# MySQL Connector/Python - MySQL driver written in Python.
# Copyright (c) 2009, 2014, Oracle and/or its affiliates. All rights reserved.

# MySQL Connector/Python is licensed under the terms of the GPLv2
# <http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>, like most
# MySQL Connectors. There are special exceptions to the terms and
# conditions of the GPLv2 as it is applied to this software, see the
# FOSS License Exception
# <http://www.mysql.com/about/legal/licensing/foss-exception.html>.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

"""
MySQL Connector/Python - MySQL drive written in Python
"""

from . import version
from .connection import MySQLConnection
from .errors import (  # pylint: disable=W0622
    Error, Warning, InterfaceError, DatabaseError,
    NotSupportedError, DataError, IntegrityError, ProgrammingError,
    OperationalError, InternalError, custom_error_exception, PoolError)
from .constants import FieldFlag, FieldType, CharacterSet, \
    RefreshOption, ClientFlag
from .dbapi import (
    Date, Time, Timestamp, Binary, DateFromTicks, DateFromTicks,
    TimestampFromTicks, TimeFromTicks,
    STRING, BINARY, NUMBER, DATETIME, ROWID,
    apilevel, threadsafety, paramstyle)
from .optionfiles import read_option_files

_CONNECTION_POOLS = {}


def _get_pooled_connection(**kwargs):
    """Return a pooled MySQL connection"""
    # If no pool name specified, generate one
    from .pooling import (
        MySQLConnectionPool, generate_pool_name,
        CONNECTION_POOL_LOCK)

    try:
        pool_name = kwargs['pool_name']
    except KeyError:
        pool_name = generate_pool_name(**kwargs)

    # Setup the pool, ensuring only 1 thread can update at a time
    with CONNECTION_POOL_LOCK:
        if pool_name not in _CONNECTION_POOLS:
            _CONNECTION_POOLS[pool_name] = MySQLConnectionPool(**kwargs)
        elif isinstance(_CONNECTION_POOLS[pool_name], MySQLConnectionPool):
            # pool_size must be the same
            check_size = _CONNECTION_POOLS[pool_name].pool_size
            if ('pool_size' in kwargs
                    and kwargs['pool_size'] != check_size):
                raise PoolError("Size can not be changed "
                                "for active pools.")

    # Return pooled connection
    try:
        return _CONNECTION_POOLS[pool_name].get_connection()
    except AttributeError:
        raise InterfaceError(
            "Failed getting connection from pool '{0}'".format(pool_name))


def _get_failover_connection(**kwargs):
    """Return a MySQL connection and try to failover if needed

    An InterfaceError is raise when no MySQL is available. ValueError is
    raised when the failover server configuration contains an illegal
    connection argument. Supported arguments are user, password, host, port,
    unix_socket and database. ValueError is also raised when the failover
    argument was not provided.

    Returns MySQLConnection instance.
    """
    config = kwargs.copy()
    try:
        failover = config['failover']
    except KeyError:
        raise ValueError('failover argument not provided')
    del config['failover']

    support_cnx_args = set(
        ['user', 'password', 'host', 'port', 'unix_socket',
         'database', 'pool_name', 'pool_size'])

    # First check if we can add all use the configuration
    for server in failover:
        diff = set(server.keys()) - support_cnx_args
        if diff:
            raise ValueError(
                "Unsupported connection argument {0} in failover: {1}".format(
                    's' if len(diff) > 1 else '',
                    ', '.join(diff)))

    for server in failover:
        new_config = config.copy()
        new_config.update(server)
        try:
            return connect(**new_config)
        except Error:
            # If we failed to connect, we try the next server
            pass

    raise InterfaceError("Could not failover: no MySQL server available")


def connect(*args, **kwargs):
    """Create or get a MySQL connection object

    In its simpliest form, Connect() will open a connection to a
    MySQL server and return a MySQLConnection object.

    When any connection pooling arguments are given, for example pool_name
    or pool_size, a pool is created or a previously one is used to return
    a PooledMySQLConnection.

    Returns MySQLConnection or PooledMySQLConnection.
    """
    # Option files
    if 'option_files' in kwargs:
        new_config = read_option_files(**kwargs)
        return connect(**new_config)

    if all(['fabric' in kwargs, 'failover' in kwargs]):
        raise InterfaceError("fabric and failover arguments can not be used")

    if 'fabric' in kwargs:
        if 'pool_name' in kwargs:
            raise AttributeError("'pool_name' argument is not supported with "
                                 " MySQL Fabric. Use 'pool_size' instead.")
        from .fabric import connect as fabric_connect
        return fabric_connect(*args, **kwargs)

    # Failover
    if 'failover' in kwargs:
        return _get_failover_connection(**kwargs)

    # Pooled connections
    try:
        from .pooling import CNX_POOL_ARGS
        if any([key in kwargs for key in CNX_POOL_ARGS]):
            return _get_pooled_connection(**kwargs)
    except NameError:
        # No pooling
        pass

    # Regular connection
    return MySQLConnection(*args, **kwargs)
Connect = connect  # pylint: disable=C0103

__version_info__ = version.VERSION
__version__ = version.VERSION_TEXT

__all__ = [
    'MySQLConnection', 'Connect', 'custom_error_exception',

    # Some useful constants
    'FieldType', 'FieldFlag', 'ClientFlag', 'CharacterSet', 'RefreshOption',

    # Error handling
    'Error', 'Warning',
    'InterfaceError', 'DatabaseError',
    'NotSupportedError', 'DataError', 'IntegrityError', 'ProgrammingError',
    'OperationalError', 'InternalError',

    # DBAPI PEP 249 required exports
    'connect', 'apilevel', 'threadsafety', 'paramstyle',
    'Date', 'Time', 'Timestamp', 'Binary',
    'DateFromTicks', 'DateFromTicks', 'TimestampFromTicks', 'TimeFromTicks',
    'STRING', 'BINARY', 'NUMBER',
    'DATETIME', 'ROWID',
    ]
