"""异步研究 Job API（Phase 4）：提交 / 查询 / SSE 进度。

POST /api/jobs          创建 Job（BackgroundTasks 后台执行），立即返回 job_id
GET  /api/jobs/{id}     状态 + 结果（成功时内嵌 result）
GET  /api/jobs/{id}/events  SSE 进度（queued→running→success|failed）

执行模式见 config job.mode：subprocess 时研究任务在独立子进程跑（内存隔离），
API worker 不被重任务拖垮（内存优化专项）。
"""

from __future__ import annotations

import asyncio
import json
from datetime import datetime

from fastapi import APIRouter, BackgroundTasks, HTTPException
from fastapi.responses import StreamingResponse

from app.api.deps import DbSession, JobRepoDep
from app.application.services.job_executor import new_id, run_job_background
from app.domain.entities.research import (
    BacktestResult,
    FactorTestReport,
    JobRecord,
    JobStatus,
    ResearchSpec,
)
from app.infrastructure.persistence.sqlalchemy.repositories.jobs_impl import (
    SqlAlchemyJobRepository,
)
from app.infrastructure.persistence.sqlalchemy.session import SessionLocal

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


def _decode_result(kind: str, result_json: str | None):
    if result_json is None:
        return None
    model = BacktestResult if kind == "backtest" else FactorTestReport
    return model.model_validate_json(result_json)


def _job_view(job: JobRecord) -> dict:
    view = job.model_dump()
    view["result"] = _decode_result(job.kind, job.result_json)
    view.pop("result_json", None)
    view["spec"] = json.loads(job.spec_json)
    return view


@router.post("", summary="创建异步研究 Job")
def create_job(
    spec: ResearchSpec,
    background: BackgroundTasks,
    session: DbSession,
    job_repo: JobRepoDep,
) -> dict:
    job = JobRecord(
        id=new_id("JOB"),
        kind=spec.type,
        spec_json=spec.model_dump_json(),
        status=JobStatus.QUEUED,
        created_at=datetime.now(),
    )
    job_repo.create(job)
    session.commit()
    background.add_task(run_job_background, job.id)
    return {"job_id": job.id, "status": job.status}


@router.get("/{job_id}", summary="查询 Job 状态与结果")
def get_job(job_id: str, job_repo: JobRepoDep) -> dict:
    job = job_repo.get(job_id)
    if job is None:
        raise HTTPException(status_code=404, detail=f"Job {job_id} 不存在")
    return _job_view(job)


@router.get("/{job_id}/events", summary="Job 进度 SSE")
async def job_events(job_id: str) -> StreamingResponse:
    async def gen():
        while True:
            with SessionLocal() as session:
                job = SqlAlchemyJobRepository(session).get(job_id)
            if job is None:
                yield "event: error\ndata: job not found\n\n"
                return
            payload = json.dumps(
                {"job_id": job.id, "status": job.status, "stage": job.stage}, ensure_ascii=False
            )
            yield f"data: {payload}\n\n"
            if job.status in (JobStatus.SUCCESS, JobStatus.FAILED, JobStatus.CANCELLED):
                return
            await asyncio.sleep(0.4)

    return StreamingResponse(gen(), media_type="text/event-stream")