"""카카오톡 채널 발화자를 우리 user_id 에 묶는다 — 에이전트의 모든 도구가 이 매핑 위에 선다."""

import hashlib
import secrets
from datetime import datetime, timedelta, timezone
from uuid import UUID

from sqlalchemy import select, text, update

from common.database.db_session_manager import DB_SESSION_MNG
from common.database.model.models import owner_kakao_links as Link
from common.enums import KakaoLinkStatus
from config import agent_config as config

# 사장님이 카톡 대화창에 손으로 친다.
_CODE_ALPHABET = "ABCDEFGHJKMNPQRSTUVWXYZ23456789"
_CODE_LENGTH = 6


class KakaoLinkError(RuntimeError):
    """도메인 예외."""

    def __init__(self, code="KAKAO_LINK_FAILED"):
        super().__init__(code)


def enabled() -> bool:
    return config.kakao_link_enabled()


def _now():
    return datetime.now(timezone.utc)


def _sha(code: str) -> str:
    return hashlib.sha256(code.strip().upper().encode()).hexdigest()


def _new_code() -> str:
    return "".join(secrets.choice(_CODE_ALPHABET) for _ in range(_CODE_LENGTH))


async def _lock_user(s, user_id):
    """연결·재발급·해제가 같은 잠금을 공유한다(social_account_service.lock_user 와 같은 방식)."""
    await s.execute(
        text("SELECT pg_advisory_xact_lock(hashtextextended(:key, 0))"),
        {"key": f"kakao_link:{user_id}"},
    )


async def _active(s, user_id):
    return (
        await s.execute(
            select(Link).where(
                Link.user_id == user_id,
                Link.deleted.is_(False),
                Link.status.in_([KakaoLinkStatus.PENDING.value, KakaoLinkStatus.LINKED.value]),
            )
        )
    ).scalars().first()


async def state(user_id: UUID) -> dict:
    """빌더 카드가 읽는 값."""

    async def run(s):
        row = await _active(s, user_id)
        return {
            "connection_enabled": enabled(),
            "channel_url": config.channel_url(),
            "status": row.status if row else None,
            "linked_at": row.linked_at.isoformat() if row and row.linked_at else None,
            "code_expires_at": (
                row.code_expires_at.isoformat()
                if row and row.status == KakaoLinkStatus.PENDING.value and row.code_expires_at
                else None
            ),
        }

    return await DB_SESSION_MNG.execute_lambda_write(Link.DBType(), run)


async def issue_code(user_id: UUID) -> dict:
    """일회용 코드를 낸다."""
    if not enabled():
        raise KakaoLinkError("KAKAO_LINK_DISABLED")

    code = _new_code()
    expires = _now() + timedelta(minutes=int(config.get("KAKAO_LINK_CODE_TTL_MIN", 10)))

    async def run(s):
        await _lock_user(s, user_id)
        row = await _active(s, user_id)
        if row is not None and row.status == KakaoLinkStatus.LINKED.value:
            raise KakaoLinkError("KAKAO_LINK_ALREADY")
        if row is None:
            row = Link(user_id=user_id, status=KakaoLinkStatus.PENDING.value)
            s.add(row)
        row.code_sha = _sha(code)
        row.code_expires_at = expires
        row.code_attempts = 0
        return {"code": code, "expires_at": expires.isoformat(), "channel_url": config.channel_url()}

    return await DB_SESSION_MNG.execute_lambda_write(Link.DBType(), run)


async def redeem(code: str, channel_user_key: str) -> UUID:
    """채널에서 들어온 코드를 소비하고 user_id 를 돌려준다."""
    sha = _sha(code)
    max_attempts = int(config.get("KAKAO_LINK_MAX_ATTEMPTS", 5))

    async def run(s):
        # 한 문장 CAS.
        row = (
            await s.execute(
                text("""UPDATE owner_kakao_links
                   SET status='LINKED', channel_user_key=:key, linked_at=now(),
                       last_seen_at=now(), code_sha=NULL, code_expires_at=NULL, updated_at=now()
                 WHERE code_sha=:sha AND deleted=false AND status='PENDING'
                   AND code_expires_at > now() AND code_attempts < :max
             RETURNING user_id"""),
                {"sha": sha, "key": channel_user_key, "max": max_attempts},
            )
        ).first()
        if row is None:
            # 맞는 코드가 없으면 셀 행도 없다.
            await s.execute(
                text("""UPDATE owner_kakao_links SET code_attempts = code_attempts + 1, updated_at=now()
                     WHERE code_sha=:sha AND deleted=false AND status='PENDING'"""),
                {"sha": sha},
            )
            raise KakaoLinkError("KAKAO_LINK_CODE_INVALID")
        return row.user_id

    return await DB_SESSION_MNG.execute_lambda_write(Link.DBType(), run)


async def resolve(channel_user_key: str) -> UUID | None:
    """채널 발화자 → user_id."""

    async def run(s):
        row = (
            await s.execute(
                select(Link).where(
                    Link.channel_user_key == channel_user_key,
                    Link.deleted.is_(False),
                    Link.status == KakaoLinkStatus.LINKED.value,
                )
            )
        ).scalars().first()
        if row is None:
            return None
        row.last_seen_at = _now()
        return row.user_id

    return await DB_SESSION_MNG.execute_lambda_write(Link.DBType(), run)


async def linked_key(user_id) -> str | None:
    """사장님에게 연결된 카톡 발화자 키(botUserKey). 연결이 없거나 끊겼으면 None.

    ★ 승인 알림을 **먼저 보낼** 때 쓴다(Event API). resolve() 와 방향이 반대다 —
      그건 들어온 발화자로 사장님을 찾는다. 여기서는 사장님으로 발화자를 찾는다."""

    async def run(s):
        row = (
            await s.execute(
                select(Link).where(
                    Link.user_id == user_id,
                    Link.deleted.is_(False),
                    Link.status == KakaoLinkStatus.LINKED.value,
                    Link.channel_user_key.is_not(None),
                )
            )
        ).scalars().first()
        return row.channel_user_key if row is not None else None

    return await DB_SESSION_MNG.execute_lambda_write(Link.DBType(), run)


async def disconnect(user_id: UUID) -> None:
    """연결을 끊는다."""

    async def run(s):
        await _lock_user(s, user_id)
        result = await s.execute(
            update(Link)
            .where(
                Link.user_id == user_id,
                Link.deleted.is_(False),
                Link.status.in_([KakaoLinkStatus.PENDING.value, KakaoLinkStatus.LINKED.value]),
            )
            .values(status=KakaoLinkStatus.REVOKED.value, code_sha=None, code_expires_at=None)
        )
        if result.rowcount == 0:
            raise KakaoLinkError("KAKAO_LINK_NOT_FOUND")

    await DB_SESSION_MNG.execute_lambda_write(Link.DBType(), run)