using System;
using System.Threading.Tasks;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using Plume.WPF.Commands;
using Plume.WPF.Mvvm;

namespace Orbit.Module.ViewModel
{
    class ImageViewerViewModel : BindableBase
    {
        private readonly ImageManager _imageManager;
        private BitmapSource _imageSource;
        private string _title;
        private string _errorText;
        private bool _isLoading;
        private Stretch _imageStretch;

        public BitmapSource ImageSource
        {
            get => _imageSource;
            set => SetProperty(ref _imageSource, value);
        }


        public string Title
        {
            get => _title;
            set => SetProperty(ref _title, value);
        }

        public bool IsLoading
        {
            get => _isLoading;
            set => SetProperty(ref _isLoading, value);
        }

        public Stretch ImageStretch
        {
            get => _imageStretch;
            set => SetProperty(ref _imageStretch, value);
        }

        public string ErrorText
        {
            get => _errorText;
            set => SetProperty(ref _errorText, value);
        }

        public DelegateCommand CommandRight { get; }
        public DelegateCommand CommandLeft { get; }
        public DelegateCommand CommandUp { get; }
        public DelegateCommand CommandDown { get; }
        public DelegateCommand CommandToggleFitToScreen { get; }

        public ImageViewerViewModel()
        {
            _imageManager = new ImageManager();
            _imageManager.Loaded += On_Loaded;
            _imageManager.Loading += On_Loading;

            CommandRight = new DelegateCommand(OnCommandRight);
            CommandLeft = new DelegateCommand(OnCommandLeft);
            CommandUp = new DelegateCommand(OnCommandUp);
            CommandDown = new DelegateCommand(OnCommandDown);
            CommandToggleFitToScreen = new DelegateCommand(OnCommandToggleFitToScreen);

            ImageStretch = Stretch.None;
        }

        public async Task Initialize(string path)
        {
            await _imageManager.Load(path);
        }

        private void On_Loading(object sender, EventArgs e)
        {
            IsLoading = true;
            ErrorText = "Loading Image";
            ImageSource = null;
        }

        private void On_Loaded(object sender, Exception e)
        {
            IsLoading = false;
            ErrorText = string.Empty;

            if (_imageManager.Image != null)
            {
                ImageSource = _imageManager.Image.ToBitmapSource();
                Title = _imageManager.FileInfo;
            }
            else
            {
                ErrorText = e?.Message;
            }
        }

        private void OnCommandToggleFitToScreen()
        {
            if (ImageStretch == Stretch.None)
                ImageStretch = Stretch.Uniform;
            else
                ImageStretch = Stretch.None;
        }

        private async void OnCommandLeft()
        {
            await _imageManager.Previous();
        }

        private async void OnCommandRight()
        {
            await _imageManager.Next();
        }

        private void OnCommandUp()
        {
            _imageManager.NextFrame();
        }

        private void OnCommandDown()
        {
            _imageManager.PreviousFrame();
        }
    }
}