Fetch users from Phabricator to link to issues

We fetch the users from Phabricator based on their Phabricator ID. If
a user with the same username exists and is a member of the project,
we set them as assignee or author.

When a user is applicable, we also cache it in Redis so we don't have
to perform the request again for the same phid.

7 files changed, 160 insertions, 5 deletions

diff --git a/lib/gitlab/phabricator_import/cache/map.rb b/lib/gitlab/phabricator_import/cache/map.rb
index fa8b37b20ca..6a2841b6a8e 100644
--- a/lib/gitlab/phabricator_import/cache/map.rb
+++ b/lib/gitlab/phabricator_import/cache/map.rb
@@ -9,9 +9,15 @@ module Gitlab
 
         def get_gitlab_model(phabricator_id)
           cached_info = get(phabricator_id)
-          return unless cached_info[:classname] && cached_info[:database_id]
 
-          cached_info[:classname].constantize.find_by_id(cached_info[:database_id])
+          if cached_info[:classname] && cached_info[:database_id]
+            object = cached_info[:classname].constantize.find_by_id(cached_info[:database_id])
+          else
+            object = yield if block_given?
+            set_gitlab_model(object, phabricator_id) if object
+          end
+
+          object
         end
 
         def set_gitlab_model(object, phabricator_id)
diff --git a/lib/gitlab/phabricator_import/conduit/user.rb b/lib/gitlab/phabricator_import/conduit/user.rb
new file mode 100644
index 00000000000..fc8c3f7cde9
--- /dev/null
+++ b/lib/gitlab/phabricator_import/conduit/user.rb
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+module Gitlab
+  module PhabricatorImport
+    module Conduit
+      class User
+        MAX_PAGE_SIZE = 100
+
+        def initialize(phabricator_url:, api_token:)
+          @client = Client.new(phabricator_url, api_token)
+        end
+
+        def users(phids)
+          phids.each_slice(MAX_PAGE_SIZE).map { |limited_phids| get_page(limited_phids) }
+        end
+
+        private
+
+        def get_page(phids)
+          UsersResponse.new(get_users(phids))
+        end
+
+        def get_users(phids)
+          client.get('user.search',
+                     params: { constraints: { phids: phids } })
+        end
+
+        attr_reader :client
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/phabricator_import/conduit/users_response.rb b/lib/gitlab/phabricator_import/conduit/users_response.rb
new file mode 100644
index 00000000000..3dfb29a7be5
--- /dev/null
+++ b/lib/gitlab/phabricator_import/conduit/users_response.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module PhabricatorImport
+    module Conduit
+      class UsersResponse
+        def initialize(conduit_response)
+          @conduit_response = conduit_response
+        end
+
+        def users
+          @users ||= conduit_response.data.map do |user_json|
+            Gitlab::PhabricatorImport::Representation::User.new(user_json)
+          end
+        end
+
+        private
+
+        attr_reader :conduit_response
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/phabricator_import/issues/task_importer.rb b/lib/gitlab/phabricator_import/issues/task_importer.rb
index 40d4392cbc1..77ee11c7cdd 100644
--- a/lib/gitlab/phabricator_import/issues/task_importer.rb
+++ b/lib/gitlab/phabricator_import/issues/task_importer.rb
@@ -8,9 +8,7 @@ module Gitlab
         end
 
         def execute
-          # TODO: get the user from the project namespace from the username loaded by Phab-id
-          # https://gitlab.com/gitlab-org/gitlab-ce/issues/60565
-          issue.author = User.ghost
+          issue.author = user_finder.find(task.author_phid) || User.ghost
 
           # TODO: Reformat the description with attachments, escaping accidental
           # links and add attachments
@@ -19,6 +17,10 @@ module Gitlab
 
           save!
 
+          if owner = user_finder.find(task.owner_phid)
+            issue.assignees << owner
+          end
+
           issue
         end
 
@@ -41,6 +43,10 @@ module Gitlab
             project.issues.new
         end
 
+        def user_finder
+          @issue_finder ||= Gitlab::PhabricatorImport::UserFinder.new(project, task.phids)
+        end
+
         def find_issue_by_phabricator_id(phabricator_id)
           object_map.get_gitlab_model(phabricator_id)
         end
diff --git a/lib/gitlab/phabricator_import/representation/task.rb b/lib/gitlab/phabricator_import/representation/task.rb
index 6aedc71b626..ba93fb37a8e 100644
--- a/lib/gitlab/phabricator_import/representation/task.rb
+++ b/lib/gitlab/phabricator_import/representation/task.rb
@@ -11,6 +11,18 @@ module Gitlab
           json['phid']
         end
 
+        def author_phid
+          json['fields']['authorPHID']
+        end
+
+        def owner_phid
+          json['fields']['ownerPHID']
+        end
+
+        def phids
+          @phids ||= [author_phid, owner_phid]
+        end
+
         def issue_attributes
           @issue_attributes ||= {
             title: issue_title,
diff --git a/lib/gitlab/phabricator_import/representation/user.rb b/lib/gitlab/phabricator_import/representation/user.rb
new file mode 100644
index 00000000000..7fd7cecc6ae
--- /dev/null
+++ b/lib/gitlab/phabricator_import/representation/user.rb
@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module PhabricatorImport
+    module Representation
+      class User
+        def initialize(json)
+          @json = json
+        end
+
+        def phabricator_id
+          json['phid']
+        end
+
+        def username
+          json['fields']['username']
+        end
+
+        private
+
+        attr_reader :json
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/phabricator_import/user_finder.rb b/lib/gitlab/phabricator_import/user_finder.rb
new file mode 100644
index 00000000000..4b50431e0e0
--- /dev/null
+++ b/lib/gitlab/phabricator_import/user_finder.rb
@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module PhabricatorImport
+    class UserFinder
+      def initialize(project, phids)
+        @project, @phids = project, phids
+        @loaded_phids = Set.new
+      end
+
+      def find(phid)
+        found_user = object_map.get_gitlab_model(phid) do
+          find_user_for_phid(phid)
+        end
+
+        loaded_phids << phid
+
+        found_user
+      end
+
+      private
+
+      attr_reader :project, :phids, :loaded_phids
+
+      def object_map
+        @object_map ||= Gitlab::PhabricatorImport::Cache::Map.new(project)
+      end
+
+      def find_user_for_phid(phid)
+        phabricator_user = phabricator_users.find { |u| u.phabricator_id == phid }
+        return unless phabricator_user
+
+        project.authorized_users.find_by_username(phabricator_user.username)
+      end
+
+      def phabricator_users
+        @user_responses ||= client.users(users_to_request).flat_map(&:users)
+      end
+
+      def users_to_request
+        phids - loaded_phids.to_a
+      end
+
+      def client
+        @client ||=
+          Gitlab::PhabricatorImport::Conduit::User
+            .new(phabricator_url: project.import_data.data['phabricator_url'],
+                 api_token: project.import_data.credentials[:api_token])
+      end
+    end
+  end
+end