/*

 * Copyright (C) 2008 Apple Inc. All Rights Reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY

 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY

 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include "config.h"

#include "StorageMap.h"

#if ENABLE(DOM_STORAGE)

namespace WebCore {

PassRefPtr<StorageMap> StorageMap::create(unsigned quota)

{

    return adoptRef(new StorageMap(quota));

}

StorageMap::StorageMap(unsigned quota)

    : m_iterator(m_map.end())

    , m_iteratorIndex(UINT_MAX)

    , m_quotaSize(quota)  // quota measured in bytes

    , m_currentLength(0)

{

}

PassRefPtr<StorageMap> StorageMap::copy()

{

    RefPtr<StorageMap> newMap = create(m_quotaSize);

    newMap->m_map = m_map;

    return newMap.release();

}

void StorageMap::invalidateIterator()

{

    m_iterator = m_map.end();

    m_iteratorIndex = UINT_MAX;

}

void StorageMap::setIteratorToIndex(unsigned index)

{

    // FIXME: Once we have bidirectional iterators for HashMap we can be more intelligent about this.

    // The requested index will be closest to begin(), our current iterator, or end(), and we

    // can take the shortest route.

    // Until that mechanism is available, we'll always increment our iterator from begin() or current.

    if (m_iteratorIndex == index)

        return;

    if (index < m_iteratorIndex) {

        m_iteratorIndex = 0;

        m_iterator = m_map.begin();

        ASSERT(m_iterator != m_map.end());

    }

    while (m_iteratorIndex < index) {

        ++m_iteratorIndex;

        ++m_iterator;

        ASSERT(m_iterator != m_map.end());

    }

}

unsigned StorageMap::length() const

{

    return m_map.size();

}

String StorageMap::key(unsigned index)

{

    if (index >= length())

        return String();

    setIteratorToIndex(index);

    return m_iterator->first;

}

String StorageMap::getItem(const String& key) const

{

    return m_map.get(key);

}

PassRefPtr<StorageMap> StorageMap::setItem(const String& key, const String& value, String& oldValue, bool& quotaException)

{

    ASSERT(!value.isNull());

    quotaException = false;

    // Implement copy-on-write semantics here.  We're guaranteed that the only refs of StorageMaps belong to Storage objects

    // so if more than one Storage object refs this map, copy it before mutating it.

    if (refCount() > 1) {

        RefPtr<StorageMap> newStorageMap = copy();

        newStorageMap->setItem(key, value, oldValue, quotaException);

        return newStorageMap.release();

    }

    // Quota tracking.  If the quota is enabled and this would go over it, bail.

    oldValue = m_map.get(key);

    unsigned newLength = m_currentLength + value.length() - oldValue.length();

    bool overQuota = newLength > m_quotaSize / sizeof(UChar);

    bool overflow = (newLength > m_currentLength) != (value.length() > oldValue.length());

    ASSERT(!overflow);  // If we're debugging, make a fuss.  But it's still worth checking this in the following if statement.

    if (m_quotaSize != noQuota && (overflow || overQuota)) {

        quotaException = true;

        return 0;

    }

    m_currentLength = newLength;

    pair<HashMap<String, String>::iterator, bool> addResult = m_map.add(key, value);

    if (!addResult.second)

        addResult.first->second = value;

    invalidateIterator();

    return 0;

}

PassRefPtr<StorageMap> StorageMap::removeItem(const String& key, String& oldValue)

{

    // Implement copy-on-write semantics here.  We're guaranteed that the only refs of StorageMaps belong to Storage objects

    // so if more than one Storage object refs this map, copy it before mutating it.

    if (refCount() > 1) {

        RefPtr<StorageMap> newStorage = copy();

        newStorage->removeItem(key, oldValue);

        return newStorage.release();

    }

    oldValue = m_map.take(key);

    if (!oldValue.isNull())

        invalidateIterator();

    // Update quota.

    ASSERT(m_currentLength - oldValue.length() <= m_currentLength);

    m_currentLength -= oldValue.length();

    return 0;

}

bool StorageMap::contains(const String& key) const

{

    return m_map.contains(key);

}

void StorageMap::importItem(const String& key, const String& value)

{

    // Be sure to copy the keys/values as items imported on a background thread are destined

    // to cross a thread boundary

    pair<HashMap<String, String>::iterator, bool> result = m_map.add(key.threadsafeCopy(), String());

    if (result.second)

        result.first->second = value.threadsafeCopy();

    // Update quota.

    ASSERT(m_currentLength + value.length() >= m_currentLength);

    m_currentLength += value.length();

}

}

#endif // ENABLE(DOM_STORAGE)