#!/usr/bin/ruby

require 'rubygems'
require 'date'
gem 'home_run', '>= 0'
require 'apache_log_regex'

NUM_LINES = 10000

def uris_from_logs
  lines = Array.new
  max_time = nil
  min_time = nil
  parser = ApacheLogRegex.new('%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\" %x')
  IO.popen("tail -n #{NUM_LINES} /var/log/apache2/access.log").each_line do |line|
    begin
      hash = parser.parse(line)
      uri = hash["%r"]
      t = DateTime.strptime(hash["%t"], "[%d/%b/%Y:%H:%M:%S %z]")
      min_time = [min_time, t].compact.min
      max_time = [max_time, t].compact.max
      lines << uri
    rescue ApacheLogRegex::ParseError => e
      # nil
    end
  end
  [min_time, max_time, lines]
end

CALL_TYPES = {
  :map => "Map API calls",
  :upload => "Changeset diff uploads",
  :amf => "AMF API calls",
  :history => "Element history fetches",
  :full => "Full element fetches",
  :trkpts => "GPX trackpoints calls",
  :web => "Web site traffic",
  :other => "Other API calls"
}

def categorise_uri(line)
  uri = line.split(" ")[1]

  case uri
  when /api\/0\.6\/map/ then :map
  when /api\/0\.6\/changeset\/[0-9]*\/upload/ then :upload
  when /api\/0\.6\/amf/ then :amf
  when /api\/0\.6\/(node|way|relation)\/[0-9]*\/history/ then :history
  when /api\/0\.6\/(node|way|relation)\/[0-9]*\/full/ then :full
  when /api\/0\.6\/trackpoints/ then :trkpts
  when /api\/0\.6\// then :other
  else :web
  end
end

if ARGV[0] == 'config'
  puts "graph_title Requests processed"
  puts "graph_vlabel Number of requests per minute"
  puts "graph_category api"
  CALL_TYPES.each { |k, v| puts "#{k}.label #{v}" }

else
  min_time, max_time, lines = uris_from_logs
  delta_t = (max_time - min_time).to_f * 24 * 60
  counts = lines.
      collect { |x| categorise_uri(x) }.
      inject(Hash.new) do |h, e|
    if h.has_key? e
      h[e] += 1
    else
      h[e] = 1
    end
    h
  end

  CALL_TYPES.keys.each do |type|
    count = counts[type] || 0
    puts "#{type}.value #{count / delta_t}"
  end
end