Make player names unique within a tournament. (#412)

* Make player names unique within a tournament.

* Fix lint.

db/migrate/20250217194837_make_player_names_unique.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+class MakePlayerNamesUnique < ActiveRecord::Migration[7.2]
+  def change
+    # Add a "(duplicate #N)"" suffix to any duplicate player names before applying the index.
+    dupes = Player.select(:tournament_id, :name)
+                  .group(:tournament_id, :name)
+                  .having('COUNT(*) > 1')
+    dupes.each do |dupe|
+      players = Player.where(tournament_id: dupe.tournament_id, name: dupe.name)
+      players.each_with_index do |player, index|
+        player.update!(name: "#{player.name} (duplicate ##{index + 1})")
+      end
+    end
+    add_index :players, %i[tournament_id name], unique: true, name: 'idx_uniq_players_tournament_id_name'
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.2].define(version: 2024_11_16_155531) do
+ActiveRecord::Schema[7.2].define(version: 2025_02_17_194837) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
 
@@ -140,6 +140,7 @@
     t.integer "fixed_table_number"
     t.index ["corp_identity_ref_id"], name: "index_players_on_corp_identity_ref_id"
     t.index ["runner_identity_ref_id"], name: "index_players_on_runner_identity_ref_id"
+    t.index ["tournament_id", "name"], name: "idx_uniq_players_tournament_id_name", unique: true
     t.index ["tournament_id"], name: "index_players_on_tournament_id"
     t.index ["user_id"], name: "index_players_on_user_id"
   end