# mssql/pymssql.py
# Copyright (C) 2005-2019 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php

"""
.. dialect:: mssql+pymssql
    :name: pymssql
    :dbapi: pymssql
    :connectstring: mssql+pymssql://<username>:<password>@<freetds_name>/?charset=utf8
    :url: http://pymssql.org/

pymssql is a Python module that provides a Python DBAPI interface around
`FreeTDS <http://www.freetds.org/>`_.  Compatible builds are available for
Linux, MacOSX and Windows platforms.

Modern versions of this driver work very well with SQL Server and
FreeTDS from Linux and is highly recommended.

"""  # noqa
import re

from .base import MSDialect
from .base import MSIdentifierPreparer
from ... import processors
from ... import types as sqltypes
from ... import util


class _MSNumeric_pymssql(sqltypes.Numeric):
    def result_processor(self, dialect, type_):
        if not self.asdecimal:
            return processors.to_float
        else:
            return sqltypes.Numeric.result_processor(self, dialect, type_)


class MSIdentifierPreparer_pymssql(MSIdentifierPreparer):
    def __init__(self, dialect):
        super(MSIdentifierPreparer_pymssql, self).__init__(dialect)
        # pymssql has the very unusual behavior that it uses pyformat
        # yet does not require that percent signs be doubled
        self._double_percents = False


class MSDialect_pymssql(MSDialect):
    supports_native_decimal = True
    driver = "pymssql"

    preparer = MSIdentifierPreparer_pymssql

    colspecs = util.update_copy(
        MSDialect.colspecs,
        {sqltypes.Numeric: _MSNumeric_pymssql, sqltypes.Float: sqltypes.Float},
    )

    @classmethod
    def dbapi(cls):
        module = __import__("pymssql")
        # pymmsql < 2.1.1 doesn't have a Binary method.  we use string
        client_ver = tuple(int(x) for x in module.__version__.split("."))
        if client_ver < (2, 1, 1):
            # TODO: monkeypatching here is less than ideal
            module.Binary = lambda x: x if hasattr(x, "decode") else str(x)

        if client_ver < (1,):
            util.warn(
                "The pymssql dialect expects at least "
                "the 1.0 series of the pymssql DBAPI."
            )
        return module

    def _get_server_version_info(self, connection):
        vers = connection.scalar("select @@version")
        m = re.match(r"Microsoft .*? - (\d+).(\d+).(\d+).(\d+)", vers)
        if m:
            return tuple(int(x) for x in m.group(1, 2, 3, 4))
        else:
            return None

    def create_connect_args(self, url):
        opts = url.translate_connect_args(username="user")
        opts.update(url.query)
        port = opts.pop("port", None)
        if port and "host" in opts:
            opts["host"] = "%s:%s" % (opts["host"], port)
        return [[], opts]

    def is_disconnect(self, e, connection, cursor):
        for msg in (
            "Adaptive Server connection timed out",
            "Net-Lib error during Connection reset by peer",
            "message 20003",  # connection timeout
            "Error 10054",
            "Not connected to any MS SQL server",
            "Connection is closed",
            "message 20006",  # Write to the server failed
            "message 20017",  # Unexpected EOF from the server
            "message 20047",  # DBPROCESS is dead or not enabled
        ):
            if msg in str(e):
                return True
        else:
            return False

    def set_isolation_level(self, connection, level):
        if level == "AUTOCOMMIT":
            connection.autocommit(True)
        else:
            connection.autocommit(False)
            super(MSDialect_pymssql, self).set_isolation_level(
                connection, level
            )


dialect = MSDialect_pymssql
