"""
Utilities for working with the Telegram API itself (such as handy methods
to convert between an entity like an User, Chat, etc. into its Input version)
"""
import base64
import binascii
import itertools
import math
import mimetypes
import os
import re
import struct
from mimetypes import guess_extension
from types import GeneratorType

from .extensions import markdown, html
from .helpers import add_surrogate, del_surrogate
from .tl import types

try:
    import hachoir
    import hachoir.metadata
    import hachoir.parser
except ImportError:
    hachoir = None

# .webp (stickers) and .ogg (some voice notes) mimetypes are unknown on some
# operative systems. Manually register them here to make them work everywhere.
mimetypes.add_type('image/webp', '.webp')
mimetypes.add_type('audio/ogg', '.ogg')

USERNAME_RE = re.compile(
    r'@|(?:https?://)?(?:www\.)?(?:telegram\.(?:me|dog)|t\.me)/(joinchat/)?'
)

# The only shorter-than-five-characters usernames are those used for some
# special, very well known bots. This list may be incomplete though:
#    "[...] @gif, @vid, @pic, @bing, @wiki, @imdb and @bold [...]"
#
# See https://telegram.org/blog/inline-bots#how-does-it-work
VALID_USERNAME_RE = re.compile(
    r'^([a-z]((?!__)[\w\d]){3,30}[a-z\d]'
    r'|gif|vid|pic|bing|wiki|imdb|bold|vote|like|coub|ya)$',
    re.IGNORECASE
)


class Default:
    """
    Sentinel value to indicate that the default value should be used.
    Currently used for the ``parse_mode``, where a ``None`` mode should
    be considered different from using the default.
    """


def chunks(iterable, size=100):
    """
    Turns the given iterable into chunks of the specified size,
    which is 100 by default since that's what Telegram uses the most.
    """
    it = iter(iterable)
    size -= 1
    for head in it:
        yield itertools.chain([head], itertools.islice(it, size))


def get_display_name(entity):
    """
    Gets the display name for the given entity, if it's an :tl:`User`,
    :tl:`Chat` or :tl:`Channel`. Returns an empty string otherwise.
    """
    if isinstance(entity, types.User):
        if entity.last_name and entity.first_name:
            return '{} {}'.format(entity.first_name, entity.last_name)
        elif entity.first_name:
            return entity.first_name
        elif entity.last_name:
            return entity.last_name
        else:
            return ''

    elif isinstance(entity, (types.Chat, types.Channel)):
        return entity.title

    return ''


def get_extension(media):
    """Gets the corresponding extension for any Telegram media."""

    # Photos are always compressed as .jpg by Telegram
    if isinstance(media, (types.UserProfilePhoto,
                          types.ChatPhoto, types.MessageMediaPhoto)):
        return '.jpg'

    # Documents will come with a mime type
    if isinstance(media, types.MessageMediaDocument):
        media = media.document
    if isinstance(media, (
            types.Document, types.WebDocument, types.WebDocumentNoProxy)):
        if media.mime_type == 'application/octet-stream':
            # Octet stream are just bytes, which have no default extension
            return ''
        else:
            return guess_extension(media.mime_type) or ''

    return ''


def _raise_cast_fail(entity, target):
    raise TypeError('Cannot cast {} to any kind of {}.'.format(
        type(entity).__name__, target))


def get_input_peer(entity, allow_self=True):
    """
    Gets the input peer for the given "entity" (user, chat or channel).
    A ``TypeError`` is raised if the given entity isn't a supported type.
    """
    try:
        if entity.SUBCLASS_OF_ID == 0xc91c90b6:  # crc32(b'InputPeer')
            return entity
    except AttributeError:
        # e.g. custom.Dialog (can't cyclic import).
        if allow_self and hasattr(entity, 'input_entity'):
            return entity.input_entity
        elif hasattr(entity, 'entity'):
            return get_input_peer(entity.entity)
        else:
            _raise_cast_fail(entity, 'InputPeer')

    if isinstance(entity, types.User):
        if entity.is_self and allow_self:
            return types.InputPeerSelf()
        else:
            return types.InputPeerUser(entity.id, entity.access_hash or 0)

    if isinstance(entity, (types.Chat, types.ChatEmpty, types.ChatForbidden)):
        return types.InputPeerChat(entity.id)

    if isinstance(entity, (types.Channel, types.ChannelForbidden)):
        return types.InputPeerChannel(entity.id, entity.access_hash or 0)

    if isinstance(entity, types.InputUser):
        return types.InputPeerUser(entity.user_id, entity.access_hash)

    if isinstance(entity, types.InputChannel):
        return types.InputPeerChannel(entity.channel_id, entity.access_hash)

    if isinstance(entity, types.InputUserSelf):
        return types.InputPeerSelf()

    if isinstance(entity, types.UserEmpty):
        return types.InputPeerEmpty()

    if isinstance(entity, types.UserFull):
        return get_input_peer(entity.user)

    if isinstance(entity, types.ChatFull):
        return types.InputPeerChat(entity.id)

    if isinstance(entity, types.PeerChat):
        return types.InputPeerChat(entity.chat_id)

    _raise_cast_fail(entity, 'InputPeer')


def get_input_channel(entity):
    """Similar to :meth:`get_input_peer`, but for :tl:`InputChannel`'s alone."""
    try:
        if entity.SUBCLASS_OF_ID == 0x40f202fd:  # crc32(b'InputChannel')
            return entity
    except AttributeError:
        _raise_cast_fail(entity, 'InputChannel')

    if isinstance(entity, (types.Channel, types.ChannelForbidden)):
        return types.InputChannel(entity.id, entity.access_hash or 0)

    if isinstance(entity, types.InputPeerChannel):
        return types.InputChannel(entity.channel_id, entity.access_hash)

    _raise_cast_fail(entity, 'InputChannel')


def get_input_user(entity):
    """Similar to :meth:`get_input_peer`, but for :tl:`InputUser`'s alone."""
    try:
        if entity.SUBCLASS_OF_ID == 0xe669bf46:  # crc32(b'InputUser'):
            return entity
    except AttributeError:
        _raise_cast_fail(entity, 'InputUser')

    if isinstance(entity, types.User):
        if entity.is_self:
            return types.InputUserSelf()
        else:
            return types.InputUser(entity.id, entity.access_hash or 0)

    if isinstance(entity, types.InputPeerSelf):
        return types.InputUserSelf()

    if isinstance(entity, (types.UserEmpty, types.InputPeerEmpty)):
        return types.InputUserEmpty()

    if isinstance(entity, types.UserFull):
        return get_input_user(entity.user)

    if isinstance(entity, types.InputPeerUser):
        return types.InputUser(entity.user_id, entity.access_hash)

    _raise_cast_fail(entity, 'InputUser')


def get_input_dialog(dialog):
    """Similar to :meth:`get_input_peer`, but for dialogs"""
    try:
        if dialog.SUBCLASS_OF_ID == 0xa21c9795:  # crc32(b'InputDialogPeer')
            return dialog
        if dialog.SUBCLASS_OF_ID == 0xc91c90b6:  # crc32(b'InputPeer')
            return types.InputDialogPeer(dialog)
    except AttributeError:
        _raise_cast_fail(dialog, 'InputDialogPeer')

    try:
        return types.InputDialogPeer(get_input_peer(dialog))
    except TypeError:
        pass

    _raise_cast_fail(dialog, 'InputDialogPeer')


def get_input_document(document):
    """Similar to :meth:`get_input_peer`, but for documents"""
    try:
        if document.SUBCLASS_OF_ID == 0xf33fdb68:  # crc32(b'InputDocument'):
            return document
    except AttributeError:
        _raise_cast_fail(document, 'InputDocument')

    if isinstance(document, types.Document):
        return types.InputDocument(
            id=document.id, access_hash=document.access_hash)

    if isinstance(document, types.DocumentEmpty):
        return types.InputDocumentEmpty()

    if isinstance(document, types.MessageMediaDocument):
        return get_input_document(document.document)

    if isinstance(document, types.Message):
        return get_input_document(document.media)

    _raise_cast_fail(document, 'InputDocument')


def get_input_photo(photo):
    """Similar to :meth:`get_input_peer`, but for photos"""
    try:
        if photo.SUBCLASS_OF_ID == 0x846363e0:  # crc32(b'InputPhoto'):
            return photo
    except AttributeError:
        _raise_cast_fail(photo, 'InputPhoto')

    if isinstance(photo, types.photos.Photo):
        photo = photo.photo

    if isinstance(photo, types.Photo):
        return types.InputPhoto(id=photo.id, access_hash=photo.access_hash)

    if isinstance(photo, types.PhotoEmpty):
        return types.InputPhotoEmpty()

    _raise_cast_fail(photo, 'InputPhoto')


def get_input_geo(geo):
    """Similar to :meth:`get_input_peer`, but for geo points"""
    try:
        if geo.SUBCLASS_OF_ID == 0x430d225:  # crc32(b'InputGeoPoint'):
            return geo
    except AttributeError:
        _raise_cast_fail(geo, 'InputGeoPoint')

    if isinstance(geo, types.GeoPoint):
        return types.InputGeoPoint(lat=geo.lat, long=geo.long)

    if isinstance(geo, types.GeoPointEmpty):
        return types.InputGeoPointEmpty()

    if isinstance(geo, types.MessageMediaGeo):
        return get_input_geo(geo.geo)

    if isinstance(geo, types.Message):
        return get_input_geo(geo.media)

    _raise_cast_fail(geo, 'InputGeoPoint')


def get_input_media(media, is_photo=False):
    """
    Similar to :meth:`get_input_peer`, but for media.

    If the media is a file location and ``is_photo`` is known to be ``True``,
    it will be treated as an :tl:`InputMediaUploadedPhoto`.
    """
    try:
        if media.SUBCLASS_OF_ID == 0xfaf846f4:  # crc32(b'InputMedia')
            return media
        elif media.SUBCLASS_OF_ID == 0x846363e0:  # crc32(b'InputPhoto')
            return types.InputMediaPhoto(media)
        elif media.SUBCLASS_OF_ID == 0xf33fdb68:  # crc32(b'InputDocument')
            return types.InputMediaDocument(media)
    except AttributeError:
        _raise_cast_fail(media, 'InputMedia')

    if isinstance(media, types.MessageMediaPhoto):
        return types.InputMediaPhoto(
            id=get_input_photo(media.photo),
            ttl_seconds=media.ttl_seconds
        )

    if isinstance(media, (types.Photo, types.photos.Photo, types.PhotoEmpty)):
        return types.InputMediaPhoto(
            id=get_input_photo(media)
        )

    if isinstance(media, types.MessageMediaDocument):
        return types.InputMediaDocument(
            id=get_input_document(media.document),
            ttl_seconds=media.ttl_seconds
        )

    if isinstance(media, (types.Document, types.DocumentEmpty)):
        return types.InputMediaDocument(
            id=get_input_document(media)
        )

    if isinstance(media, types.FileLocation):
        if is_photo:
            return types.InputMediaUploadedPhoto(file=media)
        else:
            return types.InputMediaUploadedDocument(
                file=media,
                mime_type='application/octet-stream',  # unknown, assume bytes
                attributes=[types.DocumentAttributeFilename('unnamed')]
            )

    if isinstance(media, types.MessageMediaGame):
        return types.InputMediaGame(id=media.game.id)

    if isinstance(media, (types.ChatPhoto, types.UserProfilePhoto)):
        if isinstance(media.photo_big, types.FileLocationUnavailable):
            media = media.photo_small
        else:
            media = media.photo_big
        return get_input_media(media, is_photo=True)

    if isinstance(media, types.MessageMediaContact):
        return types.InputMediaContact(
            phone_number=media.phone_number,
            first_name=media.first_name,
            last_name=media.last_name,
            vcard=''
        )

    if isinstance(media, types.MessageMediaGeo):
        return types.InputMediaGeoPoint(geo_point=get_input_geo(media.geo))

    if isinstance(media, types.MessageMediaVenue):
        return types.InputMediaVenue(
            geo_point=get_input_geo(media.geo),
            title=media.title,
            address=media.address,
            provider=media.provider,
            venue_id=media.venue_id,
            venue_type=''
        )

    if isinstance(media, (
            types.MessageMediaEmpty, types.MessageMediaUnsupported,
            types.ChatPhotoEmpty, types.UserProfilePhotoEmpty,
            types.FileLocationUnavailable)):
        return types.InputMediaEmpty()

    if isinstance(media, types.Message):
        return get_input_media(media.media, is_photo=is_photo)

    _raise_cast_fail(media, 'InputMedia')


def get_input_message(message):
    """Similar to :meth:`get_input_peer`, but for input messages."""
    try:
        if isinstance(message, int):  # This case is really common too
            return types.InputMessageID(message)
        elif message.SUBCLASS_OF_ID == 0x54b6bcc5:  # crc32(b'InputMessage'):
            return message
        elif message.SUBCLASS_OF_ID == 0x790009e3:  # crc32(b'Message'):
            return types.InputMessageID(message.id)
    except AttributeError:
        pass

    _raise_cast_fail(message, 'InputMedia')


def get_message_id(message):
    """Similar to :meth:`get_input_peer`, but for message IDs."""
    if message is None:
        return None

    if isinstance(message, int):
        return message

    try:
        if message.SUBCLASS_OF_ID == 0x790009e3:
            # hex(crc32(b'Message')) = 0x790009e3
            return message.id
    except AttributeError:
        pass

    raise TypeError('Invalid message type: {}'.format(type(message)))


def get_attributes(file, *, attributes=None, mime_type=None,
                   force_document=False, voice_note=False, video_note=False):
    """
    Get a list of attributes for the given file and
    the mime type as a tuple ([attribute], mime_type).
    """
    name = file if isinstance(file, str) else getattr(file, 'name', 'unnamed')
    if mime_type is None:
        mime_type = mimetypes.guess_type(name)[0]

    attr_dict = {types.DocumentAttributeFilename:
        types.DocumentAttributeFilename(os.path.basename(name))}

    if is_audio(file) and hachoir is not None:
        with hachoir.parser.createParser(file) as parser:
            m = hachoir.metadata.extractMetadata(parser)
            attr_dict[types.DocumentAttributeAudio] = \
                types.DocumentAttributeAudio(
                    voice=voice_note,
                    title=m.get('title') if m.has('title') else None,
                    performer=m.get('author') if m.has('author') else None,
                    duration=int(m.get('duration').seconds
                                 if m.has('duration') else 0)
                )

    if not force_document and is_video(file):
        if hachoir:
            with hachoir.parser.createParser(file) as parser:
                m = hachoir.metadata.extractMetadata(parser)
                doc = types.DocumentAttributeVideo(
                    round_message=video_note,
                    w=m.get('width') if m.has('width') else 0,
                    h=m.get('height') if m.has('height') else 0,
                    duration=int(m.get('duration').seconds
                                 if m.has('duration') else 0)
                )
        else:
            doc = types.DocumentAttributeVideo(
                0, 1, 1, round_message=video_note)

        attr_dict[types.DocumentAttributeVideo] = doc

    if voice_note:
        if types.DocumentAttributeAudio in attr_dict:
            attr_dict[types.DocumentAttributeAudio].voice = True
        else:
            attr_dict[types.DocumentAttributeAudio] = \
                types.DocumentAttributeAudio(0, voice=True)

    # Now override the attributes if any. As we have a dict of
    # {cls: instance}, we can override any class with the list
    # of attributes provided by the user easily.
    if attributes:
        for a in attributes:
            attr_dict[type(a)] = a

    # Ensure we have a mime type, any; but it cannot be None
    # 'The "octet-stream" subtype is used to indicate that a body
    # contains arbitrary binary data.'
    if not mime_type:
        mime_type = 'application/octet-stream'

    return list(attr_dict.values()), mime_type


def sanitize_parse_mode(mode):
    """
    Converts the given parse mode into an object with
    ``parse`` and ``unparse`` callable properties.
    """
    if not mode:
        return None

    if callable(mode):
        class CustomMode:
            @staticmethod
            def unparse(text, entities):
                raise NotImplementedError

        CustomMode.parse = mode
        return CustomMode
    elif (all(hasattr(mode, x) for x in ('parse', 'unparse'))
          and all(callable(x) for x in (mode.parse, mode.unparse))):
        return mode
    elif isinstance(mode, str):
        try:
            return {
                'md': markdown,
                'markdown': markdown,
                'htm': html,
                'html': html
            }[mode.lower()]
        except KeyError:
            raise ValueError('Unknown parse mode {}'.format(mode))
    else:
        raise TypeError('Invalid parse mode type {}'.format(mode))


def get_input_location(location):
    """
    Similar to :meth:`get_input_peer`, but for input messages.

    Note that this returns a tuple ``(dc_id, location)``, the
    ``dc_id`` being present if known.
    """
    try:
        if location.SUBCLASS_OF_ID == 0x1523d462:
            return None, location  # crc32(b'InputFileLocation'):
    except AttributeError:
        _raise_cast_fail(location, 'InputFileLocation')

    if isinstance(location, types.Message):
        location = location.media

    if isinstance(location, types.MessageMediaDocument):
        location = location.document
    elif isinstance(location, types.MessageMediaPhoto):
        location = location.photo

    if isinstance(location, types.Document):
        return (location.dc_id, types.InputDocumentFileLocation(
            location.id, location.access_hash, location.version))
    elif isinstance(location, types.Photo):
        try:
            location = next(
                x for x in reversed(location.sizes)
                if not isinstance(x, types.PhotoSizeEmpty)
            ).location
        except StopIteration:
            pass

    if isinstance(location, (
            types.FileLocation, types.FileLocationUnavailable)):
        return (getattr(location, 'dc_id', None), types.InputFileLocation(
            location.volume_id, location.local_id, location.secret))

    _raise_cast_fail(location, 'InputFileLocation')


def _get_extension(file):
    """
    Gets the extension for the given file, which can be either a
    str or an ``open()``'ed file (which has a ``.name`` attribute).
    """
    if isinstance(file, str):
        return os.path.splitext(file)[-1]
    elif getattr(file, 'name', None):
        return _get_extension(file.name)
    else:
        return ''


def is_image(file):
    """
    Returns ``True`` if the file extension looks like an image file to Telegram.
    """
    return re.match(r'\.(png|jpe?g)', _get_extension(file), re.IGNORECASE)


def is_gif(file):
    """
    Returns ``True`` if the file extension looks like a gif file to Telegram.
    """
    return re.match(r'\.gif', _get_extension(file), re.IGNORECASE)


def is_audio(file):
    """Returns ``True`` if the file extension looks like an audio file."""
    file = 'a' + _get_extension(file)
    return (mimetypes.guess_type(file)[0] or '').startswith('audio/')


def is_video(file):
    """Returns ``True`` if the file extension looks like a video file."""
    file = 'a' + _get_extension(file)
    return (mimetypes.guess_type(file)[0] or '').startswith('video/')


def is_list_like(obj):
    """
    Returns ``True`` if the given object looks like a list.

    Checking ``if hasattr(obj, '__iter__')`` and ignoring ``str/bytes`` is not
    enough. Things like ``open()`` are also iterable (and probably many
    other things), so just support the commonly known list-like objects.
    """
    return isinstance(obj, (list, tuple, set, dict, GeneratorType))


def parse_phone(phone):
    """Parses the given phone, or returns ``None`` if it's invalid."""
    if isinstance(phone, int):
        return str(phone)
    else:
        phone = re.sub(r'[+()\s-]', '', str(phone))
        if phone.isdigit():
            return phone


def parse_username(username):
    """Parses the given username or channel access hash, given
       a string, username or URL. Returns a tuple consisting of
       both the stripped, lowercase username and whether it is
       a joinchat/ hash (in which case is not lowercase'd).

       Returns ``None`` if the ``username`` is not valid.
    """
    username = username.strip()
    m = USERNAME_RE.match(username)
    if m:
        username = username[m.end():]
        is_invite = bool(m.group(1))
        if is_invite:
            return username, True
        else:
            username = username.rstrip('/')

    if VALID_USERNAME_RE.match(username):
        return username.lower(), False
    else:
        return None, False


def get_inner_text(text, entities):
    """
    Gets the inner text that's surrounded by the given entities.
    For instance: text = 'hey!', entity = MessageEntityBold(2, 2) -> 'y!'.

    :param text:     the original text.
    :param entities: the entity or entities that must be matched.
    :return: a single result or a list of the text surrounded by the entities.
    """
    text = add_surrogate(text)
    result = []
    for e in entities:
        start = e.offset
        end = e.offset + e.length
        result.append(del_surrogate(text[start:end]))

    return result


def get_peer(peer):
    try:
        if peer.SUBCLASS_OF_ID == 0x2d45687:
            return peer
        elif isinstance(peer, (
                types.contacts.ResolvedPeer, types.InputNotifyPeer,
                types.TopPeer)):
            return peer.peer
        elif isinstance(peer, types.ChannelFull):
            return types.PeerChannel(peer.id)

        peer = get_input_peer(peer, allow_self=False)
        if isinstance(peer, types.InputPeerUser):
            return types.PeerUser(peer.user_id)
        elif isinstance(peer, types.InputPeerChat):
            return types.PeerChat(peer.chat_id)
        elif isinstance(peer, types.InputPeerChannel):
            return types.PeerChannel(peer.channel_id)
    except (AttributeError, TypeError):
        _raise_cast_fail(peer, 'Peer')


def get_peer_id(peer, add_mark=True):
    """
    Finds the ID of the given peer, and converts it to the "bot api" format
    so it the peer can be identified back. User ID is left unmodified,
    chat ID is negated, and channel ID is prefixed with -100.

    The original ID and the peer type class can be returned with
    a call to :meth:`resolve_id(marked_id)`.
    """
    # First we assert it's a Peer TLObject, or early return for integers
    if isinstance(peer, int):
        return peer if add_mark else resolve_id(peer)[0]

    try:
        peer = get_peer(peer)
    except TypeError:
        _raise_cast_fail(peer, 'int')

    if isinstance(peer, types.PeerUser):
        return peer.user_id
    elif isinstance(peer, types.PeerChat):
        # Check in case the user mixed things up to avoid blowing up
        if not (0 < peer.chat_id <= 0x7fffffff):
            peer.chat_id = resolve_id(peer.chat_id)[0]

        return -peer.chat_id if add_mark else peer.chat_id
    else:  # if isinstance(peer, types.PeerChannel):
        # Check in case the user mixed things up to avoid blowing up
        if not (0 < peer.channel_id <= 0x7fffffff):
            peer.channel_id = resolve_id(peer.channel_id)[0]

        if not add_mark:
            return peer.channel_id

        # Concat -100 through math tricks, .to_supergroup() on
        # Madeline IDs will be strictly positive -> log works.
        return -(peer.channel_id + pow(
            10, math.floor(math.log10(peer.channel_id) + 3)))


def resolve_id(marked_id):
    """Given a marked ID, returns the original ID and its :tl:`Peer` type."""
    if marked_id >= 0:
        return marked_id, types.PeerUser

    # There have been report of chat IDs being 10000xyz, which means their
    # marked version is -10000xyz, which in turn looks like a channel but
    # it becomes 00xyz (= xyz). Hence, we must assert that there are only
    # two zeroes.
    m = re.match(r'-100([^0]\d*)', str(marked_id))
    if m:
        return int(m.group(1)), types.PeerChannel

    return -marked_id, types.PeerChat


def _rle_decode(data):
    """
    Decodes run-length-encoded `data`.
    """
    if not data:
        return data

    new = b''
    last = b''
    for cur in data:
        if last == b'\0':
            new += last * cur
            last = b''
        else:
            new += last
            last = bytes([cur])

    return new + last


def _rle_encode(string):
    new = b''
    count = 0
    for cur in string:
        if not cur:
            count += 1
        else:
            if count:
                new += b'\0' + bytes([count])
                count = 0

            new += bytes([cur])
    return new


def _decode_telegram_base64(string):
    """
    Decodes an url-safe base64-encoded string into its bytes
    by first adding the stripped necessary padding characters.

    This is the way Telegram shares binary data as strings,
    such as Bot API-style file IDs or invite links.

    Returns ``None`` if the input string was not valid.
    """
    try:
        return base64.urlsafe_b64decode(string + '=' * (len(string) % 4))
    except (binascii.Error, ValueError, TypeError):
        return None  # not valid base64, not valid ascii, not a string


def _encode_telegram_base64(string):
    """
    Inverse for `_decode_telegram_base64`.
    """
    try:
        return base64.urlsafe_b64encode(string).rstrip(b'=').decode('ascii')
    except (binascii.Error, ValueError, TypeError):
        return None  # not valid base64, not valid ascii, not a string


def resolve_bot_file_id(file_id):
    """
    Given a Bot API-style `file_id`, returns the media it represents.
    If the `file_id` is not valid, ``None`` is returned instead.

    Note that the `file_id` does not have information such as image
    dimensions or file size, so these will be zero if present.

    For thumbnails, the photo ID and hash will always be zero.
    """
    data = _rle_decode(_decode_telegram_base64(file_id))
    if not data or data[-1] == b'\x02':
        return None

    data = data[:-1]
    if len(data) == 24:
        file_type, dc_id, media_id, access_hash = struct.unpack('<iiqq', data)
        attributes = []
        if file_type == 3 or file_type == 9:
            attributes.append(types.DocumentAttributeAudio(
                duration=0,
                voice=file_type == 3
            ))
        elif file_type == 4 or file_type == 13:
            attributes.append(types.DocumentAttributeVideo(
                duration=0,
                w=0,
                h=0,
                round_message=file_type == 13
            ))
        # elif file_type == 5:  # other, cannot know which
        elif file_type == 8:
            attributes.append(types.DocumentAttributeSticker(
                alt='',
                stickerset=types.InputStickerSetEmpty()
            ))
        elif file_type == 10:
            attributes.append(types.DocumentAttributeAnimated())

        return types.Document(
            id=media_id,
            access_hash=access_hash,
            date=None,
            mime_type='',
            size=0,
            thumb=types.PhotoSizeEmpty('s'),
            dc_id=dc_id,
            version=0,
            attributes=attributes
        )
    elif len(data) == 44:
        (file_type, dc_id, media_id, access_hash,
            volume_id, secret, local_id) = struct.unpack('<iiqqqqi', data)

        # Thumbnails (small) always have ID 0; otherwise size 'x'
        photo_size = 's' if media_id or access_hash else 'x'
        return types.Photo(id=media_id, access_hash=access_hash, sizes=[
            types.PhotoSize(photo_size, location=types.FileLocation(
                dc_id=dc_id,
                volume_id=volume_id,
                secret=secret,
                local_id=local_id
            ), w=0, h=0, size=0)
        ], date=None)


def pack_bot_file_id(file):
    """
    Inverse operation for `resolve_bot_file_id`.

    The only parameters this method will accept are :tl:`Document` and
    :tl:`Photo`, and it will return a variable-length ``file_id`` string.

    If an invalid parameter is given, it will ``return None``.
    """
    if isinstance(file, types.Document):
        file_type = 5
        for attribute in file.attributes:
            if isinstance(attribute, types.DocumentAttributeAudio):
                file_type = 3 if attribute.voice else 9
            elif isinstance(attribute, types.DocumentAttributeVideo):
                file_type = 13 if attribute.round_message else 4
            elif isinstance(attribute, types.DocumentAttributeSticker):
                file_type = 8
            elif isinstance(attribute, types.DocumentAttributeAnimated):
                file_type = 10
            else:
                continue
            break

        return _encode_telegram_base64(_rle_encode(struct.pack(
            '<iiqqb', file_type, file.dc_id, file.id, file.access_hash, 2)))

    elif isinstance(file, types.Photo):
        size = next((x for x in reversed(file.sizes) if isinstance(
            x, (types.PhotoSize, types.PhotoCachedSize))), None)

        if not size or not isinstance(size.location, types.FileLocation):
            return None

        size = size.location
        return _encode_telegram_base64(_rle_encode(struct.pack(
            '<iiqqqqib', 2, size.dc_id, file.id, file.access_hash,
            size.volume_id, size.secret, size.local_id, 2
        )))
    else:
        return None


def resolve_invite_link(link):
    """
    Resolves the given invite link. Returns a tuple of
    ``(link creator user id, global chat id, random int)``.

    Note that for broadcast channels, the link creator
    user ID will be zero to protect their identity.
    Normal chats and megagroup channels will have such ID.

    Note that the chat ID may not be accurate for chats
    with a link that were upgraded to megagroup, since
    the link can remain the same, but the chat ID will
    be correct once a new link is generated.
    """
    link_hash, is_link = parse_username(link)
    if not is_link:
        # Perhaps the user passed the link hash directly
        link_hash = link

    try:
        return struct.unpack('>LLQ', _decode_telegram_base64(link_hash))
    except (struct.error, TypeError):
        return None, None, None


def resolve_inline_message_id(inline_msg_id):
    """
    Resolves an inline message ID. Returns a tuple of
    ``(message id, peer, dc id, access hash)``

    The ``peer`` may either be a :tl:`PeerUser` referencing
    the user who sent the message via the bot in a private
    conversation or small group chat, or a :tl:`PeerChannel`
    if the message was sent in a channel.

    The ``access_hash`` does not have any use yet.
    """
    try:
        dc_id, message_id, pid, access_hash = \
            struct.unpack('<iiiq', _decode_telegram_base64(inline_msg_id))
        peer = types.PeerChannel(-pid) if pid < 0 else types.PeerUser(pid)
        return message_id, peer, dc_id, access_hash
    except (struct.error, TypeError):
        return None, None, None, None


def get_appropriated_part_size(file_size):
    """
    Gets the appropriated part size when uploading or downloading files,
    given an initial file size.
    """
    if file_size <= 104857600:  # 100MB
        return 128
    if file_size <= 786432000:  # 750MB
        return 256
    if file_size <= 1572864000:  # 1500MB
        return 512

    raise ValueError('File size too large')