"""
Ported to Python 3.
"""

from io import BytesIO

from zope.interface import implementer
from twisted.internet import defer
from twisted.protocols import basic
from allmydata.interfaces import IImmutableFileNode, ICheckable
from allmydata.uri import LiteralFileURI


class _ImmutableFileNodeBase(object):

    def get_write_uri(self):
        return None

    def get_readonly_uri(self):
        return self.get_uri()

    def is_mutable(self):
        return False

    def is_readonly(self):
        return True

    def is_unknown(self):
        return False

    def is_allowed_in_immutable_directory(self):
        return True

    def raise_error(self):
        pass

    def __hash__(self):
        return self.u.__hash__()

    def __eq__(self, other):
        if isinstance(other, _ImmutableFileNodeBase):
            return self.u == other.u
        else:
            return False

    def __ne__(self, other):
        return not self == other


@implementer(IImmutableFileNode, ICheckable)
class LiteralFileNode(_ImmutableFileNodeBase):

    def __init__(self, filecap):
        assert isinstance(filecap, LiteralFileURI)
        self.u = filecap

    def get_size(self):
        return len(self.u.data)
    def get_current_size(self):
        return defer.succeed(self.get_size())

    def get_cap(self):
        return self.u
    def get_readcap(self):
        return self.u
    def get_verify_cap(self):
        return None
    def get_repair_cap(self):
        return None

    def get_uri(self):
        return self.u.to_string()

    def get_storage_index(self):
        return None

    def check(self, monitor, verify=False, add_lease=False):
        return defer.succeed(None)

    def check_and_repair(self, monitor, verify=False, add_lease=False):
        return defer.succeed(None)

    def read(self, consumer, offset=0, size=None):
        if size is None:
            data = self.u.data[offset:]
        else:
            data = self.u.data[offset:offset+size]

        # We use twisted.protocols.basic.FileSender, which only does
        # non-streaming, i.e. PullProducer, where the receiver/consumer must
        # ask explicitly for each chunk of data. There are only two places in
        # the Twisted codebase that can't handle streaming=False, both of
        # which are in the upload path for an FTP/SFTP server
        # (protocols.ftp.FileConsumer and
        # vfs.adapters.ftp._FileToConsumerAdapter), neither of which is
        # likely to be used as the target for a Tahoe download.

        d = basic.FileSender().beginFileTransfer(BytesIO(data), consumer)
        d.addCallback(lambda lastSent: consumer)
        return d

    # IReadable, IFileNode, IFilesystemNode
    def get_best_readable_version(self):
        return defer.succeed(self)


    def download_best_version(self):
        return defer.succeed(self.u.data)


    download_to_data = download_best_version
    get_size_of_best_version = get_current_size