#!/usr/bin/ruby

require 'time'

class HTLogRRD

  def xsystem ary
    STDOUT.puts(ary.inspect) if STDOUT.tty? or STDERR.tty?
    system(*ary)
  end

  def create_rrd btime
    bopt = (btime.strftime('%s').to_i - 10).to_s
    dspan = @span * 2  # 600 s by default
    cmd = [@rrdtool, 'create', @rrd, '-b', bopt,
      "DS:r2:GAUGE:#{dspan}:U:U", 'RRA:AVERAGE:0.5:1:512',
      'RRA:AVERAGE:0.5:12:512', 'RRA:AVERAGE:0.5:288:512',
      "DS:r3:GAUGE:#{dspan}:U:U", 'RRA:AVERAGE:0.5:1:512',
      'RRA:AVERAGE:0.5:12:512', 'RRA:AVERAGE:0.5:288:512',
      "DS:r4:GAUGE:#{dspan}:U:U", 'RRA:AVERAGE:0.5:1:512',
      'RRA:AVERAGE:0.5:12:512', 'RRA:AVERAGE:0.5:288:512',
      "DS:r5:GAUGE:#{dspan}:U:U", 'RRA:AVERAGE:0.5:1:512',
      'RRA:AVERAGE:0.5:12:512', 'RRA:AVERAGE:0.5:288:512',
      "DS:sz:GAUGE:#{dspan}:U:U", 'RRA:AVERAGE:0.5:1:512',
      'RRA:AVERAGE:0.5:12:512', 'RRA:AVERAGE:0.5:288:512',
      "DS:u2:GAUGE:#{dspan}:U:U", 'RRA:AVERAGE:0.5:1:512',
      'RRA:AVERAGE:0.5:12:512', 'RRA:AVERAGE:0.5:288:512' ]
    xsystem(cmd)
  end

  PAT1 = %r{^\S+ (?:\S+ )?- (\S+) \[([^\]]+)\] "([^"]+)" (\d\d\d) (\d+)}
  PAT2 = %r{^\S+ (?:\S+ )?- (\S+) \[([^\]]+)\] ".*" (\d\d\d) (\d+)}

  def register uname, rtime, reql, resp, size
    rtime = Time.strptime(rtime, '%d/%b/%Y:%H:%M:%S %z')
    htime = Time.at((rtime.to_i / @span) * @span)
    @result[htime] = Hash.new(0) unless @result.include?(htime)
    rec = @result[htime]
    case resp
    when /^2/ then
      rec[:r2] += 1
      rec[:sz] += size.to_i
      rec[:u2] += 1 if uname != '-'
    when /^3/ then rec[:r3] += 1
    when /^4/ then rec[:r4] += 1
    when /^5/ then rec[:r5] += 1
    end
  end

  def scanfile fp
    malf = 0
    for line in fp
      line.chomp!
      case line
      when PAT1 then register($1, $2, $3, $4, $5)
      when PAT2 then register($1, $2, nil, $3, $4)
      else
        STDERR.puts "bad log <#{line}>" if malf.zero?
        malf += 1
        next
      end
    end
    STDERR.puts "bad #{malf} lines" unless malf.zero?
  end

  def scanlog iday
    case iday
    when 0
      File.open(@acclog) {|fp| scanfile(fp) }
    when 1
      File.open("#{@acclog}.1") {|fp| scanfile(fp) }
    else
      require 'zlib'
      Zlib::GzipReader.open("#{@acclog}.#{iday}.gz") {|fp| scanfile(fp) }
    end
  end

  def rrdupdate
    create_rrd(@result.keys.sort.first) if @create_flag
    tlist = @result.keys.sort
    if tlist.last > (Time.now - @span)
      t = tlist.pop
      puts "incomplete span #{t} omitted" if STDOUT.tty?
    end
    tlist = tlist[-2..-1] if @last_flag
    for htime in tlist
      datastr = [htime.strftime('%s'),
        @result[htime][:r2],
        @result[htime][:r3],
        @result[htime][:r4],
        @result[htime][:r5],
        @result[htime][:sz],
        @result[htime][:u2]].join(':')
      cmd = [@rrdtool, 'update', @rrd, '-s', datastr]
      xsystem(cmd)
    end
  end

  def graph
    basename = @rrd.sub(/(\.rrd)?$/, '')
    cmd = [@rrdtool, 'graph', "#{basename}-c1.png",
      "DEF:r2=#{@rrd}:r2:AVERAGE", "DEF:r3=#{@rrd}:r3:AVERAGE",
      "DEF:r4=#{@rrd}:r4:AVERAGE", "DEF:r5=#{@rrd}:r5:AVERAGE",
      "DEF:u2=#{@rrd}:u2:AVERAGE",
      "LINE1:r2#FF0000:2xx", "LINE1:r3#00FF00:3xx",
      "LINE1:r4#0088FF:4xx", "LINE1:r5#FFFF00:5xx",
      "LINE1:u2#88FF00:2xx/auth",
      '--imginfo', '']
    xsystem(cmd)
    cmd = [@rrdtool, 'graph', "#{basename}-s1.png",
      "DEF:sz=#{@rrd}:sz:AVERAGE",
      "LINE1:sz#FF8800:size",
      '--imginfo', '']
    xsystem(cmd)
    cmd = [@rrdtool, 'graph', "#{basename}-c10.png",
      '-e', 'now', '-s', 'end-864000s',
      "DEF:r2=#{@rrd}:r2:AVERAGE", "DEF:r3=#{@rrd}:r3:AVERAGE",
      "DEF:r4=#{@rrd}:r4:AVERAGE", "DEF:r5=#{@rrd}:r5:AVERAGE",
      "DEF:u2=#{@rrd}:u2:AVERAGE",
      "LINE1:r2#FF0000:2xx", "LINE1:r3#00FF00:3xx",
      "LINE1:r4#0088FF:4xx", "LINE1:r5#FFFF00:5xx",
      "LINE1:u2#88FF00:2xx/auth",
      '--imginfo', '']
    xsystem(cmd)
  end

  def run
    @backdays.downto(0) {|iday| scanlog(iday) }
    rrdupdate
    graph if @graph_flag
  end

  def initialize argv
    @rrd = "htlog.rrd"
    @rrdtool = "/usr/bin/rrdtool"
    @create_flag = false
    @last_flag = true
    @acclog = "/var/log/apache2/access.log"
    @backdays = 1
    @span = 300
    @graph_flag = nil
    cmds = []
    for arg in argv
      case arg
      when /^rrd=/ then @rrd = $'
      when /^rrdtool=/ then @rrdtool = $'
      when /^a(ccess)?=/ then @acclog = $'
      when /^b(ack)?=/ then
        @backdays = ($').to_i
        @last_flag = false
      when 'create' then
        @create_flag = true
        @last_flag = false
      when 'graph' then
        @graph_flag = true
      when /^span=(\d+)$/ then
        @span = $1.to_i
      when 'help' then
        puts "#$0 [rrd=path] [rrdtool=path] [access=logfile] [back=days] [create] [graph] [span=secs]"
        exit 1
      else STDERR.puts "unknown command #{arg}"
      end
    end
    @result = {}
  end

end

HTLogRRD.new(ARGV).run