# frozen_string_literal: true

require "net/pop"

module Jobs
  class PollMailbox < ::Jobs::Scheduled
    every SiteSetting.pop3_polling_period_mins.minutes
    sidekiq_options retry: false

    include Email::BuildEmailHelper

    def execute(args)
      @args = args
      poll_pop3 if should_poll?

      DiscoursePluginRegistry.mail_pollers.each do |poller|
        next if !poller.enabled?

        poller.poll_mailbox(method(:process_popmail))
      end
    end

    def should_poll?
      return false if Rails.env.development? && ENV["POLL_MAILBOX"].nil?
      SiteSetting.pop3_polling_enabled?
    end

    def process_popmail(mail_string)
      Email::Processor.process!(mail_string, source: :pop3_poll)
    end

    POLL_MAILBOX_TIMEOUT_ERROR_KEY = "poll_mailbox_timeout_error_key"

    def poll_pop3
      pop3 = Net::POP3.new(SiteSetting.pop3_polling_host, SiteSetting.pop3_polling_port)

      if SiteSetting.pop3_polling_ssl
        if SiteSetting.pop3_polling_openssl_verify
          pop3.enable_ssl(max_version: OpenSSL::SSL::TLS1_2_VERSION)
        else
          pop3.enable_ssl(OpenSSL::SSL::VERIFY_NONE)
        end
      end

      pop3.start(SiteSetting.pop3_polling_username, SiteSetting.pop3_polling_password) do |pop|
        pop.each_mail do |p|
          mail_string = p.pop
          next if mail_too_old?(mail_string)
          process_popmail(mail_string)
          p.delete if SiteSetting.pop3_polling_delete_from_server?
        rescue => e
          Discourse.handle_job_exception(
            e,
            error_context(@args, "Failed to process incoming email."),
          )
        end
      end
    rescue Net::OpenTimeout => e
      count = Discourse.redis.incr(POLL_MAILBOX_TIMEOUT_ERROR_KEY).to_i

      if count == 1
        Discourse.redis.expire(
          POLL_MAILBOX_TIMEOUT_ERROR_KEY,
          SiteSetting.pop3_polling_period_mins.minutes * 3,
        )
      end

      if count > 3
        Discourse.redis.del(POLL_MAILBOX_TIMEOUT_ERROR_KEY)
        mark_as_errored!
        track_problem(:poll_pop3_timeout)
        Discourse.handle_job_exception(
          e,
          error_context(
            @args,
            "Connecting to '#{SiteSetting.pop3_polling_host}' for polling emails.",
          ),
        )
      end
    rescue Net::POPAuthenticationError => e
      mark_as_errored!
      track_problem(:poll_pop3_auth_error)
      Discourse.handle_job_exception(e, error_context(@args, "Signing in to poll incoming emails."))
    end

    POLL_MAILBOX_ERRORS_KEY = "poll_mailbox_errors"

    def self.errors_in_past_24_hours
      Discourse.redis.zremrangebyscore(POLL_MAILBOX_ERRORS_KEY, 0, 24.hours.ago.to_i)
      Discourse.redis.zcard(POLL_MAILBOX_ERRORS_KEY).to_i
    end

    def mail_too_old?(mail_string)
      mail = Mail.new(mail_string)
      date_header = mail.header["Date"]
      return false if date_header.blank?

      date = Time.parse(date_header.to_s)
      date < 1.week.ago
    end

    def mark_as_errored!
      now = Time.now.to_i
      Discourse.redis.zadd(POLL_MAILBOX_ERRORS_KEY, now, now.to_s)
    end

    def track_problem(identifier)
      ProblemCheckTracker[identifier].problem!
    end
  end
end