"""
Shared aiohttp ClientSession singleton.

Reuses a single TCP connection pool across all HTTP clients,
avoiding repeated TCP/TLS handshake overhead per request.
"""

import logging
from typing import Optional

import aiohttp

logger = logging.getLogger(__name__)

_session: Optional[aiohttp.ClientSession] = None


async def get_http_session() -> aiohttp.ClientSession:
    """Get or create the shared aiohttp ClientSession."""
    global _session
    if _session is None or _session.closed:
        _session = aiohttp.ClientSession(
            timeout=aiohttp.ClientTimeout(total=30),
        )
    return _session


async def close_http_session() -> None:
    """Close the shared session. Call on app shutdown."""
    global _session
    if _session and not _session.closed:
        await _session.close()
        _session = None