[evolution] I#1447 - templates: Include In-Reply-To/References headers

[Milan Crha <mcrha src gnome org>]

commit 7c8fdde61014cb94d8283c3c219eaf3cbca4c437
Author: Milan Crha <mcrha redhat com>
Date:   Tue Apr 6 15:18:07 2021 +0200

    I#1447 - templates: Include In-Reply-To/References headers
    
    Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/1447

 src/mail/e-mail-templates.c | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)
---
diff --git a/src/mail/e-mail-templates.c b/src/mail/e-mail-templates.c
index 47fb3aafce..7466bccc8f 100644
--- a/src/mail/e-mail-templates.c
+++ b/src/mail/e-mail-templates.c
@@ -515,6 +515,7 @@ e_mail_templates_apply_sync (CamelMimeMessage *source_message,
        CamelDataWrapper *dw;
        const CamelNameValueArray *headers;
        CamelMimePart *template_part = NULL;
+       gchar *references, *message_id;
        guint ii, len;
 
        g_return_val_if_fail (CAMEL_IS_MIME_MESSAGE (source_message), NULL);
@@ -577,7 +578,10 @@ e_mail_templates_apply_sync (CamelMimeMessage *source_message,
                        continue;
 
                if (g_ascii_strncasecmp (header_name, "content-", 8) != 0 &&
-                   g_ascii_strcasecmp (header_name, "from") != 0) {
+                   g_ascii_strcasecmp (header_name, "from") != 0 &&
+                   g_ascii_strcasecmp (header_name, "Message-ID") != 0 &&
+                   g_ascii_strcasecmp (header_name, "In-Reply-To") != 0 &&
+                   g_ascii_strcasecmp (header_name, "References") != 0) {
                        gchar *new_header_value = NULL;
 
                        /* Some special handling of the 'subject' header */
@@ -628,6 +632,32 @@ e_mail_templates_apply_sync (CamelMimeMessage *source_message,
        if (camel_mime_message_get_reply_to (template_message))
                camel_mime_message_set_reply_to (result_message, camel_mime_message_get_reply_to 
(template_message));
 
+       /* Add In-Reply-To and References. */
+
+       message_id = camel_header_unfold (camel_medium_get_header (CAMEL_MEDIUM (source_message), 
"Message-ID"));
+       references = camel_header_unfold (camel_medium_get_header (CAMEL_MEDIUM (source_message), 
"References"));
+
+       if (message_id && *message_id) {
+               gchar *reply_refs;
+
+               camel_medium_add_header (CAMEL_MEDIUM (result_message), "In-Reply-To", message_id);
+
+               if (references)
+                       reply_refs = g_strdup_printf ("%s %s", references, message_id);
+               else
+                       reply_refs = NULL;
+
+               camel_medium_add_header (CAMEL_MEDIUM (result_message), "References", reply_refs ? reply_refs 
: message_id);
+
+               g_free (reply_refs);
+
+       } else if (references && *references) {
+               camel_medium_add_header (CAMEL_MEDIUM (result_message), "References", references);
+       }
+
+       g_free (message_id);
+       g_free (references);
+
        g_clear_object (&template_message);
        g_clear_object (&new_multipart);