/*
 * Copyright (C) 2016 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. AND ITS CONTRIBUTORS ``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 ITS 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 "WebResourceLoadStatisticsStore.h"

#include "WebProcessMessages.h"
#include "WebProcessPool.h"
#include "WebResourceLoadStatisticsStoreMessages.h"
#include <WebCore/KeyedCoding.h>
#include <WebCore/ResourceLoadStatistics.h>
#include <wtf/threads/BinarySemaphore.h>

using namespace WebCore;

namespace WebKit {

// Sub frame classification thresholds
static const unsigned subframeUnderTopFrameOriginsThreshold = 3;
    
// Subresource classification thresholds
static const unsigned subresourceUnderTopFrameOriginsThreshold = 5;
static const unsigned subresourceHasBeenRedirectedFromToUniqueDomainsThreshold = 3;
static const unsigned redirectedToOtherPrevalentResourceOriginsThreshold = 2;

Ref<WebResourceLoadStatisticsStore> WebResourceLoadStatisticsStore::create(const String& resourceLoadStatisticsDirectory)
{
    return adoptRef(*new WebResourceLoadStatisticsStore(resourceLoadStatisticsDirectory));
}

WebResourceLoadStatisticsStore::WebResourceLoadStatisticsStore(const String& resourceLoadStatisticsDirectory)
    : m_resourceStatisticsStore(WebCore::ResourceLoadStatisticsStore::create())
    , m_statisticsQueue(WorkQueue::create("WebResourceLoadStatisticsStore Process Data Queue"))
    , m_storagePath(resourceLoadStatisticsDirectory)
{
}

WebResourceLoadStatisticsStore::~WebResourceLoadStatisticsStore()
{
}

static inline bool hasPrevalentResourceCharacteristics(const ResourceLoadStatistics& resourceStatistic)
{
    return resourceStatistic.subframeUnderTopFrameOrigins.size() > subframeUnderTopFrameOriginsThreshold
        || resourceStatistic.subresourceUnderTopFrameOrigins.size() > subresourceUnderTopFrameOriginsThreshold
        || resourceStatistic.subresourceUniqueRedirectsTo.size() > subresourceHasBeenRedirectedFromToUniqueDomainsThreshold
        || resourceStatistic.redirectedToOtherPrevalentResourceOrigins.size() > redirectedToOtherPrevalentResourceOriginsThreshold;
}
    
static inline void classifyPrevalentResources(ResourceLoadStatistics& resourceStatistic, Vector<String>& prevalentResources, Vector<String>& prevalentResourcesWithUserInteraction)
{
    if (resourceStatistic.isPrevalentResource || hasPrevalentResourceCharacteristics(resourceStatistic)) {
        resourceStatistic.isPrevalentResource = true;
        if (resourceStatistic.hadUserInteraction)
            prevalentResourcesWithUserInteraction.append(resourceStatistic.highLevelDomain);
        else
            prevalentResources.append(resourceStatistic.highLevelDomain);
    }
}

void WebResourceLoadStatisticsStore::resourceLoadStatisticsUpdated(const Vector<WebCore::ResourceLoadStatistics>& origins)
{
    coreStore().mergeStatistics(origins);

    Vector<String> prevalentResources, prevalentResourcesWithUserInteraction;
    if (coreStore().hasEnoughDataForStatisticsProcessing()) {
        coreStore().processStatistics([this, &prevalentResources, &prevalentResourcesWithUserInteraction] (ResourceLoadStatistics& resourceStatistic) {
            classifyPrevalentResources(resourceStatistic, prevalentResources, prevalentResourcesWithUserInteraction);
        });
    }

    // FIXME: Notify individual WebProcesses of prevalent domains using the two vectors populated by the classifier. <rdar://problem/24703099>
    auto encoder = coreStore().createEncoderFromData();
    
    writeEncoderToDisk(*encoder.get(), "full_browsing_session");
}

void WebResourceLoadStatisticsStore::setResourceLoadStatisticsEnabled(bool enabled)
{
    if (enabled == m_resourceLoadStatisticsEnabled)
        return;

    m_resourceLoadStatisticsEnabled = enabled;

    readDataFromDiskIfNeeded();
}

bool WebResourceLoadStatisticsStore::resourceLoadStatisticsEnabled() const
{
    return m_resourceLoadStatisticsEnabled;
}

void WebResourceLoadStatisticsStore::readDataFromDiskIfNeeded()
{
    if (!m_resourceLoadStatisticsEnabled)
        return;

    m_statisticsQueue->dispatch([this, protectedThis = makeRef(*this)] {
        coreStore().clear();

        auto decoder = createDecoderFromDisk("full_browsing_session");
        if (!decoder)
            return;

        coreStore().readDataFromDecoder(*decoder);
    });
}

void WebResourceLoadStatisticsStore::processWillOpenConnection(WebProcessProxy&, IPC::Connection& connection)
{
    connection.addWorkQueueMessageReceiver(Messages::WebResourceLoadStatisticsStore::messageReceiverName(), &m_statisticsQueue.get(), this);
}

void WebResourceLoadStatisticsStore::processDidCloseConnection(WebProcessProxy&, IPC::Connection& connection)
{
    connection.removeWorkQueueMessageReceiver(Messages::WebResourceLoadStatisticsStore::messageReceiverName());
}

void WebResourceLoadStatisticsStore::applicationWillTerminate()
{
    BinarySemaphore semaphore;
    m_statisticsQueue->dispatch([this, &semaphore] {
        // Make sure any ongoing work in our queue is finished before we terminate.
        semaphore.signal();
    });
    semaphore.wait(std::numeric_limits<double>::max());
}

String WebResourceLoadStatisticsStore::persistentStoragePath(const String& label) const
{
    if (m_storagePath.isEmpty())
        return emptyString();
    
    // TODO Decide what to call this file
    return pathByAppendingComponent(m_storagePath, label + "_resourceLog.plist");
}

void WebResourceLoadStatisticsStore::writeEncoderToDisk(KeyedEncoder& encoder, const String& label) const
{
    RefPtr<SharedBuffer> rawData = encoder.finishEncoding();
    if (!rawData)
        return;
    
    String resourceLog = persistentStoragePath(label);
    if (resourceLog.isEmpty())
        return;
    
    if (!m_storagePath.isEmpty())
        makeAllDirectories(m_storagePath);
    
    auto handle = openFile(resourceLog, OpenForWrite);
    if (!handle)
        return;
    
    int64_t writtenBytes = writeToFile(handle, rawData->data(), rawData->size());
    closeFile(handle);
    
    if (writtenBytes != static_cast<int64_t>(rawData->size()))
        WTFLogAlways("WebResourceLoadStatisticsStore: We only wrote %d out of %d bytes to disk", static_cast<unsigned>(writtenBytes), rawData->size());
}

std::unique_ptr<KeyedDecoder> WebResourceLoadStatisticsStore::createDecoderFromDisk(const String& label) const
{
    String resourceLog = persistentStoragePath(label);
    if (resourceLog.isEmpty())
        return nullptr;
    
    RefPtr<SharedBuffer> rawData = SharedBuffer::createWithContentsOfFile(resourceLog);
    if (!rawData)
        return nullptr;
    
    return KeyedDecoder::decoder(reinterpret_cast<const uint8_t*>(rawData->data()), rawData->size());
}

} // namespace WebKit