add Match model

main-server/app/models/user.rb

@@ -2,6 +2,8 @@ class User < ApplicationRecord
   has_secure_password validations: false
 
   has_many :sessions, dependent: :destroy
+  has_many :matches_as_player1, class_name: "Match", foreign_key: :player1_id, dependent: :restrict_with_exception, inverse_of: :player1
+  has_many :matches_as_player2, class_name: "Match", foreign_key: :player2_id, dependent: :restrict_with_exception, inverse_of: :player2
   has_one_attached :avatar
 
   normalizes :nickname, with: ->(n) { n.strip }
@@ -11,6 +13,13 @@ class User < ApplicationRecord
   validates :password, presence: true, length: { minimum: 6 }, if: -> { new_record? || password_digest_changed? }
   validate :avatar_content_type, if: -> { avatar.attached? }
 
+  # All matches of this user that have finished, newest first.
+  def finished_matches
+    Match.where("player1_id = :id OR player2_id = :id", id: id)
+         .where.not(finished_at: nil)
+         .order(finished_at: :desc)
+  end
+
   private
     def avatar_content_type
       unless avatar.blob.content_type.in?(%w[image/png image/jpeg image/gif image/webp])