[PATCH v3 5/6] send-email: --in-reply-to=<file> populates the fields

[Tom Russello <tom.russello@grenoble-inp.org>]

Take an email message file, parse it and fill the "From", "To", "Cc",
"In-reply-to", "References" fields appropriately.

If `--compose` option is set, it will also fill the subject field with
`Re: [<email_file>'s subject]` in the introductory message.

Signed-off-by: Tom RUSSELLO <tom.russello@grenoble-inp.org>
Signed-off-by: Samuel GROOT <samuel.groot@grenoble-inp.org>
Signed-off-by: Matthieu MOY <matthieu.moy@grenoble-inp.fr>
---
Check if the string given by argument with `--in-reply-to` leads to
an existing plain text file. If not, consider it as a message-id.

Changes sinces v2:
	- Fill the References: field to keep the thread even if some
	  emails have been removed
	- Explicit error with a proper "if" when an error occured during
	  email file opening
	- More precise comments
	- More tests

 Documentation/git-send-email.txt |  9 +++--
 git-send-email.perl              | 49 +++++++++++++++++++++++-
 t/t9001-send-email.sh            | 83 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 136 insertions(+), 5 deletions(-)

diff --git a/Documentation/git-send-email.txt b/Documentation/git-send-email.txt
index edbba3a..21776f0 100644
--- a/Documentation/git-send-email.txt
+++ b/Documentation/git-send-email.txt
@@ -84,13 +84,16 @@ See the CONFIGURATION section for 'sendemail.multiEdit'.
 	the value of GIT_AUTHOR_IDENT, or GIT_COMMITTER_IDENT if that is not
 	set, as returned by "git var -l".
 
---in-reply-to=<identifier>::
+--in-reply-to=<Message-Id|email_file>::
 	Make the first mail (or all the mails with `--no-thread`) appear as a
-	reply to the given Message-Id, which avoids breaking threads to
-	provide a new patch series.
+	reply to the given Message-Id (given directly by argument or via the email
+	file), which avoids breaking threads to provide a new patch series.
 	The second and subsequent emails will be sent as replies according to
 	the `--[no]-chain-reply-to` setting.
 +
+Furthermore, if the argument is an email file, parse it and populate header
+fields appropriately for the reply.
++
 So for example when `--thread` and `--no-chain-reply-to` are specified, the
 second and subsequent patches will be replies to the first one like in the
 illustration below where `[PATCH v2 0/3]` is in reply to `[PATCH 0/2]`:
diff --git a/git-send-email.perl b/git-send-email.perl
index db114ae..66aa2cd 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -55,6 +55,7 @@ git send-email --dump-aliases
     --[no-]bcc              <str>  * Email Bcc:
     --subject               <str>  * Email "Subject:"
     --in-reply-to           <str>  * Email "In-Reply-To:"
+    --in-reply-to          <file>  * Populate header fields appropriately.
     --[no-]xmailer                 * Add "X-Mailer:" header (default).
     --[no-]annotate                * Review each patch that will be sent in an editor.
     --compose                      * Open an editor for introduction.
@@ -160,7 +161,7 @@ my $re_encoded_word = qr/=\?($re_token)\?($re_token)\?($re_encoded_text)\?=/;
 
 # Variables we fill in automatically, or via prompting:
 my (@to,$no_to,@initial_to,@cc,$no_cc,@initial_cc,@bcclist,$no_bcc,@xh,
-	$initial_reply_to,$initial_subject,@files,
+	$initial_reply_to,$initial_references,$initial_subject,@files,
 	$author,$sender,$smtp_authpass,$annotate,$use_xmailer,$compose,$time);
 
 my $envelope_sender;
@@ -639,6 +640,50 @@ if (@files) {
 	usage();
 }
 
+if ($initial_reply_to && -f $initial_reply_to) {
+	my $error = validate_patch($initial_reply_to);
+	die "fatal: $initial_reply_to: $error\nwarning: no patches were sent\n"
+		if $error;
+
+	open my $fh, "<", $initial_reply_to or die "can't open file $initial_reply_to";
+	my $mail = parse_email($fh);
+	close $fh;
+
+	my $initial_sender = $sender || $repoauthor || $repocommitter || '';
+
+	my $prefix_re = "";
+	my $subject_re = $mail->{"subject"}[0];
+	if ($subject_re =~ /^[^Re:]/) {
+		$prefix_re = "Re: ";
+	}
+	$initial_subject = $prefix_re . $subject_re;
+
+	push @initial_to, $mail->{"from"}[0];
+
+	foreach my $to_addr (parse_address_line(join ",", @{$mail->{"to"}})) {
+		if (!($to_addr eq $initial_sender)) {
+			push @initial_cc, $to_addr;
+		}
+	}
+
+	foreach my $cc_addr (parse_address_line(join ",", @{$mail->{"cc"}})) {
+		my $qaddr = unquote_rfc2047($cc_addr);
+		my $saddr = sanitize_address($qaddr);
+		if ($saddr eq $initial_sender) {
+			next if ($suppress_cc{'self'});
+		} else {
+			next if ($suppress_cc{'cc'});
+		}
+		push @initial_cc, $cc_addr;
+	}
+
+	$initial_reply_to = $mail->{"message-id"}[0];
+	if ($mail->{"references"}) {
+		$initial_references = join("", @{$mail->{"references"}}) .
+			" " . $initial_reply_to;
+	}
+}
+
 sub get_patch_subject {
 	my $fn = shift;
 	open (my $fh, '<', $fn);
@@ -1426,7 +1471,7 @@ Message-Id: $message_id
 }
 
 $reply_to = $initial_reply_to;
-$references = $initial_reply_to || '';
+$references = $initial_references || $initial_reply_to || '';
 $subject = $initial_subject;
 $message_num = 0;
 
diff --git a/t/t9001-send-email.sh b/t/t9001-send-email.sh
index 9b1e56f..2d67f6d 100755
--- a/t/t9001-send-email.sh
+++ b/t/t9001-send-email.sh
@@ -1892,4 +1892,87 @@ test_expect_success $PREREQ 'leading and trailing whitespaces are removed' '
 	test_cmp_noorder expected-list actual-list
 '
 
+test_expect_success $PREREQ 'setup expect' '
+	cat >email <<-\EOF
+	Subject: subject goes here
+	From: author@example.com
+	To: to1@example.com
+	Cc: cc1@example.com, cc2@example.com,
+     cc3@example.com
+	Date: Sat, 12 Jun 2010 15:53:58 +0200
+	Message-Id: <author_123456@example.com>
+	References: <firstauthor_654321@example.com>
+        <secondauthor_01546567@example.com>
+        <thirdauthor_1395838@example.com>
+
+	Have you seen my previous email?
+	> Previous content
+	EOF
+'
+
+test_expect_success $PREREQ 'Fields with --in-reply-to are correct' '
+	clean_fake_sendmail &&
+	git send-email \
+		--in-reply-to=email \
+		--from="Example <nobody@example.com>" \
+		--smtp-server="$(pwd)/fake.sendmail" \
+		-2 \
+		2>errors &&
+	grep "From: Example <nobody@example.com>" msgtxt1 &&
+	grep "In-Reply-To: <author_123456@example.com>" msgtxt1 &&
+	to_adr=$(awk "/^To: /{flag=1}/^Cc: /{flag=0} flag {print}" msgtxt1) &&
+	cc_adr=$(awk "/^Cc: /{flag=1}/^Subject: /{flag=0} flag {print}" msgtxt1) &&
+	ref_adr=$(awk "/^References: /{flag=1}/^MIME-Version: /{flag=0} flag {print}" \
+		msgtxt1) &&
+	echo "$to_adr" | grep author@example.com &&
+	echo "$cc_adr" | grep to1@example.com &&
+	echo "$cc_adr" | grep cc1@example.com &&
+	echo "$cc_adr" | grep cc2@example.com &&
+	echo "$cc_adr" | grep cc3@example.com &&
+	echo "$ref_adr" | grep "<firstauthor_654321@example.com>" &&
+	echo "$ref_adr" | grep "<secondauthor_01546567@example.com>" &&
+	echo "$ref_adr" | grep "<thirdauthor_1395838@example.com>" &&
+	echo "$ref_adr" | grep "<author_123456@example.com>" &&
+	echo "$ref_adr" | grep -v "References: <author_123456@example.com>"
+'
+
+test_expect_success $PREREQ 'Fields with --in-reply-to and --compose are correct' '
+	clean_fake_sendmail &&
+	git send-email \
+		--in-reply-to=email \
+		--compose \
+		--from="Example <nobody@example.com>" \
+		--smtp-server="$(pwd)/fake.sendmail" \
+		-1 \
+		2>errors &&
+	grep "From: Example <nobody@example.com>" msgtxt1 &&
+	grep "In-Reply-To: <author_123456@example.com>" msgtxt1 &&
+	grep "Subject: Re: subject goes here" msgtxt1 &&
+	to_adr=$(awk "/^To: /{flag=1}/^Cc: /{flag=0} flag {print}" msgtxt1) &&
+	cc_adr=$(awk "/^Cc: /{flag=1}/^Subject: /{flag=0} flag {print}" msgtxt1) &&
+	ref_adr=$(awk "/^References: /{flag=1}/^MIME-Version: /{flag=0} flag {print}" \
+		msgtxt1) &&
+	echo "$to_adr" | grep author@example.com &&
+	echo "$cc_adr" | grep to1@example.com &&
+	echo "$cc_adr" | grep cc1@example.com &&
+	echo "$cc_adr" | grep cc2@example.com &&
+	echo "$cc_adr" | grep cc3@example.com &&
+	echo "$ref_adr" | grep "<firstauthor_654321@example.com>" &&
+	echo "$ref_adr" | grep "<secondauthor_01546567@example.com>" &&
+	echo "$ref_adr" | grep "<thirdauthor_1395838@example.com>" &&
+	echo "$ref_adr" | grep "<author_123456@example.com>" &&
+	echo "$ref_adr" | grep -v "References: <author_123456@example.com>"
+'
+
+test_expect_success $PREREQ 'Re: written only once with --in-reply-to and --compose ' '
+	git send-email \
+		--in-reply-to=msgtxt1 \
+		--compose \
+		--from="Example <nobody@example.com>" \
+		--smtp-server="$(pwd)/fake.sendmail" \
+		-1 \
+		2>errors &&
+	grep "Subject: Re: subject goes here" msgtxt3
+'
+
 test_done
-- 
2.8.3