#!/usr/bin/ruby

require 'optparse'
require 'thread'

Thread.abort_on_exception = true

GNUPG = "/usr/bin/gpg"

$program_name = File.basename($0, '.*')


class GnuPG
  @@my_keys = nil

  def GnuPG.readwrite3(intxt, infd, stdoutfd, stderrfd, statusfd)
    outtxt, stderrtxt, statustxt = ''
    thread_in = Thread.new {
      infd.print intxt
      infd.close
    }
    thread_out = Thread.new {
      outtxt = stdoutfd.read
      stdoutfd.close
    }
    thread_err = Thread.new {
      errtxt = stderrfd.read
      stderrfd.close
    }
    thread_status = Thread.new {
      statustxt = statusfd.read
      statusfd.close
    } if (statusfd)

    thread_in.join
    thread_out.join
    thread_err.join
    thread_status.join if thread_status

    return outtxt, stderrtxt, statustxt
  end

  def GnuPG.gpgcall(intxt, args, require_success = false)
    inR, inW = IO.pipe
    outR, outW = IO.pipe
    errR, errW = IO.pipe
    statR, statW = IO.pipe

    pid = Kernel.fork do
      inW.close
      outR.close
      errR.close
      statR.close
      STDIN.reopen(inR)
      STDOUT.reopen(outW)
      STDERR.reopen(errW)
      exec(GNUPG, "--status-fd=#{statW.fileno}",  *args)
      raise ("Calling gnupg failed")
    end
    inR.close
    outW.close
    errW.close
    statW.close
    (outtxt, stderrtxt, statustxt) = readwrite3(intxt, inW, outR, errR, statR);
    wpid, status = Process.waitpid2 pid
    throw "Unexpected pid: #{pid} vs #{wpid}" unless pid == wpid
    throw "Process has not exited!?" unless status.exited?
    throw "gpg call did not exit sucessfully" if (require_success and status.exitstatus != 0)
    return outtxt, stderrtxt, statustxt, status.exitstatus
  end

  def GnuPG.init_keys()
    return if @@my_keys
    (outtxt, stderrtxt, statustxt) = GnuPG.gpgcall('', %w{--fast-list-mode --with-colons --list-secret-keys}, true)
    @@my_keys = []
    outtxt.split("\n").each do |line|
      parts = line.split(':')
      if (parts[0] == "ssb" or parts[0] == "sec")
        @@my_keys.push parts[4]
      end
    end
  end

  def GnuPG.get_my_keys()
    init_keys
    @@my_keys
  end
end

class EncryptedFile
  attr_reader :readable, :encrypted

  def initialize(filename)
    content = File.read(filename)
    (outtxt, stderrtxt, statustxt) = GnuPG.gpgcall(content, %w{--with-colons --no-default-keyring --secret-keyring=/dev/null --keyring=/dev/null})
    @encrypted = !(statustxt =~ /\[GNUPG:\] NODATA/)
    if @encrypted
      @readers = EncryptedFile.list_readers(statustxt)
      @readable = EncryptedFile.determine_readable(@readers)
    end
  end

  def EncryptedFile.determine_readable(readers)
    GnuPG.get_my_keys.each do |keyid|
      return true if readers.include?(keyid)
    end
    return false
  end

  def EncryptedFile.list_readers(statustxt)
    readers = []
    statustxt.split("\n").each do |line|
      m = /^\[GNUPG:\] ENC_TO ([0-9A-F]+)/.match line
      next unless m
      readers.push m[1]
    end
    return readers
  end
end

class Ls
  def help(parser, code=0, io=STDOUT)
    io.puts "Usage: #{$program_name} ls [<directory> ...]"
    io.puts parser.summarize
    io.puts "Lists the contents of the given directory/directories, or the current"
    io.puts "directory if none is given.  For each file show whether it is PGP-encrypted"
    io.puts "file, and if yes whether we can read it."
    exit(code)
  end

  def ls_dir(dirname)
    begin
      dir = Dir.open(dirname)
    rescue Exception => e
      STDERR.puts e
      return
    end
    puts "#{dirname}:"
    Dir.chdir(dirname) do
      dir.sort.each do |filename|
        next if (filename =~ /^\./) and not (@all >= 3)
        stat = File::Stat.new(filename)
        if stat.symlink?
          puts "(sym)      #{filename}" if (@all >= 2)
        elsif stat.directory?
          puts "(dir)      #{filename}" if (@all >= 2)
        elsif !stat.file?
          puts "(other)    #{filename}" if (@all >= 2)
        else
          f = EncryptedFile.new(filename)
          if f.encrypted
            if f.readable
              puts "(ok)       #{filename}"
            else
              puts "(locked)   #{filename}" if (@all >= 1)
            end
          else
            puts "(file)     #{filename}" if (@all >= 2)
          end
        end
      end
    end
  end

  def initialize()
    @all = 0
    ARGV.options do |opts|
      opts.on_tail("-h", "--help" , "Display this help screen") { help(opts) }
      opts.on_tail("-a", "--all" , "Show all files (use up to 3 times to show even more than all)") { @all = @all+1 }
      opts.parse!
    end

    dirs = ARGV
    dirs.push('.') unless dirs.size > 0
    dirs.each { |dir| ls_dir(dir) }
  end
end

case ARGV.shift
  when 'ls': Ls.new
  else
    STDERR.puts "What!?"
end

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