##############################################################################
#
# Copyright (c) 2004 Zope Corporation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE
#
##############################################################################
"""A storage used for unittests.

The primary purpose of this module is to have a minimal multi-version
storage to use for unit tests.  MappingStorage isn't sufficient.
Since even a minimal storage has some complexity, we run standard
storage tests against the test storage.
"""

import bisect
import threading
import unittest

from ZODB.BaseStorage import BaseStorage
from ZODB import POSException
from ZODB.utils import z64

from ZODB.tests import StorageTestBase
from ZODB.tests \
     import BasicStorage, MTStorage, Synchronization, PackableStorage, \
     RevisionStorage

class Transaction(object):
    """Hold data for current transaction for MinimalMemoryStorage."""

    def __init__(self, tid):
        self.index = {}
        self.tid = tid

    def store(self, oid, data):
        self.index[(oid, self.tid)] = data

    def cur(self):
        return dict.fromkeys([oid for oid, tid in self.index.keys()], self.tid)

class MinimalMemoryStorage(BaseStorage, object):
    """Simple in-memory storage that supports revisions.

    This storage is needed to test multi-version concurrency control.
    It is similar to MappingStorage, but keeps multiple revisions.  It
    does not support versions.  It doesn't implement operations like
    pack(), because they aren't necessary for testing.
    """

    def __init__(self):
        super(MinimalMemoryStorage, self).__init__("name")
        # _index maps oid, tid pairs to data records
        self._index = {}
        # _cur maps oid to current tid
        self._cur = {}

    def isCurrent(self, oid, serial):
        return serial == self._cur[oid]

    def hook(self, oid, tid, version):
        # A hook for testing
        pass

    def __len__(self):
        return len(self._index)

    def _clear_temp(self):
        pass

    def loadEx(self, oid, version):
        self._lock_acquire()
        try:
            assert not version
            tid = self._cur[oid]
            self.hook(oid, tid, version)
            return self._index[(oid, tid)], tid, ""
        finally:
            self._lock_release()

    def load(self, oid, version):
        return self.loadEx(oid, version)[:2]

    def _begin(self, tid, u, d, e):
        self._txn = Transaction(tid)

    def store(self, oid, serial, data, v, txn):
        if txn is not self._transaction:
            raise POSException.StorageTransactionError(self, txn)
        assert not v
        if self._cur.get(oid) != serial:
            if not (serial is None or self._cur.get(oid) in [None, z64]):
                raise POSException.ConflictError(
                    oid=oid, serials=(self._cur.get(oid), serial), data=data)
        self._txn.store(oid, data)
        return self._tid

    def _abort(self):
        del self._txn

    def _finish(self, tid, u, d, e):
        self._lock_acquire()
        try:
            self._index.update(self._txn.index)
            self._cur.update(self._txn.cur())
            self._ltid = self._tid
        finally:
            self._lock_release()

    def lastTransaction(self):
        return self._ltid

    def loadBefore(self, the_oid, the_tid):
        # It's okay if loadBefore() is really expensive, because this
        # storage is just used for testing.
        self._lock_acquire()
        try:
            tids = [tid for oid, tid in self._index if oid == the_oid]
            if not tids:
                raise KeyError(the_oid)
            tids.sort()
            i = bisect.bisect_left(tids, the_tid) - 1
            if i == -1:
                return None
            tid = tids[i]
            j = i + 1
            if j == len(tids):
                end_tid = None
            else:
                end_tid = tids[j]
            return self._index[(the_oid, tid)], tid, end_tid
        finally:
            self._lock_release()

    def loadSerial(self, oid, serial):
        self._lock_acquire()
        try:
            return self._index[(oid, serial)]
        finally:
            self._lock_release()

class MinimalTestSuite(StorageTestBase.StorageTestBase,
                       BasicStorage.BasicStorage,
                       MTStorage.MTStorage,
                       Synchronization.SynchronizedStorage,
                       RevisionStorage.RevisionStorage,
                       ):

    def setUp(self):
        self._storage = MinimalMemoryStorage()

    # we don't implement undo

    def checkLoadBeforeUndo(self):
        pass

def test_suite():
    return unittest.makeSuite(MinimalTestSuite, "check")
