require 'thread'
require 'securerandom'

module RestFtpDaemon
  class JobQueue < Queue
    # attr_reader :queued
    # attr_reader :popped

    attr_reader :queue
    attr_reader :jobs

    if Settings.newrelic_enabled?
      include ::NewRelic::Agent::Instrumentation::ControllerInstrumentation
    end

    def initialize
      # Instance variables
      @queue = []
      @jobs = []
      @waiting = []
      @queue.taint          # enable tainted communication
      @waiting.taint
      self.taint
      @mutex = Mutex.new

      # Logger
      @logger = RestFtpDaemon::LoggerPool.instance.get :queue

      # Identifiers generator
      @last_id = 0
      @prefix = Helpers.identifier JOB_IDENT_LEN
      info "queue initialized with prefix: #{@prefix}"

      # Mutex for counters
      @counters = {}
      @mutex_counters = Mutex.new

      # Conchita configuration
      @conchita = Settings.conchita
      if @conchita.nil?
        info "conchita: missing conchita.* configuration"
      elsif @conchita[:timer].nil?
        info "conchita: missing conchita.timer value"
      else
        Thread.new {
          begin
            conchita_loop
          rescue Exception => e
            info "CONCHITA EXCEPTION: #{e.inspect}"
          end
          }
      end

    end

    def generate_id
      # rand(36**8).to_s(36)
      @mutex.synchronize do
        @last_id ||= 0
        @last_id += 1
      end
      prefixed_id @last_id
    end

    def counter_add name, value
      @mutex_counters.synchronize do
        @counters[name] ||= 0
        @counters[name] += value
      end
    end

    def counter_inc name
      counter_add name, 1
    end

    def counter_get name
      @mutex_counters.synchronize do
        @counters[name]
      end
    end

    def counters
      @mutex_counters.synchronize do
        @counters
      end
    end

    def filter_jobs status
      # No status filter: return all execept queued
      if status.empty?
        @jobs.reject { |job| job.status == JOB_STATUS_QUEUED }

      # Status filtering: only those jobs
      else
        @jobs.select { |job| job.status == status.to_sym }

      end
    end

    def counts_by_status
      statuses = {}
      @jobs.group_by { |job| job.status }.map { |status, jobs| statuses[status] = jobs.size }
      statuses
    end

    def jobs # change for accessor
      @jobs
    end

    def jobs_count
      @jobs.length
    end

    def queued_ids
      @queue.collect(&:id)
    end

    def jobs_ids
      @jobs.collect(&:id)
    end

    def find_by_id id, prefixed = false
      # Build a prefixed id if expected
      id = prefixed_id(id) if prefixed
      info "find_by_id (#{id}, #{prefixed}) > #{id}"

      # Search in jobs queues
      @jobs.select { |item| item.id == id }.last
    end

    def push job
      # Check that item responds to "priorty" method
      raise "JobQueue.push: job should respond to priority method" unless job.respond_to? :priority
      raise "JobQueue.push: job should respond to id method" unless job.respond_to? :id

      @mutex.synchronize do
        # Push job into the queue
        @queue.push job

        # Store the job into the global jobs list
        @jobs.push job

        # Inform the job that it's been queued
        job.set_queued if job.respond_to? :set_queued

        # Refresh queue order
        sort_queue!

        # Try to wake a worker up
        begin
          t = @waiting.shift
          t.wakeup if t
        rescue ThreadError
          retry
        end
      end
    end
    alias << push
    alias enq push

    def pop non_block=false
      @mutex.synchronize do
        while true
          if @queue.empty?
            # info "JobQueue.pop: empty"
            raise ThreadError, "queue empty" if non_block
            @waiting.push Thread.current
            @mutex.sleep
          else
            return @queue.pop
          end
        end
      end
    end
    alias shift pop
    alias deq pop

    def empty?
      @queue.empty?
    end

    def clear
      @queue.clear
    end

    def num_waiting
      @waiting.size
    end

  protected

    def prefixed_id id
      "#{@prefix}.#{id}"
    end

    def sort_queue!
      @mutex_counters.synchronize do
        @queue.sort_by! &:weight
      end
    end

    def conchita_loop
      info "conchita starting with: #{@conchita.inspect}"
      loop do
        # Do the cleanup locking the queues
        # info "conchita: cleanup expired jobs"
        @mutex.synchronize do
          conchita_clean JOB_STATUS_FINISHED
          conchita_clean JOB_STATUS_FAILED
          conchita_clean JOB_STATUS_QUEUED
        end
        sleep @conchita[:timer]
      end
    end

    def conchita_clean status     # FIXME: clean both @jobs and @queue
      # Init
      return if status.nil?

      # Read config state
      maxage = @conchita["clean_#{status.to_s}"] || 0
      #info "conchita_clean status[#{status.to_s}] \t maxage[#{maxage}] s"
      return unless maxage > 0

      # Delete jobs from the queue if their status is (status)
      @jobs.delete_if do |job|

        # Skip if wrong status
        next unless job.status == status.to_sym

        # Skip if updated_at invalid
        next if job.updated_at.nil?

        # Skip if not aged enough yet
        age = Time.now - job.updated_at
        next if age < maxage

        # Ok, we have to clean it up ..
        info "conchita_clean status[#{status.to_s}] maxage[#{maxage}] job[#{job.id}] age[#{age}]"

        # Remove it from the queue if present
        job_in_queue = @queue.delete job
        info "   removed queued job [#{job.id}]" unless job_in_queue.nil?

        # Accept to delete it from @jobs
        true
      end

    end


  private

    def info message, lines = []
      return if @logger.nil?

      # Forward to logger
      @logger.info_with_id message,
        id: @id,
        lines: lines,
        origin: self.class.to_s
    end

    if Settings.newrelic_enabled?
      add_transaction_tracer :push, :category => :task
      add_transaction_tracer :pop, :category => :task
    end

  end
end