From 4bf5cad1d4f42dc8b7321e84fba8acf4ece5d6a1 Mon Sep 17 00:00:00 2001
From: P. J. McDermott <pj@pehjota.net>
Date: Sat, 28 Aug 2021 17:53:27 -0400
Subject: datetime: Further implement

Simplify concatenation, factor out formats, and determine date if not
specified.
---
(limited to 'src/datetime.c')

diff --git a/src/datetime.c b/src/datetime.c
index f39f80c..74ef2d3 100644
--- a/src/datetime.c
+++ b/src/datetime.c
@@ -1,7 +1,27 @@
+/*
+ * Copyright (C) 2021  P. J. McDermott
+ *
+ * This file is part of @
+ *
+ * @ is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @ is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with @.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
 #define _XOPEN_SOURCE
 
 #include <ctype.h>
 #include <errno.h>
+#include <limits.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -10,42 +30,22 @@
 #include "datetime.h"
 
 static const char *DATETIME_FMTS_[] = {
-	"%H:%M:%S",
-	"%I:%M:%S %p",
-	"%H:%M",
-	"%Y-%m-%dT%H:%M:%S",
-	"%Y-%m-%d %H:%M:%S",
-	"%A %B %d, %Y %H:%M:%S",
+#include "datetime-formats.c"
 	NULL
 };
 
 static char *
-datetime_normalize_spacing(int argc, const char *argv[])
+datetime_concat_args(int argc, const char *argv[])
 {
 	int   buf_l;
 	int   i;
-	int   l;
-	bool  was_space;
-	int   j;
 	char *buf;
 	int   buf_i;
+	int   j;
 
 	buf_l = 0;
 	for (i = 0; i < argc; ++i) {
-		l = strlen(argv[i]);
-		was_space = true;
-		for (j = 0; j < l; ++j) {
-			if (isspace(argv[i][j]) != 0) {
-				if (was_space == false) {
-					buf_l++;
-					was_space = true;
-				}
-			} else {
-				buf_l++;
-				was_space = false;
-			}
-		}
-		++buf_l;
+		buf_l += strlen(argv[i]) + 1;
 	}
 
 	buf = calloc(buf_l, sizeof(*buf));
@@ -57,18 +57,8 @@ datetime_normalize_spacing(int argc, const char *argv[])
 
 	buf_i = 0;
 	for (i = 0; i < argc; ++i) {
-		l = strlen(argv[i]);
-		was_space = true;
-		for (j = 0; j < l; ++j) {
-			if (isspace(argv[i][j]) != 0) {
-				if (was_space == false) {
-					buf[buf_i++] = ' ';
-					was_space = true;
-				}
-			} else {
-				buf[buf_i++] = argv[i][j];
-				was_space = false;
-			}
+		for (j = 0; argv[i][j] != '\0'; ++j) {
+			buf[buf_i++] = argv[i][j];
 		}
 		buf[buf_i++] = ' ';
 	}
@@ -78,27 +68,58 @@ datetime_normalize_spacing(int argc, const char *argv[])
 }
 
 int
-datetime_parse(int argc, const char *argv[], struct tm *tm)
+datetime_parse(int argc, const char *argv[], struct tm *arg_tm)
 {
-	int   e   = -1;
-	char *buf;
-	int   i;
-	char *end;
+	char      *buf;
+	int        i;
+	char      *end;
+	time_t     arg_sec;
+	time_t     now_sec;
+	struct tm *now_tm;
 
-	buf = datetime_normalize_spacing(argc, argv);
+	buf = datetime_concat_args(argc, argv);
 	if (buf == NULL) {
 		return -1;
 	}
 
+	arg_tm->tm_mday = INT_MIN;  /* Sentinel */
+	arg_tm->tm_sec  = 0;        /* Default */
+
 	for (i = 0; DATETIME_FMTS_[i] != NULL; ++i) {
-		printf("%s =~ %s\n", buf, DATETIME_FMTS_[i]);
-		end = strptime(buf, DATETIME_FMTS_[i], tm);
+		/* printf("%s =~ %s\n", buf, DATETIME_FMTS_[i]); */
+		end = strptime(buf, DATETIME_FMTS_[i], arg_tm);
 		if (end != NULL && *end == '\0') {
-			e = 0;
-			break;
+			goto found;
+		}
+	}
+
+	free(buf);
+	fprintf(stderr, "Unknown date format\n");
+	return -1;
+
+ found:
+	/* TODO: Support %a-only dates and optional years */
+	if (arg_tm->tm_mday == INT_MIN) {
+		/* No date specified; try today. */
+		now_sec = time(NULL);
+		now_tm = localtime(&now_sec);
+		arg_tm->tm_year = now_tm->tm_year;
+		arg_tm->tm_mon  = now_tm->tm_mon;
+		arg_tm->tm_mday = now_tm->tm_mday;
+		arg_sec = mktime(arg_tm);
+		if (arg_sec <= mktime(now_tm)) {
+			/* Specified time already happened today; use tomorrow.
+			 * Adding the number of seconds in a day is a shortcut
+			 * that ignores leap seconds.  One better method would
+			 * be to increment tm_mday % days in tm_mon, etc. */
+			arg_sec += 60 * 60 * 24;
+			now_tm = localtime(&arg_sec);
+			arg_tm->tm_year = now_tm->tm_year;
+			arg_tm->tm_mon  = now_tm->tm_mon;
+			arg_tm->tm_mday = now_tm->tm_mday;
 		}
 	}
 
 	free(buf);
-	return e;
+	return 0;
 }
--
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