using System;
using System.Windows.Input;

namespace LocalizationTool.ViewModels
{
    /// <summary>把方法包装成 ICommand 的通用实现。</summary>
    public class RelayCommand : ICommand
    {
        private readonly Action<object> _execute;
        private readonly Predicate<object> _canExecute;

        public RelayCommand(Action execute, Func<bool> canExecute = null)
            : this(_ => execute(), canExecute == null ? null : _ => canExecute()) { }

        public RelayCommand(Action<object> execute, Predicate<object> canExecute = null)
        {
            _execute = execute ?? throw new ArgumentNullException(nameof(execute));
            _canExecute = canExecute;
        }

        public bool CanExecute(object parameter) => _canExecute == null || _canExecute(parameter);

        public void Execute(object parameter) => _execute(parameter);

        public event EventHandler CanExecuteChanged
        {
            add => CommandManager.RequerySuggested += value;
            remove => CommandManager.RequerySuggested -= value;
        }
    }

    /// <summary>带参数版本的 RelayCommand（参数在 XAML 中经 CommandParameter 传入）。</summary>
    public class RelayCommand<T> : ICommand
    {
        private readonly Action<T> _execute;
        private readonly Predicate<T> _canExecute;

        public RelayCommand(Action<T> execute, Predicate<T> canExecute = null)
        {
            _execute = execute ?? throw new ArgumentNullException(nameof(execute));
            _canExecute = canExecute;
        }

        public bool CanExecute(object parameter) => _canExecute == null || _canExecute((T)parameter);

        public void Execute(object parameter) => _execute((T)parameter);

        public event EventHandler CanExecuteChanged
        {
            add => CommandManager.RequerySuggested += value;
            remove => CommandManager.RequerySuggested -= value;
        }
    }
}