class UserSession < ApplicationRecord
  TOKEN_LENGTH = 32

  belongs_to :user

  validates :token_digest, presence: true, uniqueness: true

  def self.create_for!(user)
    raw_token = generate_raw_token
    user_session = create!(user: user, token_digest: digest(raw_token), last_used_at: Time.current)

    [ user_session, raw_token ]
  end

  def self.find_by_token(raw_token)
    return if raw_token.blank?

    find_by(token_digest: digest(raw_token))
  end

  def self.generate_raw_token
    SecureRandom.urlsafe_base64(TOKEN_LENGTH)
  end

  def self.digest(raw_token)
    Digest::SHA256.hexdigest(raw_token.to_s)
  end
end