"""
db.py — Пул соединений с keepalive, проверкой живости, переподключением.
"""

import os
import logging
from psycopg2 import pool as _pgpool
from psycopg2 import OperationalError, InterfaceError
import psycopg2

logger = logging.getLogger(__name__)

_pool = None


def _get_pool():
    global _pool
    if _pool is None:
        _pool = _pgpool.ThreadedConnectionPool(
            minconn=2,
            maxconn=10,
            host=os.getenv("DB_HOST"),
            port=os.getenv("DB_PORT", 5432),
            dbname=os.getenv("DB_NAME"),
            user=os.getenv("DB_USER"),
            password=os.getenv("DB_PASS"),
            sslmode=os.getenv("DB_SSLMODE", "disable"),
            connect_timeout=10,
            keepalives=1,
            keepalives_idle=30,
            keepalives_interval=10,
            keepalives_count=3,
        )
    return _pool


def _pg_connect(dbname):
    """Сырое подключение к ЛЮБОЙ базе (для /test createdb)."""
    return psycopg2.connect(
        host=os.getenv("DB_HOST"),
        port=os.getenv("DB_PORT", 5432),
        dbname=dbname,
        user=os.getenv("DB_USER"),
        password=os.getenv("DB_PASS"),
        sslmode=os.getenv("DB_SSLMODE", "disable"),
    )


def connect():
    """Подключение из пула с проверкой живости."""
    pool = _get_pool()
    for attempt in range(3):
        try:
            conn = pool.getconn()
            # Проверить живость
            cur = conn.cursor()
            cur.execute("SELECT 1")
            cur.close()
            return conn, None
        except (OperationalError, InterfaceError) as e:
            if conn:
                try: pool.putconn(conn, close=True)
                except: pass
            if attempt == 2:
                return None, str(e)
        except Exception as e:
            if conn:
                try: pool.putconn(conn)
                except: pass
            return None, str(e)
    return None, "pool exhausted"


def put_conn(conn):
    """Вернуть соединение в пул."""
    try:
        _get_pool().putconn(conn)
    except Exception:
        pass


def query(sql_text, params=None):
    conn, err = connect()
    if err:
        return None, f"connect: {err}"
    try:
        cur = conn.cursor()
        cur.execute(sql_text, params)
        rows = cur.fetchall()
        cols = [desc[0] for desc in cur.description] if cur.description else []
        cur.close()
        return {"columns": cols, "rows": [list(r) for r in rows]}, None
    except Exception as e:
        return None, str(e)
    finally:
        put_conn(conn)


def execute(sql_text, params=None):
    conn, err = connect()
    if err:
        return None, f"connect: {err}"
    try:
        cur = conn.cursor()
        cur.execute(sql_text, params)
        conn.commit()
        rowcount = cur.rowcount
        cur.close()
        return rowcount, None
    except Exception as e:
        try: conn.rollback()
        except: pass
        return None, str(e)
    finally:
        put_conn(conn)


def query_one(sql_text, params=None):
    result, err = query(sql_text, params)
    if err:
        return None, err
    rows = result["rows"]
    if not rows:
        return None, None
    return dict(zip(result["columns"], rows[0])), None