4 files changed, 107 insertions, 0 deletions
diff --git a/lib/pleroma/moderation_log.ex b/lib/pleroma/moderation_log.ex
index 31c9afe2a..47036a6f6 100644
--- a/lib/pleroma/moderation_log.ex
+++ b/lib/pleroma/moderation_log.ex
@@ -320,6 +320,19 @@ defmodule Pleroma.ModerationLog do
     |> insert_log_entry_with_message()
   end
 
+  @spec insert_log(%{actor: User, action: String.t(), subject_id: String.t()}) ::
+          {:ok, ModerationLog} | {:error, any}
+  def insert_log(%{actor: %User{} = actor, action: "chat_message_delete", subject_id: subject_id}) do
+    %ModerationLog{
+      data: %{
+        "actor" => %{"nickname" => actor.nickname},
+        "action" => "chat_message_delete",
+        "subject_id" => subject_id
+      }
+    }
+    |> insert_log_entry_with_message()
+  end
+
   @spec insert_log_entry_with_message(ModerationLog) :: {:ok, ModerationLog} | {:error, any}
   defp insert_log_entry_with_message(entry) do
     entry.data["message"]
@@ -627,6 +640,17 @@ defmodule Pleroma.ModerationLog do
     "@#{actor_nickname} updated users: #{users_to_nicknames_string(subjects)}"
   end
 
+  @spec get_log_entry_message(ModerationLog) :: String.t()
+  def get_log_entry_message(%ModerationLog{
+        data: %{
+          "actor" => %{"nickname" => actor_nickname},
+          "action" => "chat_message_delete",
+          "subject_id" => subject_id
+        }
+      }) do
+    "@#{actor_nickname} deleted chat message ##{subject_id}"
+  end
+
   defp nicknames_to_string(nicknames) do
     nicknames
     |> Enum.map(&"@#{&1}")
diff --git a/lib/pleroma/web/admin_api/controllers/chat_controller.ex b/lib/pleroma/web/admin_api/controllers/chat_controller.ex
new file mode 100644
index 000000000..bcce824d2
--- /dev/null
+++ b/lib/pleroma/web/admin_api/controllers/chat_controller.ex
@@ -0,0 +1,37 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.AdminAPI.ChatController do
+  use Pleroma.Web, :controller
+
+  alias Pleroma.Activity
+  alias Pleroma.ModerationLog
+  alias Pleroma.Plugs.OAuthScopesPlug
+  alias Pleroma.Web.CommonAPI
+
+  require Logger
+
+  plug(Pleroma.Web.ApiSpec.CastAndValidate)
+
+  plug(
+    OAuthScopesPlug,
+    %{scopes: ["write:chats"], admin: true} when action in [:delete_message]
+  )
+
+  action_fallback(Pleroma.Web.AdminAPI.FallbackController)
+
+  defdelegate open_api_operation(action), to: Pleroma.Web.ApiSpec.Admin.ChatOperation
+
+  def delete_message(%{assigns: %{user: user}} = conn, %{message_id: id}) do
+    with {:ok, %Activity{}} <- CommonAPI.delete(id, user) do
+      ModerationLog.insert_log(%{
+        action: "chat_message_delete",
+        actor: user,
+        subject_id: id
+      })
+
+      json(conn, %{})
+    end
+  end
+end
diff --git a/lib/pleroma/web/api_spec/operations/admin/chat_operation.ex b/lib/pleroma/web/api_spec/operations/admin/chat_operation.ex
new file mode 100644
index 000000000..7045fd7ce
--- /dev/null
+++ b/lib/pleroma/web/api_spec/operations/admin/chat_operation.ex
@@ -0,0 +1,44 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ApiSpec.Admin.ChatOperation do
+  alias OpenApiSpex.Operation
+  alias Pleroma.Web.ApiSpec.Schemas.ApiError
+  alias Pleroma.Web.ApiSpec.Schemas.FlakeID
+
+  import Pleroma.Web.ApiSpec.Helpers
+
+  def open_api_operation(action) do
+    operation = String.to_existing_atom("#{action}_operation")
+    apply(__MODULE__, operation, [])
+  end
+
+  def delete_message_operation do
+    %Operation{
+      tags: ["Admin", "Chats"],
+      summary: "Delete an individual chat message",
+      operationId: "AdminAPI.ChatController.delete",
+      parameters: [id_param(), message_id_param()] ++ admin_api_params(),
+      security: [%{"oAuth" => ["write:chats"]}],
+      responses: %{
+        200 => empty_object_response(),
+        404 => Operation.response("Not Found", "application/json", ApiError)
+      }
+    }
+  end
+
+  def id_param do
+    Operation.parameter(:id, :path, FlakeID, "Chat ID",
+      example: "9umDrYheeY451cQnEe",
+      required: true
+    )
+  end
+
+  def message_id_param do
+    Operation.parameter(:message_id, :path, FlakeID, "Chat message ID",
+      example: "9umDrYheeY451cQnEe",
+      required: true
+    )
+  end
+end
diff --git a/lib/pleroma/web/router.ex b/lib/pleroma/web/router.ex
index c6433cc53..e438768ed 100644
--- a/lib/pleroma/web/router.ex
+++ b/lib/pleroma/web/router.ex
@@ -214,6 +214,8 @@ defmodule Pleroma.Web.Router do
     get("/media_proxy_caches", MediaProxyCacheController, :index)
     post("/media_proxy_caches/delete", MediaProxyCacheController, :delete)
     post("/media_proxy_caches/purge", MediaProxyCacheController, :purge)
+
+    delete("/chats/:id/messages/:message_id", ChatController, :delete_message)
   end
 
   scope "/api/pleroma/emoji", Pleroma.Web.PleromaAPI do