"""SQLAlchemy-backed global business → agent / chain mapping store.

Global / shared (no ``user_id`` scoping): every account reads and writes the same
rows. The four business rows are seeded once on startup (``ensure_seed_defaults``)
with empty agent/chain; users fill those in from the management page via
``update_mapping``.
"""

from __future__ import annotations

from datetime import UTC, datetime
from typing import Any

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

from deerflow.persistence.business_mapping.model import BusinessMappingRow

_UNSET = object()

# Fixed business rows (业务码 → 展示名). Seeded on first boot; agent/chain left empty.
# 8BF 页面尚未建好，先占位保留行。顺序即管理表的展示顺序。
DEFAULT_BUSINESS_ROWS: list[dict[str, Any]] = [
    {"business_code": "3Q", "label": "3QFX"},
    {"business_code": "6BF", "label": "任务FX"},
    {"business_code": "7BF", "label": "XDFX"},
    {"business_code": "8BF", "label": "8BF"},
]


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

    @staticmethod
    def _to_dict(row: BusinessMappingRow) -> dict[str, Any]:
        return {
            "business_code": row.business_code,
            "label": row.label,
            "agent_id": row.agent_id,
            "agent_name": row.agent_name,
            "chain_id": row.chain_id,
            "chain_title": row.chain_title,
            "sort_order": row.sort_order,
            "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_mappings(self) -> list[dict[str, Any]]:
        stmt = select(BusinessMappingRow).order_by(
            BusinessMappingRow.sort_order.asc(), BusinessMappingRow.business_code.asc()
        )
        async with self._sf() as session:
            result = await session.execute(stmt)
            return [self._to_dict(row) for row in result.scalars()]

    async def get_mapping(self, business_code: str) -> dict[str, Any] | None:
        async with self._sf() as session:
            row = await session.get(BusinessMappingRow, business_code)
            return self._to_dict(row) if row is not None else None

    async def update_mapping(
        self,
        business_code: str,
        *,
        agent_id=_UNSET,
        agent_name=_UNSET,
        chain_id=_UNSET,
        chain_title=_UNSET,
    ) -> dict[str, Any] | None:
        """Update an existing (seeded) business row. Returns None if the code is unknown.

        Only forwarded fields are touched; explicit ``None`` clears that field.
        """
        async with self._sf() as session:
            row = await session.get(BusinessMappingRow, business_code)
            if row is None:
                return None
            if agent_id is not _UNSET:
                row.agent_id = agent_id or None
            if agent_name is not _UNSET:
                row.agent_name = agent_name or None
            if chain_id is not _UNSET:
                row.chain_id = chain_id or None
            if chain_title is not _UNSET:
                row.chain_title = chain_title or None
            row.updated_at = datetime.now(UTC)
            await session.commit()
            await session.refresh(row)
            return self._to_dict(row)

    async def ensure_seed_defaults(self) -> int:
        """Idempotently insert the fixed business rows if missing. Returns inserted count.

        Never overwrites an existing row (respects user-configured agent/chain).
        """
        inserted = 0
        now = datetime.now(UTC)
        async with self._sf() as session:
            for idx, seed in enumerate(DEFAULT_BUSINESS_ROWS):
                existing = await session.get(BusinessMappingRow, seed["business_code"])
                if existing is not None:
                    continue
                session.add(
                    BusinessMappingRow(
                        business_code=seed["business_code"],
                        label=seed.get("label", ""),
                        agent_id=None,
                        agent_name=None,
                        chain_id=None,
                        chain_title=None,
                        sort_order=idx,
                        created_at=now,
                        updated_at=now,
                    )
                )
                inserted += 1
            if inserted:
                await session.commit()
        return inserted