FEATURE: add setting to show content of forwarded emails in topics (#7935)

lib/email/receiver.rb

@@ -660,7 +660,7 @@ module Email
     end
 
     def process_destination(destination, user, body, elided, hidden_reason_id)
-      return if SiteSetting.enable_forwarded_emails &&
+      return if SiteSetting.forwarded_emails_behaviour != "hide" &&
                 has_been_forwarded? &&
                 process_forwarded_email(destination, user)
 
@@ -800,27 +800,30 @@ module Email
 
     def process_forwarded_email(destination, user)
       user ||= stage_from_user
-      embedded = Mail.new(embedded_email_raw)
-      email, display_name = parse_from_field(embedded)
-
-      return false if email.blank? || !email["@"]
-
-      raw = try_to_encode(embedded.decoded, "UTF-8").presence || embedded.to_s
-      title = embedded.subject.presence || subject
+      case SiteSetting.forwarded_emails_behaviour
+      when "create_replies"
+        forwarded_email_create_replies(destination, user)
+      when "quote"
+        forwarded_email_quote_forwarded(destination, user)
+      else
+        false
+      end
+    end
 
+    def forwarded_email_create_topic(destination: , user: , raw: , title: , date: nil, embedded_user: nil)
       case destination[:type]
       when :group
         group = destination[:obj]
-        embedded_user = find_or_create_user(email, display_name)
-        post = create_topic(user: embedded_user,
-                            raw: raw,
-                            title: title,
-                            archetype: Archetype.private_message,
-                            target_usernames: [user.username],
-                            target_group_names: [group.name],
-                            is_group_message: true,
-                            skip_validations: true,
-                            created_at: embedded.date)
+        topic_user = embedded_user&.call || user
+        create_topic(user: topic_user,
+                     raw: raw,
+                     title: title,
+                     archetype: Archetype.private_message,
+                     target_usernames: [user.username],
+                     target_group_names: [group.name],
+                     is_group_message: true,
+                     skip_validations: true,
+                     created_at: date)
 
       when :category
         category = destination[:obj]
@@ -828,16 +831,31 @@ module Email
         return false if user.staged? && !category.email_in_allow_strangers
         return false if !user.has_trust_level?(SiteSetting.email_in_min_trust)
 
-        embedded_user = find_or_create_user(email, display_name)
-        post = create_topic(user: embedded_user,
-                            raw: raw,
-                            title: title,
-                            category: category.id,
-                            skip_validations: embedded_user.staged?,
-                            created_at: embedded.date)
+        topic_user = embedded_user&.call || user
+        create_topic(user: topic_user,
+                     raw: raw,
+                     title: title,
+                     category: category.id,
+                     skip_validations: topic_user.staged?,
+                     created_at: date)
       else
-        return false
+        false
       end
+    end
+
+    def forwarded_email_create_replies(destination, user)
+      embedded = Mail.new(embedded_email_raw)
+      email, display_name = parse_from_field(embedded)
+
+      return false if email.blank? || !email["@"]
+
+      post = forwarded_email_create_topic(destination: destination,
+                                          user: user,
+                                          raw: try_to_encode(embedded.decoded, "UTF-8").presence || embedded.to_s,
+                                          title: embedded.subject.presence || subject,
+                                          date: embedded.date,
+                                          embedded_user: lambda { find_or_create_user(email, display_name) })
+      return false unless post
 
       if post&.topic
         # mark post as seen for the forwarder
@@ -846,7 +864,7 @@ module Email
         # create reply when available
         if @before_embedded.present?
           post_type = Post.types[:regular]
-          post_type = Post.types[:whisper] if post.topic.private_message? && group.usernames[user.username]
+          post_type = Post.types[:whisper] if post.topic.private_message? && destination[:obj].usernames[user.username]
 
           create_reply(user: user,
                        raw: @before_embedded,
@@ -860,6 +878,19 @@ module Email
       true
     end
 
+    def forwarded_email_quote_forwarded(destination, user)
+      embedded = embedded_email_raw
+      raw = <<~EOF
+        #{@before_embedded}
+
+        [quote]
+        #{PlainTextToMarkdown.new(embedded).to_markdown}
+        [/quote]
+      EOF
+
+      return true if forwarded_email_create_topic(destination: destination, user: user, raw: raw, title: subject)
+    end
+
     def self.reply_by_email_address_regex(extract_reply_key = true, include_verp = false)
       reply_addresses = [SiteSetting.reply_by_email_address]
       reply_addresses << (SiteSetting.alternative_reply_by_email_addresses.presence || "").split("|")