"""CRUD API for the global business → agent / chain mapping (业务链条管理).

Binds a fixed business code (3Q / 6BF / 7BF / 8BF) to an optional 智能体 and an
optional 业务链条 (a **public** ``roundtable_chains`` row). Used to auto-pick the
business chain when a task page launches the multi-agent roundtable.

Global / shared — there is no user scoping; all accounts see and edit the same
rows. The four business rows are seeded on startup; this API only lists them and
updates the agent / chain columns (no create/delete).

Routes (prefix ``/api/business-mapping``):
    GET ""                 list all business mappings (display order)
    PUT "/{business_code}" update one row's agent / chain selection
"""

from __future__ import annotations

import logging
from datetime import datetime

from fastapi import APIRouter, HTTPException, Request
from pydantic import BaseModel, Field

logger = logging.getLogger(__name__)
router = APIRouter(prefix="/api/business-mapping", tags=["business-mapping"])


# ── schemas ────────────────────────────────────────────────────────────────


class BusinessMappingResponse(BaseModel):
    business_code: str
    label: str = ""
    agent_id: str | None = None
    agent_name: str | None = None
    chain_id: str | None = None
    chain_title: str | None = None
    sort_order: int = 0
    created_at: datetime | str | None = None
    updated_at: datetime | str | None = None


class BusinessMappingListResponse(BaseModel):
    mappings: list[BusinessMappingResponse]


class BusinessMappingUpdateRequest(BaseModel):
    # All optional → callers send only what changed; explicit null clears a field.
    agent_id: str | None = Field(default=None, max_length=64)
    agent_name: str | None = Field(default=None, max_length=191)
    chain_id: str | None = Field(default=None, max_length=64)
    chain_title: str | None = Field(default=None, max_length=512)


# ── helpers ──────────────────────────────────────────────────────────────


def _get_store(request: Request):
    store = getattr(request.app.state, "business_mapping_store", None)
    if store is None:
        raise HTTPException(status_code=503, detail="Business mapping store not available")
    return store


# ── routes ───────────────────────────────────────────────────────────────


@router.get("", response_model=BusinessMappingListResponse)
async def list_mappings(request: Request) -> BusinessMappingListResponse:
    store = _get_store(request)
    rows = await store.list_mappings()
    return BusinessMappingListResponse(
        mappings=[BusinessMappingResponse(**r) for r in rows]
    )


@router.put("/{business_code}", response_model=BusinessMappingResponse)
async def update_mapping(
    request: Request, business_code: str, body: BusinessMappingUpdateRequest
) -> BusinessMappingResponse:
    store = _get_store(request)
    # Only forward fields the caller explicitly sent (distinguish omitted vs null).
    fields = body.model_dump(exclude_unset=True)
    row = await store.update_mapping(business_code, **fields)
    if row is None:
        raise HTTPException(status_code=404, detail="Business mapping not found")
    return BusinessMappingResponse(**row)