validate max songs per account in upload form

lib/live_beats/accounts/user.ex

@@ -4,6 +4,8 @@ defmodule LiveBeats.Accounts.User do
 
   alias LiveBeats.Accounts.{User, Identity}
 
+  @max_songs 30
+
   schema "users" do
     field :email, :string
     field :name, :string
@@ -14,6 +16,7 @@ defmodule LiveBeats.Accounts.User do
     field :active_profile_user_id, :id
     field :avatar_url, :string
     field :external_homepage_url, :string
+    field :songs_number, :integer
 
     has_many :identities, Identity
 
@@ -59,6 +62,13 @@ defmodule LiveBeats.Accounts.User do
     |> validate_username()
   end
 
+  def songs_changeset(%User{} = user, params) do
+    user
+    |> cast(params, [:songs_number])
+    |> validate_required([:songs_number])
+    |> validate_number(:songs_number, less_than_or_equal_to: @max_songs)
+  end
+
   defp validate_email(changeset) do
     changeset
     |> validate_required([:email])

lib/live_beats/media_library.ex

@@ -157,6 +157,16 @@ defmodule LiveBeats.MediaLibrary do
 
         Ecto.Multi.insert(acc, {:song, ref}, chset)
       end)
+      |> Ecto.Multi.update(:update_songs_number, fn acc ->
+        new_songs = acc |> Enum.filter(&match?({{:song, _ref}, _}, &1)) |> Enum.count()
+        user = Accounts.get_user!(user.id)
+
+        user_params = %{
+          songs_number: user.songs_number + new_songs
+        }
+
+        Accounts.User.songs_changeset(user, user_params)
+      end)
 
     case LiveBeats.Repo.transaction(multi) do
       {:ok, results} ->
@@ -169,8 +179,17 @@ defmodule LiveBeats.MediaLibrary do
          end)
          |> Enum.into(%{})}
 
-      {:error, _failed_op, _failed_val, _changes} ->
-        {:error, :invalid}
+      {:error, failed_op, failed_val, _changes} ->
+        reason =
+          case {failed_op, format_errors(failed_val)} do
+            {:update_songs_number, %{songs_number: _errors}} ->
+              {:songs_number, :songs_limit_exceeded}
+
+            _ ->
+              {:form, :invalid}
+          end
+
+        {:error, reason}
     end
   end
 
@@ -338,4 +357,12 @@ defmodule LiveBeats.MediaLibrary do
   end
 
   defp topic(user_id) when is_integer(user_id), do: "profile:#{user_id}"
+
+  defp format_errors(changeset) do
+    Changeset.traverse_errors(changeset, fn {message, opts} ->
+      Regex.replace(~r"%{(\w+)}", message, fn _, key ->
+        opts |> Keyword.get(String.to_existing_atom(key), key) |> to_string()
+      end)
+    end)
+  end
 end

lib/live_beats_web/live/song_live/upload_form_component.ex

@@ -56,8 +56,12 @@ defmodule LiveBeatsWeb.SongLive.UploadFormComponent do
            |> put_flash(:info, "#{map_size(songs)} song(s) uploaded")
            |> push_redirect(to: profile_path(current_user))}
 
-        {:error, _reason} ->
-          {:noreply, socket}
+        {:error, error} ->
+          updated_socket =
+            socket
+            |> update(:error_messages, &Enum.take(&1 ++ [error], -10))
+
+          {:noreply, updated_socket}
       end
     end
   end
@@ -148,6 +152,11 @@ defmodule LiveBeatsWeb.SongLive.UploadFormComponent do
   defp file_error(%{kind: :not_accepted} = assigns), do: ~H|not a valid MP3 file|
   defp file_error(%{kind: :too_many_files} = assigns), do: ~H|too many files|
 
+  defp file_error(%{kind: :songs_limit_exceeded} = assigns),
+    do: ~H|You exceeded the limit of songs per account|
+
+  defp file_error(%{kind: :invalid} = assigns), do: ~H|Something went wrong|
+
   defp file_error(%{kind: {msg, opts}} = assigns) when is_binary(msg) and is_list(opts) do
     ~H|<%= LiveBeatsWeb.ErrorHelpers.translate_error(@kind) %>|
   end
@@ -190,7 +199,7 @@ defmodule LiveBeatsWeb.SongLive.UploadFormComponent do
     socket
     |> cancel_upload(:mp3, entry.ref)
     |> drop_changeset(entry.ref)
-    |> update(:error_messages, &(Enum.take(&1 ++ [{entry.client_name, reason}], -10)))
+    |> update(:error_messages, &Enum.take(&1 ++ [{entry.client_name, reason}], -10))
   end
 
   defp get_entry!(socket, entry_ref) do

priv/repo/migrations/20211117174157_add_songs_number_to_users.exs

@@ -0,0 +1,20 @@
+defmodule LiveBeats.Repo.Migrations.AddSongsNumberToUsers do
+  use Ecto.Migration
+
+  def up do
+    alter table(:users) do
+      add :songs_number, :integer, null: false, default: 0
+    end
+
+    execute("
+      UPDATE users set songs_number =
+        (SELECT count (*) from songs
+          where songs.user_id = users.id)")
+  end
+
+  def down do
+    alter table(:users) do
+      remove :songs_number
+    end
+  end
+end