using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Core.Scripting;

namespace ZB.MOM.WW.OtOpcUa.Core.Scripting.Tests;

/// <summary>
///     Sandbox hardening (review R05:10): <c>System.Threading</c> is denied as a namespace with a
///     type-granular allow-list (<c>CancellationToken</c>, <c>Interlocked</c>, <c>Volatile</c>) so a
///     script can no longer park its pool thread on a blocking primitive or touch a system-global kernel
///     object; <c>System.Type</c>'s reflection entry points (<c>GetType(string)</c>, <c>GetMethod*</c>,
///     <c>InvokeMember</c>, …) and <c>System.Runtime.CompilerServices.RuntimeHelpers</c> are denied so a
///     forbidden type cannot be reached by name without ever being named syntactically.
/// </summary>
[Trait("Category", "Unit")]
public sealed class ScriptSandboxHardeningTests
{
    private static ScriptSandboxViolationException Rejects(string source) =>
        Should.Throw<ScriptSandboxViolationException>(() =>
            ScriptEvaluator<FakeScriptContext, int>.Compile(source));

    // ── System.Threading blocking / synchronisation primitives ───────────────────────────────

    [Fact]
    public void Rejects_SemaphoreSlim_Wait()
    {
        var ex = Rejects("new System.Threading.SemaphoreSlim(0).Wait(); return 0;");
        ex.Rejections.ShouldContain(r => r.TypeName.Contains("SemaphoreSlim") && r.Namespace == "System.Threading");
    }

    [Fact]
    public void Rejects_SpinWait_SpinUntil()
        => Rejects("System.Threading.SpinWait.SpinUntil(() => false); return 0;");

    [Fact]
    public void Rejects_Monitor()
        => Rejects("var o = new object(); System.Threading.Monitor.Enter(o); return 0;");

    [Fact]
    public void Rejects_named_Mutex_system_global_kernel_object()
        => Rejects("using var m = new System.Threading.Mutex(false, \"Global\\\\otopcua\"); return 0;");

    [Fact]
    public void Rejects_ManualResetEventSlim()
        => Rejects("var e = new System.Threading.ManualResetEventSlim(false); e.Wait(); return 0;");

    [Fact]
    public void Rejects_EventWaitHandle()
        => Rejects("var e = new System.Threading.EventWaitHandle(false, System.Threading.EventResetMode.ManualReset); return 0;");

    [Fact]
    public void Rejects_Thread_ThreadPool_and_Timer_still()
    {
        Rejects("var t = new System.Threading.Thread(() => { }); return 0;");
        Rejects("System.Threading.ThreadPool.QueueUserWorkItem(_ => { }); return 0;");
        Rejects("var t = new System.Threading.Timer(_ => { }); return 0;");
    }

    [Fact]
    public void Rejects_Thread_Sleep()
        => Rejects("System.Threading.Thread.Sleep(10); return 0;");

    // ── the allow-list inside System.Threading ───────────────────────────────────────────────

    [Fact]
    public async Task Allows_CancellationToken()
    {
        using var ev = ScriptEvaluator<FakeScriptContext, int>.Compile(
            "var t = System.Threading.CancellationToken.None; return t.IsCancellationRequested ? 1 : 0;");
        (await ev.RunAsync(new FakeScriptContext(), TestContext.Current.CancellationToken)).ShouldBe(0);
    }

    [Fact]
    public async Task Allows_Interlocked()
    {
        using var ev = ScriptEvaluator<FakeScriptContext, int>.Compile(
            "var x = 41; System.Threading.Interlocked.Increment(ref x); return x;");
        (await ev.RunAsync(new FakeScriptContext(), TestContext.Current.CancellationToken)).ShouldBe(42);
    }

    [Fact]
    public async Task Allows_Volatile()
    {
        using var ev = ScriptEvaluator<FakeScriptContext, int>.Compile(
            "var x = 42; return System.Threading.Volatile.Read(ref x);");
        (await ev.RunAsync(new FakeScriptContext(), TestContext.Current.CancellationToken)).ShouldBe(42);
    }

    // ── System.Type reflection entry points ──────────────────────────────────────────────────

    [Fact]
    public void Rejects_Type_GetType_by_name()
    {
        var ex = Rejects("var t = System.Type.GetType(\"System.IO.File\"); return t is null ? 0 : 1;");
        ex.Rejections.ShouldContain(r => r.Message.Contains("GetType"));
    }

    [Fact]
    public void Rejects_Type_GetMethod()
        => Rejects("var m = typeof(string).GetMethod(\"Trim\"); return m is null ? 0 : 1;");

    [Fact]
    public void Rejects_Type_GetMethods()
        => Rejects("return typeof(string).GetMethods().Length;");

    [Fact]
    public void Rejects_Type_InvokeMember()
        => Rejects("""return (int)typeof(string).InvokeMember("Length", System.Reflection.BindingFlags.GetProperty, null, "abc", null)!;""");

    [Fact]
    public void Rejects_Type_GetProperty_GetField_GetMember_GetConstructor_GetEvent()
    {
        Rejects("return typeof(string).GetProperty(\"Length\") is null ? 0 : 1;");
        Rejects("return typeof(string).GetField(\"Empty\") is null ? 0 : 1;");
        Rejects("return typeof(string).GetMember(\"Length\").Length;");
        Rejects("return typeof(string).GetConstructors().Length;");
        Rejects("return typeof(string).GetEvent(\"x\") is null ? 0 : 1;");
    }

    [Fact]
    public async Task Allows_instance_GetType_and_Type_metadata_reads()
    {
        // object.GetType() is declared on System.Object, and Type.Name / IsValueType are plain metadata
        // reads — neither is a reflection entry point, and both are common in authored scripts.
        using var ev = ScriptEvaluator<FakeScriptContext, int>.Compile(
            "object o = 42; var t = o.GetType(); return t.IsValueType && typeof(int).Name == \"Int32\" ? 1 : 0;");
        (await ev.RunAsync(new FakeScriptContext(), TestContext.Current.CancellationToken)).ShouldBe(1);
    }

    // ── RuntimeHelpers ───────────────────────────────────────────────────────────────────────

    [Fact]
    public void Rejects_RuntimeHelpers()
    {
        var ex = Rejects(
            "var o = System.Runtime.CompilerServices.RuntimeHelpers.GetUninitializedObject(typeof(string)); return o is null ? 0 : 1;");
        ex.Rejections.ShouldContain(r => r.TypeName.Contains("RuntimeHelpers"));
    }

    [Fact]
    public async Task Allows_compile_time_only_CompilerServices_attributes()
    {
        // The namespace stays open for the harmless compile-time types (MethodImplOptions etc.).
        using var ev = ScriptEvaluator<FakeScriptContext, int>.Compile(
            "var o = System.Runtime.CompilerServices.MethodImplOptions.NoInlining; return (int)o;");
        (await ev.RunAsync(new FakeScriptContext(), TestContext.Current.CancellationToken)).ShouldBe(8);
    }
}