class VirtualFilesystem(AbstractedFS):
    """Represents a virtual filesystem (currently only memory and s3 are supported)
    """
    
    def __init__(self, root, cmd_channel):
        AbstractedFS.__init__(self, root, cmd_channel)
        self.cwd = root
        self.type = cmd_channel.type
        self.s3_bucket = cmd_channel.s3_bucket
        self.aws_access_key = cmd_channel.aws_access_key
        self.aws_secret_key = cmd_channel.aws_secret_key
        self.seperator = cmd_channel.seperator
        self.thread_synchronize = cmd_channel.thread_synchronize
        self.key_sync_timeout = cmd_channel.key_sync_timeout
        if not self.cmd_channel.fs_obj:
            if self.type == "memory":
                self.fs_obj = MemoryFS()
            elif self.type == "s3":
                self.fs_obj = S3FS(bucket=self.bucket, prefix=self.prefix, aws_access_key=self.aws_access_key, aws_secret_key=self.aws_secret_key, separator=self.seperator, thread_synchronize=self.thread_synchronize, key_sync_timeout=self.key_sync_timeout)
            self.cmd_channel.fs_obj = self.fs_obj
        else:
            self.fs_obj = self.cmd_channel.fs_obj
            

    def ftp2fs(self, ftppath):
        return self.ftpnorm(ftppath)

    def fs2ftp(self, fspath):
        return fspath

    def validpath(self, path):
        # validpath was used to check symlinks escaping user home
        # directory; this is no longer necessary.
        return True
    
    def open(self, filename, mode):
            f = self.fs_obj.open(filename, mode)
            f.name=filename
            return f
    
    def mkdir(self, path):
        return self.fs_obj.makedir(path)
        
    def chdir(self, path):
        return self.fs_obj.opendir(path)
    
    def listdir(self,path):
        return self.fs_obj.listdir(path)
    
    def rmdir(self, path):
        return self.fs_obj.removedir(path)
    
    def remove(self, path):
        return self.fs_obj.remove(path)
    
    def rename(self, src, dst):
        return self.fs_obj.rename(src, dst)
    
    def chmod(self, path, mode):
        return True
    
    def readlink(self, path):
        return self.ftp2fs(path)
    
    def isfile(self, path):
        return self.fs_obj.isfile(path)
    
    def islink(self, path):
        return False
    
    def getsize(self, path):
        return self.fs_obj.getsize(path)
    
    def getmtime(self, path):
        return self.fs_obj.getinfo(path)['modified_time']
    
    def realpath(self, path):
        return path
    
    def lexists(self, path):
        return self.fs_obj.exists(path)
    
    def mkstemp(self, suffix='', prefix='', mode='wb'):
        from tempfile import _RandomNameSequence as RandomName
        name = RandomName()
        if suffix != '':
            suffix = 'tmp'
        fname = suffix + name.next()
        return self.fs_obj.open(fname,mode)