Merge branch 'lt/date-human'

A new date format "--date=human" that morphs its output depending
on how far the time is from the current time has been introduced.
"--date=auto" can be used to use this new format when the output is
going to the pager or to the terminal and otherwise the default
format.

* lt/date-human:
  Add `human` date format tests.
  Add `human` format to test-tool
  Add 'human' date format documentation
  Replace the proposed 'auto' mode with 'auto:'
  Add 'human' date format

7 files changed, 176 insertions, 25 deletions

diff --git a/Documentation/git-log.txt b/Documentation/git-log.txt
index 90761f1694..b02e922dc3 100644
--- a/Documentation/git-log.txt
+++ b/Documentation/git-log.txt
@@ -192,6 +192,10 @@ log.date::
 	Default format for human-readable dates.  (Compare the
 	`--date` option.)  Defaults to "default", which means to write
 	dates like `Sat May 8 19:35:34 2010 -0500`.
++
+If the format is set to "auto:foo" and the pager is in use, format
+"foo" will be the used for the date format. Otherwise "default" will
+be used.
 
 log.follow::
 	If `true`, `git log` will act as if the `--follow` option was used when
diff --git a/Documentation/rev-list-options.txt b/Documentation/rev-list-options.txt
index 8a4867998e..cad711ce0a 100644
--- a/Documentation/rev-list-options.txt
+++ b/Documentation/rev-list-options.txt
@@ -836,6 +836,13 @@ Note that the `-local` option does not affect the seconds-since-epoch
 value (which is always measured in UTC), but does switch the accompanying
 timezone value.
 +
+`--date=human` shows the timezone if the timezone does not match the
+current time-zone, and doesn't print the whole date if that matches
+(ie skip printing year for dates that are "this year", but also skip
+the whole date itself if it's in the last few days and we can just say
+what weekday it was).  For older dates the hour and minute is also
+omitted.
++
 `--date=unix` shows the date as a Unix epoch timestamp (seconds since
 1970).  As with `--raw`, this is always in UTC and therefore `-local`
 has no effect.
diff --git a/builtin/blame.c b/builtin/blame.c
index 0074ed311c..581de0d832 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -925,6 +925,10 @@ parse_done:
 		 */
 		blame_date_width = utf8_strwidth(_("4 years, 11 months ago")) + 1; /* add the null */
 		break;
+	case DATE_HUMAN:
+		/* If the year is shown, no time is shown */
+		blame_date_width = sizeof("Thu Oct 19 16:00");
+		break;
 	case DATE_NORMAL:
 		blame_date_width = sizeof("Thu Oct 19 16:00:04 2006 -0700");
 		break;
diff --git a/cache.h b/cache.h
index 400bc0ab25..ef9f3c4eaf 100644
--- a/cache.h
+++ b/cache.h
@@ -1463,6 +1463,7 @@ extern struct object *peel_to_type(const char *name, int namelen,
 
 enum date_mode_type {
 	DATE_NORMAL = 0,
+	DATE_HUMAN,
 	DATE_RELATIVE,
 	DATE_SHORT,
 	DATE_ISO8601,
@@ -1490,6 +1491,8 @@ struct date_mode *date_mode_from_type(enum date_mode_type type);
 const char *show_date(timestamp_t time, int timezone, const struct date_mode *mode);
 void show_date_relative(timestamp_t time, const struct timeval *now,
 			struct strbuf *timebuf);
+void show_date_human(timestamp_t time, int tz, const struct timeval *now,
+			struct strbuf *timebuf);
 int parse_date(const char *date, struct strbuf *out);
 int parse_date_basic(const char *date, timestamp_t *timestamp, int *offset);
 int parse_expiry_date(const char *date, timestamp_t *timestamp);
diff --git a/date.c b/date.c
index 61449f8b2e..9c5870e102 100644
--- a/date.c
+++ b/date.c
@@ -77,22 +77,16 @@ static struct tm *time_to_tm_local(timestamp_t time)
 }
 
 /*
- * What value of "tz" was in effect back then at "time" in the
- * local timezone?
+ * Fill in the localtime 'struct tm' for the supplied time,
+ * and return the local tz.
  */
-static int local_tzoffset(timestamp_t time)
+static int local_time_tzoffset(time_t t, struct tm *tm)
 {
-	time_t t, t_local;
-	struct tm tm;
+	time_t t_local;
 	int offset, eastwest;
 
-	if (date_overflows(time))
-		die("Timestamp too large for this system: %"PRItime, time);
-
-	t = (time_t)time;
-	localtime_r(&t, &tm);
-	t_local = tm_to_time_t(&tm);
-
+	localtime_r(&t, tm);
+	t_local = tm_to_time_t(tm);
 	if (t_local == -1)
 		return 0; /* error; just use +0000 */
 	if (t_local < t) {
@@ -107,6 +101,33 @@ static int local_tzoffset(timestamp_t time)
 	return offset * eastwest;
 }
 
+/*
+ * What value of "tz" was in effect back then at "time" in the
+ * local timezone?
+ */
+static int local_tzoffset(timestamp_t time)
+{
+	struct tm tm;
+
+	if (date_overflows(time))
+		die("Timestamp too large for this system: %"PRItime, time);
+
+	return local_time_tzoffset((time_t)time, &tm);
+}
+
+static void get_time(struct timeval *now)
+{
+	const char *x;
+
+	x = getenv("GIT_TEST_DATE_NOW");
+	if (x) {
+		now->tv_sec = atoi(x);
+		now->tv_usec = 0;
+	}
+	else
+		gettimeofday(now, NULL);
+}
+
 void show_date_relative(timestamp_t time,
 			const struct timeval *now,
 			struct strbuf *timebuf)
@@ -191,9 +212,80 @@ struct date_mode *date_mode_from_type(enum date_mode_type type)
 	return &mode;
 }
 
+static void show_date_normal(struct strbuf *buf, timestamp_t time, struct tm *tm, int tz, struct tm *human_tm, int human_tz, int local)
+{
+	struct {
+		unsigned int	year:1,
+				date:1,
+				wday:1,
+				time:1,
+				seconds:1,
+				tz:1;
+	} hide = { 0 };
+
+	hide.tz = local || tz == human_tz;
+	hide.year = tm->tm_year == human_tm->tm_year;
+	if (hide.year) {
+		if (tm->tm_mon == human_tm->tm_mon) {
+			if (tm->tm_mday > human_tm->tm_mday) {
+				/* Future date: think timezones */
+			} else if (tm->tm_mday == human_tm->tm_mday) {
+				hide.date = hide.wday = 1;
+			} else if (tm->tm_mday + 5 > human_tm->tm_mday) {
+				/* Leave just weekday if it was a few days ago */
+				hide.date = 1;
+			}
+		}
+	}
+
+	/* Show "today" times as just relative times */
+	if (hide.wday) {
+		struct timeval now;
+		get_time(&now);
+		show_date_relative(time, &now, buf);
+		return;
+	}
+
+	/*
+	 * Always hide seconds for human-readable.
+	 * Hide timezone if showing date.
+	 * Hide weekday and time if showing year.
+	 *
+	 * The logic here is two-fold:
+	 *  (a) only show details when recent enough to matter
+	 *  (b) keep the maximum length "similar", and in check
+	 */
+	if (human_tm->tm_year) {
+		hide.seconds = 1;
+		hide.tz |= !hide.date;
+		hide.wday = hide.time = !hide.year;
+	}
+
+	if (!hide.wday)
+		strbuf_addf(buf, "%.3s ", weekday_names[tm->tm_wday]);
+	if (!hide.date)
+		strbuf_addf(buf, "%.3s %d ", month_names[tm->tm_mon], tm->tm_mday);
+
+	/* Do we want AM/PM depending on locale? */
+	if (!hide.time) {
+		strbuf_addf(buf, "%02d:%02d", tm->tm_hour, tm->tm_min);
+		if (!hide.seconds)
+			strbuf_addf(buf, ":%02d", tm->tm_sec);
+	} else
+		strbuf_rtrim(buf);
+
+	if (!hide.year)
+		strbuf_addf(buf, " %d", tm->tm_year + 1900);
+
+	if (!hide.tz)
+		strbuf_addf(buf, " %+05d", tz);
+}
+
 const char *show_date(timestamp_t time, int tz, const struct date_mode *mode)
 {
 	struct tm *tm;
+	struct tm human_tm = { 0 };
+	int human_tz = -1;
 	static struct strbuf timebuf = STRBUF_INIT;
 
 	if (mode->type == DATE_UNIX) {
@@ -202,6 +294,15 @@ const char *show_date(timestamp_t time, int tz, const struct date_mode *mode)
 		return timebuf.buf;
 	}
 
+	if (mode->type == DATE_HUMAN) {
+		struct timeval now;
+
+		get_time(&now);
+
+		/* Fill in the data for "current time" in human_tz and human_tm */
+		human_tz = local_time_tzoffset(now.tv_sec, &human_tm);
+	}
+
 	if (mode->local)
 		tz = local_tzoffset(time);
 
@@ -215,7 +316,7 @@ const char *show_date(timestamp_t time, int tz, const struct date_mode *mode)
 		struct timeval now;
 
 		strbuf_reset(&timebuf);
-		gettimeofday(&now, NULL);
+		get_time(&now);
 		show_date_relative(time, &now, &timebuf);
 		return timebuf.buf;
 	}
@@ -258,14 +359,7 @@ const char *show_date(timestamp_t time, int tz, const struct date_mode *mode)
 		strbuf_addftime(&timebuf, mode->strftime_fmt, tm, tz,
 				!mode->local);
 	else
-		strbuf_addf(&timebuf, "%.3s %.3s %d %02d:%02d:%02d %d%c%+05d",
-				weekday_names[tm->tm_wday],
-				month_names[tm->tm_mon],
-				tm->tm_mday,
-				tm->tm_hour, tm->tm_min, tm->tm_sec,
-				tm->tm_year + 1900,
-				mode->local ? 0 : ' ',
-				tz);
+		show_date_normal(&timebuf, time, tm, tz, &human_tm, human_tz, mode->local);
 	return timebuf.buf;
 }
 
@@ -819,6 +913,8 @@ static enum date_mode_type parse_date_type(const char *format, const char **end)
 		return DATE_SHORT;
 	if (skip_prefix(format, "default", end))
 		return DATE_NORMAL;
+	if (skip_prefix(format, "human", end))
+		return DATE_HUMAN;
 	if (skip_prefix(format, "raw", end))
 		return DATE_RAW;
 	if (skip_prefix(format, "unix", end))
@@ -833,6 +929,14 @@ void parse_date_format(const char *format, struct date_mode *mode)
 {
 	const char *p;
 
+	/* "auto:foo" is "if tty/pager, then foo, otherwise normal" */
+	if (skip_prefix(format, "auto:", &p)) {
+		if (isatty(1) || pager_in_use())
+			format = p;
+		else
+			format = "default";
+	}
+
 	/* historical alias */
 	if (!strcmp(format, "local"))
 		format = "default-local";
@@ -1205,7 +1309,7 @@ timestamp_t approxidate_careful(const char *date, int *error_ret)
 		return timestamp;
 	}
 
-	gettimeofday(&tv, NULL);
+	get_time(&tv);
 	return approxidate_str(date, &tv, error_ret);
 }
 
diff --git a/t/helper/test-date.c b/t/helper/test-date.c
index aac4d542c2..a47bfa3003 100644
--- a/t/helper/test-date.c
+++ b/t/helper/test-date.c
@@ -3,6 +3,7 @@
 
 static const char *usage_msg = "\n"
 "  test-tool date relative [time_t]...\n"
+"  test-tool date human [time_t]...\n"
 "  test-tool date show:<format> [time_t]...\n"
 "  test-tool date parse [date]...\n"
 "  test-tool date approxidate [date]...\n"
@@ -22,6 +23,14 @@ static void show_relative_dates(const char **argv, struct timeval *now)
 	strbuf_release(&buf);
 }
 
+static void show_human_dates(const char **argv)
+{
+	for (; *argv; argv++) {
+		time_t t = atoi(*argv);
+		printf("%s -> %s\n", *argv, show_date(t, 0, DATE_MODE(HUMAN)));
+	}
+}
+
 static void show_dates(const char **argv, const char *format)
 {
 	struct date_mode mode;
@@ -87,7 +96,7 @@ int cmd__date(int argc, const char **argv)
 	struct timeval now;
 	const char *x;
 
-	x = getenv("TEST_DATE_NOW");
+	x = getenv("GIT_TEST_DATE_NOW");
 	if (x) {
 		now.tv_sec = atoi(x);
 		now.tv_usec = 0;
@@ -100,6 +109,8 @@ int cmd__date(int argc, const char **argv)
 		usage(usage_msg);
 	if (!strcmp(*argv, "relative"))
 		show_relative_dates(argv+1, &now);
+	else if (!strcmp(*argv, "human"))
+		show_human_dates(argv+1);
 	else if (skip_prefix(*argv, "show:", &x))
 		show_dates(argv+1, x);
 	else if (!strcmp(*argv, "parse"))
diff --git a/t/t0006-date.sh b/t/t0006-date.sh
index ffb2975e48..d9fcc829a9 100755
--- a/t/t0006-date.sh
+++ b/t/t0006-date.sh
@@ -4,10 +4,10 @@ test_description='test date parsing and printing'
 . ./test-lib.sh
 
 # arbitrary reference time: 2009-08-30 19:20:00
-TEST_DATE_NOW=1251660000; export TEST_DATE_NOW
+GIT_TEST_DATE_NOW=1251660000; export GIT_TEST_DATE_NOW
 
 check_relative() {
-	t=$(($TEST_DATE_NOW - $1))
+	t=$(($GIT_TEST_DATE_NOW - $1))
 	echo "$t -> $2" >expect
 	test_expect_${3:-success} "relative date ($2)" "
 	test-tool date relative $t >actual &&
@@ -128,4 +128,22 @@ check_approxidate '6AM, June 7, 2009' '2009-06-07 06:00:00'
 check_approxidate '2008-12-01' '2008-12-01 19:20:00'
 check_approxidate '2009-12-01' '2009-12-01 19:20:00'
 
+check_date_format_human() {
+	t=$(($GIT_TEST_DATE_NOW - $1))
+	echo "$t -> $2" >expect
+	test_expect_success "human date $t" '
+		test-tool date human $t >actual &&
+		test_i18ncmp expect actual
+'
+}
+
+check_date_format_human 18000 "5 hours ago" # 5 hours ago
+check_date_format_human 432000 "Tue Aug 25 19:20" # 5 days ago
+check_date_format_human 1728000 "Mon Aug 10 19:20" # 3 weeks ago
+check_date_format_human 13000000 "Thu Apr 2 08:13" # 5 months ago
+check_date_format_human 31449600 "Aug 31 2008" # 12 months ago
+check_date_format_human 37500000 "Jun 22 2008" # 1 year, 2 months ago
+check_date_format_human 55188000 "Dec 1 2007" # 1 year, 9 months ago
+check_date_format_human 630000000 "Sep 13 1989" # 20 years ago
+
 test_done