#!/usr/bin/env ruby
#
# postfix main.cf:
#   relay_domains = example.com
#   transport_maps = hash:/etc/postfix/transport
#   defer_transports =
#
# postfix transports:
#   example.com   lobsters:
#
# postfix master.cf:
#   lobsters  unix  -       n       n       -       2       pipe
#    flags=Fqhu user=lobsters size=1024000 argv=/d/rails/lobsters/script/parse_inbound_mail ${recipient} ${sender}

ENV["RAILS_ENV"] ||= "production"

APP_PATH = File.expand_path('../../config/application',  __FILE__)
require File.expand_path('../../config/boot',  __FILE__)
require APP_PATH
Rails.application.require_environment!

# postfix exit codes
EX_NOUSER = 67
EX_TEMPFAIL = 75
EX_UNAVAILABLE = 69

recipient = ARGV[0]
user_token = recipient.gsub(/^#{Rails.application.shortname}-/, "").
  gsub(/@.*/, "")
sender = ARGV[1]
message = ""
email = nil

while !STDIN.eof?
  message += STDIN.gets.to_s
end

if message.match(/^X-BeenThere: #{Rails.application.shortname}-/i)
  # avoid looping
  exit
end

sending_user = User.where(:mailing_list_enabled => true,
  :mailing_list_token => user_token).first

if !sending_user
  STDERR.puts "no user with mailing list token #{user_token}"

  # if this looks like a user token but invalid, generate a bounce to be
  # helpful.  otherwise supress it to avoid talking back to spammers
  exit(recipient.match(/^#{Rails.application.shortname}-/) ? EX_NOUSER : 0)
end

# the mail gem stupidly spams STDERR while parsing e-mail, so silence that
# stream to avoid anything getting back to postfix
begin
  Utils.silence_stream(STDERR) do
    email = Mail.read_from_string(message)
  end

  if !email
    raise
  end
rescue
  STDERR.puts "error parsing e-mail"
  exit EX_UNAVAILABLE
end

# figure out what this reply is to
irt = email[:in_reply_to].to_s.gsub(/[^A-Za-z0-9@\.]/, "")

if m = irt.match(/^comment\.([^\.]+)\.\d+@/)
  parent = Comment.where(:short_id => m[1]).first
elsif m = irt.match(/^story\.([^\.]+)\.\d+@/)
  parent = Story.where(:short_id => m[1]).first
end

if !parent
  STDERR.puts "no valid comment or story being replied to"
  exit EX_NOUSER
end

body = nil
possible_charset = nil

if email.multipart?
  # parts[0] - multipart/alternative
  #  parts[0].parts[0] - text/plain
  #  parts[0].parts[1] - text/html
  if (p = email.parts.first.parts.select{|p|
  p.content_type.match(/text\/plain/) }).any?
    begin
      possible_charset = p.first.content_type_parameters["charset"]
    rescue
    end

  # parts[0] - text/plain
  elsif (p = email.parts.select{|p|
  p.content_type.match(/text\/plain/) }).any?
    body = p.first.body.to_s

    begin
      possible_charset = p.first.content_type_parameters["charset"]
    rescue
    end
  end
elsif email.content_type.to_s.match(/text\/plain/)
  body = email.body.to_s

  begin
    possible_charset = email.content_type_parameters["charset"]
  rescue
  end

elsif !email.content_type.to_s.present?
  # no content-type header, assume it's text/plain
  body = email.body.to_s
end

if !body.present?
  # oh well
  STDERR.puts "no valid text/plain body found"
  exit EX_UNAVAILABLE
end

# try to remove sig lines
body.gsub!(/^-- \n.+\z/, "")

# TODO: try to strip out attribution line, followed by an optional blank line,
# and then lines prefixed with >

body.strip!

c = Comment.new
c.user_id = sending_user.id
c.comment = body
c.is_from_email = true

if parent.is_a?(Comment)
  c.story_id = parent.story_id
  c.parent_comment_id = parent.id
else
  c.story_id = parent.id
end

if c.save
  exit
else
  STDERR.puts c.errors.inspect
  exit EX_UNAVAILABLE
end