# Copyright (C) 2012-2014 Zammad Foundation, http://zammad-foundation.org/
# rubocop:disable Rails/Output
class Scheduler < ApplicationModel

  # rubocop:disable Style/ClassVars
  @@jobs_started = {}
  # rubocop:enable Style/ClassVars

  # start threads
  def self.threads

    Thread.abort_on_exception = true

    # start worker for background jobs
    worker

    # start loop to execute scheduler jobs
    loop do
      logger.info 'Scheduler running...'

      # reconnect in case db connection is lost
      begin
        ActiveRecord::Base.connection.reconnect!
      rescue => e
        logger.error "Can't reconnect to database #{e.inspect}"
      end

      # read/load jobs and check if it is alredy started
      jobs = Scheduler.where( 'active = ?', true ).order('prio ASC')
      jobs.each {|job|

        # ignore job is still running
        next if @@jobs_started[ job.id ]

        # check job.last_run
        next if job.last_run && job.period && job.last_run > ( Time.zone.now - job.period )

        # run job as own thread
        @@jobs_started[ job.id ] = true
        start_job(job)
        sleep 10
      }
      sleep 60
    end
  end

  def self.start_job( job )

    Thread.new {

      logger.info "Started job thread for '#{job.name}' (#{job.method})..."

      # start loop for periods under 5 minutes
      if job.period && job.period <= 300
        loop do
          _start_job(job)
          job = Scheduler.lookup(id: job.id)

          # exit is job got deleted
          break if !job

          # exit if job is not active anymore
          break if !job.active

          # exit if there is no loop period defined
          break if !job.period

          # wait until next run
          sleep job.period
        end
      else
        _start_job(job)
      end
      job.pid = ''
      job.save
      logger.info " ...stopped thread for '#{job.method}'"
      ActiveRecord::Base.connection.close

      # release thread lock
      @@jobs_started[ job.id ] = false
    }
  end

  def self._start_job( job, try_count = 0, try_run_time = Time.zone.now )
    begin
      job.last_run = Time.zone.now
      job.pid      = Thread.current.object_id
      job.save
      logger.info "execute #{job.method} (try_count #{try_count})..."
      eval job.method() # rubocop:disable Lint/Eval
    rescue => e
      logger.error "execute #{job.method} (try_count #{try_count}) exited with error #{e.inspect}"

      # reconnect in case db connection is lost
      begin
        ActiveRecord::Base.connection.reconnect!
      rescue => e
        logger.error "Can't reconnect to database #{e.inspect}"
      end

      try_run_max = 10
      try_count += 1

      # reset error counter if to old
      if try_run_time + ( 60 * 5 ) < Time.zone.now
        try_count = 0
      end
      try_run_time = Time.zone.now

      # restart job again
      if try_run_max > try_count
        _start_job( job, try_count, try_run_time)
      else
        raise "STOP thread for #{job.method} after #{try_count} tries"
      end
    end
  end

  def self.worker
    wait = 8

    Thread.new {
      sleep wait

      logger.info "Starting worker thread #{Delayed::Job}"

      loop do
        result = nil

        realtime = Benchmark.realtime do
          result = Delayed::Worker.new.work_off
        end

        count = result.sum

        if count.zero?
          sleep wait
          logger.debug '*** worker thread loop'
        else
          format "*** #{count} jobs processed at %.4f j/s, %d failed ...\n", count / realtime, result.last
        end
      end

      logger.info ' ...stopped worker thread'
      ActiveRecord::Base.connection.close
    }

  end

  def self.check( name, time_warning = 10, time_critical = 20 )
    time_warning_time  = Time.zone.now - time_warning.minutes
    time_critical_time = Time.zone.now - time_critical.minutes
    scheduler = Scheduler.find_by( name: name )
    if !scheduler
      puts "CRITICAL - no such scheduler jobs '#{name}'"
      return true
    end
    logger.debug scheduler.inspect
    if !scheduler.last_run
      puts "CRITICAL - scheduler jobs never started '#{name}'"
      exit 2
    end
    if scheduler.last_run < time_critical_time
      puts "CRITICAL - scheduler jobs was not running in last '#{time_critical}' minutes - last run at '#{scheduler.last_run}' '#{name}'"
      exit 2
    end
    if scheduler.last_run < time_warning_time
      puts "CRITICAL - scheduler jobs was not running in last '#{time_warning}' minutes - last run at '#{scheduler.last_run}' '#{name}'"
      exit 2
    end
    puts "ok - scheduler jobs was running at '#{scheduler.last_run}' '#{name}'"
    exit 0
  end
end