# -*- coding: future_fstrings -*-
# mautrix-telegram - A Matrix-Telegram puppeting bridge
# Copyright (C) 2018 Tulir Asokan
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.
from typing import Optional, List, Tuple, Callable, Pattern, Match, TYPE_CHECKING
import re
import logging

from telethon.tl.types import (MessageEntityMention, MessageEntityMentionName, MessageEntityItalic,
                               TypeMessageEntity)

from ... import puppet as pu
from ...db import Message as DBMessage
from ..util import (add_surrogates, remove_surrogates, trim_reply_fallback_html,
                    trim_reply_fallback_text)
from .parser_common import ParsedMessage

try:
    from mautrix_telegram.formatter.from_matrix.parser_lxml import parse_html
except ImportError:
    from mautrix_telegram.formatter.from_matrix.parser_htmlparser import parse_html

if TYPE_CHECKING:
    from ...context import Context

log = logging.getLogger("mau.fmt.mx")  # type: logging.Logger
should_bridge_plaintext_highlights = False  # type: bool

command_regex = re.compile(r"^!([A-Za-z0-9@]+)")  # type: Pattern
not_command_regex = re.compile(r"^\\(![A-Za-z0-9@]+)")  # type: Pattern
plain_mention_regex = None  # type: Pattern


def plain_mention_to_html(match: Match) -> str:
    puppet = pu.Puppet.find_by_displayname(match.group(2))
    if puppet:
        return (f"{match.group(1)}"
                f"<a href='https://matrix.to/#/{puppet.mxid}'>"
                f"{puppet.displayname}"
                "</a>")
    return "".join(match.groups())


def cut_long_message(message: str, entities: List[TypeMessageEntity]) -> ParsedMessage:
    if len(message) > 4096:
        message = message[0:4082] + " [message cut]"
        new_entities = []
        for entity in entities:
            if entity.offset > 4082:
                continue
            if entity.offset + entity.length > 4082:
                entity.length = 4082 - entity.offset
            new_entities.append(entity)
        new_entities.append(MessageEntityItalic(4082, len(" [message cut]")))
        entities = new_entities
    return message, entities


class FormatError(Exception):
    pass


def matrix_to_telegram(html: str) -> ParsedMessage:
    try:
        html = command_regex.sub(r"<command>\1</command>", html)
        html = html.replace("\t", " " * 4)
        html = not_command_regex.sub(r"\1", html)
        if should_bridge_plaintext_highlights:
            html = plain_mention_regex.sub(plain_mention_to_html, html)

        html = add_surrogates(html)
        text, entities = parse_html(add_surrogates(html))
        text = remove_surrogates(text.strip())
        text, entities = cut_long_message(text, entities)

        return text, entities
    except Exception as e:
        raise FormatError(f"Failed to convert Matrix format: {html}") from e


def matrix_reply_to_telegram(content: dict, tg_space: int, room_id: Optional[str] = None
                             ) -> Optional[int]:
    try:
        reply = content["m.relates_to"]["m.in_reply_to"]
        room_id = room_id or reply["room_id"]
        event_id = reply["event_id"]

        try:
            if content["format"] == "org.matrix.custom.html":
                content["formatted_body"] = trim_reply_fallback_html(content["formatted_body"])
        except KeyError:
            pass
        content["body"] = trim_reply_fallback_text(content["body"])

        message = DBMessage.query.filter(DBMessage.mxid == event_id,
                                         DBMessage.tg_space == tg_space,
                                         DBMessage.mx_room == room_id).one_or_none()
        if message:
            return message.tgid
    except KeyError:
        pass
    return None


def matrix_text_to_telegram(text: str) -> ParsedMessage:
    text = command_regex.sub(r"/\1", text)
    text = text.replace("\t", " " * 4)
    text = not_command_regex.sub(r"\1", text)
    if should_bridge_plaintext_highlights:
        entities, pmr_replacer = plain_mention_to_text()
        text = plain_mention_regex.sub(pmr_replacer, text)
    else:
        entities = []
    return text, entities


def plain_mention_to_text() -> Tuple[List[TypeMessageEntity], Callable[[str], str]]:
    entities = []

    def replacer(match) -> str:
        puppet = pu.Puppet.find_by_displayname(match.group(2))
        if puppet:
            offset = match.start()
            length = match.end() - offset
            if puppet.username:
                entity = MessageEntityMention(offset, length)
                text = f"@{puppet.username}"
            else:
                entity = MessageEntityMentionName(offset, length, user_id=puppet.tgid)
                text = puppet.displayname
            entities.append(entity)
            return text
        return "".join(match.groups())

    return entities, replacer


def init_mx(context: "Context"):
    global plain_mention_regex, should_bridge_plaintext_highlights
    config = context.config
    dn_template = config.get("bridge.displayname_template", "{displayname} (Telegram)")
    dn_template = re.escape(dn_template).replace(re.escape("{displayname}"), "[^>]+")
    plain_mention_regex = re.compile(f"(\s|^)({dn_template})")
    should_bridge_plaintext_highlights = config["bridge.plaintext_highlights"] or False