/*
  ==============================================================================

   This file is part of the JUCE 6 technical preview.
   Copyright (c) 2020 - Raw Material Software Limited

   You may use this code under the terms of the GPL v3
   (see www.gnu.org/licenses).

   For this technical preview, this file is not subject to commercial licensing.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

class TreeView::ContentComponent  : public Component,
                                    public TooltipClient,
                                    public AsyncUpdater
{
public:
    ContentComponent (TreeView& tree)  : owner (tree)
    {
    }

    void mouseDown (const MouseEvent& e) override
    {
        updateButtonUnderMouse (e);

        isDragging = false;
        needSelectionOnMouseUp = false;
        Rectangle<int> pos;

        if (auto* item = findItemAt (e.y, pos))
        {
            if (isEnabled())
            {
                // (if the open/close buttons are hidden, we'll treat clicks to the left of the item
                // as selection clicks)
                if (e.x < pos.getX() && owner.openCloseButtonsVisible)
                {
                    if (e.x >= pos.getX() - owner.getIndentSize())
                        item->setOpen (! item->isOpen());

                    // (clicks to the left of an open/close button are ignored)
                }
                else
                {
                    // mouse-down inside the body of the item..
                    if (! owner.isMultiSelectEnabled())
                        item->setSelected (true, true);
                    else if (item->isSelected())
                        needSelectionOnMouseUp = ! e.mods.isPopupMenu();
                    else
                        selectBasedOnModifiers (item, e.mods);

                    if (e.x >= pos.getX())
                        item->itemClicked (e.withNewPosition (e.position - pos.getPosition().toFloat()));
                }
            }
        }
    }

    void mouseUp (const MouseEvent& e) override
    {
        updateButtonUnderMouse (e);

        if (needSelectionOnMouseUp && e.mouseWasClicked() && isEnabled())
        {
            Rectangle<int> pos;

            if (auto* item = findItemAt (e.y, pos))
                selectBasedOnModifiers (item, e.mods);
        }
    }

    void mouseDoubleClick (const MouseEvent& e) override
    {
        if (e.getNumberOfClicks() != 3 && isEnabled())  // ignore triple clicks
        {
            Rectangle<int> pos;

            if (auto* item = findItemAt (e.y, pos))
                if (e.x >= pos.getX() || ! owner.openCloseButtonsVisible)
                    item->itemDoubleClicked (e.withNewPosition (e.position - pos.getPosition().toFloat()));
        }
    }

    void mouseDrag (const MouseEvent& e) override
    {
        if (isEnabled()
             && ! (isDragging || e.mouseWasClicked()
                    || e.getDistanceFromDragStart() < 5
                    || e.mods.isPopupMenu()))
        {
            isDragging = true;
            Rectangle<int> pos;

            if (auto* item = findItemAt (e.getMouseDownY(), pos))
            {
                if (e.getMouseDownX() >= pos.getX())
                {
                    auto dragDescription = item->getDragSourceDescription();

                    if (! (dragDescription.isVoid() || (dragDescription.isString() && dragDescription.toString().isEmpty())))
                    {
                        if (auto* dragContainer = DragAndDropContainer::findParentDragContainerFor (this))
                        {
                            pos.setSize (pos.getWidth(), item->itemHeight);
                            Image dragImage (Component::createComponentSnapshot (pos, true));
                            dragImage.multiplyAllAlphas (0.6f);

                            auto imageOffset = pos.getPosition() - e.getPosition();
                            dragContainer->startDragging (dragDescription, &owner, dragImage, true, &imageOffset, &e.source);
                        }
                        else
                        {
                            // to be able to do a drag-and-drop operation, the treeview needs to
                            // be inside a component which is also a DragAndDropContainer.
                            jassertfalse;
                        }
                    }
                }
            }
        }
    }

    void mouseMove (const MouseEvent& e) override    { updateButtonUnderMouse (e); }
    void mouseExit (const MouseEvent& e) override    { updateButtonUnderMouse (e); }

    void paint (Graphics& g) override
    {
        if (owner.rootItem != nullptr)
        {
            owner.recalculateIfNeeded();

            if (! owner.rootItemVisible)
                g.setOrigin (0, -owner.rootItem->itemHeight);

            owner.rootItem->paintRecursively (g, getWidth());
        }
    }

    TreeViewItem* findItemAt (int y, Rectangle<int>& itemPosition) const
    {
        if (owner.rootItem != nullptr)
        {
            owner.recalculateIfNeeded();

            if (! owner.rootItemVisible)
                y += owner.rootItem->itemHeight;

            if (auto* ti = owner.rootItem->findItemRecursively (y))
            {
                itemPosition = ti->getItemPosition (false);
                return ti;
            }
        }

        return nullptr;
    }

    void updateComponents()
    {
        auto visibleTop = -getY();
        auto visibleBottom = visibleTop + getParentHeight();

        for (auto* i : items)
            i->shouldKeep = false;

        {
            auto* item = owner.rootItem;
            int y = (item != nullptr && ! owner.rootItemVisible) ? -item->itemHeight : 0;

            while (item != nullptr && y < visibleBottom)
            {
                y += item->itemHeight;

                if (y >= visibleTop)
                {
                    if (auto* ri = findItem (item->uid))
                    {
                        ri->shouldKeep = true;
                    }
                    else if (auto* comp = item->createItemComponent())
                    {
                        items.add (new RowItem (item, comp, item->uid));
                        addAndMakeVisible (comp);
                    }
                }

                item = item->getNextVisibleItem (true);
            }
        }

        for (int i = items.size(); --i >= 0;)
        {
            auto* ri = items.getUnchecked(i);
            bool keep = false;

            if (isParentOf (ri->component))
            {
                if (ri->shouldKeep)
                {
                    auto pos = ri->item->getItemPosition (false);
                    pos.setSize (pos.getWidth(), ri->item->itemHeight);

                    if (pos.getBottom() >= visibleTop && pos.getY() < visibleBottom)
                    {
                        keep = true;
                        ri->component->setBounds (pos);
                    }
                }

                if ((! keep) && isMouseDraggingInChildCompOf (ri->component))
                {
                    keep = true;
                    ri->component->setSize (0, 0);
                }
            }

            if (! keep)
                items.remove (i);
        }
    }

    bool isMouseOverButton (TreeViewItem* item) const noexcept
    {
        return item == buttonUnderMouse;
    }

    void resized() override
    {
        owner.itemsChanged();
    }

    String getTooltip() override
    {
        Rectangle<int> pos;

        if (auto* item = findItemAt (getMouseXYRelative().y, pos))
            return item->getTooltip();

        return owner.getTooltip();
    }

private:
    //==============================================================================
    TreeView& owner;

    struct RowItem
    {
        RowItem (TreeViewItem* it, Component* c, int itemUID)
            : component (c), item (it), uid (itemUID)
        {
        }

        ~RowItem()
        {
            delete component.get();
        }

        WeakReference<Component> component;
        TreeViewItem* item;
        int uid;
        bool shouldKeep = true;
    };

    OwnedArray<RowItem> items;
    TreeViewItem* buttonUnderMouse = nullptr;
    bool isDragging = false, needSelectionOnMouseUp = false;

    void selectBasedOnModifiers (TreeViewItem* const item, const ModifierKeys modifiers)
    {
        TreeViewItem* firstSelected = nullptr;

        if (modifiers.isShiftDown() && ((firstSelected = owner.getSelectedItem (0)) != nullptr))
        {
            auto* lastSelected = owner.getSelectedItem (owner.getNumSelectedItems() - 1);
            jassert (lastSelected != nullptr);

            auto rowStart = firstSelected->getRowNumberInTree();
            auto rowEnd = lastSelected->getRowNumberInTree();

            if (rowStart > rowEnd)
                std::swap (rowStart, rowEnd);

            auto ourRow = item->getRowNumberInTree();
            auto otherEnd = ourRow < rowEnd ? rowStart : rowEnd;

            if (ourRow > otherEnd)
                std::swap (ourRow, otherEnd);

            for (int i = ourRow; i <= otherEnd; ++i)
                owner.getItemOnRow (i)->setSelected (true, false);
        }
        else
        {
            const bool cmd = modifiers.isCommandDown();
            item->setSelected ((! cmd) || ! item->isSelected(), ! cmd);
        }
    }

    bool containsItem (TreeViewItem* const item) const noexcept
    {
        for (auto* i : items)
            if (i->item == item)
                return true;

        return false;
    }

    RowItem* findItem (const int uid) const noexcept
    {
        for (auto* i : items)
            if (i->uid == uid)
                return i;

        return nullptr;
    }

    void updateButtonUnderMouse (const MouseEvent& e)
    {
        TreeViewItem* newItem = nullptr;

        if (owner.openCloseButtonsVisible)
        {
            Rectangle<int> pos;

            if (auto* item = findItemAt (e.y, pos))
            {
                if (e.x < pos.getX() && e.x >= pos.getX() - owner.getIndentSize())
                {
                    newItem = item;

                    if (! newItem->mightContainSubItems())
                        newItem = nullptr;
                }
            }
        }

        if (buttonUnderMouse != newItem)
        {
            repaintButtonUnderMouse();
            buttonUnderMouse = newItem;
            repaintButtonUnderMouse();
        }
    }

    void repaintButtonUnderMouse()
    {
        if (buttonUnderMouse != nullptr && containsItem (buttonUnderMouse))
        {
            auto r = buttonUnderMouse->getItemPosition (false);
            repaint (0, r.getY(), r.getX(), buttonUnderMouse->getItemHeight());
        }
    }

    static bool isMouseDraggingInChildCompOf (Component* const comp)
    {
        for (auto& ms : Desktop::getInstance().getMouseSources())
            if (ms.isDragging())
                if (auto* underMouse = ms.getComponentUnderMouse())
                    if (comp == underMouse || comp->isParentOf (underMouse))
                        return true;

        return false;
    }

    void handleAsyncUpdate() override
    {
        owner.recalculateIfNeeded();
    }

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (ContentComponent)
};

//==============================================================================
class TreeView::TreeViewport  : public Viewport
{
public:
    TreeViewport() noexcept {}

    void updateComponents (const bool triggerResize)
    {
        if (auto* tvc = getContentComp())
        {
            if (triggerResize)
                tvc->resized();
            else
                tvc->updateComponents();
        }

        repaint();
    }

    void visibleAreaChanged (const Rectangle<int>& newVisibleArea) override
    {
        const bool hasScrolledSideways = (newVisibleArea.getX() != lastX);
        lastX = newVisibleArea.getX();
        updateComponents (hasScrolledSideways);
    }

    ContentComponent* getContentComp() const noexcept
    {
        return static_cast<ContentComponent*> (getViewedComponent());
    }

    bool keyPressed (const KeyPress& key) override
    {
        if (auto* tree = getParentComponent())
            if (tree->keyPressed (key))
                return true;

        return Viewport::keyPressed (key);
    }

private:
    int lastX = -1;

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (TreeViewport)
};


//==============================================================================
TreeView::TreeView (const String& name)
    : Component (name),
      viewport (new TreeViewport())
{
    addAndMakeVisible (viewport.get());
    viewport->setViewedComponent (new ContentComponent (*this));
    setWantsKeyboardFocus (true);
}

TreeView::~TreeView()
{
    if (rootItem != nullptr)
        rootItem->setOwnerView (nullptr);
}

void TreeView::setRootItem (TreeViewItem* const newRootItem)
{
    if (rootItem != newRootItem)
    {
        if (newRootItem != nullptr)
        {
            jassert (newRootItem->ownerView == nullptr); // can't use a tree item in more than one tree at once..

            if (newRootItem->ownerView != nullptr)
                newRootItem->ownerView->setRootItem (nullptr);
        }

        if (rootItem != nullptr)
            rootItem->setOwnerView (nullptr);

        rootItem = newRootItem;

        if (newRootItem != nullptr)
            newRootItem->setOwnerView (this);

        needsRecalculating = true;
        recalculateIfNeeded();

        if (rootItem != nullptr && (defaultOpenness || ! rootItemVisible))
        {
            rootItem->setOpen (false); // force a re-open
            rootItem->setOpen (true);
        }
    }
}

void TreeView::deleteRootItem()
{
    const std::unique_ptr<TreeViewItem> deleter (rootItem);
    setRootItem (nullptr);
}

void TreeView::setRootItemVisible (const bool shouldBeVisible)
{
    rootItemVisible = shouldBeVisible;

    if (rootItem != nullptr && (defaultOpenness || ! rootItemVisible))
    {
        rootItem->setOpen (false); // force a re-open
        rootItem->setOpen (true);
    }

    itemsChanged();
}

void TreeView::colourChanged()
{
    setOpaque (findColour (backgroundColourId).isOpaque());
    repaint();
}

void TreeView::setIndentSize (const int newIndentSize)
{
    if (indentSize != newIndentSize)
    {
        indentSize = newIndentSize;
        resized();
    }
}

int TreeView::getIndentSize() noexcept
{
    return indentSize >= 0 ? indentSize
                           : getLookAndFeel().getTreeViewIndentSize (*this);
}

void TreeView::setDefaultOpenness (const bool isOpenByDefault)
{
    if (defaultOpenness != isOpenByDefault)
    {
        defaultOpenness = isOpenByDefault;
        itemsChanged();
    }
}

void TreeView::setMultiSelectEnabled (const bool canMultiSelect)
{
    multiSelectEnabled = canMultiSelect;
}

void TreeView::setOpenCloseButtonsVisible (const bool shouldBeVisible)
{
    if (openCloseButtonsVisible != shouldBeVisible)
    {
        openCloseButtonsVisible = shouldBeVisible;
        itemsChanged();
    }
}

Viewport* TreeView::getViewport() const noexcept
{
    return viewport.get();
}

//==============================================================================
void TreeView::clearSelectedItems()
{
    if (rootItem != nullptr)
        rootItem->deselectAllRecursively (nullptr);
}

int TreeView::getNumSelectedItems (int maximumDepthToSearchTo) const noexcept
{
    return rootItem != nullptr ? rootItem->countSelectedItemsRecursively (maximumDepthToSearchTo) : 0;
}

TreeViewItem* TreeView::getSelectedItem (const int index) const noexcept
{
    return rootItem != nullptr ? rootItem->getSelectedItemWithIndex (index) : nullptr;
}

int TreeView::getNumRowsInTree() const
{
    return rootItem != nullptr ? (rootItem->getNumRows() - (rootItemVisible ? 0 : 1)) : 0;
}

TreeViewItem* TreeView::getItemOnRow (int index) const
{
    if (! rootItemVisible)
        ++index;

    if (rootItem != nullptr && index >= 0)
        return rootItem->getItemOnRow (index);

    return nullptr;
}

TreeViewItem* TreeView::getItemAt (int y) const noexcept
{
    auto tc = viewport->getContentComp();
    Rectangle<int> pos;
    return tc->findItemAt (tc->getLocalPoint (this, Point<int> (0, y)).y, pos);
}

TreeViewItem* TreeView::findItemFromIdentifierString (const String& identifierString) const
{
    if (rootItem == nullptr)
        return nullptr;

    return rootItem->findItemFromIdentifierString (identifierString);
}

//==============================================================================
static void addAllSelectedItemIds (TreeViewItem* item, XmlElement& parent)
{
    if (item->isSelected())
        parent.createNewChildElement ("SELECTED")->setAttribute ("id", item->getItemIdentifierString());

    auto numSubItems = item->getNumSubItems();

    for (int i = 0; i < numSubItems; ++i)
        addAllSelectedItemIds (item->getSubItem(i), parent);
}

std::unique_ptr<XmlElement> TreeView::getOpennessState (bool alsoIncludeScrollPosition) const
{
    std::unique_ptr<XmlElement> e;

    if (rootItem != nullptr)
    {
        e.reset (rootItem->getOpennessState (false));

        if (e != nullptr)
        {
            if (alsoIncludeScrollPosition)
                e->setAttribute ("scrollPos", viewport->getViewPositionY());

            addAllSelectedItemIds (rootItem, *e);
        }
    }

    return e;
}

void TreeView::restoreOpennessState (const XmlElement& newState, const bool restoreStoredSelection)
{
    if (rootItem != nullptr)
    {
        rootItem->restoreOpennessState (newState);

        needsRecalculating = true;
        recalculateIfNeeded();

        if (newState.hasAttribute ("scrollPos"))
            viewport->setViewPosition (viewport->getViewPositionX(),
                                       newState.getIntAttribute ("scrollPos"));

        if (restoreStoredSelection)
        {
            clearSelectedItems();

            forEachXmlChildElementWithTagName (newState, e, "SELECTED")
                if (auto* item = rootItem->findItemFromIdentifierString (e->getStringAttribute ("id")))
                    item->setSelected (true, false);
        }
    }
}

//==============================================================================
void TreeView::paint (Graphics& g)
{
    g.fillAll (findColour (backgroundColourId));
}

void TreeView::resized()
{
    viewport->setBounds (getLocalBounds());

    itemsChanged();
    recalculateIfNeeded();
}

void TreeView::enablementChanged()
{
    repaint();
}

void TreeView::moveSelectedRow (const int delta)
{
    auto numRowsInTree = getNumRowsInTree();

    if (numRowsInTree > 0)
    {
        int rowSelected = 0;

        if (auto* firstSelected = getSelectedItem (0))
            rowSelected = firstSelected->getRowNumberInTree();

        rowSelected = jlimit (0, numRowsInTree - 1, rowSelected + delta);

        for (;;)
        {
            if (auto* item = getItemOnRow (rowSelected))
            {
                if (! item->canBeSelected())
                {
                    // if the row we want to highlight doesn't allow it, try skipping
                    // to the next item..
                    auto nextRowToTry = jlimit (0, numRowsInTree - 1, rowSelected + (delta < 0 ? -1 : 1));

                    if (rowSelected != nextRowToTry)
                    {
                        rowSelected = nextRowToTry;
                        continue;
                    }

                    break;
                }

                item->setSelected (true, true);
                scrollToKeepItemVisible (item);
            }

            break;
        }
    }
}

void TreeView::scrollToKeepItemVisible (TreeViewItem* item)
{
    if (item != nullptr && item->ownerView == this)
    {
        recalculateIfNeeded();

        item = item->getDeepestOpenParentItem();

        auto y = item->y;
        auto viewTop = viewport->getViewPositionY();

        if (y < viewTop)
        {
            viewport->setViewPosition (viewport->getViewPositionX(), y);
        }
        else if (y + item->itemHeight > viewTop + viewport->getViewHeight())
        {
            viewport->setViewPosition (viewport->getViewPositionX(),
                                       (y + item->itemHeight) - viewport->getViewHeight());
        }
    }
}

bool TreeView::toggleOpenSelectedItem()
{
    if (auto* firstSelected = getSelectedItem (0))
    {
        if (firstSelected->mightContainSubItems())
        {
            firstSelected->setOpen (! firstSelected->isOpen());
            return true;
        }
    }

    return false;
}

void TreeView::moveOutOfSelectedItem()
{
    if (auto* firstSelected = getSelectedItem (0))
    {
        if (firstSelected->isOpen())
        {
            firstSelected->setOpen (false);
        }
        else
        {
            auto* parent = firstSelected->parentItem;

            if ((! rootItemVisible) && parent == rootItem)
                parent = nullptr;

            if (parent != nullptr)
            {
                parent->setSelected (true, true);
                scrollToKeepItemVisible (parent);
            }
        }
    }
}

void TreeView::moveIntoSelectedItem()
{
    if (auto* firstSelected = getSelectedItem (0))
    {
        if (firstSelected->isOpen() || ! firstSelected->mightContainSubItems())
            moveSelectedRow (1);
        else
            firstSelected->setOpen (true);
    }
}

void TreeView::moveByPages (int numPages)
{
    if (auto* currentItem = getSelectedItem (0))
    {
        auto pos = currentItem->getItemPosition (false);
        auto targetY = pos.getY() + numPages * (getHeight() - pos.getHeight());
        auto currentRow = currentItem->getRowNumberInTree();

        for (;;)
        {
            moveSelectedRow (numPages);
            currentItem = getSelectedItem (0);

            if (currentItem == nullptr)
                break;

            auto y = currentItem->getItemPosition (false).getY();

            if ((numPages < 0 && y <= targetY) || (numPages > 0 && y >= targetY))
                break;

            auto newRow = currentItem->getRowNumberInTree();

            if (newRow == currentRow)
                break;

            currentRow = newRow;
        }
    }
}

bool TreeView::keyPressed (const KeyPress& key)
{
    if (rootItem != nullptr)
    {
        if (key == KeyPress::upKey)       { moveSelectedRow (-1); return true; }
        if (key == KeyPress::downKey)     { moveSelectedRow (1);  return true; }
        if (key == KeyPress::homeKey)     { moveSelectedRow (-0x3fffffff); return true; }
        if (key == KeyPress::endKey)      { moveSelectedRow (0x3fffffff);  return true; }
        if (key == KeyPress::pageUpKey)   { moveByPages (-1); return true; }
        if (key == KeyPress::pageDownKey) { moveByPages (1);  return true; }
        if (key == KeyPress::returnKey)   { return toggleOpenSelectedItem(); }
        if (key == KeyPress::leftKey)     { moveOutOfSelectedItem();  return true; }
        if (key == KeyPress::rightKey)    { moveIntoSelectedItem();   return true; }
    }

    return false;
}

void TreeView::itemsChanged() noexcept
{
    needsRecalculating = true;
    repaint();
    viewport->getContentComp()->triggerAsyncUpdate();
}

void TreeView::recalculateIfNeeded()
{
    if (needsRecalculating)
    {
        needsRecalculating = false;

        const ScopedLock sl (nodeAlterationLock);

        if (rootItem != nullptr)
            rootItem->updatePositions (rootItemVisible ? 0 : -rootItem->itemHeight);

        viewport->updateComponents (false);

        if (rootItem != nullptr)
        {
            viewport->getViewedComponent()
                ->setSize (jmax (viewport->getMaximumVisibleWidth(), rootItem->totalWidth + 50),
                           rootItem->totalHeight - (rootItemVisible ? 0 : rootItem->itemHeight));
        }
        else
        {
            viewport->getViewedComponent()->setSize (0, 0);
        }
    }
}

//==============================================================================
struct TreeView::InsertPoint
{
    InsertPoint (TreeView& view, const StringArray& files,
                 const DragAndDropTarget::SourceDetails& dragSourceDetails)
        : pos (dragSourceDetails.localPosition),
          item (view.getItemAt (dragSourceDetails.localPosition.y))
    {
        if (item != nullptr)
        {
            auto itemPos = item->getItemPosition (true);
            insertIndex = item->getIndexInParent();
            auto oldY = pos.y;
            pos.y = itemPos.getY();

            if (item->getNumSubItems() == 0 || ! item->isOpen())
            {
                if (files.size() > 0 ? item->isInterestedInFileDrag (files)
                                     : item->isInterestedInDragSource (dragSourceDetails))
                {
                    // Check if we're trying to drag into an empty group item..
                    if (oldY > itemPos.getY() + itemPos.getHeight() / 4
                         && oldY < itemPos.getBottom() - itemPos.getHeight() / 4)
                    {
                        insertIndex = 0;
                        pos.x = itemPos.getX() + view.getIndentSize();
                        pos.y = itemPos.getBottom();
                        return;
                    }
                }
            }

            if (oldY > itemPos.getCentreY())
            {
                pos.y += item->getItemHeight();

                while (item->isLastOfSiblings() && item->getParentItem() != nullptr
                        && item->getParentItem()->getParentItem() != nullptr)
                {
                    if (pos.x > itemPos.getX())
                        break;

                    item = item->getParentItem();
                    itemPos = item->getItemPosition (true);
                    insertIndex = item->getIndexInParent();
                }

                ++insertIndex;
            }

            pos.x = itemPos.getX();
            item = item->getParentItem();
        }
        else if (auto* root = view.getRootItem())
        {
            // If they're dragging beyond the bottom of the list, then insert at the end of the root item..
            item = root;
            insertIndex = root->getNumSubItems();
            pos = root->getItemPosition (true).getBottomLeft();
            pos.x += view.getIndentSize();
        }
    }

    Point<int> pos;
    TreeViewItem* item;
    int insertIndex = 0;
};

//==============================================================================
class TreeView::InsertPointHighlight   : public Component
{
public:
    InsertPointHighlight()
    {
        setSize (100, 12);
        setAlwaysOnTop (true);
        setInterceptsMouseClicks (false, false);
    }

    void setTargetPosition (const InsertPoint& insertPos, const int width) noexcept
    {
        lastItem = insertPos.item;
        lastIndex = insertPos.insertIndex;
        auto offset = getHeight() / 2;
        setBounds (insertPos.pos.x - offset, insertPos.pos.y - offset,
                   width - (insertPos.pos.x - offset), getHeight());
    }

    void paint (Graphics& g) override
    {
        Path p;
        auto h = (float) getHeight();
        p.addEllipse (2.0f, 2.0f, h - 4.0f, h - 4.0f);
        p.startNewSubPath (h - 2.0f, h / 2.0f);
        p.lineTo ((float) getWidth(), h / 2.0f);

        g.setColour (findColour (TreeView::dragAndDropIndicatorColourId, true));
        g.strokePath (p, PathStrokeType (2.0f));
    }

    TreeViewItem* lastItem = nullptr;
    int lastIndex = 0;

private:
    JUCE_DECLARE_NON_COPYABLE (InsertPointHighlight)
};

//==============================================================================
class TreeView::TargetGroupHighlight   : public Component
{
public:
    TargetGroupHighlight()
    {
        setAlwaysOnTop (true);
        setInterceptsMouseClicks (false, false);
    }

    void setTargetPosition (TreeViewItem* const item) noexcept
    {
        setBounds (item->getItemPosition (true)
                     .withHeight (item->getItemHeight()));
    }

    void paint (Graphics& g) override
    {
        g.setColour (findColour (TreeView::dragAndDropIndicatorColourId, true));
        g.drawRoundedRectangle (1.0f, 1.0f, getWidth() - 2.0f, getHeight() - 2.0f, 3.0f, 2.0f);
    }

private:
    JUCE_DECLARE_NON_COPYABLE (TargetGroupHighlight)
};

//==============================================================================
void TreeView::showDragHighlight (const InsertPoint& insertPos) noexcept
{
    beginDragAutoRepeat (100);

    if (dragInsertPointHighlight == nullptr)
    {
        dragInsertPointHighlight.reset (new InsertPointHighlight());
        dragTargetGroupHighlight.reset (new TargetGroupHighlight());

        addAndMakeVisible (dragInsertPointHighlight.get());
        addAndMakeVisible (dragTargetGroupHighlight.get());
    }

    dragInsertPointHighlight->setTargetPosition (insertPos, viewport->getViewWidth());
    dragTargetGroupHighlight->setTargetPosition (insertPos.item);
}

void TreeView::hideDragHighlight() noexcept
{
    dragInsertPointHighlight.reset();
    dragTargetGroupHighlight.reset();
}

void TreeView::handleDrag (const StringArray& files, const SourceDetails& dragSourceDetails)
{
    const bool scrolled = viewport->autoScroll (dragSourceDetails.localPosition.x,
                                                dragSourceDetails.localPosition.y, 20, 10);

    InsertPoint insertPos (*this, files, dragSourceDetails);

    if (insertPos.item != nullptr)
    {
        if (scrolled || dragInsertPointHighlight == nullptr
             || dragInsertPointHighlight->lastItem != insertPos.item
             || dragInsertPointHighlight->lastIndex != insertPos.insertIndex)
        {
            if (files.size() > 0 ? insertPos.item->isInterestedInFileDrag (files)
                                 : insertPos.item->isInterestedInDragSource (dragSourceDetails))
                showDragHighlight (insertPos);
            else
                hideDragHighlight();
        }
    }
    else
    {
        hideDragHighlight();
    }
}

void TreeView::handleDrop (const StringArray& files, const SourceDetails& dragSourceDetails)
{
    hideDragHighlight();

    InsertPoint insertPos (*this, files, dragSourceDetails);

    if (insertPos.item == nullptr)
        insertPos.item = rootItem;

    if (insertPos.item != nullptr)
    {
        if (files.size() > 0)
        {
            if (insertPos.item->isInterestedInFileDrag (files))
                insertPos.item->filesDropped (files, insertPos.insertIndex);
        }
        else
        {
            if (insertPos.item->isInterestedInDragSource (dragSourceDetails))
                insertPos.item->itemDropped (dragSourceDetails, insertPos.insertIndex);
        }
    }
}

//==============================================================================
bool TreeView::isInterestedInFileDrag (const StringArray&)
{
    return true;
}

void TreeView::fileDragEnter (const StringArray& files, int x, int y)
{
    fileDragMove (files, x, y);
}

void TreeView::fileDragMove (const StringArray& files, int x, int y)
{
    handleDrag (files, SourceDetails (var(), this, { x, y }));
}

void TreeView::fileDragExit (const StringArray&)
{
    hideDragHighlight();
}

void TreeView::filesDropped (const StringArray& files, int x, int y)
{
    handleDrop (files, SourceDetails (var(), this, { x, y }));
}

bool TreeView::isInterestedInDragSource (const SourceDetails& /*dragSourceDetails*/)
{
    return true;
}

void TreeView::itemDragEnter (const SourceDetails& dragSourceDetails)
{
    itemDragMove (dragSourceDetails);
}

void TreeView::itemDragMove (const SourceDetails& dragSourceDetails)
{
    handleDrag (StringArray(), dragSourceDetails);
}

void TreeView::itemDragExit (const SourceDetails& /*dragSourceDetails*/)
{
    hideDragHighlight();
}

void TreeView::itemDropped (const SourceDetails& dragSourceDetails)
{
    handleDrop (StringArray(), dragSourceDetails);
}

//==============================================================================
TreeViewItem::TreeViewItem()
    : selected (false),
      redrawNeeded (true),
      drawLinesInside (false),
      drawLinesSet (false),
      drawsInLeftMargin (false),
      drawsInRightMargin (false),
      openness (opennessDefault)
{
    static int nextUID = 0;
    uid = nextUID++;
}

TreeViewItem::~TreeViewItem()
{
}

String TreeViewItem::getUniqueName() const
{
    return {};
}

void TreeViewItem::itemOpennessChanged (bool)
{
}

int TreeViewItem::getNumSubItems() const noexcept
{
    return subItems.size();
}

TreeViewItem* TreeViewItem::getSubItem (const int index) const noexcept
{
    return subItems[index];
}

void TreeViewItem::clearSubItems()
{
    if (ownerView != nullptr)
    {
        const ScopedLock sl (ownerView->nodeAlterationLock);

        if (! subItems.isEmpty())
        {
            removeAllSubItemsFromList();
            treeHasChanged();
        }
    }
    else
    {
        removeAllSubItemsFromList();
    }
}

void TreeViewItem::removeAllSubItemsFromList()
{
    for (int i = subItems.size(); --i >= 0;)
        removeSubItemFromList (i, true);
}

void TreeViewItem::addSubItem (TreeViewItem* const newItem, const int insertPosition)
{
    if (newItem != nullptr)
    {
        newItem->parentItem = nullptr;
        newItem->setOwnerView (ownerView);
        newItem->y = 0;
        newItem->itemHeight = newItem->getItemHeight();
        newItem->totalHeight = 0;
        newItem->itemWidth = newItem->getItemWidth();
        newItem->totalWidth = 0;
        newItem->parentItem = this;

        if (ownerView != nullptr)
        {
            const ScopedLock sl (ownerView->nodeAlterationLock);
            subItems.insert (insertPosition, newItem);
            treeHasChanged();

            if (newItem->isOpen())
                newItem->itemOpennessChanged (true);
        }
        else
        {
            subItems.insert (insertPosition, newItem);

            if (newItem->isOpen())
                newItem->itemOpennessChanged (true);
        }
    }
}

void TreeViewItem::removeSubItem (int index, bool deleteItem)
{
    if (ownerView != nullptr)
    {
        const ScopedLock sl (ownerView->nodeAlterationLock);

        if (removeSubItemFromList (index, deleteItem))
            treeHasChanged();
    }
    else
    {
        removeSubItemFromList (index, deleteItem);
    }
}

bool TreeViewItem::removeSubItemFromList (int index, bool deleteItem)
{
    if (auto* child = subItems[index])
    {
        child->parentItem = nullptr;
        subItems.remove (index, deleteItem);
        return true;
    }

    return false;
}

TreeViewItem::Openness TreeViewItem::getOpenness() const noexcept
{
    return (Openness) openness;
}

void TreeViewItem::setOpenness (Openness newOpenness)
{
    const bool wasOpen = isOpen();
    openness = newOpenness;
    const bool isNowOpen = isOpen();

    if (isNowOpen != wasOpen)
    {
        treeHasChanged();
        itemOpennessChanged (isNowOpen);
    }
}

bool TreeViewItem::isOpen() const noexcept
{
    if (openness == opennessDefault)
        return ownerView != nullptr && ownerView->defaultOpenness;

    return openness == opennessOpen;
}

void TreeViewItem::setOpen (const bool shouldBeOpen)
{
    if (isOpen() != shouldBeOpen)
        setOpenness (shouldBeOpen ? opennessOpen
                                  : opennessClosed);
}

bool TreeViewItem::isFullyOpen() const noexcept
{
    if (! isOpen())
        return false;

    for (auto* i : subItems)
        if (! i->isFullyOpen())
            return false;

    return true;
}

void TreeViewItem::restoreToDefaultOpenness()
{
    setOpenness (opennessDefault);
}

bool TreeViewItem::isSelected() const noexcept
{
    return selected;
}

void TreeViewItem::deselectAllRecursively (TreeViewItem* itemToIgnore)
{
    if (this != itemToIgnore)
        setSelected (false, false);

    for (auto* i : subItems)
        i->deselectAllRecursively (itemToIgnore);
}

void TreeViewItem::setSelected (const bool shouldBeSelected,
                                const bool deselectOtherItemsFirst,
                                const NotificationType notify)
{
    if (shouldBeSelected && ! canBeSelected())
        return;

    if (deselectOtherItemsFirst)
        getTopLevelItem()->deselectAllRecursively (this);

    if (shouldBeSelected != selected)
    {
        selected = shouldBeSelected;

        if (ownerView != nullptr)
            ownerView->repaint();

        if (notify != dontSendNotification)
            itemSelectionChanged (shouldBeSelected);
    }
}

void TreeViewItem::paintItem (Graphics&, int, int)
{
}

void TreeViewItem::paintOpenCloseButton (Graphics& g, const Rectangle<float>& area, Colour backgroundColour, bool isMouseOver)
{
    getOwnerView()->getLookAndFeel()
       .drawTreeviewPlusMinusBox (g, area, backgroundColour, isOpen(), isMouseOver);
}

void TreeViewItem::paintHorizontalConnectingLine (Graphics& g, const Line<float>& line)
{
   g.setColour (ownerView->findColour (TreeView::linesColourId));
   g.drawLine (line);
}

void TreeViewItem::paintVerticalConnectingLine (Graphics& g, const Line<float>& line)
{
   g.setColour (ownerView->findColour (TreeView::linesColourId));
   g.drawLine (line);
}

void TreeViewItem::itemClicked (const MouseEvent&)
{
}

void TreeViewItem::itemDoubleClicked (const MouseEvent&)
{
    if (mightContainSubItems())
        setOpen (! isOpen());
}

void TreeViewItem::itemSelectionChanged (bool)
{
}

String TreeViewItem::getTooltip()
{
    return {};
}

void TreeViewItem::ownerViewChanged (TreeView*)
{
}

var TreeViewItem::getDragSourceDescription()
{
    return {};
}

bool TreeViewItem::isInterestedInFileDrag (const StringArray&)
{
    return false;
}

void TreeViewItem::filesDropped (const StringArray& /*files*/, int /*insertIndex*/)
{
}

bool TreeViewItem::isInterestedInDragSource (const DragAndDropTarget::SourceDetails& /*dragSourceDetails*/)
{
    return false;
}

void TreeViewItem::itemDropped (const DragAndDropTarget::SourceDetails& /*dragSourceDetails*/, int /*insertIndex*/)
{
}

Rectangle<int> TreeViewItem::getItemPosition (const bool relativeToTreeViewTopLeft) const noexcept
{
    auto indentX = getIndentX();
    auto width = itemWidth;

    if (ownerView != nullptr && width < 0)
        width = ownerView->viewport->getViewWidth() - indentX;

    Rectangle<int> r (indentX, y, jmax (0, width), totalHeight);

    if (relativeToTreeViewTopLeft && ownerView != nullptr)
        r -= ownerView->viewport->getViewPosition();

    return r;
}

void TreeViewItem::treeHasChanged() const noexcept
{
    if (ownerView != nullptr)
        ownerView->itemsChanged();
}

void TreeViewItem::repaintItem() const
{
    if (ownerView != nullptr && areAllParentsOpen())
        ownerView->viewport->repaint (getItemPosition (true).withLeft (0));
}

bool TreeViewItem::areAllParentsOpen() const noexcept
{
    return parentItem == nullptr
            || (parentItem->isOpen() && parentItem->areAllParentsOpen());
}

void TreeViewItem::updatePositions (int newY)
{
    y = newY;
    itemHeight = getItemHeight();
    totalHeight = itemHeight;
    itemWidth = getItemWidth();
    totalWidth = jmax (itemWidth, 0) + getIndentX();

    if (isOpen())
    {
        newY += totalHeight;

        for (auto* i : subItems)
        {
            i->updatePositions (newY);
            newY += i->totalHeight;
            totalHeight += i->totalHeight;
            totalWidth = jmax (totalWidth, i->totalWidth);
        }
    }
}

TreeViewItem* TreeViewItem::getDeepestOpenParentItem() noexcept
{
    TreeViewItem* result = this;
    TreeViewItem* item = this;

    while (item->parentItem != nullptr)
    {
        item = item->parentItem;

        if (! item->isOpen())
            result = item;
    }

    return result;
}

void TreeViewItem::setOwnerView (TreeView* const newOwner) noexcept
{
    ownerView = newOwner;

    for (auto* i : subItems)
    {
        i->setOwnerView (newOwner);
        i->ownerViewChanged (newOwner);
    }
}

int TreeViewItem::getIndentX() const noexcept
{
    int x = ownerView->rootItemVisible ? 1 : 0;

    if (! ownerView->openCloseButtonsVisible)
        --x;

    for (auto* p = parentItem; p != nullptr; p = p->parentItem)
        ++x;

    return x * ownerView->getIndentSize();
}

void TreeViewItem::setDrawsInLeftMargin (bool canDrawInLeftMargin) noexcept
{
    drawsInLeftMargin = canDrawInLeftMargin;
}

void TreeViewItem::setDrawsInRightMargin (bool canDrawInRightMargin) noexcept
{
    drawsInRightMargin = canDrawInRightMargin;
}

namespace TreeViewHelpers
{
    static int calculateDepth (const TreeViewItem* item, const bool rootIsVisible) noexcept
    {
        jassert (item != nullptr);
        int depth = rootIsVisible ? 0 : -1;

        for (auto* p = item->getParentItem(); p != nullptr; p = p->getParentItem())
            ++depth;

        return depth;
    }
}

bool TreeViewItem::areLinesDrawn() const
{
    return drawLinesSet ? drawLinesInside
                        : (ownerView != nullptr && ownerView->getLookAndFeel().areLinesDrawnForTreeView (*ownerView));
}

void TreeViewItem::paintRecursively (Graphics& g, int width)
{
    jassert (ownerView != nullptr);

    if (ownerView == nullptr)
        return;

    auto indent = getIndentX();
    auto itemW = (itemWidth < 0 || drawsInRightMargin) ? width - indent : itemWidth;

    {
        Graphics::ScopedSaveState ss (g);
        g.setOrigin (indent, 0);

        if (g.reduceClipRegion (drawsInLeftMargin ? -indent : 0, 0,
                                drawsInLeftMargin ? itemW + indent : itemW, itemHeight))
        {
            if (isSelected())
                g.fillAll (ownerView->findColour (TreeView::selectedItemBackgroundColourId));
            else
                g.fillAll ((getRowNumberInTree() % 2 == 0) ? ownerView->findColour (TreeView::oddItemsColourId)
                                                           : ownerView->findColour (TreeView::evenItemsColourId));

            paintItem (g, itemWidth < 0 ? width - indent : itemWidth, itemHeight);
        }
    }

    auto halfH = itemHeight * 0.5f;
    auto indentWidth = ownerView->getIndentSize();
    auto depth = TreeViewHelpers::calculateDepth (this, ownerView->rootItemVisible);

    if (depth >= 0 && ownerView->openCloseButtonsVisible)
    {
        auto x = (depth + 0.5f) * indentWidth;

        const bool parentLinesDrawn = parentItem != nullptr && parentItem->areLinesDrawn();

        if (parentLinesDrawn)
            paintVerticalConnectingLine (g, Line<float> (x, 0, x, isLastOfSiblings() ? halfH : (float) itemHeight));

        if (parentLinesDrawn || (parentItem == nullptr && areLinesDrawn()))
            paintHorizontalConnectingLine (g, Line<float> (x, halfH, x + indentWidth / 2, halfH));

        {
            auto* p = parentItem;
            int d = depth;

            while (p != nullptr && --d >= 0)
            {
                x -= (float) indentWidth;

                if ((p->parentItem == nullptr || p->parentItem->areLinesDrawn()) && ! p->isLastOfSiblings())
                    p->paintVerticalConnectingLine (g, Line<float> (x, 0, x, (float) itemHeight));

                p = p->parentItem;
            }
        }

        if (mightContainSubItems())
        {
            auto backgroundColour = ownerView->findColour (TreeView::backgroundColourId);

            paintOpenCloseButton (g, Rectangle<float> ((float) (depth * indentWidth), 0, (float) indentWidth, (float) itemHeight),
                                  backgroundColour.isTransparent() ? Colours::white : backgroundColour,
                                  ownerView->viewport->getContentComp()->isMouseOverButton (this));
        }
    }

    if (isOpen())
    {
        auto clip = g.getClipBounds();

        for (auto* ti : subItems)
        {
            auto relY = ti->y - y;

            if (relY >= clip.getBottom())
                break;

            if (relY + ti->totalHeight >= clip.getY())
            {
                Graphics::ScopedSaveState ss (g);

                g.setOrigin (0, relY);

                if (g.reduceClipRegion (0, 0, width, ti->totalHeight))
                    ti->paintRecursively (g, width);
            }
        }
    }
}

bool TreeViewItem::isLastOfSiblings() const noexcept
{
    return parentItem == nullptr
            || parentItem->subItems.getLast() == this;
}

int TreeViewItem::getIndexInParent() const noexcept
{
    return parentItem == nullptr ? 0
                                 : parentItem->subItems.indexOf (this);
}

TreeViewItem* TreeViewItem::getTopLevelItem() noexcept
{
    return parentItem == nullptr ? this
                                 : parentItem->getTopLevelItem();
}

int TreeViewItem::getNumRows() const noexcept
{
    int num = 1;

    if (isOpen())
        for (auto* i : subItems)
            num += i->getNumRows();

    return num;
}

TreeViewItem* TreeViewItem::getItemOnRow (int index) noexcept
{
    if (index == 0)
        return this;

    if (index > 0 && isOpen())
    {
        --index;

        for (auto* i : subItems)
        {
            if (index == 0)
                return i;

            auto numRows = i->getNumRows();

            if (numRows > index)
                return i->getItemOnRow (index);

            index -= numRows;
        }
    }

    return nullptr;
}

TreeViewItem* TreeViewItem::findItemRecursively (int targetY) noexcept
{
    if (isPositiveAndBelow (targetY, totalHeight))
    {
        auto h = itemHeight;

        if (targetY < h)
            return this;

        if (isOpen())
        {
            targetY -= h;

            for (auto* i : subItems)
            {
                if (targetY < i->totalHeight)
                    return i->findItemRecursively (targetY);

                targetY -= i->totalHeight;
            }
        }
    }

    return nullptr;
}

int TreeViewItem::countSelectedItemsRecursively (int depth) const noexcept
{
    int total = isSelected() ? 1 : 0;

    if (depth != 0)
        for (auto* i : subItems)
            total += i->countSelectedItemsRecursively (depth - 1);

    return total;
}

TreeViewItem* TreeViewItem::getSelectedItemWithIndex (int index) noexcept
{
    if (isSelected())
    {
        if (index == 0)
            return this;

        --index;
    }

    if (index >= 0)
    {
        for (auto* i : subItems)
        {
            if (auto* found = i->getSelectedItemWithIndex (index))
                return found;

            index -= i->countSelectedItemsRecursively (-1);
        }
    }

    return nullptr;
}

int TreeViewItem::getRowNumberInTree() const noexcept
{
    if (parentItem != nullptr && ownerView != nullptr)
    {
        if (! parentItem->isOpen())
            return parentItem->getRowNumberInTree();

        int n = 1 + parentItem->getRowNumberInTree();

        int ourIndex = parentItem->subItems.indexOf (this);
        jassert (ourIndex >= 0);

        while (--ourIndex >= 0)
            n += parentItem->subItems [ourIndex]->getNumRows();

        if (parentItem->parentItem == nullptr
             && ! ownerView->rootItemVisible)
            --n;

        return n;
    }

    return 0;
}

void TreeViewItem::setLinesDrawnForSubItems (const bool drawLines) noexcept
{
    drawLinesInside = drawLines;
    drawLinesSet = true;
}

TreeViewItem* TreeViewItem::getNextVisibleItem (const bool recurse) const noexcept
{
    if (recurse && isOpen() && ! subItems.isEmpty())
        return subItems.getFirst();

    if (parentItem != nullptr)
    {
        const int nextIndex = parentItem->subItems.indexOf (this) + 1;

        if (nextIndex >= parentItem->subItems.size())
            return parentItem->getNextVisibleItem (false);

        return parentItem->subItems [nextIndex];
    }

    return nullptr;
}

static String escapeSlashesInTreeViewItemName (const String& s)
{
    return s.replaceCharacter ('/', '\\');
}

String TreeViewItem::getItemIdentifierString() const
{
    String s;

    if (parentItem != nullptr)
        s = parentItem->getItemIdentifierString();

    return s + "/" + escapeSlashesInTreeViewItemName (getUniqueName());
}

TreeViewItem* TreeViewItem::findItemFromIdentifierString (const String& identifierString)
{
    auto thisId = "/" + escapeSlashesInTreeViewItemName (getUniqueName());

    if (thisId == identifierString)
        return this;

    if (identifierString.startsWith (thisId + "/"))
    {
        auto remainingPath = identifierString.substring (thisId.length());

        const bool wasOpen = isOpen();
        setOpen (true);

        for (auto* i : subItems)
            if (auto* item = i->findItemFromIdentifierString (remainingPath))
                return item;

        setOpen (wasOpen);
    }

    return nullptr;
}

void TreeViewItem::restoreOpennessState (const XmlElement& e)
{
    if (e.hasTagName ("CLOSED"))
    {
        setOpen (false);
    }
    else if (e.hasTagName ("OPEN"))
    {
        setOpen (true);

        Array<TreeViewItem*> items;
        items.addArray (subItems);

        forEachXmlChildElement (e, n)
        {
            auto id = n->getStringAttribute ("id");

            for (int i = 0; i < items.size(); ++i)
            {
                auto* ti = items.getUnchecked(i);

                if (ti->getUniqueName() == id)
                {
                    ti->restoreOpennessState (*n);
                    items.remove (i);
                    break;
                }
            }
        }

        // for any items that weren't mentioned in the XML, reset them to default:
        for (auto* i : items)
            i->restoreToDefaultOpenness();
    }
}

std::unique_ptr<XmlElement> TreeViewItem::getOpennessState() const
{
    return std::unique_ptr<XmlElement> (getOpennessState (true));
}

XmlElement* TreeViewItem::getOpennessState (bool canReturnNull) const
{
    auto name = getUniqueName();

    if (name.isNotEmpty())
    {
        XmlElement* e;

        if (isOpen())
        {
            if (canReturnNull && ownerView != nullptr && ownerView->defaultOpenness && isFullyOpen())
                return nullptr;

            e = new XmlElement ("OPEN");

            for (int i = subItems.size(); --i >= 0;)
                e->prependChildElement (subItems.getUnchecked(i)->getOpennessState (true));
        }
        else
        {
            if (canReturnNull && ownerView != nullptr && ! ownerView->defaultOpenness)
                return nullptr;

            e = new XmlElement ("CLOSED");
        }

        e->setAttribute ("id", name);
        return e;
    }

    // trying to save the openness for an element that has no name - this won't
    // work because it needs the names to identify what to open.
    jassertfalse;
    return nullptr;
}

//==============================================================================
TreeViewItem::OpennessRestorer::OpennessRestorer (TreeViewItem& item)
    : treeViewItem (item),
      oldOpenness (item.getOpennessState())
{
}

TreeViewItem::OpennessRestorer::~OpennessRestorer()
{
    if (oldOpenness != nullptr)
        treeViewItem.restoreOpennessState (*oldOpenness);
}

} // namespace juce