"""SQLAlchemy-backed roundtable business-chain store.

The ``seats`` JSON column is stored as a serialized string in
``PortableLongText`` and round-tripped here with ``json.dumps`` / ``json.loads``
— same approach as ``roundtable_drafts`` / ``ai_writing_sessions``.

All write/read paths are scoped by ``user_id`` for ownership isolation; a row
that belongs to another user is treated as not found.
"""

from __future__ import annotations

import json
from datetime import UTC, datetime
from typing import Any

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker

from deerflow.persistence.roundtable_chains.model import RoundtableChainRow

_UNSET = object()


def _loads(value: Any) -> Any:
    if not isinstance(value, str):
        return value
    if not value:
        return None
    try:
        return json.loads(value)
    except Exception:
        return None


def _dumps(value: Any) -> str | None:
    if value is None:
        return None
    return json.dumps(value, ensure_ascii=False)


class RoundtableChainRepository:
    def __init__(self, session_factory: async_sessionmaker[AsyncSession]) -> None:
        self._sf = session_factory

    @staticmethod
    def _to_dict(row: RoundtableChainRow) -> dict[str, Any]:
        return {
            "id": row.id,
            "title": row.title,
            "description": row.description,
            "seats": _loads(row.seats) or [],
            "created_at": row.created_at.isoformat() if isinstance(row.created_at, datetime) else row.created_at,
            "updated_at": row.updated_at.isoformat() if isinstance(row.updated_at, datetime) else row.updated_at,
        }

    async def list_chains(self, user_id: str, *, limit: int = 200) -> list[dict[str, Any]]:
        stmt = (
            select(RoundtableChainRow)
            .where(RoundtableChainRow.user_id == user_id)
            .order_by(RoundtableChainRow.updated_at.desc())
            .limit(limit)
        )
        async with self._sf() as session:
            result = await session.execute(stmt)
            return [self._to_dict(row) for row in result.scalars()]

    async def get_chain(self, chain_id: str, user_id: str) -> dict[str, Any] | None:
        async with self._sf() as session:
            row = await session.get(RoundtableChainRow, chain_id)
            if row is None or row.user_id != user_id:
                return None
            return self._to_dict(row)

    async def create_chain(self, user_id: str, data: dict[str, Any]) -> dict[str, Any]:
        now = datetime.now(UTC)
        row = RoundtableChainRow(
            id=data["id"],
            user_id=user_id,
            title=(data.get("title") or "").strip(),
            description=(data.get("description") or None),
            seats=_dumps(data.get("seats") or []),
            created_at=now,
            updated_at=now,
        )
        async with self._sf() as session:
            session.add(row)
            await session.commit()
            await session.refresh(row)
            return self._to_dict(row)

    async def update_chain(
        self,
        chain_id: str,
        user_id: str,
        *,
        title=_UNSET,
        description=_UNSET,
        seats=_UNSET,
    ) -> dict[str, Any] | None:
        async with self._sf() as session:
            row = await session.get(RoundtableChainRow, chain_id)
            if row is None or row.user_id != user_id:
                return None
            if title is not _UNSET and title is not None:
                row.title = str(title).strip()
            if description is not _UNSET:
                row.description = description or None
            if seats is not _UNSET:
                row.seats = _dumps(seats)
            row.updated_at = datetime.now(UTC)
            await session.commit()
            await session.refresh(row)
            return self._to_dict(row)

    async def delete_chain(self, chain_id: str, user_id: str) -> bool:
        async with self._sf() as session:
            row = await session.get(RoundtableChainRow, chain_id)
            if row is None or row.user_id != user_id:
                return False
            await session.delete(row)
            await session.commit()
            return True