import sys, types, weakref
from collections import deque
import config
from sqlalchemy.util import function_named, callable
import re
import warnings

class ConnectionKiller(object):
    def __init__(self):
        self.proxy_refs = weakref.WeakKeyDictionary()

    def checkout(self, dbapi_con, con_record, con_proxy):
        self.proxy_refs[con_proxy] = True

    def _apply_all(self, methods):
        # must copy keys atomically
        for rec in self.proxy_refs.keys():
            if rec is not None and rec.is_valid:
                try:
                    for name in methods:
                        if callable(name):
                            name(rec)
                        else:
                            getattr(rec, name)()
                except (SystemExit, KeyboardInterrupt):
                    raise
                except Exception, e:
                    warnings.warn("testing_reaper couldn't close connection: %s" % e)

    def rollback_all(self):
        self._apply_all(('rollback',))

    def close_all(self):
        self._apply_all(('rollback', 'close'))

    def assert_all_closed(self):
        for rec in self.proxy_refs:
            if rec.is_valid:
                assert False

testing_reaper = ConnectionKiller()

def drop_all_tables(metadata):
    testing_reaper.close_all()
    metadata.drop_all()
    
def assert_conns_closed(fn):
    def decorated(*args, **kw):
        try:
            fn(*args, **kw)
        finally:
            testing_reaper.assert_all_closed()
    return function_named(decorated, fn.__name__)

def rollback_open_connections(fn):
    """Decorator that rolls back all open connections after fn execution."""

    def decorated(*args, **kw):
        try:
            fn(*args, **kw)
        finally:
            testing_reaper.rollback_all()
    return function_named(decorated, fn.__name__)

def close_first(fn):
    """Decorator that closes all connections before fn execution."""
    def decorated(*args, **kw):
        testing_reaper.close_all()
        fn(*args, **kw)
    return function_named(decorated, fn.__name__)
    
    
def close_open_connections(fn):
    """Decorator that closes all connections after fn execution."""

    def decorated(*args, **kw):
        try:
            fn(*args, **kw)
        finally:
            testing_reaper.close_all()
    return function_named(decorated, fn.__name__)

def all_dialects(exclude=None):
    import sqlalchemy.databases as d
    for name in d.__all__:
        # TEMPORARY
        if exclude and name in exclude:
            continue
        mod = getattr(d, name, None)
        if not mod:
            mod = getattr(__import__('sqlalchemy.databases.%s' % name).databases, name)
        yield mod.dialect()
        
class ReconnectFixture(object):
    def __init__(self, dbapi):
        self.dbapi = dbapi
        self.connections = []

    def __getattr__(self, key):
        return getattr(self.dbapi, key)

    def connect(self, *args, **kwargs):
        conn = self.dbapi.connect(*args, **kwargs)
        self.connections.append(conn)
        return conn

    def shutdown(self):
        for c in list(self.connections):
            c.close()
        self.connections = []

def reconnecting_engine(url=None, options=None):
    url = url or config.db_url
    dbapi = config.db.dialect.dbapi
    if not options:
        options = {}
    options['module'] = ReconnectFixture(dbapi)
    engine = testing_engine(url, options)
    engine.test_shutdown = engine.dialect.dbapi.shutdown
    return engine

def testing_engine(url=None, options=None):
    """Produce an engine configured by --options with optional overrides."""

    from sqlalchemy import create_engine
    from sqlalchemy.test.assertsql import asserter

    url = url or config.db_url
    options = options or config.db_opts

    options.setdefault('proxy', asserter)
    
    listeners = options.setdefault('listeners', [])
    listeners.append(testing_reaper)

    engine = create_engine(url, **options)
    
    # may want to call this, results
    # in first-connect initializers
    #engine.connect()
    
    return engine

def utf8_engine(url=None, options=None):
    """Hook for dialects or drivers that don't handle utf8 by default."""

    from sqlalchemy.engine import url as engine_url

    if config.db.driver == 'mysqldb':
        dbapi_ver = config.db.dialect.dbapi.version_info
        if (dbapi_ver < (1, 2, 1) or
            dbapi_ver in ((1, 2, 1, 'gamma', 1), (1, 2, 1, 'gamma', 2),
                          (1, 2, 1, 'gamma', 3), (1, 2, 1, 'gamma', 5))):
            raise RuntimeError('Character set support unavailable with this '
                               'driver version: %s' % repr(dbapi_ver))
        else:
            url = url or config.db_url
            url = engine_url.make_url(url)
            url.query['charset'] = 'utf8'
            url.query['use_unicode'] = '0'
            url = str(url)

    return testing_engine(url, options)

def mock_engine(dialect_name=None):
    """Provides a mocking engine based on the current testing.db.
    
    This is normally used to test DDL generation flow as emitted
    by an Engine.
    
    It should not be used in other cases, as assert_compile() and
    assert_sql_execution() are much better choices with fewer 
    moving parts.
    
    """
    
    from sqlalchemy import create_engine
    
    if not dialect_name:
        dialect_name = config.db.name

    buffer = []
    def executor(sql, *a, **kw):
        buffer.append(sql)
    def assert_sql(stmts):
        recv = [re.sub(r'[\n\t]', '', str(s)) for s in buffer]
        assert  recv == stmts, recv
        
    engine = create_engine(dialect_name + '://',
                           strategy='mock', executor=executor)
    assert not hasattr(engine, 'mock')
    engine.mock = buffer
    engine.assert_sql = assert_sql
    return engine

class ReplayableSession(object):
    """A simple record/playback tool.

    This is *not* a mock testing class.  It only records a session for later
    playback and makes no assertions on call consistency whatsoever.  It's
    unlikely to be suitable for anything other than DB-API recording.

    """

    Callable = object()
    NoAttribute = object()
    Natives = set([getattr(types, t)
                   for t in dir(types) if not t.startswith('_')]). \
                   difference([getattr(types, t)
                            # Py3K
                            #for t in ('FunctionType', 'BuiltinFunctionType',
                            #          'MethodType', 'BuiltinMethodType',
                            #          'LambdaType', )])
                            
                            # Py2K
                               for t in ('FunctionType', 'BuiltinFunctionType',
                                         'MethodType', 'BuiltinMethodType',
                                         'LambdaType', 'UnboundMethodType',)])
                            # end Py2K
    def __init__(self):
        self.buffer = deque()

    def recorder(self, base):
        return self.Recorder(self.buffer, base)

    def player(self):
        return self.Player(self.buffer)

    class Recorder(object):
        def __init__(self, buffer, subject):
            self._buffer = buffer
            self._subject = subject

        def __call__(self, *args, **kw):
            subject, buffer = [object.__getattribute__(self, x)
                               for x in ('_subject', '_buffer')]

            result = subject(*args, **kw)
            if type(result) not in ReplayableSession.Natives:
                buffer.append(ReplayableSession.Callable)
                return type(self)(buffer, result)
            else:
                buffer.append(result)
                return result
        
        @property
        def _sqla_unwrap(self):
            return self._subject
            
        def __getattribute__(self, key):
            try:
                return object.__getattribute__(self, key)
            except AttributeError:
                pass

            subject, buffer = [object.__getattribute__(self, x)
                               for x in ('_subject', '_buffer')]
            try:
                result = type(subject).__getattribute__(subject, key)
            except AttributeError:
                buffer.append(ReplayableSession.NoAttribute)
                raise
            else:
                if type(result) not in ReplayableSession.Natives:
                    buffer.append(ReplayableSession.Callable)
                    return type(self)(buffer, result)
                else:
                    buffer.append(result)
                    return result

    class Player(object):
        def __init__(self, buffer):
            self._buffer = buffer

        def __call__(self, *args, **kw):
            buffer = object.__getattribute__(self, '_buffer')
            result = buffer.popleft()
            if result is ReplayableSession.Callable:
                return self
            else:
                return result
        
        @property
        def _sqla_unwrap(self):
            return None
            
        def __getattribute__(self, key):
            try:
                return object.__getattribute__(self, key)
            except AttributeError:
                pass
            buffer = object.__getattribute__(self, '_buffer')
            result = buffer.popleft()
            if result is ReplayableSession.Callable:
                return self
            elif result is ReplayableSession.NoAttribute:
                raise AttributeError(key)
            else:
                return result

