Chats: Basic implementation.

priv/repo/migrations/20200309123730_create_chats.exs

@@ -0,0 +1,16 @@
+defmodule Pleroma.Repo.Migrations.CreateChats do
+  use Ecto.Migration
+
+  def change do
+    create table(:chats) do
+      add(:user_id, references(:users, type: :uuid))
+      # Recipient is an ActivityPub id, to future-proof for group support.
+      add(:recipient, :string)
+      add(:unread, :integer, default: 0)
+      timestamps()
+    end
+
+    # There's only one chat between a user and a recipient.
+    create(index(:chats, [:user_id, :recipient], unique: true))
+  end
+end