import asyncio
import json
import logging
import os
import re
import sys
import threading
from typing import Dict, List, Tuple

import markdown
import urllib3

import discord
import matrix
from appservice import AppService
from cache import Cache
from db import DataBase
from errors import RequestError
from gateway import Gateway
from misc import dict_cls, except_deleted, hash_str


class MatrixClient(AppService):
    def __init__(self, config: dict, http: urllib3.PoolManager) -> None:
        super().__init__(config, http)

        self.db = DataBase(config["database"])
        self.discord = DiscordClient(self, config, http)
        self.format = "_discord_"  # "{@,#}_discord_1234:localhost"

        # TODO Find a cleaner way to use these keys.
        for k in ("m_emotes", "m_members", "m_messages"):
            Cache.cache[k] = {}

    def handle_bridge(self, message: matrix.Event) -> None:
        # Ignore events that aren't for us.
        if message.sender.split(":")[
            -1
        ] != self.server_name or not message.body.startswith("!bridge"):
            return

        # Get the channel ID.
        try:
            channel = message.body.split()[1]
        except IndexError:
            return

        # Check if the given channel is valid.
        try:
            channel = self.discord.get_channel(channel)
        except RequestError as e:
            # The channel can be invalid or we may not have permissions.
            self.logger.warning(f"Failed to fetch channel {channel}: {e}")
            return

        if (
            channel.type != discord.ChannelType.GUILD_TEXT
            or channel.id in self.db.list_channels()
        ):
            return

        self.logger.info(f"Creating bridged room for channel {channel.id}.")

        self.create_room(channel, message.sender)

    def on_member(self, event: matrix.Event) -> None:
        with Cache.lock:
            # Just lazily clear the whole member cache on
            # membership update events.
            if event.room_id in Cache.cache["m_members"]:
                self.logger.info(
                    f"Clearing member cache for room '{event.room_id}'."
                )
                del Cache.cache["m_members"][event.room_id]

        if (
            event.sender.split(":")[-1] != self.server_name
            or event.state_key != self.user_id
            or not event.is_direct
        ):
            return

        # Join the direct message room.
        self.logger.info(f"Joining direct message room '{event.room_id}'.")
        self.join_room(event.room_id)

    def on_message(self, message: matrix.Event) -> None:
        if (
            message.sender.startswith((f"@{self.format}", self.user_id))
            or not message.body
        ):
            return

        # Handle bridging commands.
        self.handle_bridge(message)

        channel_id = self.db.get_channel(message.room_id)

        if not channel_id:
            return

        author = self.get_members(message.room_id)[message.sender]

        webhook = self.discord.get_webhook(
            channel_id, self.discord.webhook_name
        )

        if message.relates_to and message.reltype == "m.replace":
            with Cache.lock:
                message_id = Cache.cache["m_messages"].get(message.relates_to)

            # TODO validate if the original author sent the edit.

            if not message_id or not message.new_body:
                return

            message.new_body = self.process_message(message)

            except_deleted(self.discord.edit_webhook)(
                message.new_body, message_id, webhook
            )
        else:
            message.body = (
                f"`{message.body}`: {self.mxc_url(message.attachment)}"
                if message.attachment
                else self.process_message(message)
            )

            message_id = self.discord.send_webhook(
                webhook,
                self.mxc_url(author.avatar_url) if author.avatar_url else None,
                message.body,
                author.display_name if author.display_name else message.sender,
            ).id

            with Cache.lock:
                Cache.cache["m_messages"][message.id] = message_id

    def on_redaction(self, event: matrix.Event) -> None:
        with Cache.lock:
            message_id = Cache.cache["m_messages"].get(event.redacts)

        if not message_id:
            return

        webhook = self.discord.get_webhook(
            self.db.get_channel(event.room_id), self.discord.webhook_name
        )

        except_deleted(self.discord.delete_webhook)(message_id, webhook)

        with Cache.lock:
            del Cache.cache["m_messages"][event.redacts]

    def get_members(self, room_id: str) -> Dict[str, matrix.User]:
        with Cache.lock:
            cached = Cache.cache["m_members"].get(room_id)

        if cached:
            return cached

        resp = self.send("GET", f"/rooms/{room_id}/joined_members")

        joined = resp["joined"]

        for k, v in joined.items():
            joined[k] = dict_cls(v, matrix.User)

        with Cache.lock:
            Cache.cache["m_members"][room_id] = joined

        return joined

    def create_room(self, channel: discord.Channel, sender: str) -> None:
        """
        Create a bridged room and invite the person who invoked the command.
        """

        content = {
            "room_alias_name": f"{self.format}{channel.id}",
            "name": channel.name,
            "topic": channel.topic if channel.topic else channel.name,
            "visibility": "private",
            "invite": [sender],
            "creation_content": {"m.federate": True},
            "initial_state": [
                {
                    "type": "m.room.join_rules",
                    "content": {"join_rule": "public"},
                },
                {
                    "type": "m.room.history_visibility",
                    "content": {"history_visibility": "shared"},
                },
            ],
            "power_level_content_override": {
                "users": {sender: 100, self.user_id: 100}
            },
        }

        resp = self.send("POST", "/createRoom", content)

        self.db.add_room(resp["room_id"], channel.id)

    def create_message_event(
        self,
        message: str,
        emotes: dict,
        edit: str = "",
        reference: discord.Message = None,
    ) -> dict:
        content = {
            "body": message,
            "msgtype": "m.text",
        }

        fmt = self.get_fmt(message, emotes)

        if len(fmt) != len(message):
            content = {
                **content,
                "format": "org.matrix.custom.html",
                "formatted_body": fmt,
            }

        ref_id = None

        if reference:
            # Reply to a Discord message.
            with Cache.lock:
                ref_id = Cache.cache["d_messages"].get(reference.id)

            # Reply to a Matrix message. (maybe)
            if not ref_id:
                with Cache.lock:
                    ref_id = [
                        k
                        for k, v in Cache.cache["m_messages"].items()
                        if v == reference.id
                    ]
                    ref_id = next(iter(ref_id), "")

        if ref_id:
            event = except_deleted(self.get_event)(
                ref_id,
                self.get_room_id(self.discord.matrixify(reference.channel_id)),
            )
            if event:
                # Content with the reply fallbacks stripped.
                tmp = ""
                # We don't want to strip lines starting with "> " after
                # encountering a regular line, so we use this variable.
                got_fallback = True
                for line in event.body.split("\n"):
                    if not line.startswith("> "):
                        got_fallback = False
                    if not got_fallback:
                        tmp += line

                event.body = tmp
                event.formatted_body = (
                    re.sub("<mx-reply>.*</mx-reply>", "", event.formatted_body)
                    if event.formatted_body
                    else event.body
                )

                content = {
                    **content,
                    "body": (
                        f"> <{event.sender}> {event.body}\n{content['body']}"
                    ),
                    "m.relates_to": {"m.in_reply_to": {"event_id": event.id}},
                    "formatted_body": f"""<mx-reply><blockquote>\
<a href="https://matrix.to/#/{event.room_id}/{event.id}">\
In reply to</a><a href="https://matrix.to/#/{event.sender}">\
{event.sender}</a><br>\
{event.formatted_body if event.formatted_body else event.body}\
</blockquote></mx-reply>\
{content.get("formatted_body", content['body'])}""",
                }

        if edit:
            content = {
                **content,
                "body": f" * {content['body']}",
                "formatted_body": f" * {content.get('formatted_body', content['body'])}",
                "m.relates_to": {"event_id": edit, "rel_type": "m.replace"},
                "m.new_content": {**content},
            }

        return content

    def get_fmt(self, message: str, emotes: dict) -> str:
        message = (
            markdown.markdown(message).replace("<p>", "").replace("</p>", "")
        )

        # Upload emotes in multiple threads so that we don't
        # block the Discord bot for too long.
        upload_threads = [
            threading.Thread(
                target=self.upload_emote, args=(emote, emotes[emote])
            )
            for emote in emotes
        ]

        # Acquire the lock before starting the threads to avoid resource
        # contention by tens of threads at once.
        with Cache.lock:
            for thread in upload_threads:
                thread.start()
            for thread in upload_threads:
                thread.join()

        with Cache.lock:
            for emote in emotes:
                emote_ = Cache.cache["m_emotes"].get(emote)

                if emote_:
                    emote = f":{emote}:"
                    message = message.replace(
                        emote,
                        f"""<img alt=\"{emote}\" title=\"{emote}\" \
height=\"32\" src=\"{emote_}\" data-mx-emoticon />""",
                    )

        return message

    def process_message(self, event: matrix.Event) -> str:
        message = event.new_body if event.new_body else event.body

        id_regex = f"[0-9]{{{discord.ID_LEN}}}"

        emotes = re.findall(r":(\w*):", message)
        mentions = re.findall(
            f"@{self.format}{id_regex}:{re.escape(self.server_name)}",
            event.formatted_body,
        )

        with Cache.lock:
            for emote in set(emotes):
                emote_ = Cache.cache["d_emotes"].get(emote)
                if emote_:
                    message = message.replace(f":{emote}:", emote_)

        for mention in set(mentions):
            username = self.db.fetch_user(mention).get("username")
            if username:
                match = re.search(id_regex, mention)

                if match:
                    # Replace the 'mention' so that the user is tagged
                    # in the case of replies aswell.
                    # '> <@_discord_1234:localhost> Message'
                    for replace in (mention, username):
                        message = message.replace(
                            replace, f"<@{match.group()}>"
                        )

        # We trim the message later as emotes take up extra characters too.
        return message[: discord.MESSAGE_LIMIT]

    def upload_emote(self, emote_name: str, emote_id: str) -> None:
        # There won't be a race condition here, since only a unique
        # set of emotes are uploaded at a time.
        if emote_name in Cache.cache["m_emotes"]:
            return

        emote_url = f"{discord.CDN_URL}/emojis/{emote_id}"

        # We don't want the message to be dropped entirely if an emote
        # fails to upload for some reason.
        try:
            # TODO This is not thread safe, but we're protected by the GIL.
            Cache.cache["m_emotes"][emote_name] = self.upload(emote_url)
        except RequestError as e:
            self.logger.warning(f"Failed to upload emote {emote_id}: {e}")

    def register(self, mxid: str) -> None:
        """
        Register a dummy user on the homeserver.
        """

        content = {
            "type": "m.login.application_service",
            # "@test:localhost" -> "test" (Can't register with a full mxid.)
            "username": mxid[1:].split(":")[0],
        }

        resp = self.send("POST", "/register", content)

        self.db.add_user(resp["user_id"])

    def set_avatar(self, avatar_url: str, mxid: str) -> None:
        avatar_uri = self.upload(avatar_url)

        self.send(
            "PUT",
            f"/profile/{mxid}/avatar_url",
            {"avatar_url": avatar_uri},
            params={"user_id": mxid},
        )

        self.db.add_avatar(avatar_url, mxid)

    def set_nick(self, username: str, mxid: str) -> None:
        self.send(
            "PUT",
            f"/profile/{mxid}/displayname",
            {"displayname": username},
            params={"user_id": mxid},
        )

        self.db.add_username(username, mxid)


class DiscordClient(Gateway):
    def __init__(
        self, appservice: MatrixClient, config: dict, http: urllib3.PoolManager
    ) -> None:
        super().__init__(http, config["discord_token"])

        self.app = appservice
        self.webhook_name = "matrix_bridge"

        # TODO Find a cleaner way to use these keys.
        for k in ("d_emotes", "d_messages", "d_webhooks"):
            Cache.cache[k] = {}

    def to_return(self, message: discord.Message) -> bool:
        with Cache.lock:
            hook_ids = [hook.id for hook in Cache.cache["d_webhooks"].values()]

        return (
            message.channel_id not in self.app.db.list_channels()
            or not message.author  # Embeds can be weird sometimes.
            or message.webhook_id in hook_ids
        )

    def matrixify(self, id: str, user: bool = False) -> str:
        return (
            f"{'@' if user else '#'}{self.app.format}{id}:"
            f"{self.app.server_name}"
        )

    def sync_profile(self, user: discord.User) -> None:
        """
        Sync the avatar and username for a puppeted user.
        """

        mxid = self.matrixify(user.id, user=True)

        profile = self.app.db.fetch_user(mxid)

        # User doesn't exist.
        if not profile:
            return

        username = f"{user.username}#{user.discriminator}"

        if user.avatar_url != profile["avatar_url"]:
            self.logger.info(f"Updating avatar for Discord user '{user.id}'")
            self.app.set_avatar(user.avatar_url, mxid)
        if username != profile["username"]:
            self.logger.info(f"Updating username for Discord user '{user.id}'")
            self.app.set_nick(username, mxid)

    def wrap(self, message: discord.Message) -> Tuple[str, str]:
        """
        Get the room ID and the puppet's mxid for a given channel ID and a
        Discord user.
        """

        if message.webhook_id:
            hashed = hash_str(message.author.username)
            message.author.id = str(int(message.author.id) + hashed)

        mxid = self.matrixify(message.author.id, user=True)
        room_id = self.app.get_room_id(self.matrixify(message.channel_id))

        if not self.app.db.fetch_user(mxid):
            self.logger.info(
                f"Creating dummy user for Discord user {message.author.id}."
            )
            self.app.register(mxid)

            self.app.set_nick(
                f"{message.author.username}#"
                f"{message.author.discriminator}",
                mxid,
            )

            if message.author.avatar_url:
                self.app.set_avatar(message.author.avatar_url, mxid)

        if mxid not in self.app.get_members(room_id):
            self.logger.info(f"Inviting user '{mxid}' to room '{room_id}'.")

            self.app.send_invite(room_id, mxid)
            self.app.join_room(room_id, mxid)

        if message.webhook_id:
            # Sync webhooks here as they can't be accessed like guild members.
            self.sync_profile(message.author)

        return mxid, room_id

    def cache_emotes(self, emotes: List[discord.Emote]):
        # TODO maybe "namespace" emotes by guild in the cache ?
        with Cache.lock:
            for emote in emotes:
                Cache.cache["d_emotes"][emote.name] = (
                    f"<{'a' if emote.animated else ''}:"
                    f"{emote.name}:{emote.id}>"
                )

    def on_guild_create(self, guild: discord.Guild) -> None:
        for member in guild.members:
            self.sync_profile(member)

        self.cache_emotes(guild.emojis)

    def on_guild_emojis_update(
        self, update: discord.GuildEmojisUpdate
    ) -> None:
        self.cache_emotes(update.emojis)

    def on_guild_member_update(
        self, update: discord.GuildMemberUpdate
    ) -> None:
        self.sync_profile(update.user)

    def on_message_create(self, message: discord.Message) -> None:
        if self.to_return(message):
            return

        mxid, room_id = self.wrap(message)

        content_, emotes = self.process_message(message)

        content = self.app.create_message_event(
            content_, emotes, reference=message.referenced_message
        )

        with Cache.lock:
            Cache.cache["d_messages"][message.id] = self.app.send_message(
                room_id, content, mxid
            )

    def on_message_delete(self, message: discord.Message) -> None:
        with Cache.lock:
            event_id = Cache.cache["d_messages"].get(message.id)

        if not event_id:
            return

        room_id = self.app.get_room_id(self.matrixify(message.channel_id))
        event = except_deleted(self.app.get_event)(event_id, room_id)

        if event:
            self.app.redact(event.id, event.room_id, event.sender)

        with Cache.lock:
            del Cache.cache["d_messages"][message.id]

    def on_message_update(self, message: discord.Message) -> None:
        if self.to_return(message):
            return

        with Cache.lock:
            event_id = Cache.cache["d_messages"].get(message.id)

        if not event_id:
            return

        room_id = self.app.get_room_id(self.matrixify(message.channel_id))
        mxid = self.matrixify(message.author.id, user=True)

        # It is possible that a webhook edit's it's own old message
        # after changing it's name, hence we generate a new mxid from
        # the hashed username, but that mxid hasn't been registered before,
        # so the request fails with:
        # M_FORBIDDEN: Application service has not registered this user
        if not self.app.db.fetch_user(mxid):
            return

        content_, emotes = self.process_message(message)

        content = self.app.create_message_event(
            content_, emotes, edit=event_id
        )

        self.app.send_message(room_id, content, mxid)

    def on_typing_start(self, typing: discord.Typing) -> None:
        if typing.channel_id not in self.app.db.list_channels():
            return

        mxid = self.matrixify(typing.user_id, user=True)
        room_id = self.app.get_room_id(self.matrixify(typing.channel_id))

        if mxid not in self.app.get_members(room_id):
            return

        self.app.send_typing(room_id, mxid)

    def get_webhook(self, channel_id: str, name: str) -> discord.Webhook:
        """
        Get the webhook object for the first webhook that matches the specified
        name in a given channel, create the webhook if it doesn't exist.
        """

        # Check the cache first.
        with Cache.lock:
            webhook = Cache.cache["d_webhooks"].get(channel_id)

        if webhook:
            return webhook

        webhooks = self.send("GET", f"/channels/{channel_id}/webhooks")
        webhook = next(
            (
                dict_cls(webhook, discord.Webhook)
                for webhook in webhooks
                if webhook["name"] == name
            ),
            None,
        )

        if not webhook:
            webhook = self.create_webhook(channel_id, name)

        with Cache.lock:
            Cache.cache["d_webhooks"][channel_id] = webhook

        return webhook

    def process_message(self, message: discord.Message) -> Tuple[str, Dict]:
        content = message.content
        emotes = {}
        regex = r"<a?:(\w+):(\d+)>"

        # Mentions can either be in the form of `<@1234>` or `<@!1234>`.
        for member in message.mentions:
            for char in ("", "!"):
                content = content.replace(
                    f"<@{char}{member.id}>", f"@{member.username}"
                )

        # `except_deleted` for invalid channels.
        # TODO can this block for too long ?
        for channel in re.findall(f"<#([0-9]{{{discord.ID_LEN}}})>", content):
            discord_channel = except_deleted(self.get_channel)(channel)
            name = (
                discord_channel.name if discord_channel else "deleted-channel"
            )
            content = content.replace(f"<#{channel}>", f"#{name}")

        # { "emote_name": "emote_id" }
        for emote in re.findall(regex, content):
            emotes[emote[0]] = emote[1]

        # Replace emote IDs with names.
        content = re.sub(regex, r":\g<1>:", content)

        # Append attachments to message.
        for attachment in message.attachments:
            content += f"\n{attachment['url']}"

        # Append stickers to message.
        for sticker in message.stickers:
            if sticker.format_type != 3:  # 3 == Lottie format.
                content += f"\n{discord.CDN_URL}/stickers/{sticker.id}.png"

        return content, emotes


def config_gen(basedir: str, config_file: str) -> dict:
    config_file = f"{basedir}/{config_file}"

    config_dict = {
        "as_token": "my-secret-as-token",
        "hs_token": "my-secret-hs-token",
        "user_id": "appservice-discord",
        "homeserver": "http://127.0.0.1:8008",
        "server_name": "localhost",
        "discord_token": "my-secret-discord-token",
        "port": 5000,
        "database": f"{basedir}/bridge.db",
    }

    if not os.path.exists(config_file):
        with open(config_file, "w") as f:
            json.dump(config_dict, f, indent=4)
            print(f"Configuration dumped to '{config_file}'")
            sys.exit()

    with open(config_file, "r") as f:
        return json.loads(f.read())


def excepthook(exc_type, exc_value, exc_traceback):
    if issubclass(exc_type, KeyboardInterrupt):
        sys.__excepthook__(exc_type, exc_value, exc_traceback)
        return

    logging.critical(
        "Unknown exception:", exc_info=(exc_type, exc_value, exc_traceback)
    )


def main() -> None:
    try:
        basedir = sys.argv[1]
        if not os.path.exists(basedir):
            print(f"Path '{basedir}' does not exist!")
            sys.exit(1)
        basedir = os.path.abspath(basedir)
    except IndexError:
        basedir = os.getcwd()

    config = config_gen(basedir, "appservice.json")

    logging.basicConfig(
        level=logging.INFO,
        format="%(asctime)s %(name)s:%(levelname)s:%(message)s",
        datefmt="%Y-%m-%d %H:%M:%S",
        handlers=[
            logging.FileHandler(f"{basedir}/appservice.log"),
        ],
    )

    sys.excepthook = excepthook

    app = MatrixClient(config, urllib3.PoolManager(maxsize=10))

    # Start the bottle app in a separate thread.
    app_thread = threading.Thread(
        target=app.run, kwargs={"port": int(config["port"])}, daemon=True
    )
    app_thread.start()

    try:
        asyncio.run(app.discord.run())
    except KeyboardInterrupt:
        sys.exit()


if __name__ == "__main__":
    main()