Implement #3243 New Issue by email

So we extend Gitlab::Email::Receiver for this new behaviour,
however we might want to split it into another class for better
testing it.

Another issue is that, currently it's using this to parse project
identifier:

    Gitlab::IncomingEmail.key_from_address

Which is using:

    Gitlab.config.incoming_email.address

for the receiver name. This is probably `reply` because it's used
for replying to a specific issue. We might want to introduce another
config for this, or just use `reply` instead of `incoming`.

I'll prefer to introduce a new config for this, or just change
`reply` to `incoming` because it would make sense for replying to
there, too.

The email template used in tests were copied and modified from:
`emails/valid_reply.eml` which I hope is ok.

1 files changed, 70 insertions, 17 deletions

diff --git a/lib/gitlab/email/receiver.rb b/lib/gitlab/email/receiver.rb
index 97ef9851d71..2b57b3a20fc 100644
--- a/lib/gitlab/email/receiver.rb
+++ b/lib/gitlab/email/receiver.rb
@@ -12,6 +12,7 @@ module Gitlab
       class UserNotAuthorizedError < ProcessingError; end
       class NoteableNotFoundError < ProcessingError; end
       class InvalidNoteError < ProcessingError; end
+      class InvalidIssueError < ProcessingError; end
 
       def initialize(raw)
         @raw = raw
@@ -20,29 +21,30 @@ module Gitlab
       def execute
         raise EmptyEmailError if @raw.blank?
 
-        raise SentNotificationNotFoundError unless sent_notification
+        if sent_notification
+          process_reply
 
-        raise AutoGeneratedEmailError if message.header.to_s =~ /auto-(generated|replied)/
-
-        author = sent_notification.recipient
+        elsif message_project
+          process_create_issue
 
-        raise UserNotFoundError unless author
+        else
+          # TODO: could also be project not found
+          raise SentNotificationNotFoundError
+        end
+      end
 
-        raise UserBlockedError if author.blocked?
+      private
+      def process_reply
+        raise AutoGeneratedEmailError if message.header.to_s =~ /auto-(generated|replied)/
 
+        author = sent_notification.recipient
         project = sent_notification.project
 
-        raise UserNotAuthorizedError unless project && author.can?(:create_note, project)
+        check_input(author, project, :create_note)
 
         raise NoteableNotFoundError unless sent_notification.noteable
 
-        reply = ReplyParser.new(message).execute.strip
-
-        raise EmptyEmailError if reply.blank?
-
-        reply = add_attachments(reply)
-
-        note = create_note(reply)
+        note = create_note(extract_reply(project))
 
         unless note.persisted?
           msg = "The comment could not be created for the following reasons:"
@@ -54,7 +56,58 @@ module Gitlab
         end
       end
 
-      private
+      def process_create_issue
+        check_input(message_sender, message_project, :create_issue)
+
+        issue = Issues::CreateService.new(message_project, message_sender,
+          title: message.subject,
+          description: extract_reply(message_project)).execute
+
+        unless issue.persisted?
+          msg = "The issue could not be created for the following reasons:"
+          issue.errors.full_messages.each do |error|
+            msg << "\n\n- #{error}"
+          end
+
+          raise InvalidIssueError, msg
+        end
+      end
+
+      def check_input(author, project, permission)
+        if author
+          if author.blocked?
+            raise UserBlockedError
+          elsif project.nil? || !author.can?(permission, project)
+            # TODO: Give project not found error if author cannot read project
+            raise UserNotAuthorizedError
+          end
+        else
+          raise UserNotFoundError
+        end
+      end
+
+      # Find the first matched user in database from email From: section
+      def message_sender
+        @message_sender ||= message.from.find do |email|
+          user = User.find_by_any_email(email)
+          break user if user
+        end
+      end
+
+      def message_project
+        @message_project ||=
+          Project.find_with_namespace(reply_key) if reply_key
+      end
+
+      def extract_reply project
+        reply = ReplyParser.new(message).execute.strip
+
+        raise EmptyEmailError if reply.blank?
+
+        add_attachments(reply, project)
+
+        reply
+      end
 
       def message
         @message ||= Mail::Message.new(@raw)
@@ -93,8 +146,8 @@ module Gitlab
         SentNotification.for(reply_key)
       end
 
-      def add_attachments(reply)
-        attachments = Email::AttachmentUploader.new(message).execute(sent_notification.project)
+      def add_attachments(reply, project)
+        attachments = Email::AttachmentUploader.new(message).execute(project)
 
         attachments.each do |link|
           reply << "\n\n#{link[:markdown]}"