from fastapi import APIRouter, Request
from fastapi.responses import StreamingResponse
import datetime
import asyncio

router = APIRouter()

@router.get("/sse_ping")
async def sse_ping(request: Request):
    """
    Endpoint for Server-Sent Events.
    """
    async def event_generator():
        while True:
            # If connection to client closes, stop sending events
            if await request.is_disconnected():
                break
            
            # Send message containing current time every second
            current_time = datetime.datetime.now().strftime("%H:%M:%S")
            yield f"data: Server time: {current_time}\n\n" # \n\n is needed to separate events (SSE is text-based)
            await asyncio.sleep(1)

    return StreamingResponse(event_generator(), media_type="text/event-stream") # media_type specifies that this connection is for event streams