require "logger"

module PromMultiProc
  module Rails
    def self.init(prefix = nil)
      metrics = ENV.fetch("PROM_MULTI_PROC_DEFINITION_FILE", ::Rails.root.join("config/metrics.json").to_s)
      socket = ENV.fetch("PROM_MULTI_PROC_SOCKET", ::Rails.root.join("tmp/sockets/metrics.sock").to_s)

      program_name = File.basename($PROGRAM_NAME)
      app_name = ::Rails.application.class.name.underscore.split("/").first
      prefix ||= "#{app_name}_"

      if ENV.key?("PROM_MULTI_PROC_BATCH_SIZE")
        batch_size = ENV["PROM_MULTI_PROC_BATCH_SIZE"].to_i
      elsif %w(rails rake).include?(program_name) || ::Rails.env.development? || ::Rails.env.test?
        batch_size = 1
      elsif ::Rails.env.production?
        batch_size = 100
      else
        batch_size = 5
      end

      if ENV.key?("PROM_MULTI_PROC_BATCH_TIMEOUT")
        batch_timeout = ENV["PROM_MULTI_PROC_BATCH_TIMEOUT"].to_i
      else
        batch_timeout = 3
      end

      if ::Rails.env.development? || ::Rails.env.test?
        validate = true
      else
        validate = false
      end

      if ::Rails.logger
        logger = ::Rails.logger
      else
        logger = ::Logger.new(STDOUT)
      end

      logger.info("Setting up prom_multi_proc for #{app_name}-#{program_name}, batch size: #{batch_size}, batch timeout: #{batch_timeout} validate: #{validate}")

      Base.new(
        prefix: prefix,
        socket: socket,
        metrics: metrics,
        batch_size: batch_size,
        batch_timeout: batch_timeout,
        validate: validate,
        logger: logger
      )
    end
  end
end