flattofoldersproxymodel.cpp

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/**********************************************************************
 * LeechCraft - modular cross-platform feature rich internet client.
 * Copyright (C) 2006-2014  Georg Rudoy
 *
 * Distributed under the Boost Software License, Version 1.0.
 * (See accompanying file LICENSE or copy at https://www.boost.org/LICENSE_1_0.txt)
 **********************************************************************/

#include "flattofoldersproxymodel.h"
#include <QSet>
#include <QMimeData>
#include <QItemSelectionRange>
#include <util/sll/containerconversions.h>
#include <util/sll/prelude.h>
#include <interfaces/iinfo.h>
#include <interfaces/core/itagsmanager.h>

namespace LC::Util
{
    struct FlatTreeItem
    {
        QList<FlatTreeItem_ptr> C_;
        FlatTreeItem_ptr Parent_;

        enum class Type
        {
            Root,
            Folder,
            Item
        };

        Type Type_ = Type::Root;

        QPersistentModelIndex Index_;
        QString Tag_;

        int Row () const
        {
            if (Parent_)
            {
                const auto& c = Parent_->C_;
                for (int i = 0, size = c.size (); i < size; ++i)
                    if (c.at (i).get () == this)
                        return i;
            }
            return 0;
        }
    };

    FlatTreeItem* ToFlat (const QModelIndex& idx)
    {
        return static_cast<FlatTreeItem*> (idx.internalPointer ());
    }

    FlatToFoldersProxyModel::FlatToFoldersProxyModel (const ITagsManager *itm, QObject *parent)
    : QAbstractItemModel { parent }
    , TM_ { itm }
    , Root_ { std::make_shared<FlatTreeItem> () }
    {
    }

    int FlatToFoldersProxyModel::columnCount (const QModelIndex&) const
    {
        return SourceModel_ ?
            SourceModel_->columnCount ({}) :
            0;
    }

    QVariant FlatToFoldersProxyModel::data (const QModelIndex& index, int role) const
    {
        const auto fti = ToFlat (index);

        if (fti->Type_ == FlatTreeItem::Type::Item)
        {
            const auto& source = fti->Index_;
            return source.sibling (source.row (), index.column ()).data (role);
        }

        if (fti->Type_ == FlatTreeItem::Type::Folder && index.column () == 0)
        {
            switch (role)
            {
            case Qt::DisplayRole:
            {
                if (fti->Tag_.isEmpty ())
                    return tr ("untagged");

                const auto& ut = TM_->GetTag (fti->Tag_);
                return ut.isEmpty () ? tr ("<unknown tag>") : ut;
            }
            case +CustomDataRoles::Tags:
                return fti->Tag_;
            default:
                return {};
            }
        }

        return {};
    }

    QVariant FlatToFoldersProxyModel::headerData (int section, Qt::Orientation orient, int role) const
    {
        if (!SourceModel_)
            return {};

        return SourceModel_->headerData (section, orient, role);
    }

    Qt::ItemFlags FlatToFoldersProxyModel::flags (const QModelIndex& index) const
    {
        if (const auto fti = ToFlat (index);
            fti && fti->Type_ == FlatTreeItem::Type::Item)
            return fti->Index_.flags ();

        return Qt::ItemIsSelectable |
                Qt::ItemIsEnabled |
                Qt::ItemIsDragEnabled |
                Qt::ItemIsDropEnabled;
    }

    QModelIndex FlatToFoldersProxyModel::index (int row, int column, const QModelIndex& parent) const
    {
        if (!hasIndex (row, column, parent))
            return {};

        const auto& fti = ToFlatOrRoot (parent);
        return fti.Type_ == FlatTreeItem::Type::Item ?
                QModelIndex {} :
                createIndex (row, column, fti.C_.at (row).get ());
    }

    QModelIndex FlatToFoldersProxyModel::parent (const QModelIndex& index) const
    {
        const auto& parent = ToFlatOrRoot (index).Parent_;
        if (!parent || parent->Type_ == FlatTreeItem::Type::Root)
            return {};

        return createIndex (parent->Row (), 0, parent.get ());
    }

    int FlatToFoldersProxyModel::rowCount (const QModelIndex& index) const
    {
        return ToFlatOrRoot (index).C_.size ();
    }

    Qt::DropActions FlatToFoldersProxyModel::supportedDropActions() const
    {
        return SourceModel_ ?
                SourceModel_->supportedDropActions () :
                QAbstractItemModel::supportedDropActions ();
    }

    QStringList FlatToFoldersProxyModel::mimeTypes() const
    {
        return SourceModel_ ?
                SourceModel_->mimeTypes () :
                QAbstractItemModel::mimeTypes ();
    }

    QMimeData* FlatToFoldersProxyModel::mimeData (const QModelIndexList& indexes) const
    {
        if (!SourceModel_)
            return QAbstractItemModel::mimeData (indexes);

        QModelIndexList sourceIdxs;
        for (const auto& index : indexes)
        {
            auto item = static_cast<FlatTreeItem*> (index.internalPointer ());
            switch (item->Type_)
            {
            case FlatTreeItem::Type::Item:
                sourceIdxs << MapToSource (index);
                break;
            case FlatTreeItem::Type::Folder:
                for (const auto& subItem : item->C_)
                    sourceIdxs << subItem->Index_;
                break;
            default:
                break;
            }
        }

        return SourceModel_->mimeData (sourceIdxs);
    }

    bool FlatToFoldersProxyModel::dropMimeData (const QMimeData* data, Qt::DropAction action, int, int, const QModelIndex& parent)
    {
        if (!SourceModel_)
            return false;

        QMimeData modified;
        for (const auto& format : data->formats ())
            modified.setData (format, data->data (format));

        switch (const auto ptr = static_cast<FlatTreeItem*> (parent.internalPointer ());
                ptr->Type_)
        {
        case FlatTreeItem::Type::Folder:
        case FlatTreeItem::Type::Item:
            modified.setData (QStringLiteral ("x-leechcraft/tag"), ptr->Tag_.toLatin1 ());
            break;
        default:
            break;
        }

        return SourceModel_->dropMimeData (&modified, action, -1, -1, QModelIndex ());
    }

    void FlatToFoldersProxyModel::SetSourceModel (QAbstractItemModel *model)
    {
        if (SourceModel_)
            disconnect (SourceModel_,
                    nullptr,
                    this,
                    nullptr);

        SourceModel_ = model;

        if (model)
        {
            // We don't support changing columns (yet) so don't connect
            // to columns* signals.
            connect (model,
                    &QAbstractItemModel::headerDataChanged,
                    this,
                    &QAbstractItemModel::headerDataChanged);
            connect (model,
                    &QAbstractItemModel::dataChanged,
                    this,
                    &FlatToFoldersProxyModel::HandleDataChanged);
            connect (model,
                    &QAbstractItemModel::layoutAboutToBeChanged,
                    this,
                    &QAbstractItemModel::layoutAboutToBeChanged);
            connect (model,
                    &QAbstractItemModel::layoutChanged,
                    this,
                    &QAbstractItemModel::layoutChanged);
            connect (model,
                    &QAbstractItemModel::modelReset,
                    this,
                    &FlatToFoldersProxyModel::HandleModelReset);
            connect (model,
                    &QAbstractItemModel::rowsInserted,
                    this,
                    &FlatToFoldersProxyModel::HandleRowsInserted);
            connect (model,
                    &QAbstractItemModel::rowsAboutToBeRemoved,
                    this,
                    &FlatToFoldersProxyModel::HandleRowsAboutToBeRemoved);
        }

        HandleModelReset ();
    }

    QAbstractItemModel* FlatToFoldersProxyModel::GetSourceModel () const
    {
        return SourceModel_;
    }

    QModelIndex FlatToFoldersProxyModel::MapToSource (const QModelIndex& proxy) const
    {
        if (!GetSourceModel ())
            return {};

        if (!proxy.isValid ())
            return {};

        const auto item = ToFlat (proxy);

        if (item->Type_ != FlatTreeItem::Type::Item)
            return {};

        return item->Index_;
    }

    QList<QModelIndex> FlatToFoldersProxyModel::MapFromSource (const QModelIndex& source) const
    {
        auto tags = source.data (+CustomDataRoles::Tags).toStringList ();
        if (tags.isEmpty ())
            tags << QString ();

        QList<QModelIndex> result;
        for (const auto& tag : tags)
        {
            const auto& folder = FindFolder (tag);
            if (!folder)
            {
                qWarning () << Q_FUNC_INFO
                        << "could not find folder for tag"
                        << tag
                        << GetSourceModel ();
                continue;
            }

            const auto& folderIdx = index (folder->Row (), 0, {});

            for (int i = 0; i < folder->C_.size (); ++i)
            {
                const auto& child = folder->C_.at (i);
                if (child->Index_ != source)
                    continue;

                result << index (i, 0, folderIdx);
                break;
            }
        }
        return result;
    }

    bool FlatToFoldersProxyModel::IsFolder (const QModelIndex& index) const
    {
        const auto item = ToFlat (index);
        return item && item->Type_ == FlatTreeItem::Type::Folder;
    }

    QList<QModelIndex> FlatToFoldersProxyModel::GetChildren (const QModelIndex& index) const
    {
        if (!IsFolder (index))
            return {};

        const auto& children = ToFlat (index)->C_;
        QList<QModelIndex> result;
        result.reserve (children.size ());
        for (const auto& child : children)
            result << child->Index_;
        return result;
    }

    QList<QVariant> FlatToFoldersProxyModel::GetChildrenData (const QModelIndex& index, int role) const
    {
        const auto& children = GetChildren (index);

        QList<QVariant> result;
        result.reserve (children.size ());
        for (const auto& child : children)
            result.push_back (child.data (role));
        return result;
    }

    FlatTreeItem_ptr FlatToFoldersProxyModel::FindFolder (const QString& tag) const
    {
        for (const auto& item : Root_->C_)
            if (item->Tag_ == tag)
                return item;

        return {};
    }

    FlatTreeItem_ptr FlatToFoldersProxyModel::GetFolder (const QString& tag)
    {
        auto& c = Root_->C_;
        for (const auto& item : c)
            if (item->Tag_ == tag)
                return item;

        const auto& item = std::make_shared<FlatTreeItem> ();
        item->Type_ = FlatTreeItem::Type::Folder;
        item->Tag_ = tag;
        item->Parent_ = Root_;

        int size = c.size ();
        beginInsertRows (QModelIndex (), size, size);
        c.append (item);
        endInsertRows ();

        return item;
    }

    const FlatTreeItem& FlatToFoldersProxyModel::ToFlatOrRoot (const QModelIndex& idx) const
    {
        return idx.isValid () ? *ToFlat (idx) : *Root_;
    }

    void FlatToFoldersProxyModel::HandleRowInserted (int i)
    {
        const auto& idx = SourceModel_->index (i, 0);

        auto tags = idx.data (+CustomDataRoles::Tags).toStringList ();

        if (tags.isEmpty ())
            tags << QString ();

        QPersistentModelIndex pidx (idx);

        for (const auto& tag : std::as_const (tags))
            AddForTag (tag, pidx);
    }

    void FlatToFoldersProxyModel::HandleRowRemoved (int i)
    {
        QAbstractItemModel *model = SourceModel_;
        QModelIndex idx = model->index (i, 0);

        QStringList tags = idx.data (+CustomDataRoles::Tags).toStringList ();

        if (tags.isEmpty ())
            tags << QString ();

        QPersistentModelIndex pidx (idx);

        for (const auto& tag : tags)
            RemoveFromTag (tag, pidx);
    }

    void FlatToFoldersProxyModel::AddForTag (const QString& tag,
            const QPersistentModelIndex& pidx)
    {
        FlatTreeItem_ptr folder = GetFolder (tag);

        const auto& item = std::make_shared<FlatTreeItem> ();
        item->Type_ = FlatTreeItem::Type::Item;
        item->Index_ = pidx;
        item->Parent_ = folder;
        item->Tag_ = tag;

        int size = folder->C_.size ();
        QModelIndex iidx = index (Root_->C_.indexOf (folder), 0);
        beginInsertRows (iidx, size, size);
        folder->C_.append (item);
        Items_.insert (pidx, item);
        endInsertRows ();
    }

    void FlatToFoldersProxyModel::RemoveFromTag (const QString& tag,
            const QPersistentModelIndex& pidx)
    {
        const auto& folder = GetFolder (tag);
        auto& c = folder->C_;
        int findex = Root_->C_.indexOf (folder);
        for (int i = 0, size = c.size ();
                i < size; ++i)
        {
            if (c.at (i)->Index_ != pidx)
                continue;

            beginRemoveRows (index (findex, 0), i, i);
            Items_.remove (pidx, c.at (i));
            c.removeAt (i);
            endRemoveRows ();
            break;
        }

        if (c.isEmpty ())
        {
            beginRemoveRows (QModelIndex (), findex, findex);
            Root_->C_.removeAt (findex);
            endRemoveRows ();
        }
    }

    void FlatToFoldersProxyModel::HandleChanged (const QModelIndex& idx)
    {
        auto newTags = Util::AsSet (idx.data (+CustomDataRoles::Tags).toStringList ());
        if (newTags.isEmpty ())
            newTags << QString {};

        QPersistentModelIndex pidx (idx);

        const auto& oldTags = Util::MapAs<QSet> (Items_.values (pidx), [] (const auto& item) { return item->Tag_; });

        const auto added = QSet<QString> (newTags).subtract (oldTags);
        const auto removed = QSet<QString> (oldTags).subtract (newTags);
        const auto changed = QSet<QString> (newTags).intersect (oldTags);

        for (const auto& ch : changed)
        {
            FlatTreeItem_ptr folder = GetFolder (ch);

            QList<FlatTreeItem_ptr>& c = folder->C_;
            int findex = Root_->C_.indexOf (folder);
            QModelIndex fmi = index (findex, 0);
            for (int i = 0, size = c.size ();
                    i < size; ++i)
            {
                if (c.at (i)->Index_ != pidx)
                    continue;

                emit dataChanged (index (i, 0, fmi),
                        index (i, columnCount () - 1, fmi));
                break;
            }
        }

        for (const auto& rem : removed)
            RemoveFromTag (rem, pidx);

        for (const auto& add : added)
            AddForTag (add, pidx);
    }

    void FlatToFoldersProxyModel::HandleDataChanged (const QModelIndex& topLeft, const QModelIndex& bottomRight)
    {
        const QItemSelectionRange range
        {
            topLeft.sibling (topLeft.row (), 0),
            bottomRight.sibling (bottomRight.row (), 0)
        };
        for (const auto& index : range.indexes ())
            HandleChanged (index);
    }

    void FlatToFoldersProxyModel::HandleModelReset ()
    {
        if (const int size = Root_->C_.size ())
        {
            beginRemoveRows (QModelIndex (), 0, size - 1);
            Root_->C_.clear ();
            Items_.clear ();
            endRemoveRows ();
        }

        if (SourceModel_)
            for (int i = 0, size = SourceModel_->rowCount (); i < size; ++i)
                HandleRowInserted (i);
    }

    void FlatToFoldersProxyModel::HandleRowsInserted (const QModelIndex&, int start, int end)
    {
        for (int i = start; i <= end; ++i)
            HandleRowInserted (i);
    }

    void FlatToFoldersProxyModel::HandleRowsAboutToBeRemoved (const QModelIndex&, int start, int end)
    {
        for (int i = start; i <= end; ++i)
            HandleRowRemoved (i);
    }
}