import contextlib
import itertools
from contextlib import asynccontextmanager
from typing import List, Any, Optional

from sqlalchemy import create_engine
from sqlalchemy.ext.asyncio import create_async_engine, AsyncSession
from sqlalchemy.orm import sessionmaker

from website import settings
from website.handler import Row


# class Row(dict):
#     """A dict that allows for object-like property access syntax."""
#
#     def __getattr__(self, name):
#         try:
#             return self[name]
#         except KeyError:
#             raise AttributeError(name)


def dict_to_obj(d):
    return type('GenericClass', (object,), d)()


def to_json_list(cursor: Any) -> Optional[List[Row]]:
    column_names = list(cursor.keys())
    result = cursor.fetchall()
    if not result:
        return []

    return [Row(itertools.zip_longest(column_names, row)) for row in result]


def to_json(cursor):
    column_names = list(cursor.keys())
    result = cursor.fetchone()

    if not result:
        return {}

    return Row(itertools.zip_longest(column_names, result))


app_engine = create_engine(
    "mysql+pymysql://{}:{}@{}/{}?charset=utf8mb4".format(
        settings.mysql_app["user"],
        settings.mysql_app["password"],
        settings.mysql_app["host"],
        settings.mysql_app["database"],
    ),  # SQLAlchemy 数据库连接串，格式见下面
    echo=bool(settings.SQLALCHEMY_ECHO),  # 是不是要把所执行的SQL打印出来，一般用于调试
    pool_pre_ping=True,
    pool_size=int(settings.SQLALCHEMY_POOL_SIZE),  # 连接池大小
    max_overflow=int(settings.SQLALCHEMY_POOL_MAX_SIZE),  # 连接池最大的大小
    pool_recycle=int(settings.SQLALCHEMY_POOL_RECYCLE),  # 多久时间回收连接
)

Session = sessionmaker(bind=app_engine, expire_on_commit=False)


# Base = declarative_base(app_engine)


@contextlib.contextmanager
def get_session():
    s = Session()
    try:
        yield s
        s.commit()
    except Exception as e:
        s.rollback()
        raise e
    finally:
        s.close()


async_app_engine = create_async_engine(
    "mysql+aiomysql://{}:{}@{}/{}?charset=utf8mb4".format(
        settings.mysql_app["user"],
        settings.mysql_app["password"],
        settings.mysql_app["host"],
        settings.mysql_app["database"],
    ),
    echo=bool(settings.SQLALCHEMY_ECHO),
    pool_pre_ping=True,
    pool_size=int(settings.SQLALCHEMY_POOL_SIZE),
    max_overflow=int(settings.SQLALCHEMY_POOL_MAX_SIZE),
    pool_recycle=int(settings.SQLALCHEMY_POOL_RECYCLE),
)

AsyncSession = sessionmaker(bind=async_app_engine, class_=AsyncSession)


@asynccontextmanager
async def get_async_session():
    async with AsyncSession() as s:
        try:
            yield s
            await s.commit()
        except Exception as e:
            await s.rollback()
            raise e
        finally:
            await s.close()