Persist chat history

lib/music_library/chats/chat.ex

@@ -0,0 +1,31 @@
+defmodule MusicLibrary.Chats.Chat do
+  use Ecto.Schema
+
+  import Ecto.Changeset
+
+  alias MusicLibrary.Chats.Message
+
+  @primary_key {:id, :binary_id, autogenerate: true}
+  @foreign_key_type :binary_id
+  schema "chats" do
+    field :entity, Ecto.Enum, values: [:record, :artist]
+    field :musicbrainz_id, Ecto.UUID
+    field :topic, :string
+
+    field :message_count, :integer, virtual: true, default: 0
+
+    has_many :messages, Message, preload_order: [asc: :position]
+
+    timestamps(type: :utc_datetime)
+  end
+
+  @type t :: %__MODULE__{}
+
+  @spec changeset(t() | Ecto.Changeset.t(), map()) :: Ecto.Changeset.t()
+  def changeset(chat, attrs) do
+    chat
+    |> cast(attrs, [:entity, :musicbrainz_id, :topic])
+    |> validate_required([:entity, :musicbrainz_id])
+    |> validate_length(:topic, max: 200)
+  end
+end

lib/music_library/chats/message.ex

@@ -0,0 +1,29 @@
+defmodule MusicLibrary.Chats.Message do
+  use Ecto.Schema
+
+  import Ecto.Changeset
+
+  alias MusicLibrary.Chats.Chat
+
+  @primary_key {:id, :binary_id, autogenerate: true}
+  @foreign_key_type :binary_id
+  schema "chat_messages" do
+    field :role, :string
+    field :content, :string
+    field :position, :integer
+
+    belongs_to :chat, Chat
+
+    timestamps(type: :utc_datetime)
+  end
+
+  @type t :: %__MODULE__{}
+
+  @spec changeset(t() | Ecto.Changeset.t(), map()) :: Ecto.Changeset.t()
+  def changeset(message, attrs) do
+    message
+    |> cast(attrs, [:role, :content, :position])
+    |> validate_required([:role, :content, :position])
+    |> validate_inclusion(:role, ["user", "assistant"])
+  end
+end