from django.conf import settings
from django.core.files import File
from django.core.files.storage import FileSystemStorage
import gzip
import os

class DjangoGzipFile (File):

    def chunks( self, chunk_size=None ):
        if hasattr( self, 'seek' ):
            self.seek( 0 )
        yield self.read()

    def multiple_chunks( self, chunk_size=None ):
        return False

class GzipFileSystemStorage (FileSystemStorage):

    nocompress = ('.z','.gz','.zip','.tgz','.jpg','.png','.gif')

    def should_compress( self, name ):
        dir_name, file_name = os.path.split( name )
        file_root, file_ext = os.path.splitext( file_name )
        return file_ext.lower() not in self.nocompress

    def path( self, name, for_dir=False ):
        p = super( GzipFileSystemStorage, self ).path( name )
        if self.should_compress(name) and not for_dir:
            p = p + '.gz'
        return p

    def _open( self, name, mode='rb' ):
        if self.should_compress( name ):
            full_path = self.path( name )
            gzip_file = gzip.GzipFile( full_path, mode )
            # File._get_size chokes unless self.file has a name attribute.
            setattr( gzip_file, 'name', full_path )
            return DjangoGzipFile( gzip_file )
        else:
            return super( GzipFileSystemStorage, self )._open( name, mode )

    def _save( self, name, content ):
        if not self.should_compress( name ):
            return super( GzipFileSystemStorage, self )._save( name, content )

        full_path = self.path( self.get_available_name(name) )
        dir_name, file_name = os.path.split( full_path )

        if not os.path.exists( dir_name ):
            os.makedirs( dir_name )
        elif not os.path.isdir( dir_name ):
            raise IOError( "%s exists and is not a directory." % dir_name )

        fd = open( full_path, 'wb' )
        gzip_file = gzip.GzipFile( filename=file_name, fileobj=fd, mode='wb' )
        for chunk in content.chunks():
            gzip_file.write( chunk )
        gzip_file.close()
        fd.close()

        if settings.FILE_UPLOAD_PERMISSIONS is not None:
            os.chmod( full_path, settings.FILE_UPLOAD_PERMISSIONS )

        return name

    def listdir( self, path ):
        path = self.path( path, for_dir=True )
        directories, files = [], []
        for entry in os.listdir( path ):
            if os.path.isdir( os.path.join(path,entry) ):
                directories.append( entry )
            else:
                files.append( entry )
        return directories, files