send-email: extract email-parsing code into a subroutine

The existing code mixes parsing of email header with regular
expression and actual code. Extract the parsing code into a new
subroutine "parse_header_line()". This improves the code readability
and make parse_header_line reusable in other place.

"parsed_header_line()" and "filter_body()" could be used for
refactoring the part of code which parses the header to prepare the
email and send it.

In contrast to the previous version it doesn't keep the header order
and strip duplicate headers.

Signed-off-by: Nathan Payre <[email protected]>
Signed-off-by: Matthieu Moy <[email protected]>
Signed-off-by: Timothee Albertin <[email protected]>
Signed-off-by: Daniel Bensoussan <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
Helped-by: Ævar Arnfjörð Bjarmason <[email protected]>
Reviewed-by: Matthieu Moy <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: Nathan Payre

git-send-email.perl

@@ -703,57 +703,70 @@ sub get_patch_subject {
 		do_edit($compose_filename);
 	}
 
-	open my $c2, ">", $compose_filename . ".final"
-		or die sprintf(__("Failed to open %s.final: %s"), $compose_filename, $!);
-
 	open $c, "<", $compose_filename
 		or die sprintf(__("Failed to open %s: %s"), $compose_filename, $!);
 
-	my $need_8bit_cte = file_has_nonascii($compose_filename);
-	my $in_body = 0;
-	my $summary_empty = 1;
 	if (!defined $compose_encoding) {
 		$compose_encoding = "UTF-8";
 	}
-	while(<$c>) {
-		next if m/^GIT:/;
-		if ($in_body) {
-			$summary_empty = 0 unless (/^\n$/);
-		} elsif (/^\n$/) {
-			$in_body = 1;
-			if ($need_8bit_cte) {
-				print $c2 "MIME-Version: 1.0\n",
-					 "Content-Type: text/plain; ",
-					   "charset=$compose_encoding\n",
-					 "Content-Transfer-Encoding: 8bit\n";
-			}
-		} elsif (/^MIME-Version:/i) {
-			$need_8bit_cte = 0;
-		} elsif (/^Subject:\s*(.+)\s*$/i) {
-			$initial_subject = $1;
-			my $subject = $initial_subject;
-			$_ = "Subject: " .
-				quote_subject($subject, $compose_encoding) .
-				"\n";
-		} elsif (/^In-Reply-To:\s*(.+)\s*$/i) {
-			$initial_reply_to = $1;
-			next;
-		} elsif (/^From:\s*(.+)\s*$/i) {
-			$sender = $1;
-			next;
-		} elsif (/^(?:To|Cc|Bcc):/i) {
-			print __("To/Cc/Bcc fields are not interpreted yet, they have been ignored\n");
-			next;
+
+	my %parsed_email;
+	while (my $line = <$c>) {
+		next if $line =~ m/^GIT:/;
+		parse_header_line($line, \%parsed_email);
+		if ($line =~ /^$/) {
+			$parsed_email{'body'} = filter_body($c);
 		}
-		print $c2 $_;
 	}
 	close $c;
-	close $c2;
 
-	if ($summary_empty) {
+	open my $c2, ">", $compose_filename . ".final"
+	or die sprintf(__("Failed to open %s.final: %s"), $compose_filename, $!);
+
+
+	if ($parsed_email{'From'}) {
+		$sender = delete($parsed_email{'From'});
+	}
+	if ($parsed_email{'In-Reply-To'}) {
+		$initial_reply_to = delete($parsed_email{'In-Reply-To'});
+	}
+	if ($parsed_email{'Subject'}) {
+		$initial_subject = delete($parsed_email{'Subject'});
+		print $c2 "Subject: " .
+			quote_subject($initial_subject, $compose_encoding) .
+			"\n";
+	}
+
+	if ($parsed_email{'MIME-Version'}) {
+		print $c2 "MIME-Version: $parsed_email{'MIME-Version'}\n",
+				"Content-Type: $parsed_email{'Content-Type'};\n",
+				"Content-Transfer-Encoding: $parsed_email{'Content-Transfer-Encoding'}\n";
+		delete($parsed_email{'MIME-Version'});
+		delete($parsed_email{'Content-Type'});
+		delete($parsed_email{'Content-Transfer-Encoding'});
+	} elsif (file_has_nonascii($compose_filename)) {
+		my $content_type = (delete($parsed_email{'Content-Type'}) or
+			"text/plain; charset=$compose_encoding");
+		print $c2 "MIME-Version: 1.0\n",
+			"Content-Type: $content_type\n",
+			"Content-Transfer-Encoding: 8bit\n";
+	}
+	# Preserve unknown headers
+	foreach my $key (keys %parsed_email) {
+		next if $key eq 'body';
+		print $c2 "$key: $parsed_email{$key}";
+	}
+
+	if ($parsed_email{'body'}) {
+		print $c2 "\n$parsed_email{'body'}\n";
+		delete($parsed_email{'body'});
+	} else {
 		print __("Summary email is empty, skipping it\n");
 		$compose = -1;
 	}
+
+	close $c2;
+
 } elsif ($annotate) {
 	do_edit(@files);
 }
@@ -792,6 +805,32 @@ sub ask {
 	return;
 }
 
+sub parse_header_line {
+	my $lines = shift;
+	my $parsed_line = shift;
+	my $addr_pat = join "|", qw(To Cc Bcc);
+
+	foreach (split(/\n/, $lines)) {
+		if (/^($addr_pat):\s*(.+)$/i) {
+		        $parsed_line->{$1} = [ parse_address_line($2) ];
+		} elsif (/^([^:]*):\s*(.+)\s*$/i) {
+		        $parsed_line->{$1} = $2;
+		}
+	}
+}
+
+sub filter_body {
+	my $c = shift;
+	my $body = "";
+	while (my $body_line = <$c>) {
+		if ($body_line !~ m/^GIT:/) {
+			$body .= $body_line;
+		}
+	}
+	return $body;
+}
+
+
 my %broken_encoding;
 
 sub file_declares_8bit_cte {