optstring,
		             _("  --%s=%s"), opt->name,
		             pgettext_expr(opt->name, argname));
		break;
	case OPT_SHORT_WITHOUT_ARG:
		w = snprintf(optstring, sizeof optstring,
		             _("  -%c, --%s"), opt->val, opt->name);
		break;
	case OPT_LONG_WITHOUT_ARG:
		w = snprintf(optstring, sizeof optstring,
		             _("  --%s"), opt->name);
		break;
#endif
	default:
		assert(0);
	}

	if (w < 0)
		goto no_translate;

	w = mbsnwidth(optstring, w, 0);
	printf("%s", optstring);
	goto out;

no_translate:
	switch (option_type(opt)) {
#if HELP_GETOPT_LONG_ONLY
	case OPT_SHORT_WITH_OPTIONAL_ARG:
	case OPT_LONG_WITH_OPTIONAL_ARG:
		w = printf("  -%s [%s]", opt->name, argname);
		break;
	case OPT_SHORT_WITH_MANDATORY_ARG:
	case OPT_LONG_WITH_MANDATORY_ARG:
		w = printf("  -%s %s", opt->name, argname);
		break;
	case OPT_SHORT_WITHOUT_ARG:
	case OPT_LONG_WITHOUT_ARG:
		w = printf("  -%s", opt->name);
		break;
#else
	case OPT_SHORT_WITH_OPTIONAL_ARG:
		w = printf("  -%c, --%s[=%s]", opt->val, opt->name, argname);
		break;
	case OPT_LONG_WITH_OPTIONAL_ARG:
		w = printf("  --%s[=%s]", opt->name, argname);
		break;
	case OPT_SHORT_WITH_MANDATORY_ARG:
		w = printf("  -%c, --%s=%s", opt->val, opt->name, argname);
		break;
	case OPT_LONG_WITH_MANDATORY_ARG:
		w = printf("  --%s=%s", opt->name, argname);
		break;
	case OPT_SHORT_WITHOUT_ARG:
		w = printf("  -%c, --%s", opt->val, opt->name);
		break;
	case OPT_LONG_WITHOUT_ARG:
		w = printf("  --%s", opt->name);
		break;
#endif
	default:
		assert(0);
	}
out:
	if (w < 0 || w > l) {
		putchar('\n');
		return 0;
	}

	return w;
}

void help_print_desc(const struct option *opt, const char *s, int i, int w)
{
	if (opt)
		s = pgettext_expr(opt->name, s);

	for (; *s; w = 0) {
		const char *nl = strchr(s, '\n');
		int n = (nl ? nl-s : -1);

		printf("%*s%.*s\n", i-w, "", n, s);
		if (!nl)
			break;

		s = nl+1;
	}
}