#!/usr/bin/env python2

# -*- coding: utf-8 -*-

""".. currentmodule:: migrate.versioning.util"""

import warnings

import logging

from decorator import decorator

from pkg_resources import EntryPoint

from sqlalchemy import create_engine

from sqlalchemy.engine import Engine

from sqlalchemy.pool import StaticPool

from kallithea.lib.dbmigrate.migrate import exceptions

from kallithea.lib.dbmigrate.migrate.versioning.util.keyedinstance import KeyedInstance

from kallithea.lib.dbmigrate.migrate.versioning.util.importpath import import_path

log = logging.getLogger(__name__)

def load_model(dotted_name):

    """Import module and use module-level variable".

    :param dotted_name: path to model in form of string: ``some.python.module:Class``

    .. versionchanged:: 0.5.4

    """

    if isinstance(dotted_name, basestring):

        if ':' not in dotted_name:

            # backwards compatibility

            warnings.warn('model should be in form of module.model:User '

                'and not module.model.User', exceptions.MigrateDeprecationWarning)

            dotted_name = ':'.join(dotted_name.rsplit('.', 1))

        return EntryPoint.parse('x=%s' % dotted_name).load(False)

    else:

        # Assume it's already loaded.

        return dotted_name

def asbool(obj):

    """Do everything to use object as bool"""

    if isinstance(obj, basestring):

        obj = obj.strip().lower()

        if obj in ['true', 'yes', 'on', 'y', 't', '1']:

            return True

        elif obj in ['false', 'no', 'off', 'n', 'f', '0']:

            return False

        else:

            raise ValueError("String is not true/false: %r" % obj)

    if obj in (True, False):

        return bool(obj)

    else:

        raise ValueError("String is not true/false: %r" % obj)

def guess_obj_type(obj):

    """Do everything to guess object type from string

    .. versionadded: 0.5.4

    """

    result = None

    try:

        result = int(obj)

    except:

        pass

    if result is None:

        try:

            result = asbool(obj)

        except:

            pass

    if result is not None:

        return result

    else:

        return obj

@decorator

def catch_known_errors(f, *a, **kw):

    """Decorator that catches known api errors

    .. versionadded: 0.5.4

    """

    try:

        return f(*a, **kw)

    except exceptions.PathFoundError as e:

        raise exceptions.KnownError("The path %s already exists" % e.args[0])

def construct_engine(engine, **opts):

    """.. versionadded:: 0.5.4

    Constructs and returns SQLAlchemy engine.

    Currently, there are 2 ways to pass create_engine options to :mod:`migrate.versioning.api` functions:

    :param engine: connection string or a existing engine

    :param engine_dict: python dictionary of options to pass to `create_engine`

    :param engine_arg_*: keyword parameters to pass to `create_engine` (evaluated with :func:`migrate.versioning.util.guess_obj_type`)

    :type engine_dict: dict

    :type engine: string or Engine instance

    :type engine_arg_*: string

    :returns: SQLAlchemy Engine

    .. note::

        keyword parameters override ``engine_dict`` values.

    """

    if isinstance(engine, Engine):

        return engine

    elif not isinstance(engine, basestring):

        raise ValueError("you need to pass either an existing engine or a database uri")

    # get options for create_engine

    if opts.get('engine_dict') and isinstance(opts['engine_dict'], dict):

        kwargs = opts['engine_dict']

    else:

        kwargs = dict()

    # DEPRECATED: handle echo the old way

    echo = asbool(opts.get('echo', False))

    if echo:

        warnings.warn('echo=True parameter is deprecated, pass '

            'engine_arg_echo=True or engine_dict={"echo": True}',

            exceptions.MigrateDeprecationWarning)

        kwargs['echo'] = echo

    # parse keyword arguments

    for key, value in opts.iteritems():

        if key.startswith('engine_arg_'):

            kwargs[key[11:]] = guess_obj_type(value)

    log.debug('Constructing engine')

    # TODO: return create_engine(engine, poolclass=StaticPool, **kwargs)

    # seems like 0.5.x branch does not work with engine.dispose and staticpool

    return create_engine(engine, **kwargs)

@decorator

def with_engine(f, *a, **kw):

    """Decorator for :mod:`migrate.versioning.api` functions

    to safely close resources after function usage.

    Passes engine parameters to :func:`construct_engine` and

    resulting parameter is available as kw['engine'].

    Engine is disposed after wrapped function is executed.

    .. versionadded: 0.6.0

    """

    url = a[0]