From 8e52e5fdea416d6fda0b8d301144af0c043a5a76 Mon Sep 17 00:00:00 2001
From: "Eric Wong (Contractor, The Linux Foundation)" <e@80x24.org>
Date: Wed, 21 Mar 2018 01:52:58 +0000
Subject: use both Date: and Received: times

We want to rely on Date: to sort messages within individual
threads since it keeps messages from git-send-email(1) sorted.
However, since developers occasionally have the clock set
wrong on their machines, sort overall messages by the newest
date in a Received: header so the landing page isn't forever
polluted by messages from the future.

This also gives us determinism for commit times in most cases,
as we'll used the Received: timestamp there, as well.
---
 lib/PublicInbox/MsgTime.pm | 80 +++++++++++++++++++++++++++++++---------------
 1 file changed, 54 insertions(+), 26 deletions(-)

(limited to 'lib/PublicInbox/MsgTime.pm')

diff --git a/lib/PublicInbox/MsgTime.pm b/lib/PublicInbox/MsgTime.pm
index 87664f4b..4295e873 100644
--- a/lib/PublicInbox/MsgTime.pm
+++ b/lib/PublicInbox/MsgTime.pm
@@ -4,48 +4,76 @@ package PublicInbox::MsgTime;
 use strict;
 use warnings;
 use base qw(Exporter);
-our @EXPORT_OK = qw(msg_timestamp);
+our @EXPORT_OK = qw(msg_timestamp msg_datestamp);
 use Date::Parse qw(str2time);
 use Time::Zone qw(tz_offset);
 
-sub msg_timestamp ($) {
+sub zone_clamp ($) {
+	my ($zone) = @_;
+	$zone ||= '+0000';
+	# "-1200" is the furthest westermost zone offset,
+	# but git fast-import is liberal so we use "-1400"
+	if ($zone >= 1400 || $zone <= -1400) {
+		warn "bogus TZ offset: $zone, ignoring and assuming +0000\n";
+		$zone = '+0000';
+	}
+	$zone;
+}
+
+sub time_response ($) {
+	my ($ret) = @_;
+	wantarray ? @$ret : $ret->[0];
+}
+
+sub msg_received_at ($) {
 	my ($hdr) = @_; # Email::MIME::Header
-	my ($ts, $zone);
-	my $mid;
 	my @recvd = $hdr->header_raw('Received');
+	my ($ts, $zone);
 	foreach my $r (@recvd) {
 		$zone = undef;
 		$r =~ /\s*(\d+\s+[[:alpha:]]+\s+\d{2,4}\s+
 			\d+\D\d+(?:\D\d+)\s+([\+\-]\d+))/sx or next;
 		$zone = $2;
 		$ts = eval { str2time($1) } and last;
-		$mid ||= $hdr->header_raw('Message-ID');
+		my $mid = $hdr->header_raw('Message-ID');
 		warn "no date in $mid Received: $r\n";
 	}
-	unless (defined $ts) {
-		my @date = $hdr->header_raw('Date');
-		foreach my $d (@date) {
-			$zone = undef;
-			$ts = eval { str2time($d) };
-			if ($@) {
-				$mid ||= $hdr->header_raw('Message-ID');
-				warn "bad Date: $d in $mid: $@\n";
-			} elsif ($d =~ /\s+([\+\-]\d+)\s*\z/) {
-				$zone = $1;
-			}
+	defined $ts ? [ $ts, zone_clamp($zone) ] : undef;
+}
+
+sub msg_date_only ($) {
+	my ($hdr) = @_; # Email::MIME::Header
+	my @date = $hdr->header_raw('Date');
+	my ($ts, $zone);
+	foreach my $d (@date) {
+		$zone = undef;
+		$ts = eval { str2time($d) };
+		if ($@) {
+			my $mid = $hdr->header_raw('Message-ID');
+			warn "bad Date: $d in $mid: $@\n";
+		} elsif ($d =~ /\s+([\+\-]\d+)\s*\z/) {
+			$zone = $1;
 		}
 	}
-	$ts = time unless defined $ts;
-	return $ts unless wantarray;
+	defined $ts ? [ $ts, zone_clamp($zone) ] : undef;
+}
 
-	$zone ||= '+0000';
-	# "-1200" is the furthest westermost zone offset,
-	# but git fast-import is liberal so we use "-1400"
-	if ($zone >= 1400 || $zone <= -1400) {
-		warn "bogus TZ offset: $zone, ignoring and assuming +0000\n";
-		$zone = '+0000';
-	}
-	($ts, $zone);
+# Favors Received header for sorting globally
+sub msg_timestamp ($) {
+	my ($hdr) = @_; # Email::MIME::Header
+	my $ret;
+	$ret = msg_received_at($hdr) and return time_response($ret);
+	$ret = msg_date_only($hdr) and return time_response($ret);
+	wantarray ? (time, '+0000') : time;
+}
+
+# Favors the Date: header for display and sorting within a thread
+sub msg_datestamp ($) {
+	my ($hdr) = @_; # Email::MIME::Header
+	my $ret;
+	$ret = msg_date_only($hdr) and return time_response($ret);
+	$ret = msg_received_at($hdr) and return time_response($ret);
+	wantarray ? (time, '+0000') : time;
 }
 
 1;
-- 
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