from __future__ import annotations

import re
from dataclasses import dataclass

from adapter.matrix.store import (
    get_room_meta,
    get_user_meta,
    next_platform_chat_id,
    set_room_meta,
    set_user_meta,
)

_CHAT_ID_PATTERNS = (
    re.compile(r"\bC(?P<index>\d+)\b", re.IGNORECASE),
    re.compile(r"^Чат\s+(?P<index>\d+)$", re.IGNORECASE),
)


@dataclass(slots=True)
class ReconciliationResult:
    recovered_rooms: int = 0
    repaired_rooms: int = 0
    backfilled_platform_chat_ids: int = 0


def _room_name(room: object) -> str | None:
    for attr in ("name", "display_name"):
        value = getattr(room, attr, None)
        if isinstance(value, str) and value.strip():
            return value.strip()
    return None


def _chat_id_from_room(room: object, existing_meta: dict | None) -> str | None:
    chat_id = (existing_meta or {}).get("chat_id")
    if isinstance(chat_id, str) and chat_id:
        return chat_id

    name = _room_name(room)
    if not name:
        return None

    for pattern in _CHAT_ID_PATTERNS:
        match = pattern.search(name)
        if match:
            return f"C{int(match.group('index'))}"
    return None


def _space_id_for_room(room: object, rooms_by_id: dict[str, object], existing_meta: dict | None) -> str | None:
    existing_space_id = (existing_meta or {}).get("space_id")
    if isinstance(existing_space_id, str) and existing_space_id:
        return existing_space_id

    parents = getattr(room, "parents", None)
    if not parents:
        parents = getattr(room, "space_parents", None)
    if not parents:
        return None

    for parent_id in parents:
        parent = rooms_by_id.get(parent_id)
        if parent is None:
            continue
        if getattr(parent, "room_type", None) == "m.space" or getattr(parent, "children", None):
            return parent_id
        return parent_id
    return None


def _matrix_user_id_for_room(room: object, bot_user_id: str | None, existing_meta: dict | None) -> str | None:
    existing_user_id = (existing_meta or {}).get("matrix_user_id")
    if isinstance(existing_user_id, str) and existing_user_id:
        return existing_user_id

    users = getattr(room, "users", None) or {}
    for user_id in users:
        if user_id != bot_user_id:
            return user_id
    return None


async def reconcile_startup_state(client: object, runtime: object) -> ReconciliationResult:
    rooms_by_id = getattr(client, "rooms", None) or {}
    bot_user_id = getattr(client, "user_id", None)
    result = ReconciliationResult()
    max_chat_index_by_user: dict[str, int] = {}
    recovered_space_by_user: dict[str, str] = {}

    for room_id, room in rooms_by_id.items():
        if getattr(room, "room_type", None) == "m.space":
            continue

        existing_meta = await get_room_meta(runtime.store, room_id)
        if existing_meta and existing_meta.get("redirect_room_id"):
            continue

        space_id = _space_id_for_room(room, rooms_by_id, existing_meta)
        chat_id = _chat_id_from_room(room, existing_meta)
        matrix_user_id = _matrix_user_id_for_room(room, bot_user_id, existing_meta)
        if not space_id or not chat_id or not matrix_user_id:
            continue

        recovered_space_by_user[matrix_user_id] = space_id
        chat_index = int(chat_id[1:])
        max_chat_index_by_user[matrix_user_id] = max(
            max_chat_index_by_user.get(matrix_user_id, 0),
            chat_index,
        )

        display_name = (existing_meta or {}).get("display_name") or _room_name(room) or chat_id
        room_meta = dict(existing_meta or {})
        room_meta.update(
            {
                "room_type": "chat",
                "chat_id": chat_id,
                "display_name": display_name,
                "matrix_user_id": matrix_user_id,
                "space_id": space_id,
            }
        )

        if not room_meta.get("platform_chat_id"):
            room_meta["platform_chat_id"] = await next_platform_chat_id(runtime.store)
            result.backfilled_platform_chat_ids += 1

        if not room_meta.get("agent_id"):
            registry = getattr(runtime, "registry", None)
            if registry is not None:
                agent_id = registry.get_agent_id_for_user(matrix_user_id)
                if agent_id is None and registry.agents:
                    agent_id = registry.agents[0].agent_id
                if agent_id:
                    room_meta["agent_id"] = agent_id

        if existing_meta is None:
            result.recovered_rooms += 1
        elif room_meta != existing_meta:
            result.repaired_rooms += 1

        await set_room_meta(runtime.store, room_id, room_meta)
        await runtime.auth_mgr.confirm(matrix_user_id)
        await runtime.chat_mgr.get_or_create(
            user_id=matrix_user_id,
            chat_id=chat_id,
            platform="matrix",
            surface_ref=room_id,
            name=display_name,
        )

    for matrix_user_id, recovered_space_id in recovered_space_by_user.items():
        user_meta = dict(await get_user_meta(runtime.store, matrix_user_id) or {})
        user_meta["space_id"] = user_meta.get("space_id") or recovered_space_id
        next_chat_index = max_chat_index_by_user[matrix_user_id] + 1
        user_meta["next_chat_index"] = max(int(user_meta.get("next_chat_index", 1)), next_chat_index)
        await set_user_meta(runtime.store, matrix_user_id, user_meta)

    return result