// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Diagnostics;
 
#if CODEANALYSIS_V3_OR_BETTER
using System.Linq;
#endif
 
namespace Analyzer.Utilities
{
    /// <summary>
    /// MSBuild item names that are required to be threaded as analyzer config options.
    /// The analyzer config option will have the following key/value:
    /// - Key: Item name prefixed with an '_' and suffixed with a 'List' to reduce chances of conflicts with any existing project property.
    /// - Value: Concatenated item metadata values, separated by a ',' character. See https://github.com/dotnet/sdk/issues/12706#issuecomment-668219422 for details.
    /// </summary>
    internal static class MSBuildItemOptionNames
    {
        public const string SupportedPlatform = nameof(SupportedPlatform);
    }
 
    internal static class MSBuildItemOptionNamesHelpers
    {
        public const char ValuesSeparator = ',';
        private static readonly char[] s_itemMetadataValuesSeparators = new[] { ValuesSeparator };
 
        public static string GetPropertyNameForItemOptionName(string itemOptionName)
        {
            VerifySupportedItemOptionName(itemOptionName);
            return $"_{itemOptionName}List";
        }
 
        [Conditional("DEBUG")]
        public static void VerifySupportedItemOptionName(string itemOptionName)
        {
#if CODEANALYSIS_V3_OR_BETTER
            Debug.Assert(typeof(MSBuildItemOptionNames).GetFields().Single(f => f.Name == itemOptionName) != null);
#endif
        }
 
        public static ImmutableArray<string> ParseItemOptionValue(string? itemOptionValue)
        {
            if (itemOptionValue == null)
            {
                return ImmutableArray<string>.Empty;
            }
 
            return ProduceTrimmedArray(itemOptionValue).ToImmutableArray();
        }
 
        private static IEnumerable<string> ProduceTrimmedArray(string itemOptionValue)
        {
            foreach (var platform in itemOptionValue.Split(s_itemMetadataValuesSeparators, StringSplitOptions.RemoveEmptyEntries))
            {
                yield return platform.Trim();
            }
        }
    }
}