[RFC/HELP] search: multiple From/To/Cc/Subject (what about Date?)

[Eric Wong <e@80x24.org>]

We can easily support searching on messages with
multiple From/To/Cc/Subject headers.

Now, the display part in the thread skeleton could be
trickier, but not impossible...

Now, how are we supposed to support searching date ranges
when messages have multiple Date: headers? e.g:

https://lore.kernel.org/linux-renesas-soc/20160524.143422.552507610109476444.davem@davemloft.net/raw

OTOH, I'm pretty sure that's just a mangled message somebody
passed on because all 3 Message-IDs appear in standalone forms
elsewhere (e.g. lkml)

But, I also fully expect future messages will contain
horribleness in headers unless anti-spam/abuse rules start
blocking that before it hits public-inbox...
---
 lib/PublicInbox/SearchMsg.pm |  4 ++--
 t/v2reindex.t                | 16 ++++++++++++----
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/lib/PublicInbox/SearchMsg.pm b/lib/PublicInbox/SearchMsg.pm
index adadf92e..7561e7f2 100644
--- a/lib/PublicInbox/SearchMsg.pm
+++ b/lib/PublicInbox/SearchMsg.pm
@@ -107,8 +107,8 @@ sub __hdr ($$) {
 	return $val if defined $val;
 
 	my $mime = $self->{mime} or return;
-	$val = $mime->header($field);
-	$val = '' unless defined $val;
+	my @raw = $mime->header($field);
+	$val = join(', ', @raw);
 	$val =~ tr/\t\n/  /;
 	$val =~ tr/\r//d;
 	$self->{$field} = $val;
diff --git a/t/v2reindex.t b/t/v2reindex.t
index 52711f8f..3e56ddfa 100644
--- a/t/v2reindex.t
+++ b/t/v2reindex.t
@@ -439,7 +439,7 @@ ok(!-d $xap, 'Xapian directories removed again');
 	my @warn;
 	local $SIG{__WARN__} = sub { push @warn, @_ };
 	my %config = %$ibx_config;
-	$config{indexlevel} = 'basic';
+	$config{indexlevel} = 'medium';
 	my $ibx = PublicInbox::Inbox->new(\%config);
 	my $im = PublicInbox::V2Writable->new($ibx);
 	my $m3 = PublicInbox::MIME->new(<<'EOF');
@@ -447,7 +447,7 @@ Date: Tue, 24 May 2016 14:34:22 -0700 (PDT)
 Message-Id: <20160524.143422.552507610109476444.d@example.com>
 To: t@example.com
 Cc: c@example.com
-Subject: Re: [PATCH v2 2/2]
+Subject: Re: [PATCH v2 2/2] uno
 From: <f@example.com>
 In-Reply-To: <1463825855-7363-2-git-send-email-y@example.com>
 References: <1463825855-7363-1-git-send-email-y@example.com>
@@ -456,14 +456,14 @@ Date: Wed, 25 May 2016 10:01:51 +0900
 From: h@example.com
 To: g@example.com
 Cc: m@example.com
-Subject: Re: [PATCH]
+Subject: Re: [PATCH] dos
 Message-ID: <20160525010150.GD7292@example.com>
 References: <1463498133-23918-1-git-send-email-g+r@example.com>
 In-Reply-To: <1463498133-23918-1-git-send-email-g+r@example.com>
 From: s@example.com
 To: h@example.com
 Cc: m@example.com
-Subject: [PATCH 12/13]
+Subject: [PATCH 12/13] tres
 Date: Wed, 01 Jun 2016 01:32:35 +0300
 Message-ID: <1923946.Jvi0TDUXFC@wasted.example.com>
 In-Reply-To: <13205049.n7pM8utpHF@wasted.example.com>
@@ -495,6 +495,14 @@ EOF
 	eval { $im->index_sync({reindex=>1}) };
 	is($@, '', 'no error from reindexing after reused Message-ID (x3)');
 	is_deeply(\@warn, [], 'no warnings on reindex');
+
+	my %uniq;
+	for my $s (qw(uno dos tres)) {
+		my $msgs = $ibx->search->query("s:$s");
+		is(scalar(@$msgs), 1, "only one result for `$s'");
+		$uniq{$msgs->[0]->{num}}++;
+	}
+	is_deeply([values %uniq], [3], 'search on different subjects');
 }
 
 done_testing();