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)