# mssql/pymssql.py
# Copyright (C) 2005-2014 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 wraps FreeTDS (a C library) and provides a
DB-API interface, which this dialect uses.

Note that if you experience problems or limitations when using this dialect,
the problem could be in the dialect, in pymssql, or in FreeTDS (or it could
even be a limitation of SQL Server). So it would be great if you could isolate
the problem before filing tickets with these projects.

Please consult the pymssql documentation for further information.

"""
from .base import MSDialect
from ... import types as sqltypes, util, processors
import re


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 MSDialect_pymssql(MSDialect):
    supports_sane_rowcount = False
    driver = 'pymssql'

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

    @classmethod
    def dbapi(cls):
        module = __import__('pymssql')
        # pymmsql doesn't have a Binary method.  we use string
        # TODO: monkeypatching here is less than ideal
        module.Binary = lambda x: x if hasattr(x, 'decode') else str(x)

        client_ver = tuple(int(x) for x in module.__version__.split("."))
        if client_ver < (1, ):
            util.warn("The pymssql dialect expects at least "
                            "the 1.0 series of the pymssql DBAPI.")
        return module

    def __init__(self, **params):
        super(MSDialect_pymssql, self).__init__(**params)
        self.use_scope_identity = True

    def _get_server_version_info(self, connection):
        vers = connection.scalar("select @@version")
        m = re.match(
            r"Microsoft SQL Server.*? - (\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"
        ):
            if msg in str(e):
                return True
        else:
            return False

dialect = MSDialect_pymssql