"""Spawn-safe HTTP/SSE fixture, controlled only through a test-owned directory."""
import asyncio
from contextlib import asynccontextmanager
import json
import os
from pathlib import Path
import time

from fastapi import FastAPI
from starlette.responses import StreamingResponse


@asynccontextmanager
async def lifespan(app: FastAPI):
    directory = Path(os.environ["SCADA_HANDOFF_FIXTURE_DIR"])
    pid = os.getpid()
    app.state.directory = directory
    app.state.version = (directory / "version").read_text().strip()
    mode = (directory / "startup-mode").read_text().strip()
    (directory / f"started-{pid}").write_text(app.state.version)
    if mode == "fail":
        raise RuntimeError("test candidate startup failed")
    if mode == "delay":
        await asyncio.sleep(0.3)
    while mode == "wait" and not (directory / "allow-startup").exists():
        await asyncio.sleep(0.02)
    try:
        yield
    finally:
        (directory / f"stopped-{pid}").write_text(app.state.version)


app = FastAPI(lifespan=lifespan)


async def readiness_check() -> bool:
    directory = Path(os.environ["SCADA_HANDOFF_FIXTURE_DIR"])
    ready = (directory / "readiness").read_text().strip() == "true"
    (directory / f"checked-{os.getpid()}").write_text(str(ready).lower())
    await asyncio.sleep(.05)
    return ready


@app.get("/health")
async def health():
    return {"pid": os.getpid(), "version": app.state.version}


@app.get("/events")
async def events():
    async def stream():
        directory = app.state.directory
        pid = os.getpid()
        while not (directory / f"release-{pid}").exists() and not (directory / "release-all").exists():
            payload = {"pid": pid, "version": app.state.version, "time_ns": time.time_ns()}
            yield f"data: {json.dumps(payload)}\n\n"
            await asyncio.sleep(0.025)
        yield f"event: complete\ndata: {json.dumps({'pid': pid})}\n\n"

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