# Set encoding to utf-8
# encoding: UTF-8
#
# BigBlueButton open source conferencing system - http://www.bigbluebutton.org/
#
# Copyright (c) 2012 BigBlueButton Inc. and by respective authors (see below).
#
# This program is free software; you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free Software
# Foundation; either version 3.0 of the License, or (at your option) any later
# version.
#
# BigBlueButton is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
# PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with BigBlueButton; if not, see <http://www.gnu.org/licenses/>.
#

require '../../core/lib/recordandplayback'
require 'rubygems'
require 'yaml'
require 'net/http'
require 'rexml/document'
require 'open-uri'
require 'digest/md5'


BigBlueButton.logger = Logger.new("/var/log/bigbluebutton/decrypt.log",'daily' )

bbb_props = YAML::load(File.open('../../core/scripts/bigbluebutton.yml'))
mconf_props = YAML::load(File.open('mconf.yml'))

private_key = mconf_props['private_key']
get_recordings_url = mconf_props['get_recordings_url']
recording_dir = bbb_props['recording_dir'] 
raw_dir = "#{recording_dir}/raw"
archived_dir = "#{recording_dir}/status/archived"

doc = Nokogiri::XML(Net::HTTP.get_response(URI.parse(get_recordings_url)).body)
returncode = doc.xpath("//returncode")
if returncode.empty? or returncode.text != "SUCCESS"
  raise "getRecordings didn't return success"
end

doc.xpath("//recording").each do |recording|
  record_id = recording.xpath("recordID").text
  recording.xpath("//download/format").each do |format|
    type = format.xpath("type").text
    BigBlueButton.logger.info("type = #{type}")
    if type == "encrypted"
      meeting_id = record_id
      file_url = format.xpath("url").text
      key_file_url = format.xpath("key").text
      md5_value = format.xpath("md5").text

      BigBlueButton.logger.info("recordID = #{record_id}")
      BigBlueButton.logger.info("file_url = #{file_url}")
      BigBlueButton.logger.info("key_file_url = #{key_file_url}")
      BigBlueButton.logger.info("md5_value = #{md5_value}")

      encrypted_file = file_url.split("/").last
      decrypted_file = File.basename(encrypted_file, '.*') + ".zip"
      if not File.exist?("#{archived_dir}/#{meeting_id}.done") then
        Dir.chdir(raw_dir) do
          BigBlueButton.logger.info("Decrypting the recording #{meeting_id}")

          BigBlueButton.logger.info("Downloading the encrypted file to #{encrypted_file}")
          writeOut = open(encrypted_file, "wb")
          writeOut.write(open(file_url).read)
          writeOut.close

          md5_calculated = Digest::MD5.file(encrypted_file)

          if md5_calculated == md5_value
            BigBlueButton.logger.info("The calculated MD5 matches the expected value")
            key_file = key_file_url.split("/").last
            decrypted_key_file = File.basename(key_file, '.*') + ".txt"

            BigBlueButton.logger.info("Downloading the key file to #{key_file}")
            writeOut = open(key_file, "wb")
            writeOut.write(open(key_file_url).read)
            writeOut.close

            if key_file != decrypted_key_file
              command = "openssl rsautl -decrypt -inkey #{private_key} < #{key_file} > #{decrypted_key_file}"
              status = BigBlueButton.execute(command)
              if not status.success?
                raise "Couldn't decrypt the random key with the server private key"
              end
              FileUtils.rm_r "#{key_file}"
            else
              BigBlueButton.logger.info("No public key was used to encrypt the random key")
            end

            command = "openssl enc -aes-256-cbc -d -pass file:#{decrypted_key_file} < #{encrypted_file} > #{decrypted_file}"
            status = BigBlueButton.execute(command)
            if not status.success?
              raise "Couldn't decrypt the recording file using the random key"
            end
     
            BigBlueButton::MconfProcessor.unzip("#{raw_dir}/#{meeting_id}", decrypted_file)

            archived_done = File.new("#{archived_dir}/#{meeting_id}.done", "w")
            archived_done.write("Archived #{meeting_id}")
            archived_done.close
            
            [ "#{encrypted_file}", "#{decrypted_file}", "#{decrypted_key_file}" ].each { |file|
              BigBlueButton.logger.info("Removing #{file}")
              FileUtils.rm_r "#{file}"
            }

          else
            BigBlueButton.logger.error("The calculated MD5 doesn't match the expected value")
            FileUtils.rm_f(encrypted_file)
          end
        end
      end
    end
  end
end