import os
import time
import logging
import psycopg2
from typing import Generator, Any
from psycopg2.pool import ThreadedConnectionPool
from psycopg2.extensions import connection
from contextlib import contextmanager
from functools import lru_cache

from domain.exceptions import DatabaseConnectionError

log = logging.getLogger(__name__)

_MIN_CONN = 1
_MAX_CONN = 10

DB_URI = os.getenv("DATABASE_URI", "postgresql://simugaz:simugaz@db/simugaz")


@lru_cache(maxsize=1)
def get_pool() -> ThreadedConnectionPool:
    return _create_pool(DB_URI)


def _create_pool(
    uri: str, retries: int = 10, base_delay: float = 1.0
) -> ThreadedConnectionPool:
    for attempt in range(retries):
        try:
            pool = ThreadedConnectionPool(_MIN_CONN, _MAX_CONN, uri)
            log.info(
                "Pool PostgreSQL initialisé (%d–%d connexions)", _MIN_CONN, _MAX_CONN
            )
            return pool
        except psycopg2.OperationalError as e:
            delay = min(base_delay * 2**attempt, 30.0)
            log.warning(
                "Attente PostgreSQL (tentative %d/%d) : %s", attempt + 1, retries, e
            )
            time.sleep(delay)
    raise DatabaseConnectionError(
        f"Impossible de se connecter après {retries} tentatives"
    )


@contextmanager
def get_conn() -> Generator[connection, Any, None]:
    pool = get_pool()
    conn = pool.getconn()  # type: ignore
    try:
        yield conn
        conn.commit() # type: ignore
    except Exception:
        conn.rollback()  # type: ignore
        raise
    finally:
        pool.putconn(conn)  # type: ignore