Добавил генерацию колоды и улучшил бд

app/services/deck_generator.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+module ClashDeckGenerator2
+  module Services
+    class DeckGenerator
+      DECK_SIZE = 8
+
+      def initialize(cards_repo:)
+        @cards_repo = cards_repo
+      end
+
+      def call(only_meta: true)
+        pool = only_meta ? @cards_repo.meta_cards : @cards_repo.all_cards
+        deck = sample_unique(pool, DECK_SIZE)
+
+        {
+          cards: deck,
+          avg_elixir: average_elixir(deck)
+        }
+      end
+
+      private
+
+      def sample_unique(pool, n)
+        raise "Not enough cards in pool (need #{n}, have #{pool.size})" if pool.size < n
+
+        pool.sample(n)
+      end
+
+      def average_elixir(deck)
+        sum = deck.sum { |c| c[:elixir_cost].to_i }
+        sum.fdiv(deck.size).round(2)
+      end
+    end
+  end
+end