using System;
using System.Threading.Tasks;
using System.Windows.Input;
using Xamarin.Forms;
using Xamarin.Forms.Internals;

namespace Project.Helpers
{
    public class RelayCommand : ICommand {
		readonly Func<Task> _tsk;
		readonly Func<object, Task> _tskParam;
		bool _canExecute;

		public RelayCommand(Func<object, Task> task, bool canExecute = true) {
			_canExecute = canExecute;
			_tskParam = task;
		}

		public RelayCommand(Func<Task> task, bool canExecute = true) {
			_canExecute = canExecute;
			_tsk = task;
		}

		public event EventHandler CanExecuteChanged;

		public bool IsCanExecute {
			get => _canExecute;
			set {
				_canExecute = value;
				Device.BeginInvokeOnMainThread(() => { CanExecuteChanged?.Invoke(this, new EventArg<bool>(_canExecute)); });
			}
		}

		public bool CanExecute(object parameter) {
			return _canExecute;
		}

		public async void Execute(object parameter) {
			if (!_canExecute) return;
			_canExecute = false;
			CanExecuteChanged?.Invoke(this, new EventArg<bool>(_canExecute));
			if (_tskParam != null) await _tskParam?.Invoke(parameter);
			if (_tsk != null) await _tsk?.Invoke();
			_canExecute = true;
			CanExecuteChanged?.Invoke(this, new EventArg<bool>(_canExecute));
		}
	}
}