import datetime

import traceback

import MySQLdb

class Connection:

  def __init__(self, pool, internal, readonly = True):

    self.pool = pool

    self.internal = internal

    self.readonly = readonly

    self.finished = True

    self.begin()

  def cursor(self):

    assert not self.finished

    return self.internal.cursor(MySQLdb.cursors.DictCursor)

  def insert_id(self, *args, **kwargs):

    assert not self.finished

    return self.internal.insert_id(*args, **kwargs)

  def escape(self, *args, **kwargs):

    r = self.internal.escape(*args, **kwargs)

    return r.decode("utf8") if type(r) is bytes else r

  def escape_string(self, *args, **kwargs):

    r = self.internal.escape_string(*args, **kwargs)

    return r.decode("utf8") if type(r) is bytes else r

  def begin(self):

    assert self.finished

    self.finished = False

    with self.cursor() as cursor:

      cursor.execute("SET autocommit=0")

    if self.readonly:

      with self.cursor() as cursor:

        cursor.execute("SET TRANSACTION ISOLATION LEVEL REPEATABLE READ")

      with self.cursor() as cursor:

        cursor.execute("START TRANSACTION READ ONLY, WITH CONSISTENT SNAPSHOT")

    else:

      with self.cursor() as cursor:

        cursor.execute("SET TRANSACTION ISOLATION LEVEL SERIALIZABLE")

      with self.cursor() as cursor:

        cursor.execute("START TRANSACTION READ WRITE")

    self.now = datetime.datetime.now(self.pool.server.config['timezone'])

  def commit(self):

    assert not self.finished

    self.internal.commit()

    self.finished = True

  def rollback(self):

    assert not self.finished

    self.internal.rollback()

    self.finished = True

  def release(self):

    if not self.finished:

      try: self.rollback()

      except Exception as e:

        print(traceback.format_exc())

        print(e)