From e130ed9b3a982b36b75d4fbb225ad1fe8e16a7de Mon Sep 17 00:00:00 2001
From: P. J. McDermott <pj@pehjota.net>
Date: Tue, 31 Aug 2021 20:54:28 -0400
Subject: Add option to list supported formats

---
(limited to 'src/main.c')

diff --git a/src/main.c b/src/main.c
index 81096a5..f450281 100644
--- a/src/main.c
+++ b/src/main.c
@@ -36,6 +36,12 @@ extern const char *PACKAGE_VERSION_GIT;
 #if defined(HAVE_GETOPT_LONG) && HAVE_GETOPT_LONG
 struct option LONGOPTS_[] = {
 	{
+		.name    = "list-formats",
+		.has_arg = 0,
+		.flag    = NULL,
+		.val     = 'F',
+	},
+	{
 		.name    = "help",
 		.has_arg = 0,
 		.flag    = NULL,
@@ -62,15 +68,76 @@ _print_help(const char *program_name)
 	_print_usage(stdout, program_name);
 	puts("Options:");
 #if defined(HAVE_GETOPT_LONG) && HAVE_GETOPT_LONG
-	puts("\t-h, --help     Show this help information");
-	puts("\t-V, --version  Show version information");
+	puts("\t-F, --list-formats  List all supported date and time formats");
+	puts("\t-h, --help          Show this help information");
+	puts("\t-V, --version       Show version information");
 #else
+	puts("\t-F  List all supported date and time formats");
 	puts("\t-h  Show this help information");
 	puts("\t-V  Show version information");
 #endif
 }
 
 static void
+_list_formats(void)
+{
+	time_t     tim;
+	struct tm *tm;
+	char      *out;
+	size_t     out_sz;
+	char      *buf;
+	size_t     i;
+
+	tim = time(NULL);
+	tm  = localtime(&tim);
+
+	puts("Time formats:");
+	out    = NULL;
+	out_sz = 0;
+	buf    = NULL;
+	i      = 0;
+	while (datetime_strftime_time(tm, &out, &out_sz, &buf, &i) > 0) {
+		printf("  * %s\n", out);
+	}
+	if (out != NULL) {
+		free(out);
+	}
+	if (buf != NULL) {
+		free(buf);
+	}
+
+	puts("Date formats:");
+	out    = NULL;
+	out_sz = 0;
+	buf    = NULL;
+	i      = 0;
+	while (datetime_strftime_date(tm, &out, &out_sz, &buf, &i) > 0) {
+		printf("  * %s\n", out);
+	}
+	if (out != NULL) {
+		free(out);
+	}
+	if (buf != NULL) {
+		free(buf);
+	}
+
+	puts("Additional formats:");
+	out    = NULL;
+	out_sz = 0;
+	buf    = NULL;
+	i      = 0;
+	while (datetime_strftime_misc(tm, &out, &out_sz, &buf, &i) > 0) {
+		printf("  * %s\n", out);
+	}
+	if (out != NULL) {
+		free(out);
+	}
+	if (buf != NULL) {
+		free(buf);
+	}
+}
+
+static void
 _print_version(void)
 {
 	printf("@ (atsign) %s%s\n", PACKAGE_VERSION, PACKAGE_VERSION_GIT);
@@ -128,11 +195,14 @@ main(int argc, char * const argv[])
 	optind = 1;
 	opterr = 0;
 #if defined(HAVE_GETOPT_LONG) && HAVE_GETOPT_LONG
-	while ((opt = getopt_long(argc, argv, "hV", LONGOPTS_, NULL)) > 0) {
+	while ((opt = getopt_long(argc, argv, "FhV", LONGOPTS_, NULL)) > 0) {
 #else
-	while ((opt = getopt(argc, argv, "hV")) > 0) {
+	while ((opt = getopt(argc, argv, "FhV")) > 0) {
 #endif
 		switch (opt) {
+			case 'F':
+				_list_formats();
+				return EXIT_SUCCESS;
 			case 'h':
 				_print_help(argv[0]);
 				return EXIT_SUCCESS;
--
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