"""Element / Matrix delivery helpers for scheduled task results."""

from __future__ import annotations

import logging
import os
import uuid
from pathlib import Path

import httpx

logger = logging.getLogger(__name__)


class ElementDeliveryClient:
    def __init__(self, *, homeserver_url: str, access_token: str) -> None:
        self.homeserver_url = homeserver_url.rstrip("/")
        self.access_token = access_token

    @classmethod
    def from_env(cls) -> ElementDeliveryClient | None:
        enabled = os.environ.get("ELEMENT_ENABLED", "true").strip().lower()
        if enabled in {"0", "false", "no", "off"}:
            return None

        homeserver_url = os.environ.get("ELEMENT_HOMESERVER_URL", "").strip()
        if not homeserver_url:
            return None

        access_token = os.environ.get("ELEMENT_ACCESS_TOKEN", "").strip()
        if not access_token:
            access_token = _load_cached_access_token()
        if not access_token:
            try:
                access_token = _bootstrap_access_token(homeserver_url)
            except Exception:
                logger.exception("Failed to bootstrap Element bot access token")
                return None
        if not access_token:
            return None
        return cls(homeserver_url=homeserver_url, access_token=access_token)

    def _headers(self) -> dict[str, str]:
        return {"Authorization": f"Bearer {self.access_token}"}

    async def send_direct_message(self, element_user_id: str, body: str, *, room_id: str | None = None) -> str:
        if not room_id:
            room_id = await self._create_dm_room(element_user_id)
        await self._send_message(room_id, body)
        return room_id

    async def _create_dm_room(self, element_user_id: str) -> str:
        url = f"{self.homeserver_url}/_matrix/client/v3/createRoom"
        payload = {
            "preset": "trusted_private_chat",
            "is_direct": True,
            "invite": [element_user_id],
        }
        async with httpx.AsyncClient(timeout=20) as client:
            response = await client.post(url, headers=self._headers(), json=payload)
            response.raise_for_status()
            data = response.json()
        room_id = data.get("room_id")
        if not isinstance(room_id, str) or not room_id:
            raise RuntimeError("Matrix createRoom response did not include room_id")
        return room_id

    async def _send_message(self, room_id: str, body: str) -> None:
        txn_id = uuid.uuid4().hex
        url = f"{self.homeserver_url}/_matrix/client/v3/rooms/{room_id}/send/m.room.message/{txn_id}"
        payload = {
            "msgtype": "m.text",
            "body": body,
        }
        async with httpx.AsyncClient(timeout=30) as client:
            response = await client.put(url, headers=self._headers(), json=payload)
            response.raise_for_status()


def _state_file() -> Path:
    path = os.environ.get("ELEMENT_STATE_FILE", "").strip()
    if path:
        return Path(path)
    return Path(".element-bot-token")


def _load_cached_access_token() -> str | None:
    path = _state_file()
    if not path.exists():
        return None
    token = path.read_text(encoding="utf-8").strip()
    return token or None


def _save_cached_access_token(token: str) -> None:
    path = _state_file()
    path.parent.mkdir(parents=True, exist_ok=True)
    path.write_text(token, encoding="utf-8")


def _bootstrap_access_token(homeserver_url: str) -> str | None:
    username = os.environ.get("ELEMENT_BOT_USERNAME", "scheduled-bot").strip() or "scheduled-bot"
    password = os.environ.get("ELEMENT_BOT_PASSWORD", "").strip()
    auto_register = os.environ.get("ELEMENT_AUTO_REGISTER", "false").strip().lower() in {
        "1",
        "true",
        "yes",
        "on",
    }

    if auto_register:
        if not password:
            password = f"scheduled-bot-{uuid.uuid4().hex}"
        token = _register_bot(homeserver_url, username, password)
        if token:
            _save_cached_access_token(token)
            return token

    if username and password:
        token = _login_bot(homeserver_url, username, password)
        if token:
            _save_cached_access_token(token)
            return token
    return None


def _register_bot(homeserver_url: str, username: str, password: str) -> str | None:
    url = f"{homeserver_url.rstrip('/')}/_matrix/client/v3/register"
    payload = {
        "username": username,
        "password": password,
        "auth": {"type": "m.login.dummy"},
        "initial_device_display_name": "Scheduled Task Bot",
    }
    with httpx.Client(timeout=20) as client:
        response = client.post(url, json=payload)
        if response.status_code == 401:
            session = response.json().get("session")
            if session:
                payload["auth"]["session"] = session
                response = client.post(url, json=payload)
        if response.status_code == 400 and response.json().get("errcode") == "M_USER_IN_USE":
            password_env = os.environ.get("ELEMENT_BOT_PASSWORD", "").strip()
            if password_env:
                return _login_bot(homeserver_url, username, password_env)
            logger.error(
                "Element bot username %s already exists and no ELEMENT_BOT_PASSWORD was provided",
                username,
            )
            return None
        response.raise_for_status()
        data = response.json()
    token = data.get("access_token")
    return token if isinstance(token, str) and token else None


def _login_bot(homeserver_url: str, username: str, password: str) -> str | None:
    url = f"{homeserver_url.rstrip('/')}/_matrix/client/v3/login"
    payload = {
        "type": "m.login.password",
        "identifier": {"type": "m.id.user", "user": username},
        "password": password,
        "initial_device_display_name": "Scheduled Task Bot",
    }
    with httpx.Client(timeout=20) as client:
        response = client.post(url, json=payload)
        response.raise_for_status()
        data = response.json()
    token = data.get("access_token")
    return token if isinstance(token, str) and token else None