using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;

namespace athosRT.tool
{
    public class CommandBase : ICommand
    {
        private readonly Action<object> _commandpara;
        private readonly Action _command;
        private readonly Func<bool> _canExecute;

        public CommandBase(Action command, Func<bool> canExecute = null)
        {
            if (command == null)
            {
                throw new ArgumentNullException();
            }
            _canExecute = canExecute;
            _command = command;
        }

        public CommandBase(Action<object> commandpara, Func<bool> canExecute = null)
        {
            if (commandpara == null)
            {
                throw new ArgumentNullException();
            }
            _canExecute = canExecute;
            _commandpara = commandpara;
        }

        public bool CanExecute(object parameter)
        {
            return _canExecute == null || _canExecute();
        }
        public event EventHandler CanExecuteChanged
        {
            add { CommandManager.RequerySuggested += value; }
            remove { CommandManager.RequerySuggested -= value; }
        }

        public void Execute(object parameter)
        {
            if (parameter != null)
            {
                _commandpara(parameter);
            }
            else
            {
                if (_command != null)
                {
                    _command();
                }
                else if (_commandpara != null)
                {
                    _commandpara(null);
                }
            }
        }
    }
    public class DelegateCommand : ICommand
    {
        // 定义一个名为SimpleEventHandler的委托，两个参数，一个object类，一个是自定义的DelegateCommandEventArgs类
        public delegate void SimpleEventHandler(object sender, DelegateCommandEventArgs e);
        // handler是方法，别忘了，委托是用于定义方法的类
        private SimpleEventHandler handler;
        private bool isEnabled = true;

        public DelegateCommand(SimpleEventHandler handler)
        {
            this.handler = handler;
        }
        public void Execute(object parameter)
        {
            this.handler(this, new DelegateCommandEventArgs(parameter));
        }
        public bool CanExecute(object parameter)
        {
            return this.isEnabled;
        }
        public event EventHandler CanExecuteChanged;
        public bool IsEnabled
        {
            get { return this.isEnabled; }
            set
            {
                this.isEnabled = value;
                this.OnCanExecuteChanged();
            }
        }
        private void OnCanExecuteChanged()
        {
            if (this.CanExecuteChanged != null)
                this.CanExecuteChanged(this, EventArgs.Empty);
        }
    }

    public class DelegateCommandEventArgs : EventArgs
    {
        private object parameter;
        public DelegateCommandEventArgs(object parameter)
        {
            this.parameter = parameter;
        }
        public object Parameter
        {
            get { return this.parameter; }
        }
    }

}