using System;
using System.Collections.Generic;
using System.Linq;
using MonoTouch.MessageUI;
using MonoTouch.UIKit;

namespace MyApp
{
    public interface ICanCleanUpMyself
    {
        void CleanUp();
    }

    public static class MemoryUtility
    {
        public static void ReleaseUIViewWithChildren(UIView view, bool enableSelfCleaning = true)
        {
            try
            {
                if (view == null)
                    return;

                if (view.Subviews != null)
                {
                    view.Subviews
                        .ToList()
                        .ForEach(subview =>
                            ReleaseUIViewWithChildren(subview, enableSelfCleaning)
                    );
                }

                ReleaseObject(view, enableSelfCleaning);
            }
            catch (Exception exception)
            {
                // Logging ...
            }
        }

        public static void ReleaseObject(IDisposable disposableObject, bool enableSelfCleaning = true)
        {
            try
            {
                if (disposableObject == null)
                    return;

                ReleaseUIImageView(disposableObject);
                ReleaseUIButton(disposableObject);
                ReleaseUIView(disposableObject);
                ReleaseUINavigationController(disposableObject);
                ReleaseUIPageviewController(disposableObject);
                ReleaseUIViewController(disposableObject);

                if (enableSelfCleaning)
                    LetObjectCleanUpItself(disposableObject);

                disposableObject.Dispose();
            }
            catch (Exception exception)
            {
                // Logging ...
            }
        }

        public static void ReleaseObject<T>(WeakReference<T> weakReference,
                                            bool enableSelfCleaning = true) where T : class, IDisposable
        {
            T reference;
            if (weakReference == null ||
                !weakReference.TryGetTarget(out reference) || reference == null)
                return;

            ReleaseObject(reference, enableSelfCleaning);
        }

        public static void ReleaseUITableViewCell(IDisposable disposableObject)
        {
            try
            {
                var cell = disposableObject as UITableViewCell;

                if (cell == null)
                    return;

                ReleaseUIViewWithChildren(cell.BackgroundView);
                ReleaseUIViewWithChildren(cell.SelectedBackgroundView);
                ReleaseUIViewWithChildren(cell.AccessoryView);
                ReleaseUIViewWithChildren(cell.ContentView);
            }
            catch (Exception exception)
            {
                // Logging ...
            }
        }

        public static void ReleaseSubviews(UIView[] subviews)
        {
            try
            {
                if (subviews == null || subviews.Length == 0)
                    return;

                foreach (UIView subview in subviews)
                {
                    if (subview is UIActivityIndicatorView)
                        continue;

                    if (subview != null)
                        ReleaseSubviews(subview.Subviews);

                    ReleaseObject(subview);
                }
            }
            catch (Exception exception)
            {
                // Logging ...
            }
        }

        private static void ReleaseUIButton(IDisposable disposableObject)
        {
            var button = disposableObject as UIButton;

            if (button == null)
                return;

            if (button.ImageView != null)
                ReleaseUIImageView(button.ImageView);

            if (button.CurrentBackgroundImage != null)
                button.CurrentBackgroundImage.Dispose();

            if (button.CurrentImage != null)
                button.CurrentImage.Dispose();
        }

        private static void ReleaseUIImageView(IDisposable disposableObject)
        {
            var imageView = disposableObject as UIImageView;

            if (imageView == null || imageView.Image == null)
                return;

            imageView.Image.Dispose();
            imageView.Image = null;
        }

        private static void ReleaseUINavigationController(IDisposable disposableObject)
        {
            var navigationController = disposableObject as UINavigationController;

            if (navigationController == null)
                return;

            if (navigationController is MFMailComposeViewController)
                return;

            ReleaseChildControllers(navigationController.ChildViewControllers);
        }

        private static void ReleaseUIPageviewController(IDisposable disposableObject)
        {
            var pageViewController = disposableObject as UIPageViewController;

            if (pageViewController == null)
                return;

            var children = pageViewController.ChildViewControllers
                .Union(pageViewController.ViewControllers)
                .ToList();

            ReleaseChildControllers(children);

            pageViewController.RemoveFromParentViewController();
        }

        private static void ReleaseChildControllers(IEnumerable<UIViewController> children)
        {
            foreach (UIViewController child in children)
            {
                var baseDialog = child as BaseDialog;

                if (baseDialog != null)
                {
                    if (!baseDialog.IsDead)
                    {
                        baseDialog.DetachEventHandlers();
                        baseDialog.CleanUpAfterDisappearing();
                        baseDialog.CleanUp();

                        child.RemoveFromParentViewController();
                        child.Dispose();
                    }

                    continue;
                }

                var timelineDialog = child as TimelineDialog;

                if (timelineDialog != null)
                {
                    timelineDialog.DetachEventHandlers();
                    timelineDialog.CleanUp();

                    timelineDialog.RemoveFromParentViewController();
                    timelineDialog.Dispose();

                    continue;
                }

                ReleaseUIViewWithChildren(child.View);
                ReleaseObject(child);
            }
        }

        private static void ReleaseUIViewController(IDisposable disposableObject)
        {
            var viewController = disposableObject as UIViewController;

            if (viewController == null || viewController is UINavigationController || viewController is UIPageViewController)
                return;

            ReleaseUIViewWithChildren(viewController.View);

            foreach (UIViewController child in viewController.ChildViewControllers)
            {
                ReleaseObject(child);
            }

            viewController.RemoveFromParentViewController();
        }

        private static void ReleaseUIView(IDisposable disposableObject)
        {
            var view = disposableObject as UIView;

            if (view == null || view.Superview == null)
                return;

            view.RemoveFromSuperview();
        }

        private static void LetObjectCleanUpItself(IDisposable dispoableObject)
        {
            var selfCleaningObject = dispoableObject as ICanCleanUpMyself;

            if (selfCleaningObject == null)
                return;

            selfCleaningObject.CleanUp();
        }
    }
}