require 'pty'
require 'mkit/status'
require "mkit/cmd/shell_client"

#
# https://docs.docker.com/engine/reference/commandline/events
require 'mkit/app/helpers/docker_helper'
module MKIt
class StopThread < RuntimeError; end

  class DockerListener
    include MKIt::DockerHelper

    def initialize
      @queue = Queue.new
      @listener = ShellClient.new(command: "docker events --format '{{json .}}'")
    end

    def enqueue(msg)
      @queue << msg
    end

    def start
      @consumer.run if register_consumer
      register_listener
    end

    def stop
      @listener.unregister if @listener
      @consumer.raise StopThread.new
      MKItLogger.info("docker listener stopped")
    end

    private

    def parse_message(msg)
      action = msg['Action'].to_sym
      type = msg['Type'].to_sym
      MKItLogger.info("docker <#{type}> <#{action}> received: \n\t#{msg}")
      case type
      when :container
        pod_id = msg.id
        pod_name = msg.Actor.Attributes.name
        pod = Pod.find_by(name: pod_name)
        unless pod.nil?
          case action
          when :create
            pod.pod_id = pod_id
            pod.status = MKIt::Status::CREATED
            pod.save
            pod.service.update_status!
          when :start
            pod.pod_id = pod_id
            pod.save
            pod.service.update_status!
          when :kill
            pod.service.update_status!
          when :die
            pod.service.update_status!
          when :stop
            pod.service.update_status!
          else
            MKItLogger.debug("	#{type} #{action} <<TODO>>")
          end
        else
          MKItLogger.warn("docker <<#{type}>> <#{action}> received: #{msg}. But I don't know anything about pod #{pod_id}/#{pod_name}")
        end
      when :network
        pod_id = msg.Actor.Attributes.container
        inspect = inspect_instance(pod_id).to_o
        pod_name = inspect.Name[1..]
        pod = Pod.find_by(name: pod_name)
        unless pod.nil?
          case action
          when :connect
            MKItLogger.info("docker network #{action} received: #{msg} for pod #{pod_name}")
            pod.update_ip
            pod.save
          when :disconnect
            MKItLogger.debug("  #{type} #{action} <<NOOP / TODO>>")
          else
            MKItLogger.debug("  #{type} #{action} <<TODO>>")
          end
        else
          MKItLogger.warn("docker <<#{type}>> <#{action}> received: #{msg}. But I don't know anything about pod #{pod_id}/#{pod_name}")
        end
      else
        MKItLogger.info("\t#{type} #{action} <<unknown>>")
      end
    end

    def register_consumer
      return false unless @consumer.nil?

      @consumer = Thread.new do
        running = true
        while running
          begin
            parse_message(@queue.pop)
          rescue StopThread
            running = false
            MKItLogger.info("docker consumer ended")
          rescue => e
            MKItLogger.error("error while consuming docker notification: #{e}", e.message, e.backtrace.join("\n"))
          end
        end
      end
      true
    end

    def register_listener
      @listener.register do |stdout, stdin, pid|
        stdout.each { |line| enqueue JSON.parse(line).to_o }
      end
    end
  end
end