// Copyright (c) .NET Foundation and contributors. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

using System.Collections.Generic;
using System.CommandLine.Completions;
using System.CommandLine.Invocation;

namespace System.CommandLine
{
    /// <summary>
    /// Provides cross-cutting functionality that can apply across command-line apps.
    /// </summary>
    /// <remarks>
    /// Because directives are syntactically distinct from the app's own syntax, they can provide functionality that applies across apps.
    ///
    /// A directive must conform to the following syntax rules:
    /// * It's a token on the command line that comes after the app's name but before any subcommands or options.
    /// * It's enclosed in square brackets.
    /// * It doesn't contain spaces.
    /// </remarks>
    public class Directive : Symbol
    {
        /// <summary>
        /// Initializes a new instance of the Directive class.
        /// </summary>
        /// <param name="name">The name of the directive. It can't contain whitespaces.</param>
        public Directive(string name)
            : base(name)
        {
        }

        /// <summary>
        /// Gets or sets the <see cref="CommandLineAction"/> for the Directive. The handler represents the action
        /// that will be performed when the Directive is invoked.
        /// </summary>
        public virtual CommandLineAction? Action { get; set; }

        /// <inheritdoc />
        public override IEnumerable<CompletionItem> GetCompletions(CompletionContext context)
            => Array.Empty<CompletionItem>();
    }
}