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

using NuGet.Frameworks;
using NuGet.RuntimeModel;

namespace Microsoft.NET.Build.Tasks
{
    internal static partial class NuGetUtils
    {
        public static bool IsPlaceholderFile(string path)
        {
            // PERF: avoid allocations here as we check this for every file in project.assets.json
            if (!path.EndsWith("_._", StringComparison.Ordinal))
            {
                return false;
            }

            if (path.Length == 3)
            {
                return true;
            }

            char separator = path[path.Length - 4];
            return separator == '\\' || separator == '/';
        }

        public static string? GetLockFileLanguageName(string? projectLanguage)
        {
            switch (projectLanguage)
            {
                case "C#": return "cs";
                case "F#": return "fs";
                default: return projectLanguage?.ToLowerInvariant();
            }
        }

        public static NuGetFramework? ParseFrameworkName(string? frameworkName)
        {
            return frameworkName == null ? null : NuGetFramework.Parse(frameworkName);
        }

        public static bool IsApplicableAnalyzer(string file, string projectLanguage)
        {
            // This logic is preserved from previous implementations.
            // See https://github.com/NuGet/Home/issues/6279#issuecomment-353696160 for possible issues with it.

            bool IsAnalyzer()
            {
                return file.StartsWith("analyzers", StringComparison.Ordinal)
                    && file.EndsWith(".dll", StringComparison.OrdinalIgnoreCase)
                    && !file.EndsWith(".resources.dll", StringComparison.OrdinalIgnoreCase);
            }

            bool CS() => file.Contains("/cs/", StringComparison.OrdinalIgnoreCase);
            bool VB() => file.Contains("/vb/", StringComparison.OrdinalIgnoreCase);

            bool FileMatchesProjectLanguage()
            {
                switch (projectLanguage)
                {
                    case "C#":
                        return CS() || !VB();

                    case "VB":
                        return VB() || !CS();

                    default:
                        return false;
                }
            }

            return IsAnalyzer() && FileMatchesProjectLanguage();
        }

        public static string? GetBestMatchingRid(RuntimeGraph runtimeGraph, string runtimeIdentifier,
            IEnumerable<string> availableRuntimeIdentifiers, out bool wasInGraph)
        {
            return GetBestMatchingRidWithExclusion(runtimeGraph, runtimeIdentifier,
                runtimeIdentifiersToExclude: null,
                availableRuntimeIdentifiers, out wasInGraph);
        }

        public static string? GetBestMatchingRidWithExclusion(RuntimeGraph runtimeGraph, string runtimeIdentifier,
            IEnumerable<string>? runtimeIdentifiersToExclude,
            IEnumerable<string> availableRuntimeIdentifiers, out bool wasInGraph)
        {
            wasInGraph = runtimeGraph.Runtimes.ContainsKey(runtimeIdentifier);

            string? bestMatch = null;

            HashSet<string> availableRids = new(availableRuntimeIdentifiers, StringComparer.Ordinal);
            HashSet<string>? excludedRids = runtimeIdentifiersToExclude switch { null => null, _ => new HashSet<string>(runtimeIdentifiersToExclude, StringComparer.Ordinal) };
            foreach (var candidateRuntimeIdentifier in runtimeGraph.ExpandRuntime(runtimeIdentifier))
            {
                if (bestMatch == null && availableRids.Contains(candidateRuntimeIdentifier))
                {
                    bestMatch = candidateRuntimeIdentifier;
                }

                if (excludedRids != null && excludedRids.Contains(candidateRuntimeIdentifier))
                {
                    //  Don't treat this as a match
                    return null;
                }
            }

            return bestMatch;
        }
    }
}