#!/usr/bin/env ruby

require_relative '../config/initializer'

class Message < ActiveRecord::Base
  self.inheritance_column = 'disabled'
end

$input = nil

def parse_command_line
  while ARGV.any? do
    case ARGV[0]
    when '-h' then
      usage
    when '--help' then
      usage
    when '--debug' then
      require 'byebug'
      ARGV.shift
    else
      if ARGV[0] && File.exist?(ARGV[0])
        $input = File.open(ARGV[0])
      end
      ARGV.shift
    end
  end
  $input ||= ARGF
end

def usage
  puts "USAGE: "
  puts " option 1: parse-email-logs [LOGFILE]"
  puts " option 2: cat log | parse-email-logs"
  exit(0)
end

def parse_timestamp(str)
  # e.g. May 20 20:17:14
  DateTime.strptime(str, "%b %d %H:%M:%S")
end

def hash_addresses(str)
  str.split(',').map {|address|
    address = address.sub(/.*</, '').sub(/[>\"\']/, '')
    address.split('@').map {|segment|
      Digest::HMAC.hexdigest(segment, CONFIG['secret'], Digest::MD5)
    }.join('@')
  }.join(',')
end

def get_message(queue_id, timestamp)
  msg = Message.find_or_create_by(queue_id: queue_id)
  if msg.first_seen_at.nil?
    putc '.'; STDOUT.flush()
    msg.first_seen_at = parse_timestamp(timestamp)
    msg.save
  end
  return msg
end

#
# if we see this:
#  relay=0.0.0.0[0.0.0.0]:25
# then the message was an incoming message
#
# if the queue id is the same, but the recipient is different
# then duplicate the record.
#
def do_sent(m, ts, matches, line)
  recipient = hash_addresses(matches["to"])
  return if m.recipient == recipient
  if m.recipient.nil?
    if matches['relay'] == "relay=0.0.0.0[0.0.0.0]:25"
      m.is_outgoing = false
    else
      m.is_outgoing = true
    end
    if m.is_outgoing?
      m.sent_at     = m.first_seen_at
      m.received_at = parse_timestamp(ts)
    else
      m.sent_at     = m.date
      m.received_at = m.first_seen_at
    end
    m.recipient = recipient
    m.orig_to   = hash_addresses(matches["orig_to"]) if matches["orig_to"]
    m.delay     = matches['delay'].to_f
    m.delays    = matches['delays']
    m.status    = "sent"
    m.save
  else
    new_m = m.dup
    new_m.received_at = parse_timestamp(ts)
    new_m.recipient   = recipient
    new_m.orig_to     = hash_addresses(matches["orig_to"]) if matches["orig_to"]
    new_m.delay       = matches['delay'].to_f
    new_m.delays      = matches['delays']
    new_m.status      = "sent"
    new_m.save
  end
end

#
# for status=x where x != sent
#
def do_status(m, ts, matches)
  m.delay = matches['delay'].to_f
  m.delays = matches['delays']
  m.status = matches['status']
  m.save
end

#
# save the message size and the envelope sender
#
def do_queue(m, ts, matches)
  return if m.size != nil
  m.size = matches['size'].to_i
  m.sender = hash_addresses(matches['from'])
  m.save
end

#
# save the message id
#
def do_message_id(m, ts, matches, line)
  return if m.message_id
  m_id = matches['message_id'].gsub(/[<>]/,'').strip
  m.message_id = hash_addresses(m_id)
  m.save
end

#
# headers
#
def do_subject(m, ts, matches)
  m.subject_length = matches['subject'].length
  m.save
end
def do_date(m, ts, matches)
  m.date = matches['date']
  m.save
end
def do_from(m, ts, matches)
  m.from = hash_addresses(matches['from'])
  m.save
end
def do_to(m, ts, matches)
  m.to = hash_addresses(matches['to'])
  m.save
end
def do_cc(m, ts, matches)
  m.cc = hash_addresses(matches['cc'])
  m.save
end
def do_bcc(m, ts, matches)
  m.bcc = hash_addresses(matches['bcc'])
  m.save
end
def do_list(m, ts, matches)
  m.is_list = true
  m.save
end
def do_in_reply_to(m, ts, matches)
  m.re_message_id = hash_addresses(matches['in-reply-to'])
  m.save
end
def do_precedence(m, ts, matches)
  if matches['precedence'] =~ /(bulk|list)/i
    m.is_list = true
    m.save
  end
end

#
# the message was rejected, likely because milter scan thinks it is a virus.
# so we remove the record from the database
#
def do_purge_message(m, ts, matches)
  m.destroy
end

def do_error(line)
  puts
  puts "ERROR: unmatched line!"
  puts line
  puts
end

FROM_HOST = /(local|[A-Za-z0-9\.\-]+\[0.0.0.0\]);/

LINE_PARSE_MAP = {
  'postfix/smtp' => {
    /to=<(?<to>.*?)>, (orig_to=<(?<orig_to>.*?)>, )?(?<relay>relay=.*?), delay=(?<delay>[0-9\.]+), delays=(?<delays>[0-9\.\/]+), .*status=sent/ => method(:do_sent),
    /delay=(?<delay>[0-9\.]+), delays=(?<delays>[0-9\.\/]+), .*status=(?<status>[a-z]+) / => method(:do_status),
    /status=/ => :error
  },
  'postfix/qmgr' => {
    /from=<(?<from>.*)>, size=(?<size>\d+),.*\(queue active\)/ => method(:do_queue),
    /\(queue active\)/ => :error
  },
  'postfix/cleanup' => {
    /message-id=(?<message_id>.*)$/ => method(:do_message_id),
    /info: header Subject: (?<subject>.*) from #{FROM_HOST}/i => method(:do_subject),
    /info: header From: (?<from>.*) from #{FROM_HOST}/i => method(:do_from),
    /info: header To: (?<to>.*) from #{FROM_HOST}/i => method(:do_to),
    /info: header Cc: (?<cc>.*) from #{FROM_HOST}/i => method(:do_cc),
    /info: header Bcc: (?<bcc>.*) from #{FROM_HOST}/i => method(:do_bcc),
    /info: header In-Reply-To: (?<in-reply-to>.*) from #{FROM_HOST}/i => method(:do_in_reply_to),
    /info: header Precedence: (?<precedence>.*) from #{FROM_HOST}/i => method(:do_precedence),
    /info: header List-ID/i => method(:do_list),
    /info: header Mailing-list/i => method(:do_list),
    /info: header Date: (?<date>.*) from #{FROM_HOST}/i => method(:do_date),
    /info: header / => :error,
    /milter-reject/ => method(:do_purge_message),
    // => :error
  }
}

def process_line(line)
  splits    = line.split(' ')
  timestamp = splits[0..2].join(' ')
  daemon    = splits[4].split('[').first
  queue_id  = splits[5].sub(':', '')
  message   = splits[6..-1].join(' ')
  LINE_PARSE_MAP.fetch(daemon, {}).each do |re, method|
    match = re.match(line)
    next unless match
    if method == :error
      do_error(line)
    elsif !method.nil?
      msg = get_message(queue_id, timestamp)
      if method.arity == 3
        method.call(msg, timestamp, match)
      else
        method.call(msg, timestamp, match, line)
      end
    end
    break
  end
end

def main
  parse_command_line
  start_time  = Time.now
  start_msg   = Message.count
  line_count  = 0
  Message.transaction do
    $input.each_line do |line|
      process_line(line)
      line_count += 1
    end
  end
  end_time = Time.now
  end_msg = Message.count
  puts
  puts "FINISHED"
  puts "   Time: %s minutes" % ((end_time - start_time).to_i / 60)
  puts "Records: %s" % (end_msg - start_msg)
  puts "  Lines: %s" % line_count
end

main()