from contextlib import contextmanager
from typing import Any, Optional

import psycopg2
from psycopg2 import pool
from psycopg2.extras import RealDictCursor, Json

from app.config import settings

_connection_pool: Optional[pool.SimpleConnectionPool] = None


def init_pool(minconn: int = 1, maxconn: int = 10) -> None:
    global _connection_pool
    if _connection_pool is None:
        _connection_pool = pool.SimpleConnectionPool(
            minconn,
            maxconn,
            dsn=settings.database_dsn,
        )


def close_pool() -> None:
    global _connection_pool
    if _connection_pool is not None:
        _connection_pool.closeall()
        _connection_pool = None


@contextmanager
def get_connection():
    if _connection_pool is None:
        init_pool()
    conn = _connection_pool.getconn()
    try:
        yield conn
        conn.commit()
    except Exception:
        conn.rollback()
        raise
    finally:
        _connection_pool.putconn(conn)


def fetch_all(query: str, params: Optional[tuple] = None) -> list[dict[str, Any]]:
    with get_connection() as conn:
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            cur.execute(query, params)
            return [dict(row) for row in cur.fetchall()]


def fetch_one(query: str, params: Optional[tuple] = None) -> Optional[dict[str, Any]]:
    with get_connection() as conn:
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            cur.execute(query, params)
            row = cur.fetchone()
            return dict(row) if row else None


def execute_returning(query: str, params: Optional[tuple] = None) -> Optional[dict[str, Any]]:
    with get_connection() as conn:
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            cur.execute(query, params)
            row = cur.fetchone()
            return dict(row) if row else None


def execute(query: str, params: Optional[tuple] = None) -> int:
    with get_connection() as conn:
        with conn.cursor() as cur:
            cur.execute(query, params)
            return cur.rowcount


def json_param(value: Any) -> Json:
    return Json(value or {})