class EntityCache
  configure :entity_cache

  dependency :clock, Clock::UTC
  dependency :logger, Telemetry::Logger
  dependency :persistent_store, Storage::Persistent
  dependency :temporary_store, Storage::Temporary

  setting :write_behind_delay

  def self.build(subject, persistent_store: nil)
    instance = new

    Clock::UTC.configure instance
    Telemetry::Logger.configure instance

    Storage::Temporary.configure instance, subject
    Storage::Persistent.configure instance, subject, implementation: persistent_store

    instance
  end

  def get(id, include: nil)
    logger.opt_trace "Reading cache (ID: #{id.inspect}, Include: #{include.inspect})"

    record = temporary_store.get id
    record ||= restore id

    if record.nil?
      logger.opt_debug "Cache miss (ID: #{id.inspect})"
      return nil
    end

    logger.opt_debug "Cache hit (ID: #{id.inspect}, Entity Class: #{record.entity.class.name}, Version: #{record.version.inspect}, Time: #{record.time})"

    record
  end

  def put(id, entity, version, persisted_version: nil, persisted_time: nil, time: nil)
    time ||= clock.iso8601

    logger.opt_trace "Writing cache (ID: #{id}, Entity Class: #{entity.class.name}, Version: #{version.inspect}, Time: #{time}, Persistent Version: #{persisted_version.inspect}, Persistent Time: #{persisted_time.inspect})"

    record = Record.new id, entity, version, time, persisted_version, persisted_time

    put_record record

    logger.opt_debug "Cache written (ID: #{id}, Entity Class: #{record.entity.class.name}, Version: #{record.version.inspect}, Time: #{record.time}, Persistent Version: #{persisted_version.inspect}, Persistent Time: #{persisted_time.inspect})"

    record
  end

  def put_record(record)
    temporary_store.put record

    return if write_behind_delay.nil?

    if record.age >= write_behind_delay
      persistent_store.put record.id, record.entity, record.version
    end
  end

  def restore(id)
    entity, persisted_version, persisted_time = persistent_store.get id

    return nil if entity.nil?

    version = persisted_version
    time = persisted_time

    put(
      id,
      entity,
      version,
      persisted_version: persisted_version,
      persisted_time: persisted_time,
      time: time
    )
  end
end