/*
 * Copyright (C) 2010, 2011 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 "WebBackForwardListProxy.h"

#include "SessionState.h"
#include "SessionStateConversion.h"
#include "WebCoreArgumentCoders.h"
#include "WebPage.h"
#include "WebPageProxyMessages.h"
#include "WebProcess.h"
#include "WebProcessProxyMessages.h"
#include <WebCore/HistoryController.h>
#include <WebCore/HistoryItem.h>
#include <WebCore/MainFrame.h>
#include <WebCore/PageCache.h>
#include <wtf/HashMap.h>
#include <wtf/NeverDestroyed.h>

using namespace WebCore;

namespace WebKit {

// FIXME <rdar://problem/8819268>: This leaks all HistoryItems that go into these maps.
// We need to clear up the life time of these objects.

typedef HashMap<uint64_t, RefPtr<HistoryItem>> IDToHistoryItemMap; // "ID" here is the item ID.
    
struct ItemAndPageID {
    uint64_t itemID;
    uint64_t pageID;
};
typedef HashMap<RefPtr<HistoryItem>, ItemAndPageID> HistoryItemToIDMap;

static IDToHistoryItemMap& idToHistoryItemMap()
{
    static NeverDestroyed<IDToHistoryItemMap> map;
    return map;
}

static HistoryItemToIDMap& historyItemToIDMap()
{
    static NeverDestroyed<HistoryItemToIDMap> map;
    return map;
}

static uint64_t uniqueHistoryItemID = 1;

static uint64_t generateHistoryItemID()
{
    // These IDs exist in the WebProcess for items created by the WebProcess.
    // The IDs generated here need to never collide with the IDs created in WebBackForwardList in the UIProcess.
    // We accomplish this by starting from 3, and only ever using odd ids.
    uniqueHistoryItemID += 2;
    return uniqueHistoryItemID;
}

void WebBackForwardListProxy::setHighestItemIDFromUIProcess(uint64_t itemID)
{
    if (itemID <= uniqueHistoryItemID)
        return;
    
     if (itemID % 2)
         uniqueHistoryItemID = itemID;
     else
         uniqueHistoryItemID = itemID + 1;
}

static void updateBackForwardItem(uint64_t itemID, uint64_t pageID, HistoryItem* item)
{
    WebProcess::singleton().parentProcessConnection()->send(Messages::WebProcessProxy::AddBackForwardItem(itemID, pageID, toPageState(*item)), 0);
}

void WebBackForwardListProxy::addItemFromUIProcess(uint64_t itemID, Ref<HistoryItem>&& item, uint64_t pageID)
{
    // This item/itemID pair should not already exist in our maps.
    ASSERT(!historyItemToIDMap().contains(item.ptr()));
    ASSERT(!idToHistoryItemMap().contains(itemID));

    historyItemToIDMap().set<ItemAndPageID>(item.ptr(), { itemID, pageID });
    idToHistoryItemMap().set(itemID, item.ptr());
}

static void WK2NotifyHistoryItemChanged(HistoryItem* item)
{
    ItemAndPageID ids = historyItemToIDMap().get(item);
    if (!ids.itemID)
        return;

    updateBackForwardItem(ids.itemID, ids.pageID, item);
}

HistoryItem* WebBackForwardListProxy::itemForID(uint64_t itemID)
{
    return idToHistoryItemMap().get(itemID);
}

uint64_t WebBackForwardListProxy::idForItem(HistoryItem* item)
{
    ASSERT(item);
    return historyItemToIDMap().get(item).itemID;
}

void WebBackForwardListProxy::removeItem(uint64_t itemID)
{
    RefPtr<HistoryItem> item = idToHistoryItemMap().take(itemID);
    if (!item)
        return;
        
    PageCache::singleton().remove(*item);
    WebCore::Page::clearPreviousItemFromAllPages(item.get());
    historyItemToIDMap().remove(item);
}

WebBackForwardListProxy::WebBackForwardListProxy(WebPage* page)
    : m_page(page)
{
    WebCore::notifyHistoryItemChanged = WK2NotifyHistoryItemChanged;
}

void WebBackForwardListProxy::addItem(Ref<HistoryItem>&& item)
{
    ASSERT(!historyItemToIDMap().contains(item.ptr()));

    if (!m_page)
        return;

    uint64_t itemID = generateHistoryItemID();

    ASSERT(!idToHistoryItemMap().contains(itemID));

    m_associatedItemIDs.add(itemID);

    historyItemToIDMap().set<ItemAndPageID>(item.ptr(), { itemID, m_page->pageID() });
    idToHistoryItemMap().set(itemID, item.ptr());

    updateBackForwardItem(itemID, m_page->pageID(), item.ptr());
    m_page->send(Messages::WebPageProxy::BackForwardAddItem(itemID));
}

void WebBackForwardListProxy::goToItem(HistoryItem* item)
{
    if (!m_page)
        return;

    SandboxExtension::Handle sandboxExtensionHandle;
    m_page->sendSync(Messages::WebPageProxy::BackForwardGoToItem(historyItemToIDMap().get(item).itemID), Messages::WebPageProxy::BackForwardGoToItem::Reply(sandboxExtensionHandle));
    m_page->sandboxExtensionTracker().beginLoad(m_page->mainWebFrame(), sandboxExtensionHandle);
}

HistoryItem* WebBackForwardListProxy::itemAtIndex(int itemIndex)
{
    if (!m_page)
        return 0;

    uint64_t itemID = 0;
    if (!WebProcess::singleton().parentProcessConnection()->sendSync(Messages::WebPageProxy::BackForwardItemAtIndex(itemIndex), Messages::WebPageProxy::BackForwardItemAtIndex::Reply(itemID), m_page->pageID()))
        return 0;

    if (!itemID)
        return 0;

    return idToHistoryItemMap().get(itemID);
}

int WebBackForwardListProxy::backListCount()
{
    if (!m_page)
        return 0;

    int backListCount = 0;
    if (!WebProcess::singleton().parentProcessConnection()->sendSync(Messages::WebPageProxy::BackForwardBackListCount(), Messages::WebPageProxy::BackForwardBackListCount::Reply(backListCount), m_page->pageID()))
        return 0;

    return backListCount;
}

int WebBackForwardListProxy::forwardListCount()
{
    if (!m_page)
        return 0;

    int forwardListCount = 0;
    if (!WebProcess::singleton().parentProcessConnection()->sendSync(Messages::WebPageProxy::BackForwardForwardListCount(), Messages::WebPageProxy::BackForwardForwardListCount::Reply(forwardListCount), m_page->pageID()))
        return 0;

    return forwardListCount;
}

void WebBackForwardListProxy::close()
{
    for (auto& itemID : m_associatedItemIDs) {
        if (HistoryItem* item = itemForID(itemID))
            WebCore::PageCache::singleton().remove(*item);
    }

    m_associatedItemIDs.clear();
    m_page = nullptr;
}

bool WebBackForwardListProxy::isActive()
{
    // FIXME: Should check the the list is enabled and has non-zero capacity.
    return true;
}

void WebBackForwardListProxy::clear()
{
    m_page->send(Messages::WebPageProxy::BackForwardClear());
}

} // namespace WebKit
