from __future__ import annotations

import asyncio
import json
import time
from datetime import datetime, timezone
from typing import Any, Dict, Optional

from fastapi import APIRouter, Depends, Request
from fastapi.responses import StreamingResponse

from ..auth import get_current_user_event_stream
from . import requests as requests_router
from .status import services_status

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


def _sse_json(payload: Dict[str, Any]) -> str:
    return f"data: {json.dumps(payload, ensure_ascii=True, separators=(',', ':'), default=str)}\n\n"


@router.get("/stream")
async def events_stream(
    request: Request,
    recent_days: int = 90,
    user: Dict[str, Any] = Depends(get_current_user_event_stream),
) -> StreamingResponse:
    recent_days = max(0, min(int(recent_days or 90), 3650))
    recent_take = 50 if user.get("role") == "admin" else 6

    async def event_generator():
        yield "retry: 2000\n\n"
        last_recent_signature: Optional[str] = None
        last_services_signature: Optional[str] = None
        next_recent_at = 0.0
        next_services_at = 0.0
        heartbeat_counter = 0

        while True:
            if await request.is_disconnected():
                break

            now = time.monotonic()
            sent_any = False

            if now >= next_recent_at:
                next_recent_at = now + 15.0
                try:
                    recent_payload = await requests_router.recent_requests(
                        take=recent_take,
                        skip=0,
                        days=recent_days,
                        user=user,
                    )
                    results = recent_payload.get("results") if isinstance(recent_payload, dict) else []
                    payload = {
                        "type": "home_recent",
                        "ts": datetime.now(timezone.utc).isoformat(),
                        "days": recent_days,
                        "results": results if isinstance(results, list) else [],
                    }
                except Exception as exc:
                    payload = {
                        "type": "home_recent",
                        "ts": datetime.now(timezone.utc).isoformat(),
                        "days": recent_days,
                        "error": str(exc),
                    }
                signature = json.dumps(payload, ensure_ascii=True, separators=(",", ":"), default=str)
                if signature != last_recent_signature:
                    last_recent_signature = signature
                    yield _sse_json(payload)
                    sent_any = True

            if now >= next_services_at:
                next_services_at = now + 30.0
                try:
                    status_payload = await services_status()
                    payload = {
                        "type": "home_services",
                        "ts": datetime.now(timezone.utc).isoformat(),
                        "status": status_payload,
                    }
                except Exception as exc:
                    payload = {
                        "type": "home_services",
                        "ts": datetime.now(timezone.utc).isoformat(),
                        "error": str(exc),
                    }
                signature = json.dumps(payload, ensure_ascii=True, separators=(",", ":"), default=str)
                if signature != last_services_signature:
                    last_services_signature = signature
                    yield _sse_json(payload)
                    sent_any = True

            if sent_any:
                heartbeat_counter = 0
            else:
                heartbeat_counter += 1
                if heartbeat_counter >= 15:
                    yield ": ping\n\n"
                    heartbeat_counter = 0

            await asyncio.sleep(1.0)

    headers = {
        "Cache-Control": "no-cache",
        "Connection": "keep-alive",
        "X-Accel-Buffering": "no",
    }
    return StreamingResponse(event_generator(), media_type="text/event-stream", headers=headers)