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#include "qiosapplicationstate.h"

#include <qpa/qwindowsysteminterface.h>
#include <QtCore/qcoreapplication.h>

#include <QtGui/private/qguiapplication_p.h>

#import <UIKit/UIKit.h>

static Qt::ApplicationState qtApplicationState(UIApplicationState uiApplicationState)
{
    switch (uiApplicationState) {
    case UIApplicationStateActive:
        // The application is visible in front, and receiving events
        return Qt::ApplicationActive;
    case UIApplicationStateInactive:
        // The app is running in the foreground but is not receiving events. This
        // typically happens while transitioning to/from active/background, like
        // upon app launch or when receiving incoming calls.
        return Qt::ApplicationInactive;
    case UIApplicationStateBackground:
        // Normally the app would enter this state briefly before it gets
        // suspeded (you have five seconds, according to Apple).
        // You can request more time and start a background task, which would
        // normally map closer to Qt::ApplicationHidden. But since we have no
        // API for doing that yet, we handle this state as "about to be suspended".
        // Note: A screen-shot for the SpringBoard will also be taken after this
        // call returns.
        return Qt::ApplicationSuspended;
    }
}

static void handleApplicationStateChanged(UIApplicationState uiApplicationState)
{
    Qt::ApplicationState state = qtApplicationState(uiApplicationState);
    QWindowSystemInterface::handleApplicationStateChanged(state);
    QWindowSystemInterface::flushWindowSystemEvents();
}

QT_BEGIN_NAMESPACE

QIOSApplicationState::QIOSApplicationState()
{
    NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];

    m_observers.push_back([notificationCenter addObserverForName:UIApplicationDidBecomeActiveNotification
        object:nil queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification *) {
            handleApplicationStateChanged(UIApplicationStateActive);
        }
    ]);

    m_observers.push_back([notificationCenter addObserverForName:UIApplicationWillResignActiveNotification
        object:nil queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification *) {
            // Note: UIApplication is still UIApplicationStateActive at this point,
            // but since there is no separate notification for the inactive state,
            // we report UIApplicationStateInactive now.
            handleApplicationStateChanged(UIApplicationStateInactive);
        }
    ]);

    m_observers.push_back([notificationCenter addObserverForName:UIApplicationDidEnterBackgroundNotification
        object:nil queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification *) {
            handleApplicationStateChanged(UIApplicationStateBackground);
        }
    ]);

    // Initialize correct startup state, which may not be the Qt default (inactive)
    UIApplicationState startupState = [UIApplication sharedApplication].applicationState;
    QGuiApplicationPrivate::applicationState = qtApplicationState(startupState);
}

QIOSApplicationState::~QIOSApplicationState()
{
    NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];
    foreach (const NSObject* observer, m_observers)
        [notificationCenter removeObserver:observer];
}

QT_END_NAMESPACE