/*

* Copyright (c) 2010 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description: Class for asynchronously fetching and caching basic

*              contact info (see CntContactInfo) for list views.

*

*/

#include <hbapplication.h>

#include <qtcontacts.h>

#include <qcontactmanager.h>

#include "cntcache.h"

#include "cntcache_p.h"

#include "cntinfoprovider.h"

// set the singleton instance pointer to NULL

CntCache* CntCache::mInstance = NULL;

// value for first cache order to be assigned

static const int CacheOrderStartValue = 1;

// for avoiding wrap around with cache orders

static const int MaxCacheOrderValue = 10000000;

// number of items to read ahead into cache; this number is for one direction

static const int ItemsToCacheAhead = 24;

// cache size for info items (name, text, icon1name, icon2name)

static const int InfoCacheSize = 128;

// cache size for icon items (iconName and HbIcon)

static const int IconCacheSize = 50;

// number of icons in a CntContactInfo object

static const int IconsInCntContactInfo = 2;

// default empty text info field for a contact; it cannot be empty

// as the listview will then ignore it, causing rendering problems

static const QString EmptyTextField = " ";

/*!

    Provides a pointer to the CntCache singleton instance.

 */

CntCache* CntCache::instance()

{

    if (mInstance == NULL) {

        mInstance = new CntCache();

    }

    return mInstance;

}

/*!

    Creates the CntCache singleton instance.

 */

CntCache::CntCache()

    : mContactManager(new QContactManager()),

      mWorker(new CntCacheThread()),

      mNextInfoCacheOrder(CacheOrderStartValue),

      mNextIconCacheOrder(CacheOrderStartValue),

      mEmittedContactId(-1)

{

    // listen to worker updates

    connect(mWorker, SIGNAL(infoFieldUpdated(int, const ContactInfoField&, const QString&)),

            this, SLOT(onNewInfo(int, const ContactInfoField&, const QString&)));

    connect(mWorker, SIGNAL(iconUpdated(const QString&, const HbIcon&)),

            this, SLOT(onNewIcon(const QString&, const HbIcon&)));

    connect(mWorker, SIGNAL(infoCancelled(int)), this, SLOT(onInfoCancelled(int)));

    connect(mWorker, SIGNAL(iconCancelled(const QString&)), this, SLOT(onIconCancelled(const QString&)));

    connect(mWorker, SIGNAL(allJobsDone()), this, SLOT(scheduleOneReadAheadItem()));

    // listen to the database for changes to contacts

    connect(mContactManager, SIGNAL(contactsRemoved(const QList<QContactLocalId>&)), this, SLOT(removeContactsFromCache(const QList<QContactLocalId>&)));

    // shutdown only when the whole application shuts down

    connect(HbApplication::instance(), SIGNAL(aboutToQuit()), this, SLOT(onShutdown()));

}

/*!

    Destructs the CntCache singleton instance.

 */

CntCache::~CntCache()

{

    delete mWorker;

    delete mContactManager;

}

/*! 

    Fetches information about a contact: name, text (e.g. phone number or

    social status) and two icons (e.g. avatar, presence). Previously cached

    content - at the very least the name - will be returned immediately.

    Availability of more information will be checked asynchronously and

    sent to clients via contactInfoUpdated() signals.

    The function takes a row and a list rather than just a contact id because

    of read ahead caching - contacts near the requested contacts are expected

    to be needed soon and are therefore also scheduled for caching.

    \param row the row of the contact to fetch

    \param idList a list with all the IDs in the list

    \return a contact with some details filled in

 */

CntContactInfo CntCache::fetchContactInfo(int row, const QList<QContactLocalId>& idList)

{

    Q_ASSERT(row >= 0 && row < idList.count());

    QString name;

    QString text = EmptyTextField;

    HbIcon icons[IconsInCntContactInfo];

    int contactId = idList.at(row);

    if (contactId != mEmittedContactId) {

        // this request comes from the UI in response to some scrolling activity =>

        // 1) postpone all jobs so the UI can use as much of the CPU as possible

        // 2) update read ahead cache to contain all IDs of all items near this item

        mWorker->postponeJobs();

        updateReadAheadCache(row, idList);

    }

    // fetch contact

    if (mInfoCache.contains(contactId)) {

        // the item is in the cache

        CntInfoCacheItem* infoItem = mInfoCache.value(contactId);

        for (int i = 0; i < IconsInCntContactInfo; ++i) {

            QString iconName = infoItem->icons[i];

            if (!iconName.isEmpty()) {

                if (mIconCache.contains(iconName)) {

                    CntIconCacheItem* iconItem = mIconCache.value(iconName);

                    iconItem->cacheOrder = mNextIconCacheOrder++;

                    icons[i] = iconItem->icon;

                    if (!iconItem->isFetched) {

                        // if icon has not yet been received from backend, add

                        // this id to the list of contacts that want to be

                        // notified when the icon is received

                        iconItem->contactIds.insert(contactId);

                    }

                }

                else {

                    // needed icon is not in cache, so schedule it for retrieval

                    CntIconCacheItem* iconItem = createIconCacheItem(iconName);

                    iconItem->contactIds.insert(contactId);

                    mWorker->scheduleIconJob(iconName);

                }

            }

        }

        // update cache order

        infoItem->cacheOrder = mNextInfoCacheOrder++;

        name = infoItem->name;

        text = infoItem->text;

    }

    else {

        // the item is not in cache, so fetch the name and schedule the rest

        // of the info for retrieval

        if (fetchContactName(contactId, name)) {

            // contact found, so add new entry to cache

            CntInfoCacheItem* item = createInfoCacheItem(contactId);

            item->name = name;

            item->text = text;

            // ask the worker thread to fetch the information asynchronously

            mWorker->scheduleInfoJob(contactId);

        }

    }

    return CntContactInfo(contactId, name, text, icons[0], icons[1]);

}

/*! 

 */

void CntCache::clearCache()

{

    // clear info cache

    mInfoCache.clear();

    mNextInfoCacheOrder = CacheOrderStartValue;

}

/*! 

    Processes a new info field that has arrived from the worker thread.

    If the contact is in the info cache, then the info cache is updated

    accordingly.

    A contactInfoUpdated() signal is usually also emitted. The exception

    is if the info is the name of an icon and that icon is not in the icon

    cache. In this case the icon is fetched before a signal is emitted.

 */

void CntCache::onNewInfo(int contactId, const ContactInfoField& infoField, const QString& infoValue)

{

    Q_ASSERT(infoField == ContactInfoTextField || infoField == ContactInfoIcon1Field || infoField == ContactInfoIcon2Field);

    bool hasNewInfo;

    if (!mInfoCache.contains(contactId)) {

        // contact is not in cache, so nothing needs to be done

        // except notify clients that this contact has (possibly)

        // been changed

        hasNewInfo = true;

    }

    else if (infoField == ContactInfoTextField) {

        // update cache with new text for contact

        if (!infoValue.isEmpty())

            mInfoCache.value(contactId)->text = infoValue;

        else

            mInfoCache.value(contactId)->text = " ";

        hasNewInfo = true;

    }

    else {

        // update cache with new icon name for contact

        int iconIndex = (infoField == ContactInfoIcon1Field ? 0 : 1);

        CntInfoCacheItem* item = mInfoCache.value(contactId);

        QString iconName = infoValue;

        if (item->icons[iconIndex] != iconName) {

            item->icons[iconIndex] = iconName;

            if (iconName.isEmpty()) {

                hasNewInfo = true;

            }

            else if (mIconCache.contains(iconName)) {

                CntIconCacheItem* iconItem = mIconCache.value(iconName);

                if (!iconItem->isFetched) {

                    iconItem->contactIds.insert(contactId);

                    hasNewInfo = false;

                }

                else {

                    hasNewInfo = true;

                }

            }

            else {

            }

        }

        else {

            hasNewInfo = false;

        }

    }

    if (hasNewInfo) {

        emitContactInfoUpdated(contactId);

    }

}

/*! 

    Handle the case where a request for contact info is cancelled by the

    worker because of too many subsequent requests.

 */

void CntCache::onInfoCancelled(int contactId)

{

    if (mInfoCache.contains(contactId)) {

        CntInfoCacheItem* item = mInfoCache.take(contactId);

        delete item;

    }

    emitContactInfoUpdated(contactId);

}

/*! 

    Processes a new icon that has arrived from the worker thread.

    The icon cache is updated and a contactInfoUpdated() signal is

    emitted for all contacts that use this icon.

 */

void CntCache::onNewIcon(const QString& iconName, const HbIcon& icon)

{

    QSet<int> contactsToNotify;

    if (mIconCache.contains(iconName)) {

        CntIconCacheItem* item = mIconCache.value(iconName);

        item->icon = icon;

        item->isFetched = true;

        contactsToNotify = item->contactIds;

        item->contactIds.clear();

    }

    foreach (int contactId, contactsToNotify) {

        emitContactInfoUpdated(contactId);

    }

}

/*! 

    Handle the case where a request for an icon is cancelled by the worker because

    of too many subsequent requests.

 */

void CntCache::onIconCancelled(const QString& iconName)

{

    QSet<int> contactsToNotify;

    if (mIconCache.contains(iconName)) {

        CntIconCacheItem* item = mIconCache.take(iconName);

        contactsToNotify = item->contactIds;

        item->contactIds.clear();

        delete item;

    }

    foreach (int contactId, contactsToNotify) {

        emitContactInfoUpdated(contactId);

    }

}

/*! 

    Removes contacts from cache.

    /param contactIds ids of the contact that will be removed

 */

void CntCache::removeContactsFromCache(const QList<QContactLocalId>& contactIds)

{

    foreach (QContactLocalId contactId, contactIds) {

        if (mInfoCache.contains(contactId)) {

            CntInfoCacheItem* item = mInfoCache.take(contactId);

            delete item;

        }

    }

    foreach (QContactLocalId contactId, contactIds) {

        emitContactInfoUpdated(contactId);

    }

}

/*! 

    Uses an optimized function to fetch the name of a contact from

    the database.

    /param contactId the id of the contact to fetch

    /param contactName the name will be stored here if the function is successful

    /return true if the name was fetched successfully

 */

bool CntCache::fetchContactName(int contactId, QString& contactName)

{

    bool foundContact = false;

    QContactFetchHint nameOnlyFetchHint;

    QStringList details;

    details << QContactDisplayLabel::DefinitionName;

    nameOnlyFetchHint.setDetailDefinitionsHint(details);

    QContact contact = mContactManager->contact(contactId, nameOnlyFetchHint);

    if (mContactManager->error() == QContactManager::NoError) {

        contactName = contact.displayLabel();

        foundContact = true;

    }

    return foundContact;

}

/*! 

    Collects all contact IDs near the latest fetch from the UI. These will be fetched and

    precached when UI activity slows down.

    \param mostRecentRow the row of the contact that was most recently fetched

    \param idList a list with all the IDs in the list

 */

void CntCache::updateReadAheadCache(int mostRecentRow, const QList<QContactLocalId>& idList)

{

    int row;

    mReadAheadCache.clear();

    // step through the area near to last fetch item and make sure all

    // contacts in it are also in cache or in the read ahead list

    for (int i = 1; i <= ItemsToCacheAhead; ++i) {

        for (int j = 0; j < 2; ++j) {

            if (j == 0) {

                row = mostRecentRow - i;

                if (row <= 0) {

                    continue;

                }

            }

            else {

                row = mostRecentRow + i;

                if (row >= idList.count()) {

                    continue;

                }

            }

            int contactId = idList.at(row);

            if (!mInfoCache.contains(contactId)) {

                // contact is not in cache, so put the id to items to read into cache

                mReadAheadCache.append(contactId);

            }

            else {

                // contact is in cache; update cache order as we want to keep this item in cache

                mInfoCache.value(contactId)->cacheOrder = mNextInfoCacheOrder++;

            }

        }

    }

}

/*! 

    Schedules one uncached item in the read-ahead list for retrieval.

 */

void CntCache::scheduleOneReadAheadItem()

{

    QString name;

    while (mReadAheadCache.count() > 0) {

        int contactId = mReadAheadCache.takeFirst();

        if (!mInfoCache.contains(contactId)) {

            // contact is not in cache, so schedule it for retreival

            if (fetchContactName(contactId, name)) {

                // contact found, so add new entry to cache

                CntInfoCacheItem* item = createInfoCacheItem(contactId);

                item->name = name;

                item->text = EmptyTextField;

                // schedule the info for retrieval

                mWorker->scheduleInfoJob(contactId);

                break;

            }

        }

    }

}

/*! 

    Creates a new item in the info cache. If the cache is full,

    then the least recently accessed item is removed from cache.

    /param contactId id of contact for which to create the new cache item

    /return the newly created cache item

 */

CntInfoCacheItem* CntCache::createInfoCacheItem(int contactId)

{