require 'rubygems'
require 'rubygems/package'
require 'zlib'
require 'fileutils'

module Nuri
	module Util
		module Tar
			def targzip(path, prefix="")
				gzip(tar(path, prefix))
			end
	
			# Creates a tar file in memory recursively
			# from the given path.
			#
			# Returns a StringIO whose underlying String
			# is the contents of the tar file.
			def tar(path, prefix="")
				prefix += "/" unless prefix[-1] == '/' or prefix.length <= 0
				tarfile = StringIO.new("")
				Gem::Package::TarWriter.new(tarfile) do |tar|
					Dir[File.join(path, "**/*")].each do |file|
						mode = File.stat(file).mode
						relative_file = file.sub /^#{Regexp::escape path}\/?/, ''
						relative_file = prefix + relative_file
				
						if File.directory?(file)
							tar.mkdir relative_file, mode
						else
							tar.add_file relative_file, mode do |tf|
								File.open(file, "rb") { |f| tf.write f.read }
							end
						end
					end
				end
		
				tarfile.rewind
				tarfile
			end
		
			# gzips the underlying string in the given StringIO,
			# returning a new StringIO representing the 
			# compressed file.
			def gzip(tarfile)
				gz = StringIO.new("")
				z = Zlib::GzipWriter.new(gz)
				z.write tarfile.string
				z.close # this is necessary!
				
				# z was closed to write the gzip footer, so
				# now we need a new StringIO
				StringIO.new gz.string
			end
		
			# un-gzips the given IO, returning the
			# decompressed version as a StringIO
			def ungzip(tarfile)
				z = Zlib::GzipReader.new(tarfile)
				unzipped = StringIO.new(z.read)
				z.close
				unzipped
			end
		
			# untars the given IO into the specified
			# directory
			def untar(io, destination)
				Gem::Package::TarReader.new io do |tar|
					tar.each do |tarfile|
						destination_file = File.join destination, tarfile.full_name
						
						if tarfile.directory?
							FileUtils.mkdir_p destination_file
						else
							destination_directory = File.dirname(destination_file)
							FileUtils.mkdir_p destination_directory unless File.directory?(destination_directory)
							File.open destination_file, "wb" do |f|
								#f.print tarfile.read
								f.write tarfile.read
							end
						end
					end
				end
			end
		end
	end
end

### Usage Example: ###
#
# include Util::Tar
# 
# io = tar("./Desktop")   # io is a TAR of files
# gz = gzip(io)           # gz is a TGZ
# 
# io = ungzip(gz)         # io is a TAR
# untar(io, "./untarred") # files are untarred
#