// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.Linq;
using System.Xml.Linq;

namespace Microsoft.AspNetCore.Server.IntegrationTesting.IIS
{
    internal static class XElementExtensions
    {
        public static XElement RequiredElement(this XElement element, string name)
        {
            var existing = element.Element(name);
            if (existing == null)
            {
                throw new InvalidOperationException($"Element with name {name} not found in {element}");
            }

            return existing;
        }

        public static XElement GetOrAdd(this XElement element, string name)
        {
            var existing = element.Element(name);
            if (existing == null)
            {
                existing = new XElement(name);
                element.Add(existing);
            }

            return existing;
        }

        public static XElement GetOrAdd(this XElement element, string name, string attribute, string attributeValue)
        {
            var existing = element.Elements(name).FirstOrDefault(e => e.Attribute(attribute)?.Value == attributeValue);
            if (existing == null)
            {
                existing = new XElement(name, new XAttribute(attribute, attributeValue));
                element.Add(existing);
            }

            return existing;
        }
    }
}