"""Kernel Run API（rewrite/1.0 新契约首个端点）。

POST /api/v1/runs：创建占位前台 Run（M0 骨架），事件流经既有
GET /api/v1/runs/{run_id}/stream 订阅（SSE + Last-Event-ID 断线续传）。
与旧 runs 路由共存：本模块只新增 POST，不改动旧读端点（M2 重建时收敛）。
"""

from __future__ import annotations

from fastapi import APIRouter, Depends, Request
from pydantic import BaseModel, Field
from sqlalchemy.ext.asyncio import AsyncSession

from app.api.v1.deps import get_current_user
from app.db.session import get_session
from app.kernel import Kernel
from app.schemas.auth import CurrentUser
from app.schemas.runtime import RunResponse
from app.services.characters import resolve_active_character
from app.services.runtime import get_run_response

router = APIRouter(prefix="/runs", tags=["kernel"])


class KernelRunCreate(BaseModel):
    """占位 Run 创建请求：M0 无镜树挂载，prompt 直接作为用户输入。"""

    prompt: str = Field(default="你好，请介绍一下你自己。", min_length=1, max_length=8000)
    character_id: str | None = Field(default=None, description="缺省用当前激活人物")


def _get_kernel(request: Request) -> Kernel:
    kernel: Kernel | None = getattr(request.app.state, "kernel", None)
    if kernel is None:
        from app.core.errors import AppError

        raise AppError("service_unavailable", "Kernel 运行时未就绪。", status_code=503)
    return kernel


@router.post("", response_model=RunResponse, status_code=200)
async def create_kernel_run(
    payload: KernelRunCreate,
    request: Request,
    user: CurrentUser = Depends(get_current_user),
    db: AsyncSession = Depends(get_session),
) -> RunResponse:
    kernel = _get_kernel(request)
    character = await resolve_active_character(
        db, payload.character_id, owner_scope=user.owner_scope
    )
    run = await kernel.start_foreground_run(
        character_id=character.id, prompt=payload.prompt, owner_id=user.owner_scope
    )
    return await get_run_response(run.id)