'''
VK data (exported by [[https://github.com/Totktonada/vk_messages_backup][Totktonada/vk_messages_backup]])
'''
# note: could reuse the original repo, but little point I guess since VK closed their API
from datetime import datetime
from dataclasses import dataclass
import json
from typing import Dict, Iterable, NamedTuple

import pytz

from my.core import stat, Stats, Json, Res, datetime_aware

from my.config import vk_messages_backup as config


# I think vk_messages_backup used this tz?
# not sure if vk actually used to return this tz in api?
TZ = pytz.timezone('Europe/Moscow')


Uid = int

@dataclass(frozen=True)
class User:
    id: Uid
    first_name: str
    last_name: str


@dataclass(frozen=True)
class Chat:
    chat_id: str
    title: str


@dataclass
class Message:
    dt: datetime_aware
    chat: Chat
    id: str  # todo not sure it's unique?
    user: User
    body: str


Users = Dict[Uid, User]
def users() -> Users:
    files = list(sorted(config.storage_path.glob('user_*.json')))
    res = {}
    for f in files:
        j = json.loads(f.read_text())
        uid = j['id']
        res[uid] = User(
            id=uid,
            first_name=j['first_name'],
            last_name=j['last_name'],
        )
    return res


# USERCHAT_TITLE = " ... "
def _parse_chat(*, msg: Json, udict: Users) -> Chat:
    group_chat_id = msg.get('chat_id')
    if group_chat_id is not None:
        chat_id = group_chat_id
        title = msg['title']
    else:
        user_id = msg.get('user_id') or msg.get('from_id')
        assert user_id is not None
        user = udict[user_id]
        chat_id = user_id
        title = f'{user.first_name} {user.last_name}'
    return Chat(
        chat_id=chat_id,
        title=title,
    )


def _parse_msg(*, msg: Json, chat: Chat, udict: Users) -> Message:
    mid = msg['id']
    md  = msg['date']

    dt = datetime.fromtimestamp(md, tz=TZ)

    # todo attachments? e.g. url could be an attachment
    # todo might be forwarded?
    mb  = msg.get('body')
    if mb is None:
        mb = msg.get('text')
    assert mb is not None, msg

    out = msg['out'] == 1
    if out:
        user = udict[config.user_id]
    else:
        mu  = msg.get('user_id') or msg.get('from_id')
        assert mu is not None, msg
        user = udict[mu]
    return Message(
        dt=dt,
        chat=chat,
        id=mid,
        user=user,
        body=mb,
    )


def messages() -> Iterable[Res[Message]]:
    udict = users()

    uchats = list(sorted(config.storage_path.glob('userchat_*.json' ))) + \
             list(sorted(config.storage_path.glob('groupchat_*.json')))
    for f in uchats:
        j = json.loads(f.read_text())
        # extract chat from last message
        try:
            last = j[-1]
            chat = _parse_chat(msg=last, udict=udict)
        except Exception as e:
            yield e
            continue

        for msg in j:
            try:
                yield _parse_msg(msg=msg, chat=chat, udict=udict)
            except Exception as e:
                yield e


def stats() -> Stats:
    return {
        **stat(users),
        **stat(messages),
    }