require "fluent/input"
require 'fluent/mixin/rewrite_tag_name'
require 'fluent/mixin/type_converter'

module Fluent
  class WatchProcessInput < Fluent::Input
    Plugin.register_input('watch_process', self)

    config_param :tag, :string
    config_param :command, :string, :default => nil
    config_param :keys, :string, :default => nil
    config_param :interval, :string, :default => '5s'
    config_param :lookup_user, :string, :default => nil
    config_param :hostname_command, :string, :default => 'hostname'

    DEFAULT_KEYS = %w(start_time user pid parent_pid cpu_time cpu_percent memory_percent mem_rss mem_size state proc_name command)
    DEFAULT_TYPES = "pid:integer,parent_pid:integer,cpu_percent:float,memory_percent:float,mem_rss:integer,mem_size:integer"

    include Fluent::HandleTagNameMixin
    include Fluent::Mixin::RewriteTagName
    include Fluent::Mixin::TypeConverter
    config_set_default :types, DEFAULT_TYPES

    def initialize
      super
      require 'time'
    end

    def configure(conf)
      super

      @command = @command || get_ps_command
      @keys = @keys.nil? ? DEFAULT_KEYS : @keys.to_s.gsub(' ', '').split(',')
      @lookup_user = @lookup_user.gsub(' ', '').split(',') unless @lookup_user.nil?
      @interval = Config.time_value(@interval)
      $log.info "watch_process: polling start. :tag=>#{@tag} :lookup_user=>#{@lookup_user} :interval=>#{@interval} :command=>#{@command}"
    end

    def start
      @thread = Thread.new(&method(:run))
    end

    def shutdown
      Thread.kill(@thread)
    end

    def run
      loop do
        io = IO.popen(@command, 'r')
        io.gets
        while result = io.gets
          keys_size = @keys.size
          if result =~ /(?<lstart>(^\w+\s+\w+\s+\d+\s+\d\d:\d\d:\d\d \d+))/
            lstart = Time.parse($~[:lstart])
            result = result.sub($~[:lstart], '')
            keys_size -= 1
          end
          values = [lstart.to_s, result.chomp.strip.split(/\s+/, keys_size)]
          data = Hash[@keys.zip(values.reject(&:empty?).flatten)]
          data['elapsed_time'] = (Time.now - Time.parse(data['start_time'])).to_i if data['start_time']
          next unless @lookup_user.nil? || @lookup_user.include?(data['user'])
          emit_tag = tag.dup
          filter_record(emit_tag, Engine.now, data)
          router.emit(emit_tag, Engine.now, data)
        end
        io.close
        sleep @interval
      end
      rescue StandardError => e
        $log.error "watch_process: error has occured. #{e.message}"
    end

    def get_ps_command
      if OS.linux?
        "LANG=en_US.UTF-8 && ps -ewwo lstart,user:20,pid,ppid,time,%cpu,%mem,rss,sz,s,comm,cmd"
      elsif OS.mac?
        "LANG=en_US.UTF-8 && ps -ewwo lstart,user,pid,ppid,time,%cpu,%mem,rss,vsz,state,comm,command"
      end
    end

    module OS
      # ref. http://stackoverflow.com/questions/170956/how-can-i-find-which-operating-system-my-ruby-program-is-running-on
      def OS.windows?
        (/cygwin|mswin|mingw|bccwin|wince|emx/ =~ RUBY_PLATFORM) != nil
      end

      def OS.mac?
       (/darwin/ =~ RUBY_PLATFORM) != nil
      end

      def OS.unix?
        !OS.windows?
      end

      def OS.linux?
        OS.unix? and not OS.mac?
      end
    end
  end
end