class HealthCheck

  CUSTOM_ITEMS = %w(hostname url client_ip localtime utctime)

  BOOLEAN_ITEMS = %w(database_connection database_persistence database_integrity)

  TEST_SETTINGS_KEY = 'healthcheck_test_key'

  def self.checkup(env)

    new(env).checkup

   end

  def initialize(env)

    @env = env

  end

  def checkup

    diagnosis = {}

    CUSTOM_ITEMS.each do |symptom|

      diagnosis[symptom] = self.send(symptom)

    end

    BOOLEAN_ITEMS.each do |symptom|

      diagnosis[symptom] = stringify(self.send(symptom))

    end

    diagnosis

  end

  private

  def hostname

    Socket.gethostname

  end

  def url

    @env.fetch('REQUEST_URI', 'FAILED: no REQUEST_URI present in env')

  end

  def client_ip

    @env.fetch('REMOTE_ADDR', 'FAILED: no REMOTE_ADDR present in env')

  end

  def localtime

    Time.current.rfc2822

  end

  def utctime

    Time.current.getutc.rfc2822

  end

  def stringify(b)

    b ? 'OK' : 'FAILED'

  end

  def database_connection

    ActiveRecord::Base.establish_connection

    ActiveRecord::Base.connection

    true

  rescue

    false

  end

  def database_persistence

    return false unless database_connection

    return false unless Site.first_or_create

    return false unless Site.last_checked_at!

    true

  rescue

    false

  end

  def database_integrity

    return false unless database_connection

    !ActiveRecord::Migrator.needs_migration?

  end

end