// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.CommandLine;
 
namespace Microsoft.TemplateEngine.Cli.Help;
 
internal static class HelpBuilderExtensions
{
    internal static IEnumerable<Symbol> GetParameters(this Symbol symbol)
    {
        switch (symbol)
        {
            case Option option:
                yield return option;
                yield break;
            case Command command:
                foreach (var argument in command.Arguments)
                {
                    yield return argument;
                }
                yield break;
            case Argument argument:
                yield return argument;
                yield break;
            default:
                throw new NotSupportedException();
        }
    }
 
    internal static (string? Prefix, string Alias) SplitPrefix(this string rawAlias)
    {
        if (rawAlias[0] == '/')
        {
            return ("/", rawAlias.Substring(1));
        }
        else if (rawAlias[0] == '-')
        {
            if (rawAlias.Length > 1 && rawAlias[1] == '-')
            {
                return ("--", rawAlias.Substring(2));
            }
 
            return ("-", rawAlias.Substring(1));
        }
 
        return (null, rawAlias);
    }
 
    internal static IEnumerable<T> RecurseWhileNotNull<T>(this T? source, Func<T, T?> next) where T : class
    {
        while (source is not null)
        {
            yield return source;
 
            source = next(source);
        }
    }
}