import asyncio
import html
import inspect
import json
import logging as log
import platform
from contextlib import suppress
from datetime import datetime
from enum import Enum
from pathlib import Path
from types import ModuleType
from typing import DefaultDict, Dict, Optional, Set, Tuple, Type, Union
from uuid import uuid4

import nio

from . import __about__, utils
from .html_filter import HTML_FILTER
from .models.items import Account, Event, Member, Room
from .models.model_store import ModelStore


class UploadError(Enum):
    forbidden = "M_FORBIDDEN"
    too_large = "M_TOO_LARGE"
    unknown   = "UNKNOWN"


class MatrixClient(nio.AsyncClient):
    def __init__(self,
                 backend,
                 user:       str,
                 homeserver: str           = "https://matrix.org",
                 device_id:  Optional[str] = None) -> None:

        store = Path(backend.app.appdirs.user_data_dir) / "encryption"
        store.mkdir(parents=True, exist_ok=True)

        # TODO: ensure homeserver starts by a scheme://
        # TODO: pass a ClientConfig with a pickle key
        super().__init__(
            homeserver = homeserver,
            user       = user,
            device_id  = device_id,
            store_path = store,
        )

        from .backend import Backend
        self.backend: Backend    = backend
        self.models:  ModelStore = self.backend.models

        self.sync_task:           Optional[asyncio.Future] = None
        self.first_sync_happened: asyncio.Event            = asyncio.Event()

        self.send_locks: DefaultDict[str, asyncio.Lock] = \
                DefaultDict(asyncio.Lock)  # {room_id: lock}

        self.past_tokens:        Dict[str, str] = {}     # {room_id: token}
        self.fully_loaded_rooms: Set[str]       = set()  # {room_id}
        self.loaded_once_rooms:  Set[str]       = set()  # {room_id}

        self.local_echoes_uuid: Set[str]       = set()
        self.resolved_echoes:   Dict[str, str] = {}  # {event_id: echo_uuid}

        self.skipped_events: DefaultDict[str, int] = DefaultDict(lambda: 0)

        self.connect_callbacks()


    def __repr__(self) -> str:
        return "%s(user_id=%r, homeserver=%r, device_id=%r)" % (
            type(self).__name__, self.user_id, self.homeserver, self.device_id,
        )


    @staticmethod
    def _classes_defined_in(module: ModuleType) -> Dict[str, Type]:
        return {
            m[0]: m[1] for m in inspect.getmembers(module, inspect.isclass)
            if not m[0].startswith("_") and
            m[1].__module__.startswith(module.__name__)
        }


    def connect_callbacks(self) -> None:
        for name, class_ in self._classes_defined_in(nio.responses).items():
            with suppress(AttributeError):
                self.add_response_callback(getattr(self, f"on{name}"), class_)

        for name, class_ in self._classes_defined_in(nio.events).items():
            with suppress(AttributeError):
                self.add_event_callback(getattr(self, f"on{name}"), class_)

        self.add_ephemeral_callback(
            self.onTypingNoticeEvent, nio.events.TypingNoticeEvent,
        )


    @property
    def default_device_name(self) -> str:
        os_ = f" on {platform.system()}".rstrip()
        os_ = f"{os_} {platform.release()}".rstrip() if os_ != " on" else ""
        return f"{__about__.__pretty_name__}{os_}"


    async def login(self, password: str, device_name: str = "") -> None:
        response = await super().login(
            password, device_name or self.default_device_name,
        )

        if isinstance(response, nio.LoginError):
            log.error(response)
        else:
            await self.start()


    async def resume(self, user_id: str, token: str, device_id: str) -> None:
        response = nio.LoginResponse(user_id, device_id, token)
        await self.receive_response(response)
        await self.start()


    async def logout(self) -> None:
        if self.sync_task:
            self.sync_task.cancel()
            with suppress(asyncio.CancelledError):
                await self.sync_task

        await self.close()


    async def start(self) -> None:
        def on_profile_response(future) -> None:
            resp = future.result()
            if isinstance(resp, nio.ProfileGetResponse):
                account                 = self.models[Account][self.user_id]
                account.profile_updated = datetime.now()
                account.display_name    = resp.displayname or ""
                account.avatar_url      = resp.avatar_url or ""

        ft = asyncio.ensure_future(self.backend.get_profile(self.user_id))
        ft.add_done_callback(on_profile_response)

        def on_unexpected_sync_stop(future) -> None:
            raise future.exception()

        self.sync_task = asyncio.ensure_future(
            self.sync_forever(timeout=10_000),
        )
        self.sync_task.add_done_callback(on_unexpected_sync_stop)


    @property
    def all_rooms(self) -> Dict[str, nio.MatrixRoom]:
        return {**self.invited_rooms, **self.rooms}


    async def send_markdown(self, room_id: str, text: str) -> None:
        escape = False
        if text.startswith("//") or text.startswith(r"\/"):
            escape = True
            text   = text[1:]

        if text.startswith("/me ") and not escape:
            event_type = nio.RoomMessageEmote.__name__
            text       = text[len("/me "): ]
            content    = {"body": text, "msgtype": "m.emote"}
            to_html    = HTML_FILTER.from_markdown_inline(text, outgoing=True)
        else:
            event_type = nio.RoomMessageText.__name__
            content    = {"body": text, "msgtype": "m.text"}
            to_html    = HTML_FILTER.from_markdown(text, outgoing=True)

        if to_html not in (html.escape(text), f"<p>{html.escape(text)}</p>"):
            content["format"]         = "org.matrix.custom.html"
            content["formatted_body"] = to_html

        uuid = str(uuid4())
        self.local_echoes_uuid.add(uuid)

        our_info        = self.models[Member, room_id][self.user_id]
        display_content = content.get("formatted_body") or content["body"]

        local = Event(
            client_id      = f"echo-{uuid}",
            event_id       = "",
            event_type     = event_type,
            date           = datetime.now(),
            content        = display_content,
            inline_content = HTML_FILTER.filter_inline(display_content),
            is_local_echo  = True,

            sender_id     = self.user_id,
            sender_name   = our_info.display_name,
            sender_avatar = our_info.avatar_url,
        )
        for user_id in self.models[Account]:
            if user_id in self.models[Member, room_id]:
                self.models[Event, user_id, room_id][f"echo-{uuid}"] = local

        async with self.send_locks[room_id]:
            response = await self.room_send(
                room_id                   = room_id,
                message_type              = "m.room.message",
                content                   = content,
                tx_id                     = uuid,
                ignore_unverified_devices = True,
            )

            if isinstance(response, nio.RoomSendError):
                log.error("Failed to send message: %s", response)


    async def load_past_events(self, room_id: str) -> bool:
        if room_id in self.fully_loaded_rooms or room_id in self.invited_rooms:
            return False

        await self.first_sync_happened.wait()

        response = await self.room_messages(
            room_id = room_id,
            start   = self.past_tokens[room_id],
            limit   = 100 if room_id in self.loaded_once_rooms else 25,
        )

        self.loaded_once_rooms.add(room_id)
        more_to_load = True

        if self.past_tokens[room_id] == response.end:
            self.fully_loaded_rooms.add(room_id)
            more_to_load = False

        self.past_tokens[room_id] = response.end

        for event in response.chunk:
            for cb in self.event_callbacks:
                if (cb.filter is None or isinstance(event, cb.filter)):
                    await cb.func(self.all_rooms[room_id], event)

        return more_to_load


    async def load_rooms_without_visible_events(self) -> None:
        for room_id in self.models[Room, self.user_id]:
            asyncio.ensure_future(
                self._load_room_without_visible_events(room_id),
            )


    async def _load_room_without_visible_events(self, room_id: str) -> None:
        events = self.models[Event, self.user_id, room_id]
        more   = True

        while self.skipped_events[room_id] and not events and more:
            more = await self.load_past_events(room_id)


    async def room_forget(self, room_id: str) -> None:
        await super().room_forget(room_id)
        self.models[Room, self.user_id].pop(room_id, None)
        self.models.pop([Event, self.user_id, room_id], None)
        self.models.pop([Member, room_id], None)


    async def upload_file(self, path: Union[Path, str]) -> str:
        path = Path(path)

        with open(path, "rb") as file:
            mime = utils.guess_mime(file)
            file.seek(0, 0)

            resp = await self.upload(file, mime, path.name)

        if not isinstance(resp, nio.ErrorResponse):
            return resp.content_uri

        if resp.status_code == 403:
            return UploadError.forbidden.value

        if resp.status_code == 413:
            return UploadError.too_large.value

        return UploadError.unknown.value


    async def set_avatar_from_file(self, path: Union[Path, str],
                                  ) -> Union[bool, str]:
        resp = await self.upload_file(path)

        if resp in (i.value for i in UploadError):
            return resp

        await self.set_avatar(resp)
        return True


    # Functions to register data into models

    async def set_room_last_event(self, room_id: str, item: Event) -> None:
        room = self.models[Room, self.user_id][room_id]

        if room.last_event is None:
            room.last_event = item.__dict__
            return

        for_us       = item.target_id in self.backend.clients
        is_member_ev = item.event_type == nio.RoomMemberEvent.__name__

        # If there were no better events available to show previously
        prev_is_member_ev = \
            room.last_event["event_type"] == nio.RoomMemberEvent.__name__

        if is_member_ev and for_us and not prev_is_member_ev:
            return

        if item.date < room.last_event["date"]:  # If this is a past event
            return

        room.last_event = item.__dict__


    async def register_nio_room(self, room: nio.MatrixRoom, left: bool = False,
                               ) -> None:
        # Generate the room name
        name = room.name or room.canonical_alias
        if not name:
            name = room.group_name()
            name = "" if name == "Empty room?" else name

        # Add room
        try:
            last_ev = self.models[Room, self.user_id][room.room_id].last_event
        except KeyError:
            last_ev = None

        self.models[Room, self.user_id][room.room_id] = Room(
            room_id        = room.room_id,
            display_name   = name,
            avatar_url     = room.gen_avatar_url or "",
            topic          = room.topic or "",
            inviter_id     = getattr(room, "inviter", "") or "",
            left           = left,
            filter_string  = " ".join({name, room.topic or ""}).strip(),
            last_event     = last_ev,
        )

        # Add the room members to the added room
        new_dict = {
            user_id: Member(
                user_id       = user_id,
                display_name  = room.user_name(user_id)  # disambiguated
                                if member.display_name else "",
                avatar_url    = member.avatar_url or "",
                typing        = user_id in room.typing_users,
                power_level   = member.power_level,
                filter_string = " ".join({
                    member.name, room.user_name(user_id),
                }).strip(),
            ) for user_id, member in room.users.items()
        }
        self.models[Member, room.room_id].update(new_dict)


    async def get_member_name_avatar(self, room_id: str, user_id: str,
                                    ) -> Tuple[str, str]:
        try:
            item = self.models[Member, room_id][user_id]
        except KeyError:  # e.g. user is not anymore in the room
            info = await self.backend.get_profile(user_id)

            return (info.displayname or "", info.avatar_url or "") \
                   if isinstance(info, nio.ProfileGetResponse) else \
                   ("", "")
        else:
            return (item.display_name, item.avatar_url)


    async def register_nio_event(self,
                                 room:    nio.MatrixRoom,
                                 ev:      nio.Event,
                                 content: str) -> None:

        await self.register_nio_room(room)

        sender_name, sender_avatar = \
            await self.get_member_name_avatar(room.room_id, ev.sender)

        target_id = getattr(ev, "state_key", "") or ""

        target_name, target_avatar = \
            await self.get_member_name_avatar(room.room_id, target_id) \
            if target_id else ("", "")

        # Create Event ModelItem
        item = Event(
            client_id      = ev.event_id,
            event_id       = ev.event_id,
            event_type     = type(ev).__name__,
            content        = content,
            inline_content = HTML_FILTER.filter_inline(content),
            date          = datetime.fromtimestamp(ev.server_timestamp / 1000),

            sender_id     = ev.sender,
            sender_name   = sender_name,
            sender_avatar = sender_avatar,

            target_id     = target_id,
            target_name   = target_name,
            target_avatar = target_avatar,
        )

        # Add the Event to model
        if ev.transaction_id in self.local_echoes_uuid:
            self.resolved_echoes[ev.event_id] = ev.transaction_id
            self.local_echoes_uuid.discard(ev.transaction_id)
            item.client_id = f"echo-{ev.transaction_id}"

        elif ev.sender in self.backend.clients:
            client = self.backend.clients[ev.sender]

            # Wait until our other account has no more pending local echoes,
            # so that we can know if this event should replace an echo
            # from that client by finding its ID in the resolved_echoes dict.
            # Server only gives back the transaction ID to the original sender.
            while client.local_echoes_uuid:  # while there are pending echoes
                await asyncio.sleep(0.1)

            with suppress(KeyError):
                item.client_id = f"echo-{client.resolved_echoes[ev.event_id]}"

        self.models[Event, self.user_id, room.room_id][item.client_id] = item

        await self.set_room_last_event(room.room_id, item)


    # Callbacks for nio responses

    async def onSyncResponse(self, resp: nio.SyncResponse) -> None:
        for room_id, info in resp.rooms.join.items():
            if room_id not in self.past_tokens:
                self.past_tokens[room_id] = info.timeline.prev_batch

        # TODO: way of knowing if a nio.MatrixRoom is left
        for room_id, info in resp.rooms.leave.items():
            # TODO: handle in nio, these are rooms that were left before
            # starting the client.
            if room_id not in self.rooms:
                continue

            # TODO: handle left events in nio async client
            for ev in info.timeline.events:
                if isinstance(ev, nio.RoomMemberEvent):
                    await self.onRoomMemberEvent(self.rooms[room_id], ev)

            await self.register_nio_room(self.rooms[room_id], left=True)

        if not self.first_sync_happened.is_set():
            asyncio.ensure_future(self.load_rooms_without_visible_events())

        self.first_sync_happened.set()


    async def onErrorResponse(self, resp: nio.ErrorResponse) -> None:
        # TODO: show something in the client
        try:
            log.warning("%s - %s", resp, json.dumps(resp.__dict__, indent=4))
        except Exception:
            log.warning(repr(resp))


    # Callbacks for nio room events
    # Content: %1 is the sender, %2 the target (ev.state_key).

    async def onRoomMessageText(self, room, ev) -> None:
        co = HTML_FILTER.filter(
            ev.formatted_body
            if ev.format == "org.matrix.custom.html" else html.escape(ev.body),
        )
        await self.register_nio_event(room, ev, content=co)


    async def onRoomMessageEmote(self, room, ev) -> None:
        co = HTML_FILTER.filter_inline(
            ev.formatted_body
            if ev.format == "org.matrix.custom.html" else html.escape(ev.body),
        )
        await self.register_nio_event(room, ev, content=co)


    async def onRoomCreateEvent(self, room, ev) -> None:
        co = "%1 allowed users on other matrix servers to join this room." \
             if ev.federate else \
             "%1 blocked users on other matrix servers from joining this room."
        await self.register_nio_event(room, ev, content=co)


    async def onRoomGuestAccessEvent(self, room, ev) -> None:
        allowed = "allowed" if ev.guest_access else "forbad"
        co      = f"%1 {allowed} guests to join the room."
        await self.register_nio_event(room, ev, content=co)


    async def onRoomJoinRulesEvent(self, room, ev) -> None:
        access = "public" if ev.join_rule == "public" else "invite-only"
        co     = f"%1 made the room {access}."
        await self.register_nio_event(room, ev, content=co)


    async def onRoomHistoryVisibilityEvent(self, room, ev) -> None:
        if ev.history_visibility == "shared":
            to = "all room members"
        elif ev.history_visibility == "world_readable":
            to = "any member or outsider"
        elif ev.history_visibility == "joined":
            to = "all room members, since the time they joined"
        elif ev.history_visibility == "invited":
            to = "all room members, since the time they were invited"
        else:
            to = "???"
            log.warning("Invalid visibility - %s",
                        json.dumps(ev.__dict__, indent=4))

        co = f"%1 made future room history visible to {to}."
        await self.register_nio_event(room, ev, content=co)


    async def onPowerLevelsEvent(self, room, ev) -> None:
        co = "%1 changed the room's permissions."  # TODO: improve
        await self.register_nio_event(room, ev, content=co)


    async def process_room_member_event(self, room, ev) -> Optional[str]:
        prev            = ev.prev_content
        now             = ev.content
        membership      = ev.membership
        prev_membership = ev.prev_membership
        ev_date         = datetime.fromtimestamp(ev.server_timestamp / 1000)

        # Membership changes
        if not prev or membership != prev_membership:
            reason = f" Reason: {now['reason']}" if now.get("reason") else ""

            if membership == "join":
                return (
                    "%1 accepted their invitation."
                    if prev and prev_membership == "invite" else
                    "%1 joined the room."
                )

            if membership == "invite":
                return "%1 invited %2 to the room."

            if membership == "leave":
                if ev.state_key == ev.sender:
                    return (
                        f"%1 declined their invitation.{reason}"
                        if prev and prev_membership == "invite" else
                        f"%1 left the room.{reason}"
                    )

                return (
                    f"%1 withdrew %2's invitation.{reason}"
                    if prev and prev_membership == "invite" else

                    f"%1 unbanned %2 from the room.{reason}"
                    if prev and prev_membership == "ban" else

                    f"%1 kicked out %2 from the room.{reason}"
                )

            if membership == "ban":
                return f"%1 banned %2 from the room.{reason}"

        # Profile changes
        changed = []

        if prev and now["avatar_url"] != prev["avatar_url"]:
            changed.append("profile picture")  # TODO: <img>s

        if prev and now["displayname"] != prev["displayname"]:
            changed.append('display name from "{}" to "{}"'.format(
                prev["displayname"] or ev.state_key,
                now["displayname"] or ev.state_key,
            ))

        if changed:
            # Update our account profile if the event is newer than last update
            if ev.state_key == self.user_id:
                account = self.models[Account][self.user_id]

                if account.profile_updated < ev_date:
                    account.profile_updated = ev_date
                    account.display_name    = now["displayname"] or ""
                    account.avatar_url      = now["avatar_url"] or ""

            if ev.state_key in self.backend.clients or len(room.users) > 50:
                self.skipped_events[room.room_id] += 1
                return None

            return "%1 changed their {}.".format(" and ".join(changed))

        log.warning("Invalid member event - %s",
                    json.dumps(ev.__dict__, indent=4))
        return None


    async def onRoomMemberEvent(self, room, ev) -> None:
        co = await self.process_room_member_event(room, ev)

        if co is None:
            # This is run from register_nio_event otherwise
            await self.register_nio_room(room)
        else:
            await self.register_nio_event(room, ev, content=co)


    async def onRoomAliasEvent(self, room, ev) -> None:
        co = f"%1 set the room's main address to {ev.canonical_alias}."
        await self.register_nio_event(room, ev, content=co)


    async def onRoomNameEvent(self, room, ev) -> None:
        co = f"%1 changed the room's name to \"{ev.name}\"."
        await self.register_nio_event(room, ev, content=co)


    async def onRoomTopicEvent(self, room, ev) -> None:
        co = f"%1 changed the room's topic to \"{ev.topic}\"."
        await self.register_nio_event(room, ev, content=co)


    async def onRoomEncryptionEvent(self, room, ev) -> None:
        co = "%1 turned on encryption for this room."
        await self.register_nio_event(room, ev, content=co)


    async def onOlmEvent(self, room, ev) -> None:
        co = "%1 sent an undecryptable olm message."
        await self.register_nio_event(room, ev, content=co)


    async def onMegolmEvent(self, room, ev) -> None:
        co = "%1 sent an undecryptable message."
        await self.register_nio_event(room, ev, content=co)


    async def onBadEvent(self, room, ev) -> None:
        co = "%1 sent a malformed event."
        await self.register_nio_event(room, ev, content=co)


    async def onUnknownBadEvent(self, room, ev) -> None:
        co = "%1 sent an event this client doesn't understand."
        await self.register_nio_event(room, ev, content=co)


    # Callbacks for nio invite events

    async def onInviteEvent(self, room, ev) -> None:
        await self.register_nio_room(room)


    # Callbacks for nio ephemeral events

    async def onTypingNoticeEvent(self, room, ev) -> None:
        # Prevent recent past typing notices from being shown for a split
        # second on client startup:
        if not self.first_sync_happened.is_set():
            return

        self.models[Room, self.user_id][room.room_id].typing_members = sorted(
            room.user_name(user_id) for user_id in ev.users
            if user_id not in self.backend.clients
        )