require 'thread'
require 'fluent/output'
require 'fluent/plugin/kafka_plugin_util'

class Fluent::KafkaOutputBuffered < Fluent::BufferedOutput
  Fluent::Plugin.register_output('kafka_buffered', self)

  config_param :brokers, :string, :default => 'localhost:9092',
               :desc => <<-DESC
Set brokers directly:
<broker1_host>:<broker1_port>,<broker2_host>:<broker2_port>,..
Brokers: you can choose to use either brokers or zookeeper.
DESC
  config_param :zookeeper, :string, :default => nil,
               :desc => <<-DESC
Set brokers via Zookeeper:
<zookeeper_host>:<zookeeper_port>
DESC
  config_param :zookeeper_path, :string, :default => '/brokers/ids',
               :desc => "Path in path for Broker id. Default to /brokers/ids"
  config_param :default_topic, :string, :default => nil,
               :desc => "Output topic"
  config_param :default_partition_key, :string, :default => nil
  config_param :client_id, :string, :default => 'kafka'
  config_param :output_data_type, :string, :default => 'json',
               :desc => <<-DESC
Supported format: (json|ltsv|msgpack|attr:<record name>|<formatter name>)
DESC
  config_param :output_include_tag, :bool, :default => false
  config_param :output_include_time, :bool, :default => false
  config_param :kafka_agg_max_bytes, :size, :default => 4*1024  #4k

  # ruby-kafka producer options
  config_param :max_send_retries, :integer, :default => 1,
               :desc => "Number of times to retry sending of messages to a leader."
  config_param :required_acks, :integer, :default => 0,
               :desc => "The number of acks required per request."
  config_param :ack_timeout, :time, :default => nil,
               :desc => "How long the producer waits for acks."
  config_param :compression_codec, :string, :default => nil,
               :desc => <<-DESC
The codec the producer uses to compress messages.
Supported codecs: (gzip|snappy)
DESC

  config_param :time_format, :string, :default => nil

  include Fluent::KafkaPluginUtil::SSLSettings

  attr_accessor :output_data_type
  attr_accessor :field_separator

  unless method_defined?(:log)
    define_method("log") { $log }
  end

  def initialize
    super

    require 'kafka'
    require 'fluent/plugin/kafka_producer_ext'

    @kafka = nil
    @producers = {}
    @producers_mutex = Mutex.new
  end

  def refresh_client(raise_error = true)
    if @zookeeper
      @seed_brokers = []
      z = Zookeeper.new(@zookeeper)
      z.get_children(:path => @zookeeper_path)[:children].each do |id|
        broker = Yajl.load(z.get(:path => @zookeeper_path + "/#{id}")[:data])
        @seed_brokers.push("#{broker['host']}:#{broker['port']}")
      end
      z.close
      log.info "brokers has been refreshed via Zookeeper: #{@seed_brokers}"
    end
    begin
      if @seed_brokers.length > 0
        @kafka = Kafka.new(seed_brokers: @seed_brokers, client_id: @client_id, ssl_ca_cert: read_ssl_file(@ssl_ca_cert),
                           ssl_client_cert: read_ssl_file(@ssl_client_cert), ssl_client_cert_key: read_ssl_file(@ssl_client_cert_key))
        log.info "initialized kafka producer: #{@client_id}"
      else
        log.warn "No brokers found on Zookeeper"
      end
    rescue Exception => e
      if raise_error # During startup, error should be reported to engine and stop its phase for safety.
        raise e
      else
        log.error e
      end
    end
  end

  def configure(conf)
    super

    if @zookeeper
      require 'zookeeper'
    else
      @seed_brokers = @brokers.match(",").nil? ? [@brokers] : @brokers.split(",")
      log.info "brokers has been set directly: #{@seed_brokers}"
    end

    if conf['ack_timeout_ms']
      log.warn "'ack_timeout_ms' parameter is deprecated. Use second unit 'ack_timeout' instead"
      @ack_timeout = conf['ack_timeout_ms'].to_i / 1000
    end

    @f_separator = case @field_separator
                   when /SPACE/i then ' '
                   when /COMMA/i then ','
                   when /SOH/i then "\x01"
                   else "\t"
                   end

    @formatter_proc = setup_formatter(conf)

    @producer_opts = {max_retries: @max_send_retries, required_acks: @required_acks}
    @producer_opts[:ack_timeout] = @ack_timeout if @ack_timeout
    @producer_opts[:compression_codec] = @compression_codec.to_sym if @compression_codec
  end

  def start
    super
    refresh_client
  end

  def shutdown
    super
    shutdown_producers
    @kafka = nil
  end

  def emit(tag, es, chain)
    super(tag, es, chain, tag)
  end

  def format_stream(tag, es)
    es.to_msgpack_stream
  end

  def shutdown_producers
    @producers_mutex.synchronize {
      @producers.each { |key, producer|
        producer.shutdown
      }
      @producers = {}
    }
  end

  def get_producer
    @producers_mutex.synchronize {
      producer = @producers[Thread.current.object_id]
      unless producer
        producer = @kafka.producer(@producer_opts)
        @producers[Thread.current.object_id] = producer
      end
      producer
    }
  end

  def setup_formatter(conf)
    if @output_data_type == 'json'
      require 'yajl'
      Proc.new { |tag, time, record| Yajl::Encoder.encode(record) }
    elsif @output_data_type == 'ltsv'
      require 'ltsv'
      Proc.new { |tag, time, record| LTSV.dump(record) }
    elsif @output_data_type == 'msgpack'
      require 'msgpack'
      Proc.new { |tag, time, record| record.to_msgpack }
    elsif @output_data_type =~ /^attr:(.*)$/
      @custom_attributes = $1.split(',').map(&:strip).reject(&:empty?)
      @custom_attributes.unshift('time') if @output_include_time
      @custom_attributes.unshift('tag') if @output_include_tag
      Proc.new { |tag, time, record|
        @custom_attributes.map { |attr|
          record[attr].nil? ? '' : record[attr].to_s
        }.join(@f_separator)
      }
    else
      @formatter = Fluent::Plugin.new_formatter(@output_data_type)
      @formatter.configure(conf)
      @formatter.method(:format)
    end
  end

  def write(chunk)
    tag = chunk.key
    def_topic = @default_topic || tag
    producer = get_producer

    records_by_topic = {}
    bytes_by_topic = {}
    messages = 0
    messages_bytes = 0
    begin
      chunk.msgpack_each { |time, record|
        if @output_include_time
          if @time_format
            record['time'.freeze] = Time.at(time).strftime(@time_format)
          else
            record['time'.freeze] = time
          end
        end

        record['tag'] = tag if @output_include_tag
        topic = record['topic'.freeze] || def_topic
        partition_key = record['partition_key'.freeze] || @default_partition_key

        records_by_topic[topic] ||= 0
        bytes_by_topic[topic] ||= 0

        record_buf = @formatter_proc.call(tag, time, record)
        record_buf_bytes = record_buf.bytesize
        if (messages > 0) and (messages_bytes + record_buf_bytes > @kafka_agg_max_bytes)
          log.on_trace { log.trace("#{messages} messages send.") }
          producer.deliver_messages
          messages = 0
          messages_bytes = 0
        end
        log.on_trace { log.trace("message will send to #{topic} with key: #{partition_key} and value: #{record_buf}.") }
        messages += 1
        producer.produce2(record_buf, topic: topic, partition_key: partition_key)
        messages_bytes += record_buf_bytes

        records_by_topic[topic] += 1
        bytes_by_topic[topic] += record_buf_bytes
      }
      if messages > 0
        log.trace { "#{messages} messages send." }
        producer.deliver_messages
      end
      log.debug { "(records|bytes) (#{records_by_topic}|#{bytes_by_topic})" }
    end
  rescue Exception => e
    log.warn "Send exception occurred: #{e}"
    # For safety, refresh client and its producers
    shutdown_producers
    refresh_client(false)
    # Raise exception to retry sendind messages
    raise e
  end
end