using Elwig.Helpers;
using System;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Input;

namespace Elwig.Windows {
    public abstract class ContextWindow : Window {

        private bool _lockContext = false;
        protected bool LockContext {
            get => _lockContext;
            set {
                _lockContext = value;
                if (!_lockContext && _renewPending) {
                    Dispatcher.BeginInvoke(async () => await EnsureContextRenewed());
                }
            }
        }

        private bool _renewPending = false;

        private readonly RoutedCommand CtrlR = new("CtrlR", typeof(ContextWindow), [new KeyGesture(Key.R, ModifierKeys.Control)]);
        private readonly RoutedCommand F5 = new("F5", typeof(ContextWindow), [new KeyGesture(Key.F5)]);

        public ContextWindow() : base() {
            CommandBindings.Add(new CommandBinding(CtrlR, ForceContextReload));
            CommandBindings.Add(new CommandBinding(F5, ForceContextReload));
            Loaded += OnLoaded;
        }

        public async void ForceContextReload(object sender, EventArgs evt) {
            await ForceContextReload();
        }

        public async Task ForceContextReload() {
            HintContextChange();
            await TryContextReload();
        }

        public void HintContextChange() {
            _renewPending = true;
        }

        public async Task TryContextReload() {
            if (LockContext) return;
            await EnsureContextRenewed();
        }

        protected async void OnLoaded(object? sender, RoutedEventArgs? evt) {
            Mouse.OverrideCursor = Cursors.AppStarting;
            using var ctx = new AppDbContext();
            await OnRenewContext(ctx);
            await OnInit(ctx);
            Mouse.OverrideCursor = null;
        }

        protected async Task EnsureContextRenewed() {
            if (!_renewPending) return;
            _renewPending = false;
            using var ctx = new AppDbContext();
            await OnRenewContext(ctx);
        }

        virtual protected async Task OnInit(AppDbContext ctx) { }

        abstract protected Task OnRenewContext(AppDbContext ctx);
    }
}