Add base infra to store assets

lib/music_library/assets.ex

@@ -0,0 +1,10 @@
+defmodule MusicLibrary.Assets do
+  alias MusicLibrary.Assets.Asset
+  alias MusicLibrary.Repo
+
+  def store(params) do
+    %Asset{}
+    |> Asset.changeset(params)
+    |> Repo.insert()
+  end
+end

lib/music_library/assets/asset.ex

@@ -0,0 +1,36 @@
+defmodule MusicLibrary.Assets.Asset do
+  use Ecto.Schema
+
+  import Ecto.Changeset
+
+  @primary_key {:hash, :string, autogenerate: false}
+  schema "assets" do
+    field :content, :binary
+    field :format, :string
+    field :properties, :map, default: %{}, read_after_writes: true
+
+    timestamps(type: :utc_datetime)
+  end
+
+  def changeset(asset, attrs) do
+    asset
+    |> cast(attrs, [:content, :format, :properties])
+    |> validate_required([:content, :format])
+    |> generate_hash()
+    |> unique_constraint(:hash)
+  end
+
+  defp generate_hash(changeset) do
+    case get_change(changeset, :content) do
+      nil ->
+        changeset
+
+      content ->
+        put_change(changeset, :hash, hash(content))
+    end
+  end
+
+  defp hash(content) do
+    :crypto.hash(:sha256, content) |> Base.encode16()
+  end
+end

priv/repo/migrations/20250901072717_create_assets.exs

@@ -0,0 +1,14 @@
+defmodule MusicLibrary.Repo.Migrations.CreateAssets do
+  use Ecto.Migration
+
+  def change do
+    create table(:assets, primary_key: false) do
+      add :hash, :string, primary_key: true
+      add :content, :binary, null: false
+      add :format, :string, null: false
+      add :properties, :map, default: %{}
+
+      timestamps(type: :utc_datetime)
+    end
+  end
+end

test/music_library/assets_test.exs

@@ -0,0 +1,34 @@
+defmodule MusicLibrary.AssetsTest do
+  use MusicLibrary.DataCase
+
+  alias MusicLibrary.Assets
+
+  describe "store/1" do
+    test "stores using the hash as key" do
+      params = %{
+        content: "some content",
+        format: "text/plain",
+        properties: %{language: "english"}
+      }
+
+      assert {:ok, asset} = Assets.store(params)
+      assert asset.hash == "290F493C44F5D63D06B374D0A5ABD292FAE38B92CAB2FAE5EFEFE1B0E9347F56"
+      assert asset.properties == %{"language" => "english"}
+      assert asset.content == "some content"
+      assert asset.format == "text/plain"
+    end
+
+    test "prevents duplicates" do
+      params = %{
+        content: "some content",
+        format: "text/plain",
+        properties: %{language: "english"}
+      }
+
+      assert {:ok, _asset} = Assets.store(params)
+      assert {:error, changeset} = Assets.store(params)
+
+      assert [hash: {"has already been taken", _}] = changeset.errors
+    end
+  end
+end