using Shouldly;
using Xunit;

namespace ZB.MOM.WW.OtOpcUa.Host.IntegrationTests;

/// <summary>
///     R3-01 T7 — a source-scan guard, following the solution-root-walk idiom
///     <c>ZB.MOM.WW.OtOpcUa.Driver.S7.Cli.Tests.FlushLoggingConventionTests</c> uses. Complements the
///     endpoint-metadata census (<c>MeshGrpcAnonymousMetadataTests</c>): the census catches a map
///     added to <c>MeshGrpcEndpoints</c> without the <c>AllowAnonymous</c> convention, but it cannot
///     catch a map added to <c>Program.cs</c> that bypasses the helper entirely — that shape never
///     goes through <c>MapOtOpcUaMeshGrpcServices</c> at all, so the census would simply never see it.
/// </summary>
/// <remarks>
///     Would have FAILED at HEAD before T1: <c>Program.cs</c> used to carry the five map sites
///     inline (<c>MapZbLocalDbSync()</c>, four <c>MapGrpcService&lt;T&gt;()</c> calls) with no
///     <c>MapOtOpcUaMeshGrpcServices</c> call at all.
/// </remarks>
public sealed class MeshGrpcMapConventionTests
{
    private static readonly string ProgramCsPath = LocateProgramCs();

    [Fact]
    public void ProgramCs_ContainsNoDirectMeshGrpcMapSites_AndExactlyOneMapperCall()
    {
        var source = File.ReadAllText(ProgramCsPath);

        // Guard-of-the-guard: a bad path (an empty file, or one that never had the mapper in the
        // first place) must not pass this test by finding nothing to count.
        source.ShouldNotBeNullOrWhiteSpace();
        source.ShouldContain("MapOtOpcUaMeshGrpcServices(");

        CountOccurrences(source, "MapGrpcService<").ShouldBe(0,
            "every MapGrpcService<T>() call must live inside MeshGrpcEndpoints.MapOtOpcUaMeshGrpcServices, " +
            "not inline in Program.cs (03/S14 — a map added outside the helper is invisible to the " +
            "endpoint-metadata census).");
        CountOccurrences(source, "MapZbLocalDbSync(").ShouldBe(0,
            "the LocalDb sync map must live inside MeshGrpcEndpoints.MapOtOpcUaMeshGrpcServices, not inline " +
            "in Program.cs, for the same reason as MapGrpcService<T>() above.");
        CountOccurrences(source, "MapOtOpcUaMeshGrpcServices(").ShouldBe(1,
            "Program.cs must call the mapper exactly once; more than one call would map the mesh gRPC " +
            "services twice (a route conflict) and zero calls would drop them entirely.");
    }

    private static int CountOccurrences(string source, string needle)
    {
        var count = 0;
        var index = 0;
        while ((index = source.IndexOf(needle, index, StringComparison.Ordinal)) >= 0)
        {
            count++;
            index += needle.Length;
        }

        return count;
    }

    private static string LocateProgramCs()
    {
        var dir = new DirectoryInfo(AppContext.BaseDirectory);
        while (dir is not null && !File.Exists(Path.Combine(dir.FullName, "ZB.MOM.WW.OtOpcUa.slnx")))
            dir = dir.Parent;
        dir.ShouldNotBeNull("Could not find solution root (ZB.MOM.WW.OtOpcUa.slnx).");
        return Path.Combine(dir!.FullName, "src", "Server", "ZB.MOM.WW.OtOpcUa.Host", "Program.cs");
    }
}