import itertools
import string

from .users import UserMethods
from .. import utils
from ..requestiter import RequestIter
from ..tl import types, functions, custom

_MAX_PARTICIPANTS_CHUNK_SIZE = 200
_MAX_ADMIN_LOG_CHUNK_SIZE = 100


class _ParticipantsIter(RequestIter):
    async def _init(self, entity, filter, search, aggressive):
        if isinstance(filter, type):
            if filter in (types.ChannelParticipantsBanned,
                          types.ChannelParticipantsKicked,
                          types.ChannelParticipantsSearch,
                          types.ChannelParticipantsContacts):
                # These require a `q` parameter (support types for convenience)
                filter = filter('')
            else:
                filter = filter()

        entity = await self.client.get_input_entity(entity)
        if search and (filter
                       or not isinstance(entity, types.InputPeerChannel)):
            # We need to 'search' ourselves unless we have a PeerChannel
            search = search.lower()

            self.filter_entity = lambda ent: (
                search in utils.get_display_name(ent).lower() or
                search in (getattr(ent, 'username', '') or None).lower()
            )
        else:
            self.filter_entity = lambda ent: True

        if isinstance(entity, types.InputPeerChannel):
            self.total = (await self.client(
                functions.channels.GetFullChannelRequest(entity)
            )).full_chat.participants_count

            if self.limit <= 0:
                raise StopAsyncIteration

            self.seen = set()
            if aggressive and not filter:
                self.requests = [functions.channels.GetParticipantsRequest(
                    channel=entity,
                    filter=types.ChannelParticipantsSearch(x),
                    offset=0,
                    limit=_MAX_PARTICIPANTS_CHUNK_SIZE,
                    hash=0
                ) for x in (search or string.ascii_lowercase)]
            else:
                self.requests = [functions.channels.GetParticipantsRequest(
                    channel=entity,
                    filter=filter or types.ChannelParticipantsSearch(search),
                    offset=0,
                    limit=_MAX_PARTICIPANTS_CHUNK_SIZE,
                    hash=0
                )]

        elif isinstance(entity, types.InputPeerChat):
            full = await self.client(
                functions.messages.GetFullChatRequest(entity.chat_id))
            if not isinstance(
                    full.full_chat.participants, types.ChatParticipants):
                # ChatParticipantsForbidden won't have ``.participants``
                self.total = 0
                raise StopAsyncIteration

            self.total = len(full.full_chat.participants.participants)

            users = {user.id: user for user in full.users}
            for participant in full.full_chat.participants.participants:
                user = users[participant.user_id]
                if not self.filter_entity(user):
                    continue

                user = users[participant.user_id]
                user.participant = participant
                self.buffer.append(user)

            return True
        else:
            self.total = 1
            if self.limit != 0:
                user = await self.client.get_entity(entity)
                if self.filter_entity(user):
                    user.participant = None
                    self.buffer.append(user)

            return True

    async def _load_next_chunk(self):
        if not self.requests:
            return True

        # Only care about the limit for the first request
        # (small amount of people, won't be aggressive).
        #
        # Most people won't care about getting exactly 12,345
        # members so it doesn't really matter not to be 100%
        # precise with being out of the offset/limit here.
        self.requests[0].limit = min(
            self.limit - self.requests[0].offset, _MAX_PARTICIPANTS_CHUNK_SIZE)

        if self.requests[0].offset > self.limit:
            return True

        results = await self.client(self.requests)
        for i in reversed(range(len(self.requests))):
            participants = results[i]
            if not participants.users:
                self.requests.pop(i)
                continue

            self.requests[i].offset += len(participants.participants)
            users = {user.id: user for user in participants.users}
            for participant in participants.participants:
                user = users[participant.user_id]
                if not self.filter_entity(user) or user.id in self.seen:
                    continue

                self.seen.add(participant.user_id)
                user = users[participant.user_id]
                user.participant = participant
                self.buffer.append(user)


class _AdminLogIter(RequestIter):
    async def _init(
            self, entity, admins, search, min_id, max_id,
            join, leave, invite, restrict, unrestrict, ban, unban,
            promote, demote, info, settings, pinned, edit, delete
    ):
        if any((join, leave, invite, restrict, unrestrict, ban, unban,
                promote, demote, info, settings, pinned, edit, delete)):
            events_filter = types.ChannelAdminLogEventsFilter(
                join=join, leave=leave, invite=invite, ban=restrict,
                unban=unrestrict, kick=ban, unkick=unban, promote=promote,
                demote=demote, info=info, settings=settings, pinned=pinned,
                edit=edit, delete=delete
            )
        else:
            events_filter = None

        self.entity = await self.client.get_input_entity(entity)

        admin_list = []
        if admins:
            if not utils.is_list_like(admins):
                admins = (admins,)

            for admin in admins:
                admin_list.append(await self.client.get_input_entity(admin))

        self.request = functions.channels.GetAdminLogRequest(
            self.entity, q=search or '', min_id=min_id, max_id=max_id,
            limit=0, events_filter=events_filter, admins=admin_list or None
        )

    async def _load_next_chunk(self):
        self.request.limit = min(self.left, _MAX_ADMIN_LOG_CHUNK_SIZE)
        r = await self.client(self.request)
        entities = {utils.get_peer_id(x): x
                    for x in itertools.chain(r.users, r.chats)}

        self.request.max_id = min((e.id for e in r.events), default=0)
        for ev in r.events:
            if isinstance(ev.action,
                          types.ChannelAdminLogEventActionEditMessage):
                ev.action.prev_message._finish_init(
                    self.client, entities, self.entity)

                ev.action.new_message._finish_init(
                    self.client, entities, self.entity)

            elif isinstance(ev.action,
                            types.ChannelAdminLogEventActionDeleteMessage):
                ev.action.message._finish_init(
                    self.client, entities, self.entity)

            self.buffer.append(custom.AdminLogEvent(ev, entities))

        if len(r.events) < self.request.limit:
            return True


class ChatMethods(UserMethods):

    # region Public methods

    def iter_participants(
            self, entity, limit=None, *, search='',
            filter=None, aggressive=False
    ):
        """
        Iterator over the participants belonging to the specified chat.

        Args:
            entity (`entity`):
                The entity from which to retrieve the participants list.

            limit (`int`):
                Limits amount of participants fetched.

            search (`str`, optional):
                Look for participants with this string in name/username.

                If ``aggressive is True``, the symbols from this string will
                be used.

            filter (:tl:`ChannelParticipantsFilter`, optional):
                The filter to be used, if you want e.g. only admins
                Note that you might not have permissions for some filter.
                This has no effect for normal chats or users.

                .. note::

                    The filter :tl:`ChannelParticipantsBanned` will return
                    *restricted* users. If you want *banned* users you should
                    use :tl:`ChannelParticipantsKicked` instead.

            aggressive (`bool`, optional):
                Aggressively looks for all participants in the chat.

                This is useful for channels since 20 July 2018,
                Telegram added a server-side limit where only the
                first 200 members can be retrieved. With this flag
                set, more than 200 will be often be retrieved.

                This has no effect if a ``filter`` is given.

        Yields:
            The :tl:`User` objects returned by :tl:`GetParticipantsRequest`
            with an additional ``.participant`` attribute which is the
            matched :tl:`ChannelParticipant` type for channels/megagroups
            or :tl:`ChatParticipants` for normal chats.
        """
        return _ParticipantsIter(
            self,
            limit,
            entity=entity,
            filter=filter,
            search=search,
            aggressive=aggressive
        )

    async def get_participants(self, *args, **kwargs):
        """
        Same as `iter_participants`, but returns a
        `TotalList <telethon.helpers.TotalList>` instead.
        """
        return await self.iter_participants(*args, **kwargs).collect()

    def iter_admin_log(
            self, entity, limit=None, *, max_id=0, min_id=0, search=None,
            admins=None, join=None, leave=None, invite=None, restrict=None,
            unrestrict=None, ban=None, unban=None, promote=None, demote=None,
            info=None, settings=None, pinned=None, edit=None, delete=None):
        """
        Iterator over the admin log for the specified channel.

        Note that you must be an administrator of it to use this method.

        If none of the filters are present (i.e. they all are ``None``),
        *all* event types will be returned. If at least one of them is
        ``True``, only those that are true will be returned.

        Args:
            entity (`entity`):
                The channel entity from which to get its admin log.

            limit (`int` | `None`, optional):
                Number of events to be retrieved.

                The limit may also be ``None``, which would eventually return
                the whole history.

            max_id (`int`):
                All the events with a higher (newer) ID or equal to this will
                be excluded.

            min_id (`int`):
                All the events with a lower (older) ID or equal to this will
                be excluded.

            search (`str`):
                The string to be used as a search query.

            admins (`entity` | `list`):
                If present, the events will be filtered by these admins
                (or single admin) and only those caused by them will be
                returned.

            join (`bool`):
                If ``True``, events for when a user joined will be returned.

            leave (`bool`):
                If ``True``, events for when a user leaves will be returned.

            invite (`bool`):
                If ``True``, events for when a user joins through an invite
                link will be returned.

            restrict (`bool`):
                If ``True``, events with partial restrictions will be
                returned. This is what the API calls "ban".

            unrestrict (`bool`):
                If ``True``, events removing restrictions will be returned.
                This is what the API calls "unban".

            ban (`bool`):
                If ``True``, events applying or removing all restrictions will
                be returned. This is what the API calls "kick" (restricting
                all permissions removed is a ban, which kicks the user).

            unban (`bool`):
                If ``True``, events removing all restrictions will be
                returned. This is what the API calls "unkick".

            promote (`bool`):
                If ``True``, events with admin promotions will be returned.

            demote (`bool`):
                If ``True``, events with admin demotions will be returned.

            info (`bool`):
                If ``True``, events changing the group info will be returned.

            settings (`bool`):
                If ``True``, events changing the group settings will be
                returned.

            pinned (`bool`):
                If ``True``, events of new pinned messages will be returned.

            edit (`bool`):
                If ``True``, events of message edits will be returned.

            delete (`bool`):
                If ``True``, events of message deletions will be returned.

        Yields:
            Instances of `telethon.tl.custom.adminlogevent.AdminLogEvent`.
        """
        return _AdminLogIter(
            self,
            limit,
            entity=entity,
            admins=admins,
            search=search,
            min_id=min_id,
            max_id=max_id,
            join=join,
            leave=leave,
            invite=invite,
            restrict=restrict,
            unrestrict=unrestrict,
            ban=ban,
            unban=unban,
            promote=promote,
            demote=demote,
            info=info,
            settings=settings,
            pinned=pinned,
            edit=edit,
            delete=delete
        )

    async def get_admin_log(self, *args, **kwargs):
        """
        Same as `iter_admin_log`, but returns a ``list`` instead.
        """
        return await self.iter_admin_log(*args, **kwargs).collect()

    # endregion
