// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System;
using System.Collections.Generic;
using System.Xml;

namespace Microsoft.Build.Utilities;

/// <summary>
/// Represents an API contract definition
/// </summary>
internal struct ApiContract
{
    /// <summary>
    /// Name of the contract
    /// </summary>
    internal string Name;

    /// <summary>
    /// Version of the contract
    /// </summary>
    internal string Version;

    /// <summary>
    /// Constructor.
    /// </summary>
    private ApiContract(string name, string version)
    {
        Name = name;
        Version = version;
    }

    /// <summary>
    /// Returns true if this element is a "ContainedApiContracts" element.
    /// </summary>
    internal static bool IsContainedApiContractsElement(string elementName) => string.Equals(elementName, Elements.ContainedApiContracts, StringComparison.Ordinal);

    internal static bool IsVersionedContentElement(string elementName) => string.Equals(elementName, Elements.VersionedContent, StringComparison.Ordinal);

    /// <summary>
    /// Given an XML element containing API contracts, read out all contracts within that element.
    /// </summary>
    internal static void ReadContractsElement(XmlElement element, ICollection<ApiContract> apiContracts)
    {
        if (element != null && IsContainedApiContractsElement(element.Name))
        {
            // <ContainedApiContracts>
            //    <ApiContract name="UAP" version="1.0.0.0" />
            // </ContainedApiContracts>
            foreach (XmlNode contractNode in element.ChildNodes)
            {
                if (contractNode is XmlElement contractElement && string.Equals(contractNode.Name, Elements.ApiContract, StringComparison.Ordinal))
                {
                    apiContracts.Add(new ApiContract(
                        contractElement.GetAttribute(Attributes.Name),
                        contractElement.GetAttribute(Attributes.Version)));
                }
            }
        }
    }

    /// <summary>
    /// Helper class with ApiContract element names
    /// </summary>
    private static class Elements
    {
        /// <summary>
        /// Element containing a bucket of contracts
        /// </summary>
        public const string ContainedApiContracts = "ContainedApiContracts";

        /// <summary>
        /// Element representing an individual API contract
        /// </summary>
        public const string ApiContract = "ApiContract";

        /// <summary>
        /// Element representing a flag to indicate if the SDK content is versioned
        /// </summary>
        public const string VersionedContent = "VersionedContent";
    }

    /// <summary>
    /// Helper class with attribute names
    /// </summary>
    private static class Attributes
    {
        /// <summary>
        /// Name associated with this element
        /// </summary>
        public const string Name = "name";

        /// <summary>
        /// Version associated with this element
        /// </summary>
        public const string Version = "version";
    }
}