7 files changed, 255 insertions, 0 deletions
diff --git a/app/graphql/mutations/notes/base.rb b/app/graphql/mutations/notes/base.rb
new file mode 100644
index 00000000000..a7198f5fba6
--- /dev/null
+++ b/app/graphql/mutations/notes/base.rb
@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+module Mutations
+  module Notes
+    class Base < BaseMutation
+      include Gitlab::Graphql::Authorize::AuthorizeResource
+
+      field :note,
+            Types::Notes::NoteType,
+            null: true,
+            description: 'The note after mutation'
+
+      private
+
+      def find_object(id:)
+        GitlabSchema.object_from_id(id)
+      end
+
+      def check_object_is_noteable!(object)
+        unless object.is_a?(Noteable)
+          raise Gitlab::Graphql::Errors::ResourceNotAvailable,
+                'Cannot add notes to this resource'
+        end
+      end
+
+      def check_object_is_note!(object)
+        unless object.is_a?(Note)
+          raise Gitlab::Graphql::Errors::ResourceNotAvailable,
+                'Resource is not a note'
+        end
+      end
+    end
+  end
+end
diff --git a/app/graphql/mutations/notes/create/base.rb b/app/graphql/mutations/notes/create/base.rb
new file mode 100644
index 00000000000..d3a5dae2188
--- /dev/null
+++ b/app/graphql/mutations/notes/create/base.rb
@@ -0,0 +1,49 @@
+# frozen_string_literal: true
+
+module Mutations
+  module Notes
+    module Create
+      # This is a Base class for the Note creation Mutations and is not
+      # mounted as a GraphQL mutation itself.
+      class Base < Mutations::Notes::Base
+        authorize :create_note
+
+        argument :noteable_id,
+                  GraphQL::ID_TYPE,
+                  required: true,
+                  description: 'The global id of the resource to add a note to'
+
+        argument :body,
+                  GraphQL::STRING_TYPE,
+                  required: true,
+                  description: copy_field_description(Types::Notes::NoteType, :body)
+
+        private
+
+        def resolve(args)
+          noteable = authorized_find!(id: args[:noteable_id])
+
+          check_object_is_noteable!(noteable)
+
+          note = ::Notes::CreateService.new(
+            noteable.project,
+            current_user,
+            create_note_params(noteable, args)
+          ).execute
+
+          {
+            note: (note if note.persisted?),
+            errors: errors_on_object(note)
+          }
+        end
+
+        def create_note_params(noteable, args)
+          {
+            noteable: noteable,
+            note: args[:body]
+          }
+        end
+      end
+    end
+  end
+end
diff --git a/app/graphql/mutations/notes/create/diff_note.rb b/app/graphql/mutations/notes/create/diff_note.rb
new file mode 100644
index 00000000000..9b5f3092006
--- /dev/null
+++ b/app/graphql/mutations/notes/create/diff_note.rb
@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+module Mutations
+  module Notes
+    module Create
+      class DiffNote < Base
+        graphql_name 'CreateDiffNote'
+
+        argument :position,
+                  Types::Notes::DiffPositionInputType,
+                  required: true,
+                  description: copy_field_description(Types::Notes::NoteType, :position)
+
+        private
+
+        def create_note_params(noteable, args)
+          super(noteable, args).merge({
+            type: 'DiffNote',
+            position: position(noteable, args)
+          })
+        end
+
+        def position(noteable, args)
+          position = args[:position].to_h
+          position[:position_type] = 'text'
+          position.merge!(position[:paths].to_h)
+
+          Gitlab::Diff::Position.new(position)
+        end
+      end
+    end
+  end
+end
diff --git a/app/graphql/mutations/notes/create/image_diff_note.rb b/app/graphql/mutations/notes/create/image_diff_note.rb
new file mode 100644
index 00000000000..d94fd4d6ff8
--- /dev/null
+++ b/app/graphql/mutations/notes/create/image_diff_note.rb
@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+module Mutations
+  module Notes
+    module Create
+      class ImageDiffNote < Base
+        graphql_name 'CreateImageDiffNote'
+
+        argument :position,
+                  Types::Notes::DiffImagePositionInputType,
+                  required: true,
+                  description: copy_field_description(Types::Notes::NoteType, :position)
+
+        private
+
+        def create_note_params(noteable, args)
+          super(noteable, args).merge({
+            type: 'DiffNote',
+            position: position(noteable, args)
+          })
+        end
+
+        def position(noteable, args)
+          position = args[:position].to_h
+          position[:position_type] = 'image'
+          position.merge!(position[:paths].to_h)
+
+          Gitlab::Diff::Position.new(position)
+        end
+      end
+    end
+  end
+end
diff --git a/app/graphql/mutations/notes/create/note.rb b/app/graphql/mutations/notes/create/note.rb
new file mode 100644
index 00000000000..5236e48026e
--- /dev/null
+++ b/app/graphql/mutations/notes/create/note.rb
@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+module Mutations
+  module Notes
+    module Create
+      class Note < Base
+        graphql_name 'CreateNote'
+
+        argument :discussion_id,
+                  GraphQL::ID_TYPE,
+                  required: false,
+                  description: 'The global id of the discussion this note is in reply to'
+
+        private
+
+        def create_note_params(noteable, args)
+          discussion_id = nil
+
+          if args[:discussion_id]
+            discussion = GitlabSchema.object_from_id(args[:discussion_id])
+            authorize_discussion!(discussion)
+
+            discussion_id = discussion.id
+          end
+
+          super(noteable, args).merge({
+            in_reply_to_discussion_id: discussion_id
+          })
+        end
+
+        def authorize_discussion!(discussion)
+          unless Ability.allowed?(current_user, :read_note, discussion, scope: :user)
+            raise Gitlab::Graphql::Errors::ResourceNotAvailable,
+              "The discussion does not exist or you don't have permission to perform this action"
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/app/graphql/mutations/notes/destroy.rb b/app/graphql/mutations/notes/destroy.rb
new file mode 100644
index 00000000000..a81322bc9b7
--- /dev/null
+++ b/app/graphql/mutations/notes/destroy.rb
@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+module Mutations
+  module Notes
+    class Destroy < Base
+      graphql_name 'DestroyNote'
+
+      authorize :admin_note
+
+      argument :id,
+                GraphQL::ID_TYPE,
+                required: true,
+                description: 'The global id of the note to destroy'
+
+      def resolve(id:)
+        note = authorized_find!(id: id)
+
+        check_object_is_note!(note)
+
+        ::Notes::DestroyService.new(note.project, current_user).execute(note)
+
+        {
+          errors: []
+        }
+      end
+    end
+  end
+end
diff --git a/app/graphql/mutations/notes/update.rb b/app/graphql/mutations/notes/update.rb
new file mode 100644
index 00000000000..ebf57b800c0
--- /dev/null
+++ b/app/graphql/mutations/notes/update.rb
@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+module Mutations
+  module Notes
+    class Update < Base
+      graphql_name 'UpdateNote'
+
+      authorize :admin_note
+
+      argument :id,
+                GraphQL::ID_TYPE,
+                required: true,
+                description: 'The global id of the note to update'
+
+      argument :body,
+                GraphQL::STRING_TYPE,
+                required: true,
+                description: copy_field_description(Types::Notes::NoteType, :body)
+
+      def resolve(args)
+        note = authorized_find!(id: args[:id])
+
+        check_object_is_note!(note)
+
+        note = ::Notes::UpdateService.new(
+          note.project,
+          current_user,
+          { note: args[:body] }
+        ).execute(note)
+
+        {
+          note: note.reset,
+          errors: errors_on_object(note)
+        }
+      end
+    end
+  end
+end