squawk/ui/widgets/messageline/messagedelegate.cpp

/*
 * Squawk messenger. 
 * Copyright (C) 2019  Yury Gubich <blue@macaw.me>
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <QDebug>
#include <QPainter>
#include <QPainterPath>
#include <QApplication>
#include <QMouseEvent>
#include <QAbstractItemView>
#include <QAbstractTextDocumentLayout>
#include <QTextBlock>
#include <cmath>

#include "messagedelegate.h"
#include "messagefeed.h"

#include "shared/defines.h"

constexpr int textMargin = 2;
constexpr int statusIconSize = 16;

constexpr int bubbleMargin = 6;
constexpr int bubbleBorderRadius = 3;

int MessageDelegate::avatarHeight(50);
int MessageDelegate::margin(6);

MessageDelegate::MessageDelegate(QObject* parent):
    QStyledItemDelegate(parent),
    bodyFont(Shared::Global::getInstance()->defaultFont),
    nickFont(Shared::Global::getInstance()->headerFont),
    dateFont(Shared::Global::getInstance()->smallFont),
    nickMetrics(Shared::Global::getInstance()->headerFontMetrics),
    dateMetrics(Shared::Global::getInstance()->smallFontMetrics),
    bodyRenderer(new QTextDocument()),
    buttonHeight(0),
    buttonWidth(0),
    barHeight(0),
    buttons(new std::map<QString, FeedButton*>()),
    bars(new std::map<QString, QProgressBar*>()),
    statusIcons(new std::map<QString, QLabel*>()),
    pencilIcons(new std::map<QString, QLabel*>()),
    previews(new std::map<QString, Preview*>()),
    idsToKeep(new std::set<QString>()),
    clearingWidgets(false),
    currentId(""),
    selection(0, 0)
{
    bodyRenderer->setDocumentMargin(0);
    bodyRenderer->setDefaultFont(bodyFont);

    QPushButton btn(QCoreApplication::translate("MessageLine", "Download"));
    buttonHeight = btn.sizeHint().height();
    buttonWidth = btn.sizeHint().width();
    
    QProgressBar bar;
    barHeight = bar.sizeHint().height();
}

MessageDelegate::~MessageDelegate() {
    for (const std::pair<const QString, FeedButton*>& pair: *buttons)
        delete pair.second;
    
    for (const std::pair<const QString, QProgressBar*>& pair: *bars)
        delete pair.second;
    
    for (const std::pair<const QString, QLabel*>& pair: *statusIcons)
        delete pair.second;
    
    for (const std::pair<const QString, QLabel*>& pair: *pencilIcons)
        delete pair.second;
    
    for (const std::pair<const QString, Preview*>& pair: *previews)
        delete pair.second;
    
    delete statusIcons;
    delete pencilIcons;
    delete idsToKeep;
    delete buttons;
    delete bars;
    delete previews;
    delete bodyRenderer;
}

void MessageDelegate::paint(QPainter* painter, const QStyleOptionViewItem& option, const QModelIndex& index) const {
    QVariant vi = index.data(Models::MessageFeed::Bulk);
    if (!vi.isValid())
        return;

    Models::FeedItem data = qvariant_cast<Models::FeedItem>(vi);
    painter->save();
    painter->setRenderHint(QPainter::Antialiasing, true);
    
    paintBubble(data, painter, option);
    bool ntds = needToDrawSender(index, data);
    if (ntds || option.rect.y() < 1)
        paintAvatar(data, index, option, painter);
    
    QStyleOptionViewItem opt = option;
    opt.rect = option.rect.adjusted(bubbleMargin, bubbleMargin, -bubbleMargin, -bubbleMargin / 2);
    if (!data.sentByMe)
        opt.displayAlignment = Qt::AlignLeft | Qt::AlignTop;
    else
        opt.displayAlignment = Qt::AlignRight | Qt::AlignTop;

    QRect rect;
    if (ntds) {
        painter->setFont(nickFont);
        painter->drawText(opt.rect, opt.displayAlignment, data.sender, &rect);
        opt.rect.adjust(0, nickMetrics.lineSpacing() + textMargin, 0, 0);
    }

    painter->save();
    switch (data.attach.state) {
        case Models::none:
            clearHelperWidget(data);        //i can't imagine the situation where it's gonna be needed
            break;                          //but it's a possible performance problem
        case Models::uploading:
            paintPreview(data, painter, opt);
            [[fallthrough]];
        case Models::downloading:
            paintBar(getBar(data), painter, data.sentByMe, opt);
            break;
        case Models::remote:
            paintButton(getButton(data), painter, data.sentByMe, opt);
            break;
        case Models::ready:
        case Models::local:
            clearHelperWidget(data);
            paintPreview(data, painter, opt);
            break;
        case Models::errorDownload: {
            paintButton(getButton(data), painter, data.sentByMe, opt);
            paintComment(data, painter, opt);
        }
            
            break;
        case Models::errorUpload:{
            clearHelperWidget(data);
            paintPreview(data, painter, opt);
            paintComment(data, painter, opt);
        }
            break;
    }
    painter->restore();
    
    QWidget* vp = static_cast<QWidget*>(painter->device());
    paintBody(data, painter, opt);
    painter->setFont(dateFont);
    QColor q = painter->pen().color();
    QString dateString = data.date.toLocalTime().toString("hh:mm");
    q.setAlpha(180);
    painter->setPen(q);
    painter->drawText(opt.rect, opt.displayAlignment, dateString, &rect);
    int currentY = opt.rect.y();
    if (data.sentByMe) {
        QLabel* statusIcon = getStatusIcon(data);
        
        statusIcon->setParent(vp);
        statusIcon->move(opt.rect.left(), currentY);
        statusIcon->show();
        
        opt.rect.adjust(0, statusIconSize + textMargin, 0, 0);
    }
    
    if (data.correction.corrected) {
        QLabel* pencilIcon = getPencilIcon(data);
        
        pencilIcon->setParent(vp);
        if (data.sentByMe)
            pencilIcon->move(opt.rect.left() + statusIconSize + margin, currentY);
        else
            pencilIcon->move(opt.rect.right() - statusIconSize - margin, currentY);

        pencilIcon->show();
    } else {
        std::map<QString, QLabel*>::const_iterator itr = pencilIcons->find(data.id);
        if (itr != pencilIcons->end()) {
            delete itr->second;
            pencilIcons->erase(itr);
        }
    }
    
    painter->restore();
    
    if (clearingWidgets)
        idsToKeep->insert(data.id);
}

void MessageDelegate::paintBubble(const Models::FeedItem& data, QPainter* painter, const QStyleOptionViewItem& option) const {
    painter->save();
    if (data.sentByMe)
        painter->setBrush(option.palette.brush(QPalette::Inactive, QPalette::Highlight));
    else
        painter->setBrush(option.palette.brush(QPalette::Window));

    painter->setPen(Qt::NoPen);
    painter->drawRoundedRect(option.rect, bubbleBorderRadius, bubbleBorderRadius);
    painter->restore();
}


void MessageDelegate::paintAvatar(const Models::FeedItem& data, const QModelIndex& index, const QStyleOptionViewItem& option, QPainter* painter) const {
    int currentRow = index.row();
    int y = option.rect.y();
    bool firstAttempt = true;
    QIcon icon(data.avatar);
    while (y < 0 && currentRow > 0) {
        QRect rect;
        if (firstAttempt) {
            firstAttempt = false;
            rect = option.rect;
        } else {
            QModelIndex ci = index.siblingAtRow(currentRow);
            if (
                (ci.data(Models::MessageFeed::Sender).toString() != data.sender) ||
                (ci.data(Models::MessageFeed::Date).toDateTime().daysTo(data.date) != 0)
            ) {
                break;
            }
            //TODO this is really bad, but for now I have no idea how else can I access the view;
            const QAbstractItemView* view = static_cast<const QAbstractItemView*>(option.styleObject);
            rect = view->visualRect(ci);
        }
        y = std::min(0, rect.bottom() - margin - avatarHeight);
        --currentRow;
    }

    QPixmap pixmap = icon.pixmap(avatarHeight, avatarHeight);
    QPainterPath path;
    int ax;

    if (data.sentByMe)
        ax = option.rect.x() + option.rect.width() + margin;
    else
        ax = margin;

    path.addEllipse(ax, y + margin / 2, avatarHeight, avatarHeight);
    painter->save();
    painter->setClipPath(path);
    painter->drawPixmap(ax, y + margin / 2, pixmap);
    painter->restore();
}

bool MessageDelegate::needToDrawAvatar(const QModelIndex& index, const Models::FeedItem& data, const QStyleOptionViewItem& option) const {
    return (option.rect.y() < 1) || needToDrawSender(index, data);
}

bool MessageDelegate::needToDrawSender(const QModelIndex& index, const Models::FeedItem& data) const
{
    if (index.row() == index.model()->rowCount() - 1) {
        return true;
    } else {
        QModelIndex prevIndex = index.siblingAtRow(index.row() + 1);

        return  (prevIndex.data(Models::MessageFeed::Sender).toString() != data.sender) ||
                (prevIndex.data(Models::MessageFeed::Date).toDateTime().daysTo(data.date) != 0);
    }
}

QSize MessageDelegate::sizeHint(const QStyleOptionViewItem& option, const QModelIndex& index) const {
    QRect messageRect = option.rect.adjusted(bubbleMargin, margin / 2 + bubbleMargin, -(avatarHeight + 3 * margin + bubbleMargin), -(margin + bubbleMargin) / 2);
    QStyleOptionViewItem opt = option;
    opt.rect = messageRect;
    QVariant vi = index.data(Models::MessageFeed::Bulk);
    Models::FeedItem data = qvariant_cast<Models::FeedItem>(vi);
    QSize messageSize(0, 0);
    if (data.text.size() > 0) {
        bodyRenderer->setPlainText(data.text);
        bodyRenderer->setTextWidth(messageRect.size().width());

        QSizeF size = bodyRenderer->size();
        size.setWidth(bodyRenderer->idealWidth());
        messageSize = QSize(std::ceil(size.width()), std::ceil(size.height()));
        messageSize.rheight() += textMargin;
    }
    
    switch (data.attach.state) {
        case Models::none:
            break;
        case Models::uploading:
            messageSize.rheight() += Preview::calculateAttachSize(Shared::resolvePath(data.attach.localPath), messageRect).height() + textMargin;
            [[fallthrough]];
        case Models::downloading:
            messageSize.rheight() += barHeight + textMargin;
            messageSize.setWidth(messageRect.width());
            break;
        case Models::remote:
            messageSize.rheight() += buttonHeight + textMargin;
            messageSize.setWidth(std::max(messageSize.width(), buttonWidth));
            break;
        case Models::ready:
        case Models::local: {
            QSize aSize = Preview::calculateAttachSize(Shared::resolvePath(data.attach.localPath), messageRect);
            messageSize.rheight() += aSize.height() + textMargin;
            messageSize.setWidth(std::max(messageSize.width(), aSize.width()));
        }
            break;
        case Models::errorDownload: {
            QSize commentSize = dateMetrics.boundingRect(messageRect, Qt::TextWordWrap, data.attach.error).size();
            messageSize.rheight() += commentSize.height() + buttonHeight + textMargin * 2;
            messageSize.setWidth(std::max(messageSize.width(), std::max(commentSize.width(), buttonWidth)));
        }
            break;
        case Models::errorUpload: {
            QSize aSize = Preview::calculateAttachSize(Shared::resolvePath(data.attach.localPath), messageRect);
            QSize commentSize = dateMetrics.boundingRect(messageRect, Qt::TextWordWrap, data.attach.error).size();
            messageSize.rheight() += aSize.height() + commentSize.height() + textMargin * 2;
            messageSize.setWidth(std::max(messageSize.width(), std::max(commentSize.width(), aSize.width())));
        }
            break;
    }
    
    if (needToDrawSender(index, data)) {
        QSize senderSize = nickMetrics.boundingRect(messageRect, 0, data.sender).size();
        messageSize.rheight() += senderSize.height() + textMargin;
        messageSize.setWidth(std::max(senderSize.width(), messageSize.width()));
    }

    QString dateString = data.date.toLocalTime().toString("hh:mm");
    QSize dateSize = dateMetrics.boundingRect(messageRect, 0, dateString).size();
    messageSize.rheight() += bubbleMargin * 1.5;
    messageSize.rheight() += dateSize.height() > statusIconSize ? dateSize.height() : statusIconSize;

    int statusWidth = dateSize.width() + statusIconSize + margin;
    if (data.correction.corrected) {
        statusWidth += statusIconSize + margin;
    }
    messageSize.setWidth(std::max(statusWidth, messageSize.width()));
    messageSize.rwidth() += 2 * bubbleMargin;
    
    return messageSize;
}

QRect MessageDelegate::getHoveredMessageBodyRect(const QModelIndex& index, const Models::FeedItem& data, const QRect& sizeHint) const {
    QRect localHint = sizeHint.adjusted(bubbleMargin, bubbleMargin + margin, -bubbleMargin, -bubbleMargin / 2);
    if (needToDrawSender(index, data))
        localHint.adjust(0, nickMetrics.lineSpacing() + textMargin, 0, 0);

    int attachHeight = 0;
    switch (data.attach.state) {
        case Models::none:
            break;
        case Models::uploading:
            attachHeight += Preview::calculateAttachSize(Shared::resolvePath(data.attach.localPath), localHint).height() + textMargin;
            [[fallthrough]];
        case Models::downloading:
            attachHeight += barHeight + textMargin;
            break;
        case Models::remote:
            attachHeight += buttonHeight + textMargin;
            break;
        case Models::ready:
        case Models::local: {
            QSize aSize = Preview::calculateAttachSize(Shared::resolvePath(data.attach.localPath), localHint);
            attachHeight += aSize.height() + textMargin;
        }
            break;
        case Models::errorDownload: {
            QSize commentSize = dateMetrics.boundingRect(localHint, Qt::TextWordWrap, data.attach.error).size();
            attachHeight += commentSize.height() + buttonHeight + textMargin * 2;
        }
            break;
        case Models::errorUpload: {
            QSize aSize = Preview::calculateAttachSize(Shared::resolvePath(data.attach.localPath), localHint);
            QSize commentSize = dateMetrics.boundingRect(localHint, Qt::TextWordWrap, data.attach.error).size();
            attachHeight += aSize.height() + commentSize.height() + textMargin * 2;
        }
            break;
    }

    int bottomSize = std::max(dateMetrics.lineSpacing(), statusIconSize);
    localHint.adjust(0, attachHeight, 0, -(bottomSize + textMargin));

    return localHint;
}

QString MessageDelegate::getAnchor(const QPoint& point, const QModelIndex& index, const QRect& sizeHint) const {
    QVariant vi = index.data(Models::MessageFeed::Bulk);
    Models::FeedItem data = qvariant_cast<Models::FeedItem>(vi);
    if (data.text.size() > 0) {
        QRect localHint = getHoveredMessageBodyRect(index, data, sizeHint);

        if (localHint.contains(point)) {
            QPoint translated = point - localHint.topLeft();

            bodyRenderer->setHtml(Shared::processMessageBody(data.text));
            bodyRenderer->setTextWidth(localHint.size().width());

            return bodyRenderer->documentLayout()->anchorAt(translated);
        }
    }

    return QString();
}

void MessageDelegate::leftClick(const QPoint& point, const QModelIndex& index, const QRect& sizeHint) const {
    QString anchor = getAnchor(point, index, sizeHint);
    if (anchor.size() > 0)
        emit openLink(anchor);
}

QString MessageDelegate::leftDoubleClick(const QPoint& point, const QModelIndex& index, const QRect& sizeHint) {
    QVariant vi = index.data(Models::MessageFeed::Bulk);
    Models::FeedItem data = qvariant_cast<Models::FeedItem>(vi);
    if (data.text.size() > 0) {
        QRect localHint = getHoveredMessageBodyRect(index, data, sizeHint);

        if (localHint.contains(point)) {
            QPoint translated = point - localHint.topLeft();

            bodyRenderer->setHtml(Shared::processMessageBody(data.text));
            bodyRenderer->setTextWidth(localHint.size().width());

            QAbstractTextDocumentLayout* lay = bodyRenderer->documentLayout();

            int position = lay->hitTest(translated, Qt::HitTestAccuracy::FuzzyHit);
            QTextCursor cursor(bodyRenderer);
            cursor.setPosition(position, QTextCursor::MoveAnchor);
            cursor.movePosition(QTextCursor::StartOfWord, QTextCursor::MoveAnchor);
            cursor.movePosition(QTextCursor::EndOfWord, QTextCursor::KeepAnchor);

            selection.first = cursor.anchor();
            selection.second = cursor.position();
            currentId = data.id;

            if (selection.first != selection.second) {
                return cursor.selectedText();
            }
        }
    }
    return "";
}

Shared::Hover MessageDelegate::hoverType(const QPoint& point, const QModelIndex& index, const QRect& sizeHint) const {
    QVariant vi = index.data(Models::MessageFeed::Bulk);
    Models::FeedItem data = qvariant_cast<Models::FeedItem>(vi);
    if (data.text.size() > 0) {
        QRect localHint = getHoveredMessageBodyRect(index, data, sizeHint);

        if (localHint.contains(point)) {
            QPoint translated = point - localHint.topLeft();

            bodyRenderer->setHtml(Shared::processMessageBody(data.text));
            bodyRenderer->setTextWidth(localHint.size().width());

            QAbstractTextDocumentLayout* lay = bodyRenderer->documentLayout();
            QString anchor = lay->anchorAt(translated);

            if (anchor.size() > 0) {
                return Shared::Hover::anchor;
            } else {
                int position = lay->hitTest(translated, Qt::HitTestAccuracy::ExactHit);
                if (position != -1)
                    return Shared::Hover::text;
            }
        }
    }
    return Shared::Hover::nothing;
}

QString MessageDelegate::mouseDrag(const QPoint& start, const QPoint& end, const QModelIndex& index, const QRect& sizeHint) {
    QVariant vi = index.data(Models::MessageFeed::Bulk);
    Models::FeedItem data = qvariant_cast<Models::FeedItem>(vi);
    if (data.text.size() > 0) {
        QRect localHint = getHoveredMessageBodyRect(index, data, sizeHint);

        if (localHint.contains(start)) {
            QPoint tl = localHint.topLeft();
            QPoint first = start - tl;
            QPoint last = end - tl;
            last.setX(std::max(last.x(), 0));
            last.setX(std::min(last.x(), localHint.width() - 1));
            last.setY(std::max(last.y(), 0));
            last.setY(std::min(last.y(), localHint.height()));

            bodyRenderer->setHtml(Shared::processMessageBody(data.text));
            bodyRenderer->setTextWidth(localHint.size().width());
            selection.first = bodyRenderer->documentLayout()->hitTest(first, Qt::HitTestAccuracy::FuzzyHit);
            selection.second = bodyRenderer->documentLayout()->hitTest(last, Qt::HitTestAccuracy::FuzzyHit);

            currentId = data.id;

            if (selection.first != selection.second) {
                QTextCursor cursor(bodyRenderer);
                cursor.setPosition(selection.first, QTextCursor::MoveAnchor);
                cursor.setPosition(selection.second, QTextCursor::KeepAnchor);
                return cursor.selectedText();
            }
        }
    }
    return "";
}

QString MessageDelegate::clearSelection() {
    QString lastSelectedId = currentId;
    currentId = "";
    selection = std::pair(0, 0);
    return lastSelectedId;
}

bool MessageDelegate::editorEvent(QEvent* event, QAbstractItemModel* model, const QStyleOptionViewItem& option, const QModelIndex& index) {
    //qDebug() << event->type();
    return QStyledItemDelegate::editorEvent(event, model, option, index);
}

int MessageDelegate::paintButton(QPushButton* btn, QPainter* painter, bool sentByMe, QStyleOptionViewItem& option) const {
    QPoint start;
    if (sentByMe)
        start = {option.rect.x() + option.rect.width() - btn->width(), option.rect.top()};
    else
        start = option.rect.topLeft();
    
    QWidget* vp = static_cast<QWidget*>(painter->device());
    btn->setParent(vp);
    btn->move(start);
    btn->show();
    
    option.rect.adjust(0, buttonHeight + textMargin, 0, 0);
    return btn->width();
}

int MessageDelegate::paintComment(const Models::FeedItem& data, QPainter* painter, QStyleOptionViewItem& option) const {
    painter->setFont(dateFont);
    QColor q = painter->pen().color();
    q.setAlpha(180);
    painter->setPen(q);
    QRect rect;
    painter->drawText(option.rect, option.displayAlignment, data.attach.error, &rect);
    option.rect.adjust(0, rect.height() + textMargin, 0, 0);

    return rect.width();
}

int MessageDelegate::paintBar(QProgressBar* bar, QPainter* painter, bool sentByMe, QStyleOptionViewItem& option) const {
    SHARED_UNUSED(sentByMe);
    QPoint start = option.rect.topLeft();
    bar->resize(option.rect.width(), barHeight);   
    
    painter->translate(start);
    bar->render(painter, QPoint(), QRegion(), QWidget::DrawChildren);
    
    option.rect.adjust(0, barHeight + textMargin, 0, 0);

    return option.rect.width();
}

int MessageDelegate::paintPreview(const Models::FeedItem& data, QPainter* painter, QStyleOptionViewItem& option) const {
    Preview* preview = 0;
    std::map<QString, Preview*>::iterator itr = previews->find(data.id);

    QSize size = option.rect.size();
    QString path = Shared::resolvePath(data.attach.localPath);
    if (itr != previews->end()) {
        preview = itr->second;
        preview->actualize(path, size, option.rect.topLeft());
    } else {
        QWidget* vp = static_cast<QWidget*>(painter->device());
        preview = new Preview(path, size, option.rect.topLeft(), vp);
        previews->insert(std::make_pair(data.id, preview));
    }
    
    if (!preview->isFileReachable())        //this is the situation when the file preview couldn't be painted because the file was moved
        emit invalidPath(data.id);          //or deleted. This signal notifies the model, and the model notifies the core, preview can 
                                            //handle being invalid for as long as I need and can be even become valid again with a new path
    QSize pSize(preview->size());
    option.rect.adjust(0, pSize.height() + textMargin, 0, 0);

    return pSize.width();
}

QPushButton * MessageDelegate::getButton(const Models::FeedItem& data) const {
    std::map<QString, FeedButton*>::const_iterator itr = buttons->find(data.id);
    FeedButton* result = 0;
    if (itr != buttons->end()) {
        result = itr->second;
    } else {
        std::map<QString, QProgressBar*>::const_iterator barItr = bars->find(data.id);
        if (barItr != bars->end()) {
            delete barItr->second;
            bars->erase(barItr);
        }
    }
    
    if (result == 0) {
        result = new FeedButton();
        result->messageId = data.id;
        result->setText(QCoreApplication::translate("MessageLine", "Download"));
        buttons->insert(std::make_pair(data.id, result));
        connect(result, &QPushButton::clicked, this, &MessageDelegate::onButtonPushed);
    }
    
    return result;
}

QProgressBar * MessageDelegate::getBar(const Models::FeedItem& data) const {
    std::map<QString, QProgressBar*>::const_iterator barItr = bars->find(data.id);
    QProgressBar* result = 0;
    if (barItr != bars->end()) {
        result = barItr->second;
    } else {
        std::map<QString, FeedButton*>::const_iterator itr = buttons->find(data.id);
        if (itr != buttons->end()) {
            delete itr->second;
            buttons->erase(itr);
        }
    }
    
    if (result == 0) {
        result = new QProgressBar();
        result->setRange(0, 100);
        bars->insert(std::make_pair(data.id, result));
    }
    
    result->setValue(data.attach.progress * 100);
    
    return result;
}

QLabel * MessageDelegate::getStatusIcon(const Models::FeedItem& data) const {
    std::map<QString, QLabel*>::const_iterator itr = statusIcons->find(data.id);
    QLabel* result = 0;
    
    if (itr != statusIcons->end()) {
        result = itr->second;
    } else {
        result = new QLabel();
        statusIcons->insert(std::make_pair(data.id, result));
    }
    
    QIcon q(Shared::icon(Shared::messageStateThemeIcons[static_cast<uint8_t>(data.state)]));
    QString tt = Shared::Global::getName(data.state);
    if (data.state == Shared::Message::State::error) {
        if (data.error > 0)
            tt += ": " + data.error;
    }
    if (result->toolTip() != tt) {                      //If i just assign pixmap every time unconditionally
        result->setPixmap(q.pixmap(statusIconSize));    //it invokes an infinite cycle of repaint
        result->setToolTip(tt);                         //may be it's better to subclass and store last condition in int?
    }
    
    return result;
}

QLabel * MessageDelegate::getPencilIcon(const Models::FeedItem& data) const {
    std::map<QString, QLabel*>::const_iterator itr = pencilIcons->find(data.id);
    QLabel* result = 0;
    
    if (itr != pencilIcons->end()) {
        result = itr->second;
    } else {
        result = new QLabel();
        QIcon icon = Shared::icon("edit-rename");
        result->setPixmap(icon.pixmap(statusIconSize));
        pencilIcons->insert(std::make_pair(data.id, result));
    }
    
    result->setToolTip("Last time edited: " + data.correction.lastCorrection.toLocalTime().toString() 
    + "\nOriginal message: " + data.correction.original);
    
    return result;
}

template <typename T>
void removeElements(std::map<QString, T*>* elements, std::set<QString>* idsToKeep) {
    std::set<QString> toRemove;
    for (const std::pair<const QString, T*>& pair: *elements) {
        if (idsToKeep->find(pair.first) == idsToKeep->end()) {
            delete pair.second;
            toRemove.insert(pair.first);
        }
    }
    for (const QString& key : toRemove) {
        elements->erase(key);
    }
}

int MessageDelegate::paintBody(const Models::FeedItem& data, QPainter* painter, QStyleOptionViewItem& option) const
{
    if (data.text.size() > 0) {
        bodyRenderer->setHtml(Shared::processMessageBody(data.text));
        bodyRenderer->setTextWidth(option.rect.size().width());
        painter->save();
        painter->translate(option.rect.topLeft());

        if (data.id == currentId) {
            QTextCursor cursor(bodyRenderer);
            cursor.setPosition(selection.first, QTextCursor::MoveAnchor);
            cursor.setPosition(selection.second, QTextCursor::KeepAnchor);
            QTextCharFormat format = cursor.charFormat();
            format.setBackground(option.palette.color(QPalette::Active, QPalette::Highlight));
            format.setForeground(option.palette.color(QPalette::Active, QPalette::HighlightedText));
            cursor.setCharFormat(format);
        }

        bodyRenderer->drawContents(painter);

        painter->restore();
        QSize bodySize(std::ceil(bodyRenderer->idealWidth()), std::ceil(bodyRenderer->size().height()));

        option.rect.adjust(0, bodySize.height() + textMargin, 0, 0);
        return bodySize.width();
    }
    return 0;
}

void MessageDelegate::beginClearWidgets() {
    idsToKeep->clear();
    clearingWidgets = true;
}

void MessageDelegate::endClearWidgets() {
    if (clearingWidgets) {
        removeElements(buttons, idsToKeep);
        removeElements(bars, idsToKeep);
        removeElements(statusIcons, idsToKeep);
        removeElements(pencilIcons, idsToKeep);
        removeElements(previews, idsToKeep);
        
        idsToKeep->clear();
        clearingWidgets = false;
    }
}

void MessageDelegate::onButtonPushed() const {
    FeedButton* btn = static_cast<FeedButton*>(sender());
    emit buttonPushed(btn->messageId);
}

void MessageDelegate::clearHelperWidget(const Models::FeedItem& data) const {
    std::map<QString, FeedButton*>::const_iterator itr = buttons->find(data.id);
    if (itr != buttons->end()) {
        delete itr->second;
        buttons->erase(itr);
    } else {
        std::map<QString, QProgressBar*>::const_iterator barItr = bars->find(data.id);
        if (barItr != bars->end()) {
            delete barItr->second;
            bars->erase(barItr);
        }
    }
}