using Microsoft.Extensions.Logging.Abstractions;
using ZB.MOM.WW.ScadaBridge.SiteRuntime.Scripts;

namespace ZB.MOM.WW.ScadaBridge.SiteRuntime.Tests.Scripts;

/// <summary>
/// WP-19: Script Trust Model tests — validates forbidden API detection and compilation.
///
/// As of the M3.3 consolidation, <c>ScriptCompilationService.ValidateTrustModel</c>
/// delegates its forbidden-API verdict to the shared authoritative
/// <c>ScriptAnalysis.ScriptTrustValidator</c>, which is stricter than SiteRuntime's
/// original deny-list: ALL of <c>System.Net</c> is forbidden (not just Sockets/Http),
/// plus reflection gateways, <c>dynamic</c>, <c>Activator</c>,
/// <c>System.Runtime.InteropServices</c> and <c>Microsoft.Win32</c>. Only
/// <c>System.Diagnostics.Process</c> is blocked under System.Diagnostics —
/// <c>Stopwatch</c> stays allowed. The real execution-path compile against
/// <c>ScriptGlobals</c> / <c>TriggerExpressionGlobals</c> is unchanged.
/// </summary>
[Collection("SiteScriptCompileCache")]
public class ScriptCompilationServiceTests
{
    private readonly ScriptCompilationService _service;

    public ScriptCompilationServiceTests()
    {
        _service = new ScriptCompilationService(NullLogger<ScriptCompilationService>.Instance);
    }

    [Fact]
    public void Compile_ValidScript_Succeeds()
    {
        var result = _service.Compile("test", "1 + 1");
        Assert.True(result.IsSuccess);
        Assert.NotNull(result.CompiledScript);
        Assert.Empty(result.Errors);
    }

    [Fact]
    public void Compile_SameCodeTwice_SharesOneRoslynCompile()
    {
        SiteScriptCompileCache.Clear();
        var r1 = _service.Compile("deploy-gate-copy", "return 1 + 1;");
        var r2 = _service.Compile("prestart-copy", "return 1 + 1;");

        Assert.True(r1.IsSuccess);
        Assert.Same(r1.CompiledScript, r2.CompiledScript);   // one compile, shared Script<T> (N4) — the definitive proof
        // Hits is a process-global counter; other test classes in this assembly compile scripts
        // concurrently (they are not in this serialized collection), so the exact post-Clear count
        // is not deterministic under a full-assembly parallel run. The shared-Script<T> assertion
        // above is the real proof of cache reuse; here we only require the second lookup registered
        // a hit (>= 1) rather than pinning an exact global count.
        Assert.True(SiteScriptCompileCache.Hits >= 1);
    }

    [Fact]
    public void Compile_ScriptAndTriggerExpression_DoNotCrossContaminate()
    {
        SiteScriptCompileCache.Clear();
        var script = _service.Compile("s", "1 > 0");
        var trigger = _service.CompileTriggerExpression("t", "1 > 0");

        Assert.NotSame(script.CompiledScript, trigger.CompiledScript); // different globals surfaces
    }

    [Fact]
    public void Compile_InvalidSyntax_ReturnsErrors()
    {
        var result = _service.Compile("bad", "this is not valid C# {{{");
        Assert.False(result.IsSuccess);
        Assert.NotEmpty(result.Errors);
    }

    [Fact]
    public void ValidateTrustModel_SystemIO_Forbidden()
    {
        var violations = _service.ValidateTrustModel("System.IO.File.ReadAllText(\"test\")");
        Assert.NotEmpty(violations);
        Assert.Contains(violations, v => v.Contains("System.IO"));
    }

    [Fact]
    public void ValidateTrustModel_Process_Forbidden()
    {
        var violations = _service.ValidateTrustModel(
            "System.Diagnostics.Process.Start(\"cmd\")");
        Assert.NotEmpty(violations);
    }

    [Fact]
    public void ValidateTrustModel_Reflection_Forbidden()
    {
        var violations = _service.ValidateTrustModel(
            "typeof(string).GetType().GetMethods(System.Reflection.BindingFlags.Public)");
        Assert.NotEmpty(violations);
    }

    [Fact]
    public void ValidateTrustModel_Sockets_Forbidden()
    {
        var violations = _service.ValidateTrustModel(
            "new System.Net.Sockets.TcpClient()");
        Assert.NotEmpty(violations);
    }

    [Fact]
    public void ValidateTrustModel_HttpClient_Forbidden()
    {
        var violations = _service.ValidateTrustModel(
            "new System.Net.Http.HttpClient()");
        Assert.NotEmpty(violations);
    }

    [Fact]
    public void ValidateTrustModel_AsyncAwait_Allowed()
    {
        // System.Threading.Tasks should be allowed (async/await support)
        var violations = _service.ValidateTrustModel(
            "await System.Threading.Tasks.Task.Delay(100)");
        Assert.Empty(violations);
    }

    [Fact]
    public void ValidateTrustModel_CancellationToken_Allowed()
    {
        var violations = _service.ValidateTrustModel(
            "System.Threading.CancellationToken.None");
        Assert.Empty(violations);
    }

    [Fact]
    public void ValidateTrustModel_CleanCode_NoViolations()
    {
        var code = @"
            var x = 1 + 2;
            var list = new List<int> { 1, 2, 3 };
            var sum = list.Sum();
            sum";
        var violations = _service.ValidateTrustModel(code);
        Assert.Empty(violations);
    }

    [Fact]
    public void Compile_ForbiddenApi_FailsValidation()
    {
        var result = _service.Compile("evil", "System.IO.File.Delete(\"/tmp/test\")");
        Assert.False(result.IsSuccess);
        Assert.NotEmpty(result.Errors);
    }

    // ── M3.3: stricter shared-validator behavior ──

    [Fact]
    public void ValidateTrustModel_SystemNetDns_Forbidden()
    {
        // The shared validator forbids ALL of System.Net — not just Sockets/Http.
        // System.Net.Dns was allowed under the old SiteRuntime list; now blocked.
        var violations = _service.ValidateTrustModel(
            "System.Net.Dns.GetHostName()");
        Assert.NotEmpty(violations);
        Assert.Contains(violations, v => v.Contains("System.Net"));
    }

    [Fact]
    public void ValidateTrustModel_ReflectionGatewayViaPermittedType_Forbidden()
    {
        // typeof(x).Assembly.GetType(...) never spells a forbidden namespace, but
        // the shared validator rejects the reflection-gateway members regardless of
        // receiver — this was NOT caught by the old SiteRuntime list.
        var violations = _service.ValidateTrustModel(
            "typeof(string).Assembly.GetType(\"System.IO.File\")");
        Assert.NotEmpty(violations);
    }

    [Fact]
    public void ValidateTrustModel_Dynamic_Forbidden()
    {
        var violations = _service.ValidateTrustModel("dynamic d = 1; return d;");
        Assert.NotEmpty(violations);
    }

    [Fact]
    public void ValidateTrustModel_Activator_Forbidden()
    {
        var violations = _service.ValidateTrustModel(
            "Activator.CreateInstance(typeof(string))");
        Assert.NotEmpty(violations);
    }

    [Fact]
    public void ValidateTrustModel_InteropServices_Forbidden()
    {
        var violations = _service.ValidateTrustModel(
            "System.Runtime.InteropServices.Marshal.SizeOf<int>()");
        Assert.NotEmpty(violations);
    }

    [Fact]
    public void ValidateTrustModel_Stopwatch_Allowed()
    {
        // Only System.Diagnostics.Process is blocked under System.Diagnostics —
        // Stopwatch stays allowed.
        var violations = _service.ValidateTrustModel(
            "var sw = System.Diagnostics.Stopwatch.StartNew(); return sw.ElapsedMilliseconds;");
        Assert.Empty(violations);
    }

    /// <summary>
    /// Native-memory leak guard. <c>ScriptOptions.WithReferences(Assembly[])</c> resolves each
    /// assembly through <c>MetadataReference.CreateFromFile</c>, and every such reference owns an
    /// <c>AssemblyMetadata</c> → <c>PEReader</c> → <c>NativeHeapMemoryBlock</c> — an unmanaged copy
    /// of the assembly metadata that nothing here ever disposes. Building the options per compile
    /// therefore grows native memory permanently: no GC reclaims it, and it is invisible to
    /// <c>GC.GetTotalAllocatedBytes</c> and to gcdump.
    ///
    /// <para>
    /// Diagnosed from a live dump of the wonder-app-vd03 Site node (2026-08-12): 2,885 MB working
    /// set 78 min after a cold start, of which only 150 MB was live GC heap; VMMap attributed
    /// 2,469 MB to the default process heap and <c>dumpheap -stat</c> found 6,740 each of
    /// <c>AssemblyMetadata</c> / <c>PEReader</c> / <c>MetadataImageReference</c> against just 473
    /// DLLs on disk — i.e. ~1,348 undisposed copies of this service's 5-assembly reference set.
    /// </para>
    ///
    /// <para>
    /// Asserted on the artifact rather than on memory: a watch-the-bytes test would be flaky, and
    /// the leak is native so the managed allocation counters cannot see it at all. Two DISTINCT
    /// bodies are required — identical ones would be served from
    /// <see cref="SiteScriptCompileCache"/> without a second <c>CompileUncached</c>, and the test
    /// would pass without proving anything.
    /// </para>
    /// </summary>
    [Fact]
    public void Compile_DistinctScripts_ShareOneMetadataReferenceSet_SoNativeMemoryDoesNotGrow()
    {
        SiteScriptCompileCache.Clear();
        var first = _service.Compile("first", "return 1 + 1;");
        var second = _service.Compile("second", "return 2 + 2;");

        Assert.True(first.IsSuccess);
        Assert.True(second.IsSuccess);
        Assert.NotSame(first.CompiledScript, second.CompiledScript);  // two real compiles, not a cache hit

        var firstRefs = first.CompiledScript!.Options.MetadataReferences;
        var secondRefs = second.CompiledScript!.Options.MetadataReferences;

        Assert.NotEmpty(firstRefs);   // else the reference-equality checks below are vacuous
        Assert.Equal(firstRefs.Length, secondRefs.Length);

        for (var i = 0; i < firstRefs.Length; i++)
            Assert.Same(firstRefs[i], secondRefs[i]);

        // The options object itself is cached, so it must not be rebuilt either.
        Assert.Same(first.CompiledScript.Options, second.CompiledScript.Options);
    }

    [Fact]
    public void Compile_UsesProcessWideCachingMetadataResolver()
    {
        SiteScriptCompileCache.Clear();
        var result = _service.Compile("resolver-pin", "return 41 + 1;");

        Assert.True(result.IsSuccess);
        // Without the shared caching resolver, EVERY compile re-resolves the
        // transitive assembly closure via MetadataReference.CreateFromFile —
        // ~74+ fresh native metadata copies per compiled script (2026-08-12 dump).
        Assert.Same(
            ZB.MOM.WW.ScadaBridge.ScriptAnalysis.CachingScriptMetadataResolver.Instance,
            result.CompiledScript!.Options.MetadataResolver);
    }
}
