# frozen_string_literal: true

require 'posthog/defaults'

module PostHog
  class BackoffPolicy
    include PostHog::Defaults::BackoffPolicy

    # @param [Hash] opts
    # @option opts [Numeric] :min_timeout_ms The minimum backoff timeout
    # @option opts [Numeric] :max_timeout_ms The maximum backoff timeout
    # @option opts [Numeric] :multiplier The value to multiply the current
    #   interval with for each retry attempt
    # @option opts [Numeric] :randomization_factor The randomization factor
    #   to use to create a range around the retry interval
    def initialize(opts = {})
      @min_timeout_ms = opts[:min_timeout_ms] || MIN_TIMEOUT_MS
      @max_timeout_ms = opts[:max_timeout_ms] || MAX_TIMEOUT_MS
      @multiplier = opts[:multiplier] || MULTIPLIER
      @randomization_factor =
        opts[:randomization_factor] || RANDOMIZATION_FACTOR

      @attempts = 0
    end

    # @return [Numeric] the next backoff interval, in milliseconds.
    def next_interval
      interval = @min_timeout_ms * (@multiplier**@attempts)
      interval = add_jitter(interval, @randomization_factor)

      @attempts += 1

      [interval, @max_timeout_ms].min
    end

    private

    def add_jitter(base, randomization_factor)
      random_number = rand
      max_deviation = base * randomization_factor
      deviation = random_number * max_deviation

      random_number < 0.5 ? base - deviation : base + deviation
    end
  end
end