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

   This file is part of the JUCE framework.
   Copyright (c) Raw Material Software Limited

   JUCE is an open source framework subject to commercial or open source
   licensing.

   By downloading, installing, or using the JUCE framework, or combining the
   JUCE framework with any other source code, object code, content or any other
   copyrightable work, you agree to the terms of the JUCE End User Licence
   Agreement, and all incorporated terms including the JUCE Privacy Policy and
   the JUCE Website Terms of Service, as applicable, which will bind you. If you
   do not agree to the terms of these agreements, we will not license the JUCE
   framework to you, and you must discontinue the installation or download
   process and cease use of the JUCE framework.

   JUCE End User Licence Agreement: https://juce.com/legal/juce-8-licence/
   JUCE Privacy Policy: https://juce.com/juce-privacy-policy
   JUCE Website Terms of Service: https://juce.com/juce-website-terms-of-service/

   Or:

   You may also use this code under the terms of the AGPLv3:
   https://www.gnu.org/licenses/agpl-3.0.en.html

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

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

namespace juce
{

static Cursor createDraggingHandCursor();
ComponentPeer* getPeerFor (::Window);

//==============================================================================
class X11DragState
{
public:
    X11DragState() = default;

    //==============================================================================
    bool isDragging() const noexcept
    {
        return dragging;
    }

    //==============================================================================
    void handleExternalSelectionClear()
    {
        if (dragging)
            externalResetDragAndDrop();
    }

    void handleExternalSelectionRequest (const XEvent& evt)
    {
        auto targetType = evt.xselectionrequest.target;

        XEvent s;
        s.xselection.type      = SelectionNotify;
        s.xselection.requestor = evt.xselectionrequest.requestor;
        s.xselection.selection = evt.xselectionrequest.selection;
        s.xselection.target    = targetType;
        s.xselection.property  = None;
        s.xselection.time      = evt.xselectionrequest.time;

        auto* display = getDisplay();

        if (allowedTypes.contains (targetType))
        {
            s.xselection.property = evt.xselectionrequest.property;

            X11Symbols::getInstance()->xChangeProperty (display, evt.xselectionrequest.requestor, evt.xselectionrequest.property,
                                                        targetType, 8, PropModeReplace,
                                                        reinterpret_cast<const unsigned char*> (textOrFiles.toRawUTF8()),
                                                        (int) textOrFiles.getNumBytesAsUTF8());
        }

        X11Symbols::getInstance()->xSendEvent (display, evt.xselectionrequest.requestor, True, 0, &s);
    }

    void handleExternalDragAndDropStatus (const XClientMessageEvent& clientMsg)
    {
        if (expectingStatus)
        {
            expectingStatus = false;
            canDrop         = false;
            silentRect      = {};

            const auto& atoms = getAtoms();

            if ((clientMsg.data.l[1] & 1) != 0
                && ((Atom) clientMsg.data.l[4] == atoms.XdndActionCopy
                    || (Atom) clientMsg.data.l[4] == atoms.XdndActionPrivate))
            {
                if ((clientMsg.data.l[1] & 2) == 0) // target requests silent rectangle
                    silentRect.setBounds ((int) clientMsg.data.l[2] >> 16, (int) clientMsg.data.l[2] & 0xffff,
                                          (int) clientMsg.data.l[3] >> 16, (int) clientMsg.data.l[3] & 0xffff);

                canDrop = true;
            }
        }
    }

    void handleExternalDragButtonReleaseEvent()
    {
        if (dragging)
            X11Symbols::getInstance()->xUngrabPointer (getDisplay(), CurrentTime);

        if (canDrop)
        {
            sendExternalDragAndDropDrop();
        }
        else
        {
            sendExternalDragAndDropLeave();
            externalResetDragAndDrop();
        }
    }

    void handleExternalDragMotionNotify()
    {
        auto* display = getDisplay();

        auto newTargetWindow = externalFindDragTargetWindow (X11Symbols::getInstance()
                                                               ->xRootWindow (display,
                                                                              X11Symbols::getInstance()->xDefaultScreen (display)));

        if (targetWindow != newTargetWindow)
        {
            if (targetWindow != None)
                sendExternalDragAndDropLeave();

            canDrop = false;
            silentRect = {};

            if (newTargetWindow == None)
                return;

            xdndVersion = getDnDVersionForWindow (newTargetWindow);

            if (xdndVersion == -1)
                return;

            targetWindow = newTargetWindow;
            sendExternalDragAndDropEnter();
        }

        if (! expectingStatus)
            sendExternalDragAndDropPosition();
    }

    void handleDragAndDropPosition (const XClientMessageEvent& clientMsg, ComponentPeer* peer)
    {
        if (dragAndDropSourceWindow == 0)
            return;

        dragAndDropSourceWindow = (::Window) clientMsg.data.l[0];

        if (windowH == 0)
            windowH = (::Window) peer->getNativeHandle();

        const auto& displays = Desktop::getInstance().getDisplays();
        const auto logicalPos = displays.physicalToLogical (Point ((int) clientMsg.data.l[2] >> 16,
                                                                   (int) clientMsg.data.l[2] & 0xffff).toFloat());
        const auto dropPos = detail::ScalingHelpers::screenPosToLocalPos (peer->getComponent(), logicalPos).roundToInt();

        const auto& atoms = getAtoms();

        auto targetAction = atoms.XdndActionCopy;

        for (int i = numElementsInArray (atoms.allowedActions); --i >= 0;)
        {
            if ((Atom) clientMsg.data.l[4] == atoms.allowedActions[i])
            {
                targetAction = atoms.allowedActions[i];
                break;
            }
        }

        sendDragAndDropStatus (true, targetAction);

        if (dragInfo.position != dropPos)
        {
            dragInfo.position = dropPos;

            if (dragInfo.isEmpty())
                updateDraggedFileList (clientMsg, (::Window) peer->getNativeHandle());

            if (! dragInfo.isEmpty())
                peer->handleDragMove (dragInfo);
        }
    }

    void handleDragAndDropDrop (const XClientMessageEvent& clientMsg, ComponentPeer* peer)
    {
        if (dragInfo.isEmpty())
        {
            // no data, transaction finished in handleDragAndDropSelection()
            finishAfterDropDataReceived = true;
            updateDraggedFileList (clientMsg, (::Window) peer->getNativeHandle());
        }
        else
        {
            handleDragAndDropDataReceived();  // data was already received
        }
    }

    void handleDragAndDropEnter (const XClientMessageEvent& clientMsg, ComponentPeer* peer)
    {
        dragInfo.clear();
        srcMimeTypeAtomList.clear();

        dragAndDropCurrentMimeType = 0;
        auto dndCurrentVersion = (static_cast<unsigned long> (clientMsg.data.l[1]) & 0xff000000) >> 24;

        if (dndCurrentVersion < 3 || dndCurrentVersion > XWindowSystemUtilities::Atoms::DndVersion)
        {
            dragAndDropSourceWindow = 0;
            return;
        }

        const auto& atoms = getAtoms();

        dragAndDropSourceWindow = (::Window) clientMsg.data.l[0];

        if ((clientMsg.data.l[1] & 1) != 0)
        {
            XWindowSystemUtilities::ScopedXLock xLock;

            XWindowSystemUtilities::GetXProperty prop (getDisplay(),
                                                       dragAndDropSourceWindow,
                                                       atoms.XdndTypeList,
                                                       0,
                                                       0x8000000L,
                                                       false,
                                                       XA_ATOM);

            if (prop.success && prop.actualType == XA_ATOM && prop.actualFormat == 32 && prop.numItems != 0)
            {
                auto* types = prop.data;

                for (unsigned long i = 0; i < prop.numItems; ++i)
                {
                    unsigned long type;
                    memcpy (&type, types, sizeof (unsigned long));

                    if (type != None)
                        srcMimeTypeAtomList.add (type);

                    types += sizeof (unsigned long);
                }
            }
        }

        if (srcMimeTypeAtomList.isEmpty())
        {
            for (int i = 2; i < 5; ++i)
                if (clientMsg.data.l[i] != None)
                    srcMimeTypeAtomList.add ((unsigned long) clientMsg.data.l[i]);

            if (srcMimeTypeAtomList.isEmpty())
            {
                dragAndDropSourceWindow = 0;
                return;
            }
        }

        for (int i = 0; i < srcMimeTypeAtomList.size() && dragAndDropCurrentMimeType == 0; ++i)
            for (int j = 0; j < numElementsInArray (atoms.allowedMimeTypes); ++j)
                if (srcMimeTypeAtomList[i] == atoms.allowedMimeTypes[j])
                    dragAndDropCurrentMimeType = atoms.allowedMimeTypes[j];

        handleDragAndDropPosition (clientMsg, peer);
    }

    void handleDragAndDropExit()
    {
        if (auto* peer = getPeerFor (windowH))
            peer->handleDragExit (dragInfo);

        resetDragAndDrop();
    }

    void handleDragAndDropSelection (const XEvent& evt)
    {
        dragInfo.clear();

        if (evt.xselection.property != None)
        {
            StringArray lines;

            {
                MemoryBlock dropData;

                for (;;)
                {
                    XWindowSystemUtilities::GetXProperty prop (getDisplay(),
                                                               evt.xany.window,
                                                               evt.xselection.property,
                                                               (long) (dropData.getSize() / 4),
                                                               65536,
                                                               false,
                                                               AnyPropertyType);

                    if (! prop.success)
                        break;

                    dropData.append (prop.data, (size_t) (prop.actualFormat / 8) * prop.numItems);

                    if (prop.bytesLeft <= 0)
                        break;
                }

                lines.addLines (dropData.toString());
            }

            if (XWindowSystemUtilities::Atoms::isMimeTypeFile (getDisplay(), dragAndDropCurrentMimeType))
            {
                for (const auto& line : lines)
                {
                    const auto escaped = line.replace ("+", "%2B").replace ("file://", String(), true);
                    dragInfo.files.add (URL::removeEscapeChars (escaped));
                }

                dragInfo.files.trim();
                dragInfo.files.removeEmptyStrings();
            }
            else
            {
                dragInfo.text = lines.joinIntoString ("\n");
            }

            if (finishAfterDropDataReceived)
                handleDragAndDropDataReceived();
        }
    }

    void externalResetDragAndDrop()
    {
        if (dragging)
        {
            XWindowSystemUtilities::ScopedXLock xLock;
            X11Symbols::getInstance()->xUngrabPointer (getDisplay(), CurrentTime);
        }

        NullCheckedInvocation::invoke (completionCallback);

        dragging = false;
    }

    bool externalDragInit (::Window window, bool text, const String& str, std::function<void()>&& cb)
    {
        windowH            = window;
        isText             = text;
        textOrFiles        = str;
        targetWindow       = windowH;
        completionCallback = std::move (cb);

        auto* display = getDisplay();

        allowedTypes.add (XWindowSystemUtilities::Atoms::getCreating (display, isText ? "text/plain" : "text/uri-list"));

        auto pointerGrabMask = (unsigned int) (Button1MotionMask | ButtonReleaseMask);

        XWindowSystemUtilities::ScopedXLock xLock;

        if (X11Symbols::getInstance()->xGrabPointer (display, windowH, True, pointerGrabMask,
                                                     GrabModeAsync, GrabModeAsync, None, None, CurrentTime) == GrabSuccess)
        {
            const auto& atoms = getAtoms();

            // No other method of changing the pointer seems to work, this call is needed from this very context
            X11Symbols::getInstance()->xChangeActivePointerGrab (display, pointerGrabMask, (Cursor) createDraggingHandCursor(), CurrentTime);

            X11Symbols::getInstance()->xSetSelectionOwner (display, atoms.XdndSelection, windowH, CurrentTime);

            // save the available types to XdndTypeList
            X11Symbols::getInstance()->xChangeProperty (display, windowH, atoms.XdndTypeList, XA_ATOM, 32, PropModeReplace,
                                                        reinterpret_cast<const unsigned char*> (allowedTypes.getRawDataPointer()), allowedTypes.size());

            dragging = true;
            xdndVersion = getDnDVersionForWindow (targetWindow);

            sendExternalDragAndDropEnter();
            handleExternalDragMotionNotify();

            return true;
        }

        return false;
    }

private:
    //==============================================================================
    const XWindowSystemUtilities::Atoms& getAtoms() const noexcept  { return XWindowSystem::getInstance()->getAtoms(); }
    ::Display* getDisplay() const noexcept                          { return XWindowSystem::getInstance()->getDisplay(); }

    //==============================================================================
    void sendDragAndDropMessage (XClientMessageEvent& msg)
    {
        auto* display = getDisplay();

        msg.type      = ClientMessage;
        msg.display   = display;
        msg.window    = dragAndDropSourceWindow;
        msg.format    = 32;
        msg.data.l[0] = (long) windowH;

        XWindowSystemUtilities::ScopedXLock xLock;
        X11Symbols::getInstance()->xSendEvent (display, dragAndDropSourceWindow, False, 0, (XEvent*) &msg);
    }

    bool sendExternalDragAndDropMessage (XClientMessageEvent& msg)
    {
        auto* display = getDisplay();

        msg.type      = ClientMessage;
        msg.display   = display;
        msg.window    = targetWindow;
        msg.format    = 32;
        msg.data.l[0] = (long) windowH;

        XWindowSystemUtilities::ScopedXLock xLock;
        return X11Symbols::getInstance()->xSendEvent (display, targetWindow, False, 0, (XEvent*) &msg) != 0;
    }

    void sendExternalDragAndDropDrop()
    {
        XClientMessageEvent msg;
        zerostruct (msg);

        msg.message_type = getAtoms().XdndDrop;
        msg.data.l[2] = CurrentTime;

        sendExternalDragAndDropMessage (msg);
    }

    void sendExternalDragAndDropEnter()
    {
        XClientMessageEvent msg;
        zerostruct (msg);

        msg.message_type = getAtoms().XdndEnter;
        msg.data.l[1] = (xdndVersion << 24);

        for (int i = 0; i < 3; ++i)
            msg.data.l[i + 2] = (long) allowedTypes[i];

        sendExternalDragAndDropMessage (msg);
    }

    void sendExternalDragAndDropPosition()
    {
        XClientMessageEvent msg;
        zerostruct (msg);

        const auto& atoms = getAtoms();

        msg.message_type = atoms.XdndPosition;

        auto mousePos = Desktop::getInstance().getMousePosition();

        if (silentRect.contains (mousePos)) // we've been asked to keep silent
            return;

        mousePos = Desktop::getInstance().getDisplays().logicalToPhysical (mousePos.toFloat()).roundToInt();

        msg.data.l[1] = 0;
        msg.data.l[2] = (mousePos.x << 16) | mousePos.y;
        msg.data.l[3] = CurrentTime;
        msg.data.l[4] = (long) atoms.XdndActionCopy; // this is all JUCE currently supports

        expectingStatus = sendExternalDragAndDropMessage (msg);
    }

    void sendDragAndDropStatus (bool acceptDrop, Atom dropAction)
    {
        XClientMessageEvent msg;
        zerostruct (msg);

        msg.message_type = getAtoms().XdndStatus;
        msg.data.l[1]    = (acceptDrop ? 1 : 0) | 2; // 2 indicates that we want to receive position messages
        msg.data.l[4]    = (long) dropAction;

        sendDragAndDropMessage (msg);
    }

    void sendExternalDragAndDropLeave()
    {
        XClientMessageEvent msg;
        zerostruct (msg);

        msg.message_type = getAtoms().XdndLeave;
        sendExternalDragAndDropMessage (msg);
    }

    void sendDragAndDropFinish()
    {
        XClientMessageEvent msg;
        zerostruct (msg);

        msg.message_type = getAtoms().XdndFinished;
        sendDragAndDropMessage (msg);
    }

    void updateDraggedFileList (const XClientMessageEvent& clientMsg, ::Window requestor)
    {
        jassert (dragInfo.isEmpty());

        if (dragAndDropSourceWindow != None && dragAndDropCurrentMimeType != None)
        {
            auto* display = getDisplay();

            XWindowSystemUtilities::ScopedXLock xLock;
            X11Symbols::getInstance()->xConvertSelection (display, getAtoms().XdndSelection, dragAndDropCurrentMimeType,
                                                          XWindowSystemUtilities::Atoms::getCreating (display, "JXSelectionWindowProperty"),
                                                          requestor, (::Time) clientMsg.data.l[2]);
        }
    }

    bool isWindowDnDAware (::Window w) const
    {
        int numProperties = 0;
        auto* properties = X11Symbols::getInstance()->xListProperties (getDisplay(), w, &numProperties);

        bool dndAwarePropFound = false;

        for (int i = 0; i < numProperties; ++i)
            if (properties[i] == getAtoms().XdndAware)
                dndAwarePropFound = true;

        if (properties != nullptr)
            X11Symbols::getInstance()->xFree (properties);

        return dndAwarePropFound;
    }

    int getDnDVersionForWindow (::Window target)
    {
        XWindowSystemUtilities::GetXProperty prop (getDisplay(),
                                                   target,
                                                   getAtoms().XdndAware,
                                                   0,
                                                   2,
                                                   false,
                                                   AnyPropertyType);

        if (prop.success && prop.data != nullptr && prop.actualFormat == 32 && prop.numItems == 1)
            return jmin ((int) prop.data[0], (int) XWindowSystemUtilities::Atoms::DndVersion);

        return -1;
    }

    ::Window externalFindDragTargetWindow (::Window target)
    {
        if (target == None)
            return None;

        if (isWindowDnDAware (target))
            return target;

        ::Window child, phonyWin;
        int phony;
        unsigned int uphony;

        X11Symbols::getInstance()->xQueryPointer (getDisplay(), target, &phonyWin, &child, &phony, &phony, &phony, &phony, &uphony);

        return externalFindDragTargetWindow (child);
    }

    void handleDragAndDropDataReceived()
    {
        ComponentPeer::DragInfo dragInfoCopy (dragInfo);

        sendDragAndDropFinish();
        resetDragAndDrop();

        if (! dragInfoCopy.isEmpty())
            if (auto* peer = getPeerFor (windowH))
                peer->handleDragDrop (dragInfoCopy);
    }

    void resetDragAndDrop()
    {
        dragInfo.clear();
        dragInfo.position = Point<int> (-1, -1);
        dragAndDropCurrentMimeType = 0;
        dragAndDropSourceWindow = 0;
        srcMimeTypeAtomList.clear();
        finishAfterDropDataReceived = false;
    }

    //==============================================================================
    ::Window windowH = 0, targetWindow = 0, dragAndDropSourceWindow = 0;

    int xdndVersion = -1;
    bool isText = false, dragging = false, expectingStatus = false, canDrop = false, finishAfterDropDataReceived = false;

    Atom dragAndDropCurrentMimeType;
    Array<Atom> allowedTypes, srcMimeTypeAtomList;

    ComponentPeer::DragInfo dragInfo;
    Rectangle<int> silentRect;
    String textOrFiles;

    std::function<void()> completionCallback = nullptr;

    //==============================================================================
    JUCE_LEAK_DETECTOR (X11DragState)
};

} // namespace juce
