#!/usr/bin/ruby

# This script watches modifications on the given directory, using the new # FSEvents API in Leopard.

require 'osx/foundation'

OSX.require_framework '/System/Library/Frameworks/CoreServices.framework/Frameworks/CarbonCore.framework'

include OSX

require 'set'

require 'optparse'

require 'ostruct'

$COMMAND = File.basename($0)

$USAGE = "Usage: #{$COMMAND} [OPTIONS] <command> [<args> ...]"

def die(s)

  $stderr.puts s

  exit 1

end

options = OpenStruct.new

options.directoriesOnly = false

options.outputFile = "-"

opts = OptionParser.new do |opts|

  opts.banner = $USAGE

  opts.separator ""

  opts.separator "Specific options:"

  opts.on("-d", "--dir-only", "Only display directories") do

    options.directoriesOnly = true

  end

  opts.on("-o", "--output FILE", "Write output to a file") do |fileName|

    options.outputFile = fileName

  end

  opts.on_tail("-h", "--help", "Show this message") do

    puts opts

    exit

  end

end

opts.parse!(ARGV)

die $USAGE unless ARGV.size >= 1

if options.outputFile == "-"

  outputHandle = $stdout.clone

else

  outputHandle = File.open(options.outputFile, "w")

end

path = "/"

startId = FSEventsGetCurrentEventId()

# Used to compare with mtime, which only has second accuracy

startTime = Time.now.to_i

fork do

  begin

    exec(*ARGV)

  rescue SystemCallError  => e

    puts e.message

    exit 127

  end

end

pid = Process.wait

returnCode = $? >> 8

sleep(0.1)

allPaths = Set.new

fsevents_cb = proc do |stream, ctx, numEvents, paths, marks, eventIDs|

  paths.regard_as('*')

  numEvents.times do |n|

    allPaths.add(paths[n])

  end

end

stream = FSEventStreamCreate(

  KCFAllocatorDefault,

  fsevents_cb,

  nil,

  [path],

  startId,

  1.0,

  KFSEventStreamCreateFlagNoDefer)

die "Failed to create the FSEventStream" unless stream

FSEventStreamScheduleWithRunLoop(

  stream,

  CFRunLoopGetCurrent(),

  KCFRunLoopDefaultMode)

ok = FSEventStreamStart(stream)

die "Failed to start the FSEventStream" unless ok

FSEventStreamFlushSync(stream)

allPaths.sort.each do |path|

  if File.exists?(path)

    outputHandle.puts path

    if (!options.directoriesOnly)

      Dir.foreach(path) do |file|

        fullPath = File.join(path, file)

        stat = File.stat(fullPath)

        if (stat.mtime.to_i >= startTime)

          outputHandle.puts "  #{file}"

        end

      end

    end

  else

    outputHandle.puts "#{path} !"

  end

end

FSEventStreamStop(stream)

FSEventStreamInvalidate(stream)

FSEventStreamRelease(stream)

outputHandle.flush

exit(returnCode)