require 'sylvilagus/init'
require 'sylvilagus/ch04'
require 'json'
require 'net/smtp'
require 'rabbitmq-client.jar'

class Sylvilagus::Ch04::AlertProducer
  OPS_EMAILS = ['me@localhost'].freeze
  ADMIN_EMAILS = ['me@localhost'].freeze

  def self.send_email(recipients, subject, body)
    Net::SMTP.start('localhost', 25) do |smtp|
      msgstr = <<-EOM.gsub(/^      /, '')
      To: #{recipients.join(', ')}
      From: alerts@sylvilagus.local
      Subject: #{subject}
      Date: #{Time.now}

      #{body}
      EOM
      smtp.send_message(msgstr, 'alerts@sylvilagus.local', recipients)
    end
  end

  class CriticalNotifier < Java::ComRabbitmqClient::DefaultConsumer
    def handleDelivery(consumer_tag, envelope, properties, body)
      message = JSON.parse(
        Java::OrgJruby::RubyString.bytes_to_string(body)
      ).fetch('message')

      Sylvilagus::Ch04::AlertProducer.send_email(
        OPS_EMAILS, 'CRITICAL ALERT!', message
      )
      puts "Sent alert via email! Alert text: #{message}"
      puts "Recipients: #{OPS_EMAILS}"

      channel.basic_ack(envelope.delivery_tag, false)
    end
  end

  class RateLimitNotifier < Java::ComRabbitmqClient::DefaultConsumer
    def handleDelivery(consumer_tag, envelope, properties, body)
      message = JSON.parse(
        Java::OrgJruby::RubyString.bytes_to_string(body)
      ).fetch('message')

      Sylvilagus::Ch04::AlertProducer.send_email(
        ADMIN_EMAILS, 'RATE LIMIT ALERT!', message
      )
      puts "Sent alert via email! Alert text: #{message}"
      puts "Recipients: #{ADMIN_EMAILS}"

      channel.basic_ack(envelope.delivery_tag, false)
    end
  end

  def main
    factory = Java::ComRabbitmqClient::ConnectionFactory.new
    factory.uri = ENV.fetch('SYLVILAGUS_ALERT_AMQP_URI')
    @conn = factory.new_connection
    channel = @conn.create_channel

    channel.exchange_declare('alerts', 'topic', true, false, false, nil)
    channel.queue_declare('critical', true, false, false, nil)
    channel.queue_bind('critical', 'alerts', 'critical.*', nil)
    channel.queue_declare('rate_limit', true, false, false, nil)
    channel.queue_bind('rate_limit', 'alerts', '*.rate_limit', nil)

    critical_notifier = CriticalNotifier.new(channel)
    rate_limit_notifier = RateLimitNotifier.new(channel)

    channel.basic_consume(
      'critical', false, 'critical', critical_notifier
    )
    channel.basic_consume(
      'rate_limit', false, 'rate_limit', rate_limit_notifier
    )

    trap(:INT) { exit 0 }

    puts 'Starting consumer loop...'
    loop { sleep 1 }
  ensure
    begin
      @conn.close if @conn
    rescue NativeException
    end
  end
end

if $0 == __FILE__
  Sylvilagus::Ch04::AlertProducer.new.main
end