from __future__ import annotations

import logging
import itertools

from enum import Enum, auto
from functools import wraps
from typing import Optional, Union, Tuple, Coroutine

from telegram import Update, ReplyKeyboardMarkup
from telegram.ext import (
    Application,
    filters,
    CommandHandler,
    MessageHandler,
    CallbackQueryHandler,
    CallbackContext,
    ConversationHandler
)
from telegram.ext.filters import BaseFilter
from telegram.error import TimedOut

from home.config import config
from home.api import WebAPIClient
from home.api.types import BotType

from ._botlang import lang, languages
from ._botdb import BotDatabase
from ._botutil import ReportingHelper, exc2text, IgnoreMarkup, user_any_name
from ._botcontext import Context


db: Optional[BotDatabase] = None

_user_filter: Optional[BaseFilter] = None
_cancel_filter = filters.Text(lang.all('cancel'))
_back_filter = filters.Text(lang.all('back'))
_cancel_and_back_filter = filters.Text(lang.all('back') + lang.all('cancel'))

_logger = logging.getLogger(__name__)
_application: Optional[Application] = None
_reporting: Optional[ReportingHelper] = None
_exception_handler: Optional[Coroutine] = None
_dispatcher = None
_markup_getter: Optional[callable] = None
_start_handler_ref: Optional[Coroutine] = None


def text_filter(*args):
    if not _user_filter:
        raise RuntimeError('user_filter is not initialized')
    return filters.Text(args[0] if isinstance(args[0], list) else [*args]) & _user_filter


async def _handler_of_handler(*args, **kwargs):
    self = None
    context = None
    update = None

    _args = list(args)
    while len(_args):
        v = _args[0]
        if isinstance(v, conversation):
            self = v
            _args.pop(0)
        elif isinstance(v, Update):
            update = v
            _args.pop(0)
        elif isinstance(v, CallbackContext):
            context = v
            _args.pop(0)
            break

    ctx = Context(update,
                  callback_context=context,
                  markup_getter=lambda _ctx: None if not _markup_getter else _markup_getter(_ctx),
                  store=db)
    try:
        _args.insert(0, ctx)

        f = kwargs['f']
        del kwargs['f']

        if 'return_with_context' in kwargs:
            return_with_context = True
            del kwargs['return_with_context']
        else:
            return_with_context = False

        if 'argument' in kwargs and kwargs['argument'] == 'message_key':
            del kwargs['argument']
            mkey = None
            for k, v in lang.get_langpack(ctx.user_lang).items():
                if ctx.text == v:
                    mkey = k
                    break
            _args.insert(0, mkey)

        if self:
            _args.insert(0, self)

        result = await f(*_args, **kwargs)
        return result if not return_with_context else (result, ctx)

    except Exception as e:
        if _exception_handler:
            if not _exception_handler(e, ctx) and not isinstance(e, TimedOut):
                _logger.exception(e)
                if not ctx.is_callback_context():
                    await ctx.reply_exc(e)
                else:
                    notify_user(ctx.user_id, exc2text(e))
        else:
            _logger.exception(e)


def handler(**kwargs):
    def inner(f):
        @wraps(f)
        async def _handler(*args, **inner_kwargs):
            if 'argument' in kwargs and kwargs['argument'] == 'message_key':
                inner_kwargs['argument'] = 'message_key'
            return await _handler_of_handler(f=f, *args, **inner_kwargs)

        messages = []
        texts = []

        if 'messages' in kwargs:
            messages += kwargs['messages']
        if 'message' in kwargs:
            messages.append(kwargs['message'])

        if 'text' in kwargs:
            texts.append(kwargs['text'])
        if 'texts' in kwargs:
            texts += kwargs['texts']

        if messages or texts:
            new_messages = list(itertools.chain.from_iterable([lang.all(m) for m in messages]))
            texts += new_messages
            texts = list(set(texts))
            _application.add_handler(
                MessageHandler(text_filter(*texts), _handler),
                group=0
            )

        if 'command' in kwargs:
            _application.add_handler(CommandHandler(kwargs['command'], _handler), group=0)

        if 'callback' in kwargs:
            _application.add_handler(CallbackQueryHandler(_handler, pattern=kwargs['callback']), group=0)

        return _handler

    return inner


def simplehandler(f: Coroutine):
    @wraps(f)
    async def _handler(*args, **kwargs):
        return await _handler_of_handler(f=f, *args, **kwargs)
    return _handler


def callbackhandler(*args, **kwargs):
    def inner(f):
        @wraps(f)
        async def _handler(*args, **kwargs):
            return await _handler_of_handler(f=f, *args, **kwargs)
        pattern_kwargs = {}
        if kwargs['callback'] != '*':
            pattern_kwargs['pattern'] = kwargs['callback']
        _application.add_handler(CallbackQueryHandler(_handler, **pattern_kwargs), group=0)
        return _handler
    return inner


async def exceptionhandler(f: callable):
    global _exception_handler
    if _exception_handler:
        _logger.warning('exception handler already set, we will overwrite it')
    _exception_handler = f


def defaultreplymarkup(f: callable):
    global _markup_getter
    _markup_getter = f


def convinput(state, is_enter=False, **kwargs):
    def inner(f):
        f.__dict__['_conv_data'] = dict(
            orig_f=f,
            enter=is_enter,
            type=ConversationMethodType.ENTRY if is_enter and state == 0 else ConversationMethodType.STATE_HANDLER,
            state=state,
            **kwargs
        )

        @wraps(f)
        async def _impl(*args, **kwargs):
            result, ctx = await _handler_of_handler(f=f, *args, **kwargs, return_with_context=True)
            if result == conversation.END:
                await start(ctx)
            return result

        return _impl

    return inner


def conventer(state, **kwargs):
    return convinput(state, is_enter=True, **kwargs)


class ConversationMethodType(Enum):
    ENTRY = auto()
    STATE_HANDLER = auto()


class conversation:
    END = ConversationHandler.END
    STATE_SEQS = []

    def __init__(self, enable_back=False):
        self._logger = logging.getLogger(self.__class__.__name__)
        self._user_state_cache = {}
        self._back_enabled = enable_back

    def make_handlers(self, f: callable, **kwargs) -> list:
        messages = {}
        handlers = []

        if 'messages' in kwargs:
            if isinstance(kwargs['messages'], dict):
                messages = kwargs['messages']
            else:
                for m in kwargs['messages']:
                    messages[m] = None

        if 'message' in kwargs:
            if isinstance(kwargs['message'], str):
                messages[kwargs['message']] = None
            else:
                AttributeError('invalid message type: ' + type(kwargs['message']))

        if messages:
            for message, target_state in messages.items():
                if not target_state:
                    handlers.append(MessageHandler(text_filter(lang.all(message) if 'messages_lang_completed' not in kwargs else message), f))
                else:
                    handlers.append(MessageHandler(text_filter(lang.all(message) if 'messages_lang_completed' not in kwargs else message), self.make_invoker(target_state)))

        if 'regex' in kwargs:
            handlers.append(MessageHandler(filters.Regex(kwargs['regex']) & _user_filter, f))

        if 'command' in kwargs:
            handlers.append(CommandHandler(kwargs['command'], f, _user_filter))

        return handlers

    def make_invoker(self, state):
        def _invoke(update: Update, context: CallbackContext):
            ctx = Context(update,
                          callback_context=context,
                          markup_getter=lambda _ctx: None if not _markup_getter else _markup_getter(_ctx),
                          store=db)
            return self.invoke(state, ctx)
        return _invoke

    def invoke(self, state, ctx: Context):
        self._logger.debug(f'invoke, state={state}')
        for item in dir(self):
            f = getattr(self, item)
            if not callable(f) or item.startswith('_') or '_conv_data' not in f.__dict__:
                continue
            cd = f.__dict__['_conv_data']
            if cd['enter'] and cd['state'] == state:
                return cd['orig_f'](self, ctx)

        raise RuntimeError(f'invoke: failed to find method for state {state}')

    def get_handler(self) -> ConversationHandler:
        entry_points = []
        states = {}

        l_cancel_filter = _cancel_filter if not self._back_enabled else _cancel_and_back_filter

        for item in dir(self):
            f = getattr(self, item)
            if not callable(f) or item.startswith('_') or '_conv_data' not in f.__dict__:
                continue

            cd = f.__dict__['_conv_data']

            if cd['type'] == ConversationMethodType.ENTRY:
                entry_points = self.make_handlers(f, **cd)
            elif cd['type'] == ConversationMethodType.STATE_HANDLER:
                states[cd['state']] = self.make_handlers(f, **cd)
                states[cd['state']].append(
                    MessageHandler(_user_filter & ~l_cancel_filter, conversation.invalid)
                )

        fallbacks = [MessageHandler(_user_filter & _cancel_filter, self.cancel)]
        if self._back_enabled:
            fallbacks.append(MessageHandler(_user_filter & _back_filter, self.back))

        return ConversationHandler(
            entry_points=entry_points,
            states=states,
            fallbacks=fallbacks
        )

    def get_user_state(self, user_id: int) -> Optional[int]:
        if user_id not in self._user_state_cache:
            return None
        return self._user_state_cache[user_id]

    # TODO store in ctx.user_state
    def set_user_state(self, user_id: int, state: Union[int, None]):
        if not self._back_enabled:
            return
        if state is not None:
            self._user_state_cache[user_id] = state
        else:
            del self._user_state_cache[user_id]

    @staticmethod
    @simplehandler
    async def invalid(ctx: Context):
        await ctx.reply(ctx.lang('invalid_input'), markup=IgnoreMarkup())
        # return 0  # FIXME is this needed

    @simplehandler
    async def cancel(self, ctx: Context):
        await start(ctx)
        self.set_user_state(ctx.user_id, None)
        return conversation.END

    @simplehandler
    async def back(self, ctx: Context):
        cur_state = self.get_user_state(ctx.user_id)
        if cur_state is None:
            await start(ctx)
            self.set_user_state(ctx.user_id, None)
            return conversation.END

        new_state = None
        for seq in self.STATE_SEQS:
            if cur_state in seq:
                idx = seq.index(cur_state)
                if idx > 0:
                    return self.invoke(seq[idx-1], ctx)

        if new_state is None:
            raise RuntimeError('failed to determine state to go back to')

    @classmethod
    def add_cancel_button(cls, ctx: Context, buttons):
        buttons.append([ctx.lang('cancel')])

    @classmethod
    def add_back_button(cls, ctx: Context, buttons):
        # buttons.insert(0, [ctx.lang('back')])
        buttons.append([ctx.lang('back')])

    def reply(self,
              ctx: Context,
              state: Union[int, Enum],
              text: str,
              buttons: Optional[list],
              with_cancel=False,
              with_back=False,
              buttons_lang_completed=False):

        if buttons:
            new_buttons = []
            if not buttons_lang_completed:
                for item in buttons:
                    if isinstance(item, list):
                        item = map(lambda s: ctx.lang(s), item)
                        new_buttons.append(list(item))
                    elif isinstance(item, str):
                        new_buttons.append([ctx.lang(item)])
                    else:
                        raise ValueError('invalid type: ' + type(item))
            else:
                new_buttons = list(buttons)

            buttons = None
        else:
            if with_cancel or with_back:
                new_buttons = []
            else:
                new_buttons = None

        if with_cancel:
            self.add_cancel_button(ctx, new_buttons)
        if with_back:
            if not self._back_enabled:
                raise AttributeError(f'back is not enabled for this conversation ({self.__class__.__name__})')
            self.add_back_button(ctx, new_buttons)

        markup = ReplyKeyboardMarkup(new_buttons, one_time_keyboard=True) if new_buttons else IgnoreMarkup()
        ctx.reply(text, markup=markup)
        self.set_user_state(ctx.user_id, state)
        return state


class LangConversation(conversation):
    START, = range(1)

    @conventer(START, command='lang')
    async def entry(self, ctx: Context):
        self._logger.debug(f'current language: {ctx.user_lang}')

        buttons = []
        for name in languages.values():
            buttons.append(name)
        markup = ReplyKeyboardMarkup([buttons, [ctx.lang('cancel')]], one_time_keyboard=False)

        await ctx.reply(ctx.lang('select_language'), markup=markup)
        return self.START

    @convinput(START, messages=lang.languages)
    async def input(self, ctx: Context):
        selected_lang = None
        for key, value in languages.items():
            if value == ctx.text:
                selected_lang = key
                break

        if selected_lang is None:
            raise ValueError('could not find the language')

        db.set_user_lang(ctx.user_id, selected_lang)
        await ctx.reply(ctx.lang('saved'), markup=IgnoreMarkup())

        return self.END


def initialize():
    global _user_filter
    global _application
    # global _updater
    global _dispatcher

    # init user_filter
    _user_ids = config.app_config.get_user_ids()
    if len(_user_ids) > 0:
        _logger.info('allowed users: ' + str(_user_ids))
        _user_filter = filters.User(_user_ids)
    else:
        _user_filter = filters.ALL  # not sure if this is correct

    _application = Application.builder()\
        .token(config.app_config.get('bot.token'))\
        .connect_timeout(7)\
        .read_timeout(6)\
        .build()

    # transparently log all messages
    # _application.dispatcher.add_handler(MessageHandler(filters.ALL & _user_filter, _logging_message_handler), group=10)
    # _application.dispatcher.add_handler(CallbackQueryHandler(_logging_callback_handler), group=10)


def run(start_handler=None, any_handler=None):
    global db
    global _start_handler_ref

    if not start_handler:
        start_handler = _default_start_handler
    if not any_handler:
        any_handler = _default_any_handler
    if not db:
        db = BotDatabase()

    _start_handler_ref = start_handler

    _application.add_handler(LangConversation().get_handler(), group=0)
    _application.add_handler(CommandHandler('start',
                                            callback=simplehandler(start_handler),
                                            filters=_user_filter))
    _application.add_handler(MessageHandler(filters.ALL & _user_filter, any_handler))

    _application.run_polling()


def add_conversation(conv: conversation) -> None:
    _application.add_handler(conv.get_handler(), group=0)


def add_handler(h):
    _application.add_handler(h, group=0)


async def start(ctx: Context):
    return await _start_handler_ref(ctx)


async def _default_start_handler(ctx: Context):
    if 'start_message' not in lang:
        return await ctx.reply('Please define start_message or override start()')
    await ctx.reply(ctx.lang('start_message'))


@simplehandler
async def _default_any_handler(ctx: Context):
    if 'invalid_command' not in lang:
        return await ctx.reply('Please define invalid_command or override any()')
    await ctx.reply(ctx.lang('invalid_command'))


def _logging_message_handler(update: Update, context: CallbackContext):
    if _reporting:
        _reporting.report(update.message)


def _logging_callback_handler(update: Update, context: CallbackContext):
    if _reporting:
        _reporting.report(update.callback_query.message, text=update.callback_query.data)


def enable_logging(bot_type: BotType):
    api = WebAPIClient(timeout=3)
    api.enable_async()

    global _reporting
    _reporting = ReportingHelper(api, bot_type)


def notify_all(text_getter: callable,
               exclude: Tuple[int] = ()) -> None:
    if 'notify_users' not in config['bot']:
        _logger.error('notify_all() called but no notify_users directive found in the config')
        return

    for user_id in config['bot']['notify_users']:
        if user_id in exclude:
            continue

        text = text_getter(db.get_user_lang(user_id))
        _application.bot.send_message(chat_id=user_id,
                                  text=text,
                                  parse_mode='HTML')


def notify_user(user_id: int, text: Union[str, Exception], **kwargs) -> None:
    if isinstance(text, Exception):
        text = exc2text(text)
    _application.bot.send_message(chat_id=user_id,
                              text=text,
                              parse_mode='HTML',
                              **kwargs)


def send_photo(user_id, **kwargs):
    _application.bot.send_photo(chat_id=user_id, **kwargs)


def send_audio(user_id, **kwargs):
    _application.bot.send_audio(chat_id=user_id, **kwargs)


def send_file(user_id, **kwargs):
    _application.bot.send_document(chat_id=user_id, **kwargs)


def edit_message_text(user_id, message_id, *args, **kwargs):
    _application.bot.edit_message_text(chat_id=user_id,
                                   message_id=message_id,
                                   parse_mode='HTML',
                                   *args, **kwargs)


def delete_message(user_id, message_id):
    _application.bot.delete_message(chat_id=user_id, message_id=message_id)


def set_database(_db: BotDatabase):
    global db
    db = _db