import datetime

from sqlalchemy.event import listen
from sqlalchemy.pool import Pool, QueuePool

from paste.db import engine

AsyncPoolMaxCheckOut = 0
"""
异步连接池最大连接数量。
"""

AsyncPoolMaxCheckOutAt = datetime.datetime.now()
"""
异步连接池最大连接数量发生时间。
"""

GlobalPoolMaxCheckOut = 0
"""
普通连接池最大连接数量。
"""

GlobalPoolMaxCheckOutAt = datetime.datetime.now()
"""
普通连接池最大连接数量发生时间。
"""


def on_checkout(dbapi_connection, connection_record, connection_proxy):
    """
    当取用连接池中的连接后，立即执行的事件。这里用来记录取用峰值数据。
    """
    async_pool: QueuePool = engine.async_connect_engine().pool
    global_pool = engine.connect_engine().pool
    assert isinstance(global_pool, QueuePool), f"引擎类型错误."

    global AsyncPoolMaxCheckOut
    global AsyncPoolMaxCheckOutAt
    global GlobalPoolMaxCheckOut
    global GlobalPoolMaxCheckOutAt

    _async_checkout = async_pool.checkedout()
    if AsyncPoolMaxCheckOut < _async_checkout:
        AsyncPoolMaxCheckOut = _async_checkout
        AsyncPoolMaxCheckOutAt = datetime.datetime.now()

    _global_checkout = global_pool.checkedout()
    if GlobalPoolMaxCheckOut < _global_checkout:
        GlobalPoolMaxCheckOut = _global_checkout
        GlobalPoolMaxCheckOutAt = datetime.datetime.now()


def bind_listener():
    listen(Pool, 'checkout', on_checkout)