#!/usr/bin/ruby
# encoding: UTF-8
#
# Restore a file from the most recent backup, from the remote host.
#

$LOAD_PATH.unshift('/usr/lib/byteback')
$LOAD_PATH.unshift(File.join(File.dirname(__FILE__), '../lib')) # For development

require 'trollop'
require 'byteback/util'
require 'byteback/log'
require 'byteback/restore'
include Byteback::Util
include Byteback::Log

#
#  Run a remote command.
#
def ssh(*ssh_args)
  args = ['ssh',
          '-o', 'BatchMode=yes',
          '-o', 'ConnectionAttempts=5',
          '-o', 'ConnectTimeout=30',
          '-o', 'ServerAliveInterval=60',
          '-o', 'TCPKeepAlive=yes',
          '-x', '-a',
          '-i', @ssh_key,
          '-l', @destination_user,
          @destination_host
         ] +
         ssh_args.map { |a| a ? a : '' }

  puts args.join(" " ) if @verbose
  system(*args)
end

def list_files(pattern, snapshot, all)
  args = ['byteback-receive', '--snapshot', snapshot, '--list']
  args << "--all" if all
  args << @verbose if @verbose
  args += Byteback::Restore.encode_args(pattern)
  ssh(*args)
end

#
#  We cannot use plain 'rsync' here because the receiving-command will
# see that, and rewrite our arguments.
#
#  To cater to this we have to wrap the rsync for the restore and we
# do that by setting "rsync-path" to point to a faux script.
#
#
def restore_files(paths, snapshot, all)
  #
  # Basic args
  #
  args = %w(rsync --archive --numeric-ids --inplace --relative --compress)

  #
  #  Add on the I/O-timeout
  #
  args += ['--timeout', @io_timeout.to_s ] unless ( @io_timeout.nil? )
  args += ['--rsh', "ssh -o BatchMode=yes -x -a -i #{@ssh_key} -l #{@destination_user}"]
  args << '--verbose' if @verbose
  args += ['--rsync-path', "byteback-restore --fake-super --snapshot #{snapshot}" + (all ? " --all" : "")]

  #
  # To add extra rsync flags, a file can be used.  This can have flags all on one line, or one per line.
  #
  if File.exists?("/etc/byteback/rsync_flags")
    args += File.readlines("/etc/byteback/rsync_flags").map(&:chomp)
  end

  dst = "#{@destination_user}@#{@destination_host}:"

  paths.each do |path|
    path = Byteback::Restore.encode_args(path).first
    args << File.join(dst,path)
    dst = ":"
  end

  args << "."
  puts args.join(" ") if @verbose
  system(*args)
end

##
##  Entry-point to our code.
##
if __FILE__ == $PROGRAM_NAME

  ME = File.basename($PROGRAM_NAME)

  #
  #  Parse our command-line arguments
  #
  opts = Trollop.options do
    banner "#{ME}: Restore a file to this system from a byteback-enabled server\n "

    opt :list, "List or find files on the backup server.  This is the default mode."

    opt :restore, "Restore files from the backup server."

    opt :snapshot, "The specific snapshot to use",
        :type => :string, :default => "*"

    opt :destination, 'Backup destination (i.e. user@host:/path)',
        :type => :string

    opt :io_timeout, 'Number of seconds to allow I/O to timeout',
          :type => :integer,
          :default => 300

    opt :ssh_key, 'SSH key filename',
        :type => :string,
        :default => '/etc/byteback/key',
        :short => 'k'

    opt :all, 'List or restore all versrions of each file',
        :short => 'a'

    opt :verbose, 'Show more output'

  end

  #
  # Make sure we know what we're doing.
  #
  fatal("Please choose either --list or --restore") if opts[:list] and opts[:restore]

  @verbose = opts[:verbose] ? '--verbose' : nil
  @io_timeout = opts[:io_timeout] if opts[:io_timeout]

  # Read the default destination
  if File.exist?('/etc/byteback/destination')
    @destination = File.read('/etc/byteback/destination').chomp
  end

  # Set the default SSH key
  if File.exist?('/etc/byteback/key')
    @ssh_key = '/etc/byteback/key'
  end

  #
  # Allow the command-line to override them.
  #
  @ssh_key = opts[:ssh_key] unless  opts[:ssh_key].nil?
  @destination = opts[:destination] unless  opts[:destination].nil?

  #
  # Check our destination
  #
  fatal('Must suply --destination or put it into /etc/bytebackup/destination') unless @destination

  #
  # Check our destination is well-formed
  #
  if @destination =~ /^(?:(.+)@)?([^@:]+):(.+)?$/
    @destination_user, @destination_host, @destination_path = [Regexp.last_match(1), Regexp.last_match(2), Regexp.last_match(3)]
  else
    fatal('Destination must be a remote path, e.g. ssh@host.com:/store/backups')
  end

  #
  # Test that we have an SSH-key which we can read.
  #
  fatal("Could not read ssh key #{@ssh_key}") unless File.readable?(@ssh_key)

  #
  #  If the user didn't specify a file then we're not restoring anything,
  # and we should abort.
  #
  if ARGV.empty?
    fatal('You must specify a file to search/restore')
  end

  if opts[:restore]
    #
    #  Restore a file
    #
    restore_files(ARGV.collect{|a| File.expand_path(a)}, opts[:snapshot], opts[:all])
    exit(0)
  end

  list_files(ARGV.collect{|a| File.expand_path(a)}, opts[:snapshot], opts[:all])
  exit(0)
end