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

   This file is part of the JUCE 7 technical preview.
   Copyright (c) 2022 - Raw Material Software Limited

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

   For the technical preview this file cannot be licensed commercially.

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

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

static void juceFreeAccessibilityPlatformSpecificData (UIAccessibilityElement* element)
{
    if (auto* container = juce::getIvar<UIAccessibilityElement*> (element, "container"))
    {
        object_setInstanceVariable (element, "container", nullptr);
        object_setInstanceVariable (container, "handler", nullptr);

        [container release];
    }
}

namespace juce
{

#if defined (__IPHONE_11_0) && __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_11_0
 #define JUCE_IOS_CONTAINER_API_AVAILABLE 1
#endif

#define JUCE_NATIVE_ACCESSIBILITY_INCLUDED 1

//==============================================================================
static NSArray* getContainerAccessibilityElements (AccessibilityHandler& handler)
{
    const auto children = handler.getChildren();

    NSMutableArray* accessibleChildren = [NSMutableArray arrayWithCapacity: (NSUInteger) children.size()];

    [accessibleChildren addObject: (id) handler.getNativeImplementation()];

    for (auto* childHandler : children)
    {
        id accessibleElement = [&childHandler]
        {
            id native = (id) childHandler->getNativeImplementation();

            if (childHandler->getChildren().size() > 0)
                return [native accessibilityContainer];

            return native;
        }();

        if (accessibleElement != nil)
            [accessibleChildren addObject: accessibleElement];
    }

    return accessibleChildren;
}

//==============================================================================
class AccessibilityHandler::AccessibilityNativeImpl
{
public:
    explicit AccessibilityNativeImpl (AccessibilityHandler& handler)
        : accessibilityElement (AccessibilityElement::create (handler))
    {
    }

    UIAccessibilityElement* getAccessibilityElement() const noexcept
    {
        return accessibilityElement.get();
    }

private:
    //==============================================================================
    class AccessibilityContainer  : public ObjCClass<UIAccessibilityElement>
    {
    public:
        AccessibilityContainer()
            : ObjCClass ("JUCEUIAccessibilityElementContainer_")
        {
            addMethod (@selector (isAccessibilityElement),     getIsAccessibilityElement);
            addMethod (@selector (accessibilityFrame),         getAccessibilityFrame);
            addMethod (@selector (accessibilityElements),      getAccessibilityElements);

           #if JUCE_IOS_CONTAINER_API_AVAILABLE
            if (@available (iOS 11.0, *))
                addMethod (@selector (accessibilityContainerType), getAccessibilityContainerType);
           #endif

            addIvar<AccessibilityHandler*> ("handler");

            registerClass();
        }

    private:
        static AccessibilityHandler* getHandler (id self)
        {
            return getIvar<AccessibilityHandler*> (self, "handler");
        }

        static BOOL getIsAccessibilityElement (id, SEL)
        {
            return NO;
        }

        static CGRect getAccessibilityFrame (id self, SEL)
        {
            if (auto* handler = getHandler (self))
                return convertToCGRect (handler->getComponent().getScreenBounds());

            return CGRectZero;
        }

        static NSArray* getAccessibilityElements (id self, SEL)
        {
            if (auto* handler = getHandler (self))
                return getContainerAccessibilityElements (*handler);

            return nil;
        }

        static NSInteger getAccessibilityContainerType (id self, SEL)
        {
            if (auto* handler = getHandler (self))
            {
                if (handler->getTableInterface() != nullptr)
                {
                    if (@available (iOS 11.0, *))
                        return UIAccessibilityContainerTypeDataTable;

                    return 1; // UIAccessibilityContainerTypeDataTable
                }

                const auto role = handler->getRole();

                if (role == AccessibilityRole::popupMenu
                    || role == AccessibilityRole::list
                    || role == AccessibilityRole::tree)
                {
                    if (@available (iOS 11.0, *))
                        return UIAccessibilityContainerTypeList;

                    return 2; // UIAccessibilityContainerTypeList
                }
            }

            if (@available (iOS 11.0, *))
                return UIAccessibilityContainerTypeNone;

            return 0; // UIAccessibilityContainerTypeNone
        }
    };

    //==============================================================================
    class AccessibilityElement  : public AccessibleObjCClass<UIAccessibilityElement>
    {
    public:
        enum class Type  { defaultElement, textElement };

        static Holder create (AccessibilityHandler& handler)
        {
            static AccessibilityElement cls     { Type::defaultElement };
            static AccessibilityElement textCls { Type::textElement };

            id instance = (hasEditableText (handler) ? textCls : cls).createInstance();

            Holder element ([instance initWithAccessibilityContainer: (id) handler.getComponent().getWindowHandle()]);
            object_setInstanceVariable (element.get(), "handler", &handler);
            return element;
        }

        AccessibilityElement (Type elementType)
        {
            addMethod (@selector (isAccessibilityElement),     getIsAccessibilityElement);
            addMethod (@selector (accessibilityContainer),     getAccessibilityContainer);
            addMethod (@selector (accessibilityFrame),         getAccessibilityFrame);
            addMethod (@selector (accessibilityTraits),        getAccessibilityTraits);
            addMethod (@selector (accessibilityLabel),         getAccessibilityTitle);
            addMethod (@selector (accessibilityHint),          getAccessibilityHelp);
            addMethod (@selector (accessibilityValue),         getAccessibilityValue);
            addMethod (@selector (setAccessibilityValue:),     setAccessibilityValue);

            addMethod (@selector (accessibilityElementDidBecomeFocused), onFocusGain);
            addMethod (@selector (accessibilityElementDidLoseFocus),     onFocusLoss);
            addMethod (@selector (accessibilityElementIsFocused),        isFocused);
            addMethod (@selector (accessibilityViewIsModal),             getIsAccessibilityModal);

            addMethod (@selector (accessibilityActivate),      accessibilityPerformActivate);
            addMethod (@selector (accessibilityIncrement),     accessibilityPerformIncrement);
            addMethod (@selector (accessibilityDecrement),     accessibilityPerformDecrement);
            addMethod (@selector (accessibilityPerformEscape), accessibilityPerformEscape);

           #if JUCE_IOS_CONTAINER_API_AVAILABLE
            if (@available (iOS 11.0, *))
            {
                addMethod (@selector (accessibilityDataTableCellElementForRow:column:), getAccessibilityDataTableCellElementForRowColumn);
                addMethod (@selector (accessibilityRowCount),                           getAccessibilityRowCount);
                addMethod (@selector (accessibilityColumnCount),                        getAccessibilityColumnCount);
                addProtocol (@protocol (UIAccessibilityContainerDataTable));

                addMethod (@selector (accessibilityRowRange),                           getAccessibilityRowIndexRange);
                addMethod (@selector (accessibilityColumnRange),                        getAccessibilityColumnIndexRange);
                addProtocol (@protocol (UIAccessibilityContainerDataTableCell));
            }
           #endif

            if (elementType == Type::textElement)
            {
                addMethod (@selector (accessibilityLineNumberForPoint:),   getAccessibilityLineNumberForPoint);
                addMethod (@selector (accessibilityContentForLineNumber:), getAccessibilityContentForLineNumber);
                addMethod (@selector (accessibilityFrameForLineNumber:),   getAccessibilityFrameForLineNumber);
                addMethod (@selector (accessibilityPageContent),           getAccessibilityPageContent);

                addProtocol (@protocol (UIAccessibilityReadingContent));
            }

            addIvar<UIAccessibilityElement*> ("container");

            registerClass();
        }

    private:
        //==============================================================================
        static UIAccessibilityElement* getContainer (id self)
        {
            return getIvar<UIAccessibilityElement*> (self, "container");
        }

        //==============================================================================
        static id getAccessibilityContainer (id self, SEL)
        {
            if (auto* handler = getHandler (self))
            {
                if (handler->getComponent().isOnDesktop())
                    return (id) handler->getComponent().getWindowHandle();

                if (handler->getChildren().size() > 0)
                {
                    if (UIAccessibilityElement* container = getContainer (self))
                        return container;

                    static AccessibilityContainer cls;

                    id windowHandle = (id) handler->getComponent().getWindowHandle();
                    UIAccessibilityElement* container = [cls.createInstance() initWithAccessibilityContainer: windowHandle];

                    [container retain];

                    object_setInstanceVariable (container, "handler", handler);
                    object_setInstanceVariable (self, "container", container);

                    return container;
                }

                if (auto* parent = handler->getParent())
                    return [(id) parent->getNativeImplementation() accessibilityContainer];
            }

            return nil;
        }

        static CGRect getAccessibilityFrame (id self, SEL)
        {
            if (auto* handler = getHandler (self))
                return convertToCGRect (handler->getComponent().getScreenBounds());

            return CGRectZero;
        }

        static UIAccessibilityTraits getAccessibilityTraits (id self, SEL)
        {
            auto traits = UIAccessibilityTraits{};

            if (auto* handler = getHandler (self))
            {
                traits |= [&handler]
                {
                    switch (handler->getRole())
                    {
                        case AccessibilityRole::button:
                        case AccessibilityRole::toggleButton:
                        case AccessibilityRole::radioButton:
                        case AccessibilityRole::comboBox:      return UIAccessibilityTraitButton;

                        case AccessibilityRole::label:
                        case AccessibilityRole::staticText:    return UIAccessibilityTraitStaticText;

                        case AccessibilityRole::image:         return UIAccessibilityTraitImage;
                        case AccessibilityRole::tableHeader:   return UIAccessibilityTraitHeader;
                        case AccessibilityRole::hyperlink:     return UIAccessibilityTraitLink;
                        case AccessibilityRole::editableText:  return UIAccessibilityTraitKeyboardKey;
                        case AccessibilityRole::ignored:       return UIAccessibilityTraitNotEnabled;

                        case AccessibilityRole::slider:
                        case AccessibilityRole::menuItem:
                        case AccessibilityRole::menuBar:
                        case AccessibilityRole::popupMenu:
                        case AccessibilityRole::table:
                        case AccessibilityRole::column:
                        case AccessibilityRole::row:
                        case AccessibilityRole::cell:
                        case AccessibilityRole::list:
                        case AccessibilityRole::listItem:
                        case AccessibilityRole::tree:
                        case AccessibilityRole::treeItem:
                        case AccessibilityRole::progressBar:
                        case AccessibilityRole::group:
                        case AccessibilityRole::dialogWindow:
                        case AccessibilityRole::window:
                        case AccessibilityRole::scrollBar:
                        case AccessibilityRole::tooltip:
                        case AccessibilityRole::splashScreen:
                        case AccessibilityRole::unspecified:   break;
                    }

                    return UIAccessibilityTraitNone;
                }();

                const auto state = handler->getCurrentState();

                if (state.isSelected() || state.isChecked())
                    traits |= UIAccessibilityTraitSelected;

                if (auto* valueInterface = getValueInterface (self))
                    if (! valueInterface->isReadOnly() && valueInterface->getRange().isValid())
                        traits |= UIAccessibilityTraitAdjustable;
            }

            return traits | sendSuperclassMessage<UIAccessibilityTraits> (self, @selector (accessibilityTraits));
        }

        static NSString* getAccessibilityValue (id self, SEL)
        {
            if (auto* handler = getHandler (self))
            {
                if (handler->getCurrentState().isCheckable())
                    return handler->getCurrentState().isChecked() ? @"1" : @"0";

                return (NSString*) getAccessibilityValueFromInterfaces (*handler);
            }

            return nil;
        }

        static void onFocusGain (id self, SEL)
        {
            if (auto* handler = getHandler (self))
            {
                const WeakReference<Component> safeComponent (&handler->getComponent());

                performActionIfSupported (self, AccessibilityActionType::focus);

                if (safeComponent != nullptr)
                    handler->grabFocus();
            }
        }

        static void onFocusLoss (id self, SEL)
        {
            if (auto* handler = getHandler (self))
                handler->giveAwayFocus();
        }

        static BOOL isFocused (id self, SEL)
        {
            if (auto* handler = getHandler (self))
                return handler->hasFocus (false);

            return NO;
        }

        static BOOL accessibilityPerformActivate (id self, SEL)
        {
            if (auto* handler = getHandler (self))
            {
                // Occasionally VoiceOver sends accessibilityActivate to the wrong element, so we first query
                // which element it thinks has focus and forward the event on to that element if it differs
                id focusedElement = UIAccessibilityFocusedElement (UIAccessibilityNotificationVoiceOverIdentifier);

                if (focusedElement != nullptr && ! [(id) handler->getNativeImplementation() isEqual: focusedElement])
                    return [focusedElement accessibilityActivate];

                if (handler->hasFocus (false))
                    return accessibilityPerformPress (self, {});
            }

            return NO;
        }

        static BOOL accessibilityPerformEscape (id self, SEL)
        {
            if (auto* handler = getHandler (self))
            {
                if (auto* modal = Component::getCurrentlyModalComponent())
                {
                    if (auto* modalHandler = modal->getAccessibilityHandler())
                    {
                        if (modalHandler == handler || modalHandler->isParentOf (handler))
                        {
                            modal->exitModalState (0);
                            return YES;
                        }
                    }
                }
            }

            return NO;
        }

        static id getAccessibilityDataTableCellElementForRowColumn (id self, SEL, NSUInteger row, NSUInteger column)
        {
            if (auto* tableInterface = getEnclosingInterface (getHandler (self), &AccessibilityHandler::getTableInterface))
                if (auto* cellHandler = tableInterface->getCellHandler ((int) row, (int) column))
                    return (id) cellHandler->getNativeImplementation();

            return nil;
        }

        static NSInteger getAccessibilityLineNumberForPoint (id self, SEL, CGPoint point)
        {
            if (auto* handler = getHandler (self))
            {
                if (auto* textInterface = handler->getTextInterface())
                {
                    auto pointInt = roundToIntPoint (point);

                    if (handler->getComponent().getScreenBounds().contains (pointInt))
                    {
                        auto textBounds = textInterface->getTextBounds ({ 0, textInterface->getTotalNumCharacters() });

                        for (int i = 0; i < textBounds.getNumRectangles(); ++i)
                            if (textBounds.getRectangle (i).contains (pointInt))
                                return (NSInteger) i;
                    }
                }
            }

            return NSNotFound;
        }

        static NSString* getAccessibilityContentForLineNumber (id self, SEL, NSInteger lineNumber)
        {
            if (auto* textInterface = getTextInterface (self))
            {
                auto lines = StringArray::fromLines (textInterface->getText ({ 0, textInterface->getTotalNumCharacters() }));

                if ((int) lineNumber < lines.size())
                    return juceStringToNS (lines[(int) lineNumber]);
            }

            return nil;
        }

        static CGRect getAccessibilityFrameForLineNumber (id self, SEL, NSInteger lineNumber)
        {
            if (auto* textInterface = getTextInterface (self))
            {
                auto textBounds = textInterface->getTextBounds ({ 0, textInterface->getTotalNumCharacters() });

                if (lineNumber < textBounds.getNumRectangles())
                    return convertToCGRect (textBounds.getRectangle ((int) lineNumber));
            }

            return CGRectZero;
        }

        static NSString* getAccessibilityPageContent (id self, SEL)
        {
            if (auto* textInterface = getTextInterface (self))
                return juceStringToNS (textInterface->getText ({ 0, textInterface->getTotalNumCharacters() }));

            return nil;
        }

        //==============================================================================
        JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (AccessibilityElement)
    };

    //==============================================================================
    AccessibilityElement::Holder accessibilityElement;

    //==============================================================================
    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (AccessibilityNativeImpl)
};

//==============================================================================
AccessibilityNativeHandle* AccessibilityHandler::getNativeImplementation() const
{
    return (AccessibilityNativeHandle*) nativeImpl->getAccessibilityElement();
}

static bool areAnyAccessibilityClientsActive()
{
    return UIAccessibilityIsVoiceOverRunning();
}

static void sendAccessibilityEvent (UIAccessibilityNotifications notification, id argument)
{
    if (! areAnyAccessibilityClientsActive())
        return;

    jassert (notification != UIAccessibilityNotifications{});

    UIAccessibilityPostNotification (notification, argument);
}

void notifyAccessibilityEventInternal (const AccessibilityHandler& handler, InternalAccessibilityEvent eventType)
{
    auto notification = [eventType]
    {
        switch (eventType)
        {
            case InternalAccessibilityEvent::elementCreated:
            case InternalAccessibilityEvent::elementDestroyed:
            case InternalAccessibilityEvent::elementMovedOrResized:
            case InternalAccessibilityEvent::focusChanged:           return UIAccessibilityLayoutChangedNotification;

            case InternalAccessibilityEvent::windowOpened:
            case InternalAccessibilityEvent::windowClosed:           return UIAccessibilityScreenChangedNotification;
        }

        return UIAccessibilityNotifications{};
    }();

    if (notification != UIAccessibilityNotifications{})
    {
        const bool moveToHandler = (eventType == InternalAccessibilityEvent::focusChanged && handler.hasFocus (false));

        sendAccessibilityEvent (notification,
                                moveToHandler ? (id) handler.getNativeImplementation() : nil);
    }

}

void AccessibilityHandler::notifyAccessibilityEvent (AccessibilityEvent eventType) const
{
    auto notification = [eventType]
    {
        switch (eventType)
        {
            case AccessibilityEvent::textSelectionChanged:
            case AccessibilityEvent::rowSelectionChanged:
            case AccessibilityEvent::textChanged:
            case AccessibilityEvent::valueChanged:
            case AccessibilityEvent::titleChanged:          break;

            case AccessibilityEvent::structureChanged:      return UIAccessibilityLayoutChangedNotification;
        }

        return UIAccessibilityNotifications{};
    }();

    if (notification != UIAccessibilityNotifications{})
        sendAccessibilityEvent (notification, (id) getNativeImplementation());
}

void AccessibilityHandler::postAnnouncement (const String& announcementString, AnnouncementPriority)
{
    sendAccessibilityEvent (UIAccessibilityAnnouncementNotification, juceStringToNS (announcementString));
}

} // namespace juce