#!/usr/bin/env python3

# Libervia: an XMPP client
# Copyright (C) 2009-2021 Jérôme Poisson (goffi@goffi.org)

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.

# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

"""interfaces"""

from argparse import OPTIONAL
from pathlib import Path
from typing import Callable, Optional, Union
import uuid
import os
from zope import interface
from libervia.backend.core import exceptions
from libervia.backend.core.constants import Const as C
from libervia.backend.core.core_types import SatXMPPEntity
from libervia.backend.core.log import getLogger
from twisted.protocols import basic
from twisted.internet import interfaces

from libervia.backend.core.main import LiberviaBackend

log = getLogger(__name__)


class IStreamProducer(interface.Interface):
    def start_stream(consumer):
        """start producing the stream

        @return (D): deferred fired when stream is finished
        """
        pass


class SatFile:
    """A file-like object to have high level files manipulation"""

    # TODO: manage "with" statement

    def __init__(
        self,
        host: LiberviaBackend,
        client: SatXMPPEntity,
        path: Union[str, Path],
        mode: str = "rb",
        uid: Optional[str] = None,
        size: Optional[int] = None,
        data_cb: Optional[Callable] = None,
        auto_end_signals: bool = True,
        check_size_with_read: bool = False,
        pre_close_cb: Optional[Callable] = None,
    ) -> None:
        """
        @param host: %(doc_host)s
        @param path(Path, str): path to the file to get or write to
        @param mode(str): same as for built-in "open" function
        @param uid(unicode, None): unique id identifing this progressing element
            This uid will be used with self.host.progress_get
            will be automaticaly generated if None
        @param size(None, int): size of the file (when known in advance)
        @param data_cb(None, callable): method to call on each data read/write
            can be used to do processing like calculating hash.
            if data_cb return a non None value, it will be used instead of the
            data read/to write
        @param auto_end_signals(bool): if True, progress_finished and progress_error signals
            are automatically sent.
            if False, you'll have to call self.progress_finished and self.progress_error
            yourself.
            progress_started signal is always sent automatically
        @param check_size_with_read(bool): if True, size will be checked using number of
            bytes read or written. This is useful when data_cb modifiy len of file.
        @param pre_close_cb:
        """
        self.host = host
        self.profile = client.profile
        self.uid = uid or str(uuid.uuid4())
        self._file = open(path, mode)
        self.size = size
        self.data_cb = data_cb
        self.auto_end_signals = auto_end_signals
        self.pre_close_cb = pre_close_cb
        metadata = self.get_progress_metadata()
        self.host.register_progress_cb(
            self.uid, self.get_progress, metadata, profile=client.profile
        )
        self.host.bridge.progress_started(self.uid, metadata, client.profile)

        self._transfer_count = 0 if check_size_with_read else None

    @property
    def check_size_with_read(self):
        return self._transfer_count is not None

    @check_size_with_read.setter
    def check_size_with_read(self, value):
        if value and self._transfer_count is None:
            self._transfer_count = 0
        else:
            self._transfer_count = None

    def check_size(self):
        """Check that current size correspond to given size

        must be used when the transfer is supposed to be finished
        @return (bool): True if the position is the same as given size
        @raise exceptions.NotFound: size has not be specified
        """
        if self.check_size_with_read:
            position = self._transfer_count
        else:
            position = self._file.tell()
        if self.size is None:
            raise exceptions.NotFound
        return position == self.size

    def close(self, progress_metadata=None, error=None):
        """Close the current file

        @param progress_metadata(None, dict): metadata to send with _onProgressFinished
            message
        @param error(None, unicode): set to an error message if progress was not
            successful
            mutually exclusive with progress_metadata
            error can happen even if error is None, if current size differ from given size
        """
        if self._file.closed:
            return  # avoid double close (which is allowed) error
        if self.pre_close_cb is not None:
            self.pre_close_cb()
        if error is None:
            try:
                size_ok = self.check_size()
            except exceptions.NotFound:
                size_ok = True
            if not size_ok:
                error = "declared and actual size mismatch"
                log.warning(error)
                progress_metadata = None

        self._file.close()

        if self.auto_end_signals:
            if error is None:
                self.progress_finished(progress_metadata)
            else:
                assert progress_metadata is None
                self.progress_error(error)

        self.host.remove_progress_cb(self.uid, self.profile)
        if error is not None:
            log.error(f"file {self._file} closed with an error: {error}")

    @property
    def closed(self):
        return self._file.closed

    def progress_finished(self, metadata=None):
        if metadata is None:
            metadata = {}
        self.host.bridge.progress_finished(self.uid, metadata, self.profile)

    def progress_error(self, error):
        self.host.bridge.progress_error(self.uid, error, self.profile)

    def flush(self):
        self._file.flush()

    def write(self, buf):
        if self.data_cb is not None:
            ret = self.data_cb(buf)
            if ret is not None:
                buf = ret
        if self._transfer_count is not None:
            self._transfer_count += len(buf)
        self._file.write(buf)

    def read(self, size=-1):
        read = self._file.read(size)
        if self.data_cb is not None:
            ret = self.data_cb(read)
            if ret is not None:
                read = ret
        if self._transfer_count is not None:
            self._transfer_count += len(read)
        return read

    def seek(self, offset, whence=os.SEEK_SET):
        self._file.seek(offset, whence)

    def tell(self):
        return self._file.tell()

    @property
    def mode(self):
        return self._file.mode

    def get_progress_metadata(self):
        """Return progression metadata as given to progress_started

        @return (dict): metadata (check bridge for documentation)
        """
        metadata = {"type": C.META_TYPE_FILE}

        mode = self._file.mode
        if "+" in mode:
            pass  # we have no direction in read/write modes
        elif mode in ("r", "rb"):
            metadata["direction"] = "out"
        elif mode in ("w", "wb"):
            metadata["direction"] = "in"
        elif "U" in mode:
            metadata["direction"] = "out"
        else:
            raise exceptions.InternalError

        metadata["name"] = self._file.name

        return metadata

    def get_progress(self, progress_id, profile):
        ret = {"position": self._file.tell()}
        if self.size:
            ret["size"] = self.size
        return ret


@interface.implementer(IStreamProducer)
@interface.implementer(interfaces.IConsumer)
class FileStreamObject(basic.FileSender):
    def __init__(self, host, client, path, **kwargs):
        """

        A SatFile will be created and put in self.file_obj
        @param path(unicode): path to the file
        @param **kwargs: kw arguments to pass to SatFile
        """
        self.file_obj = SatFile(host, client, path, **kwargs)

    def registerProducer(self, producer, streaming):
        pass

    def start_stream(self, consumer):
        return self.beginFileTransfer(self.file_obj, consumer)

    def write(self, data):
        self.file_obj.write(data)

    def close(self, *args, **kwargs):
        self.file_obj.close(*args, **kwargs)
