using System.Diagnostics;
using System.Runtime.Versioning;
using System.Security.AccessControl;
using System.Security.Principal;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Core.Scripting;
using ZB.MOM.WW.OtOpcUa.Core.Scripting.OutOfProcess;

namespace ZB.MOM.WW.OtOpcUa.ScriptWorker.Tests;

/// <summary>
///     lmxopcua#890 — the installer's denies, end to end, against a real restricted worker token. A scratch copy of the
///     wonder layout (<c>&lt;deploy&gt;\{app\script-worker, pki, data, logs, backup}</c>, granting <c>BUILTIN\Users</c> read
///     plus create-files on subfolders, as a data drive does) is isolated by <c>Install-ScriptWorkerIsolation.ps1</c>
///     under Windows PowerShell with <c>-DenyPaths</c>. Under the worker token the test then cannot read <c>pki\</c>,
///     <c>data\</c>, <c>logs\</c>, <c>backup\</c> or <c>app\appsettings.json</c>, nor drop a file into the trust list,
///     while a real worker launched from the layout still runs a script. Before the install and after the uninstall the
///     same token reads and writes them (the positive control: the deny, not the layout, is what refuses).
///     <para>
///         It changes machine state while it runs (a disabled scratch anchor service, the fixed-name firewall rule, ACEs
///         in its scratch folder), so it runs only when <c>OTOPCUA_ISOLATION_INSTALLER_E2E=1</c>, elevated, on Windows,
///         and refuses when the real isolation is installed. Everything is removed in <c>finally</c>.
///     </para>
/// </summary>
[Collection(ScriptWorkerCollection.Name)]
[Trait("Category", "ScriptWorker")]
public sealed class InstallerLayoutIsolationTests
{
    public const string GateVariable = "OTOPCUA_ISOLATION_INSTALLER_E2E";
    private const string WorkerServiceName = "OtOpcUaIsoE2EWorker";
    private const string FirewallRule = "OtOpcUa-ScriptWorker-BlockOutbound";

    private static CancellationToken Ct => TestContext.Current.CancellationToken;

    [Fact]
    public async Task The_installer_denies_the_worker_every_sensitive_sibling_and_the_worker_still_runs()
    {
        if (!OperatingSystem.IsWindows()) Assert.Skip("Windows installer end-to-end");
        else if (Environment.GetEnvironmentVariable(GateVariable) != "1") Assert.Skip($"set {GateVariable}=1 (changes machine state; elevated)");
        else await RunEndToEnd();
    }

    [SupportedOSPlatform("windows")]
    private static async Task RunEndToEnd()
    {
        using (var me = WindowsIdentity.GetCurrent())
            new WindowsPrincipal(me).IsInRole(WindowsBuiltInRole.Administrator).ShouldBeTrue("run elevated");
        Run("powershell.exe", $"-NoProfile -Command \"if (Get-NetFirewallRule -Name {FirewallRule} -ErrorAction SilentlyContinue) {{ exit 3 }}\"")
            .Exit.ShouldBe(0, "the real isolation is installed on this machine (its firewall rule exists); not touching it");
        Run("sc.exe", $"query {WorkerServiceName}").Exit.ShouldNotBe(0, $"scratch service {WorkerServiceName} already exists");

        var installer = FindInstaller();
        var workerSid = ScriptWorkerIdentity.ServiceSid(WorkerServiceName);
        var deploy = Path.Combine(Path.GetPathRoot(Environment.SystemDirectory)!, "otopcua-iso-e2e-" + Guid.NewGuid().ToString("N")[..8]);
        var app = Path.Combine(deploy, "app");
        var workerFolder = Path.Combine(app, OutOfProcessScriptRunner.WorkerFolderName);
        var cache = Path.Combine(deploy + "-pecache");
        var secrets = new Dictionary<string, string>
        {
            ["pki"] = Path.Combine(deploy, "pki", "own", "private", "otopcua.pfx"),
            ["data"] = Path.Combine(deploy, "data", "secrets.db"),
            ["logs"] = Path.Combine(deploy, "logs", "otopcua-20261112.log"),
            ["backup"] = Path.Combine(deploy, "backup", "data-pre", "secrets.db"),
            ["appsettings"] = Path.Combine(app, "appsettings.json"),
        };
        var trustList = Path.Combine(deploy, "pki", "trusted", "certs");
        var denyPaths = $"{deploy},{Path.Combine(deploy, "pki")},{Path.Combine(deploy, "data")}";
        try
        {
            // ---- the layout: a copy of the built worker, the secrets beside it, a data-drive ACL on the root ----
            CopyDirectory(Path.Combine(AppContext.BaseDirectory, OutOfProcessScriptRunner.WorkerFolderName), workerFolder);
            foreach (var file in secrets.Values)
            {
                Directory.CreateDirectory(Path.GetDirectoryName(file)!);
                File.WriteAllText(file, "secret");
            }
            Directory.CreateDirectory(trustList);
            var rootAcl = new DirectoryInfo(deploy).GetAccessControl();
            var users = new SecurityIdentifier(WellKnownSidType.BuiltinUsersSid, null);
            rootAcl.AddAccessRule(new FileSystemAccessRule(users, FileSystemRights.ReadAndExecute,
                InheritanceFlags.ContainerInherit | InheritanceFlags.ObjectInherit, PropagationFlags.None, AccessControlType.Allow));
            rootAcl.AddAccessRule(new FileSystemAccessRule(users, FileSystemRights.CreateFiles | FileSystemRights.AppendData,
                InheritanceFlags.ContainerInherit, PropagationFlags.None, AccessControlType.Allow));
            new DirectoryInfo(deploy).SetAccessControl(rootAcl);
            // A protected file the inherited deny cannot reach: the installer must name it.
            var island = Path.Combine(deploy, "data", "island.bin");
            File.WriteAllText(island, "x");
            var islandAcl = new FileInfo(island).GetAccessControl();
            islandAcl.SetAccessRuleProtection(true, false);
            islandAcl.AddAccessRule(new FileSystemAccessRule(new SecurityIdentifier(WellKnownSidType.BuiltinAdministratorsSid, null),
                FileSystemRights.FullControl, AccessControlType.Allow));
            new FileInfo(island).SetAccessControl(islandAcl);
            var someWorkerFile = Directory.EnumerateFiles(workerFolder, "*.dll").First();

            // ---- before: the worker token reads and writes everything (positive control) ----
            WorkerView(workerSid, secrets.Values, trustList, someWorkerFile).ShouldAllBe(kv => kv.Value, "before the install, Users grants the worker token all of it");

            // ---- install, and install again ----
            var common = $"-InstallRoot \"{app}\" -HostServiceAccount \"{WindowsIdentity.GetCurrent().User!.Value}\" -PeCacheDir \"{cache}\" -WorkerServiceName {WorkerServiceName}";
            var first = Ps(installer, $"{common} -DenyPaths \"{denyPaths}\"");
            first.Exit.ShouldBe(0, first.Output);
            Outcomes(first.Output).Count(o => o.Outcome == "changed").ShouldBe(10, first.Output);
            first.Output.ShouldContain(island, Case.Insensitive, "the coverage audit names the protected file");
            var second = Ps(installer, $"{common} -DenyPaths \"{denyPaths}\"");
            second.Exit.ShouldBe(0, second.Output);
            Outcomes(second.Output).ShouldAllBe(o => o.Outcome == "unchanged", second.Output);
            Outcomes(second.Output).Count.ShouldBe(10);

            foreach (var dir in new[] { deploy, Path.Combine(deploy, "pki"), Path.Combine(deploy, "data"), app })
                ExplicitFor(dir, workerSid).ShouldHaveSingleItem().AccessControlType.ShouldBe(AccessControlType.Deny, dir);

            // ---- the worker token: denied every sensitive sibling, still reaches its own binaries ----
            var after = WorkerView(workerSid, secrets.Values, trustList, someWorkerFile);
            foreach (var (what, file) in secrets)
                after[file].ShouldBeFalse($"{what}: the worker token must not read {file}");
            after[trustList].ShouldBeFalse("the worker token must not drop a file into the trust list");
            after[someWorkerFile].ShouldBeTrue("the worker still reads its own binaries");
            // The host account is not affected.
            foreach (var file in secrets.Values) File.ReadAllText(file).ShouldBe("secret");

            // ---- a real worker launched from the isolated layout still runs ----
            var options = Scripts.Options(workerPath: OutOfProcessScriptRunner.ResolveWorkerEntry(workerFolder));
            options.Worker.Identity = @"NT SERVICE\" + WorkerServiceName;
            await using (var runner = Scripts.Runner(options))
            {
                runner.WorkerSid.ShouldBe(workerSid);
                var outcome = await runner.RunAsync(Scripts.Vt("vt", "return (int)ctx.GetTag(\"x\").Value + 1;", inputs: Scripts.Input("x", 41)), Ct);
                outcome.Status.ShouldBe(ScriptRunStatus.Ok, outcome.Reason);
                outcome.Value.ShouldBe(42);
            }

            // ---- uninstall WITHOUT repeating -DenyPaths: the record drives it; then again ----
            var un = Ps(installer, $"{common} -Uninstall");
            un.Exit.ShouldBe(0, un.Output);
            Outcomes(un.Output).Count(o => o.Outcome == "changed").ShouldBe(9, un.Output);
            foreach (var dir in new[] { deploy, Path.Combine(deploy, "pki"), Path.Combine(deploy, "data"), app, workerFolder })
                ExplicitFor(dir, workerSid).ShouldBeEmpty($"no worker ACE left on {dir}");
            var un2 = Ps(installer, $"{common} -Uninstall");
            un2.Exit.ShouldBe(0, un2.Output);
            Outcomes(un2.Output).ShouldAllBe(o => o.Outcome == "unchanged", un2.Output);

            // ---- after: back to the layout's own ACL (positive control for the negative assertions) ----
            WorkerView(workerSid, secrets.Values, trustList, someWorkerFile).ShouldAllBe(kv => kv.Value, "after the uninstall the deny is gone");
        }
        finally
        {
            Run("powershell.exe", $"-NoProfile -Command \"Remove-NetFirewallRule -Name {FirewallRule} -ErrorAction SilentlyContinue\"");
            Run("sc.exe", $"delete {WorkerServiceName}");
            foreach (var dir in new[] { deploy, cache })
            {
                if (!Directory.Exists(dir)) continue;
                Run("icacls.exe", $"\"{dir}\" /reset /T /C /Q");
                try { Directory.Delete(dir, recursive: true); } catch { /* best effort */ }
            }
        }
    }

    /// <summary>For each file: can the worker token read it; for the trust-list folder: can it create a file there.</summary>
    [SupportedOSPlatform("windows")]
    private static Dictionary<string, bool> WorkerView(string workerSid, IEnumerable<string> files, string trustList, string workerFile)
    {
        var result = new Dictionary<string, bool>();
        using var token = RestrictedWorkerLauncher.CreateWorkerToken(workerSid);
        WindowsIdentity.RunImpersonated(token, () =>
        {
            foreach (var file in files.Append(workerFile)) result[file] = Try(() => File.ReadAllBytes(file));
            result[trustList] = Try(() =>
            {
                // Creating the file is the escalation; deleting it needs rights Users never has, so the host cleans up below.
                File.WriteAllText(Path.Combine(trustList, "planted-" + Guid.NewGuid().ToString("N")[..6] + ".der"), "x");
            });
        });
        // The trust-list probe's file, if it got in: removed as the host.
        foreach (var f in Directory.EnumerateFiles(trustList, "planted-*")) File.Delete(f);
        return result;

        static bool Try(Action a)
        {
            try { a(); return true; }
            catch (UnauthorizedAccessException) { return false; }
        }
    }

    [SupportedOSPlatform("windows")]
    private static FileSystemAccessRule[] ExplicitFor(string dir, string sid)
        => new DirectoryInfo(dir).GetAccessControl().GetAccessRules(true, false, typeof(SecurityIdentifier))
            .Cast<FileSystemAccessRule>().Where(r => r.IdentityReference.Value == sid).ToArray();

    private static List<(string Outcome, string Id)> Outcomes(string output)
        => System.Text.RegularExpressions.Regex.Matches(output, @"\[(?<o>[a-z]+)\s*\]\s+(?<id>[A-Za-z]+)\s")
            .Select(m => (m.Groups["o"].Value, m.Groups["id"].Value)).ToList();

    private static string FindInstaller()
    {
        for (var dir = new DirectoryInfo(AppContext.BaseDirectory); dir is not null; dir = dir.Parent)
        {
            var candidate = Path.Combine(dir.FullName, "scripts", "install", "Install-ScriptWorkerIsolation.ps1");
            if (File.Exists(candidate)) return candidate;
        }
        throw new FileNotFoundException("scripts/install/Install-ScriptWorkerIsolation.ps1 not found above the test output");
    }

    // Windows PowerShell 5.1, as on the wonder boxes (no pwsh there).
    private static (int Exit, string Output) Ps(string script, string args)
        => Run("powershell.exe", $"-NoProfile -ExecutionPolicy Bypass -File \"{script}\" {args}");

    private static (int Exit, string Output) Run(string exe, string args)
    {
        var psi = new ProcessStartInfo(exe, args) { RedirectStandardOutput = true, RedirectStandardError = true, UseShellExecute = false, CreateNoWindow = true };
        // Windows PowerShell 5.1 started from a .NET process inherits a PSModulePath it cannot load its own modules from
        // (Get-Acl: "module could not be loaded"); without it, it rebuilds the default.
        psi.Environment.Remove("PSModulePath");
        using var p = Process.Start(psi)!;
        var stdout = p.StandardOutput.ReadToEndAsync();
        var stderr = p.StandardError.ReadToEndAsync();
        p.WaitForExit();
        return (p.ExitCode, stdout.Result + stderr.Result);
    }

    private static void CopyDirectory(string from, string to)
    {
        Directory.CreateDirectory(to);
        foreach (var dir in Directory.EnumerateDirectories(from, "*", SearchOption.AllDirectories))
            Directory.CreateDirectory(Path.Combine(to, Path.GetRelativePath(from, dir)));
        foreach (var file in Directory.EnumerateFiles(from, "*", SearchOption.AllDirectories))
            File.Copy(file, Path.Combine(to, Path.GetRelativePath(from, file)));
    }
}