using System.Runtime.Versioning;
using AVEVA.Historian.Client.Models;
using AVEVA.Historian.Client.Wcf;
using Xunit.Abstractions;

namespace AVEVA.Historian.Client.Tests;

/// <remarks>
/// C2 live diagnostic spike (pending.md C2): does the managed WCF event-read path return rows
/// against an event-bearing 2023 R2 historian? gRPC event reads are a proven server-side dead-end
/// (docs/reverse-engineering/grpc-event-query-capture.md); the WCF transport is C2's only listed
/// unblock but is itself unproven (the orchestrator documents native code 76 / 85 on this server).
///
/// Drives <see cref="HistorianWcfEventOrchestrator"/> directly over RemoteTcpIntegrated and dumps the
/// full native chain. It NEVER fails the suite (skip+log diagnostic) and is inert off Windows — the
/// GREEN/RED call is by reading the printed "events observed" count + native return codes.
///
/// Gated by <c>HISTORIAN_WCF_EVENT_HOST</c> (independent of the gRPC live vars so it never runs by
/// accident). Optional: <c>HISTORIAN_WCF_EVENT_PORT</c> (default 32568), <c>HISTORIAN_WCF_EVENT_USER</c>
/// + <c>HISTORIAN_WCF_EVENT_PASSWORD</c> (absent =&gt; IntegratedSecurity), <c>HISTORIAN_WCF_EVENT_SPN</c>
/// (Kerberos SPN override; the default is the LocalPipe identity and will not authenticate remotely),
/// <c>HISTORIAN_WCF_EVENT_DAYS</c> (lookback window, default 90 — the live event store held 71,332
/// events in -90d).
///
/// Run from the Windows capture rig over VPN:
///   dotnet test --filter "FullyQualifiedName~WcfEventReadSpike" -l "console;verbosity=detailed"
/// </remarks>
[SupportedOSPlatform("windows")]
public sealed class WcfEventReadSpikeTests
{
    private readonly ITestOutputHelper _output;

    public WcfEventReadSpikeTests(ITestOutputHelper output) => _output = output;

    [Fact]
    public async Task WcfEventRead_DiagnosticDump_AgainstRemoteHistorian()
    {
        string? host = Environment.GetEnvironmentVariable("HISTORIAN_WCF_EVENT_HOST");
        if (string.IsNullOrWhiteSpace(host) || !OperatingSystem.IsWindows())
        {
            return; // inert without the dedicated gate / off Windows
        }

        int port = int.TryParse(Environment.GetEnvironmentVariable("HISTORIAN_WCF_EVENT_PORT"), out int p)
            ? p : HistorianClientOptions.DefaultPort; // 32568
        int days = int.TryParse(Environment.GetEnvironmentVariable("HISTORIAN_WCF_EVENT_DAYS"), out int d)
            ? d : 90;
        string? user = Environment.GetEnvironmentVariable("HISTORIAN_WCF_EVENT_USER");
        string? password = Environment.GetEnvironmentVariable("HISTORIAN_WCF_EVENT_PASSWORD");
        string? spn = Environment.GetEnvironmentVariable("HISTORIAN_WCF_EVENT_SPN");
        string? dnsId = Environment.GetEnvironmentVariable("HISTORIAN_WCF_EVENT_DNSID");
        bool certificate = string.Equals(
            Environment.GetEnvironmentVariable("HISTORIAN_WCF_EVENT_TRANSPORT"), "certificate", StringComparison.OrdinalIgnoreCase);
        bool allowUntrusted = string.Equals(
            Environment.GetEnvironmentVariable("HISTORIAN_WCF_EVENT_ALLOW_UNTRUSTED"), "1", StringComparison.Ordinal);
        // Certificate transport carries no Windows transport credential (cert-validated TLS channel);
        // integrated derives one from the logged-in identity unless an explicit DOMAIN\user is supplied.
        // App-level ValidateClientCredential still uses UserName/Password (or the process identity).
        bool integrated = !certificate && string.IsNullOrEmpty(user);

        HistorianClientOptions options = new()
        {
            Host = host,
            Port = port,
            Transport = certificate ? HistorianTransport.RemoteTcpCertificate : HistorianTransport.RemoteTcpIntegrated,
            IntegratedSecurity = integrated,
            UserName = user ?? string.Empty,
            Password = password ?? string.Empty,
            TargetSpn = string.IsNullOrWhiteSpace(spn) ? "NT SERVICE\\aahClientAccessPoint" : spn,
            ServerDnsIdentity = string.IsNullOrWhiteSpace(dnsId) ? null : dnsId,
            AllowUntrustedServerCertificate = allowUntrusted,
        };

        HistorianWcfEventOrchestrator orchestrator = new(options);
        DateTime endUtc = DateTime.UtcNow;
        DateTime startUtc = endUtc - TimeSpan.FromDays(days);

        int observed = 0;
        bool hasFirstEvent = false;
        string outcome = "completed";
        try
        {
            await foreach (HistorianEvent evt in orchestrator.ReadEventsAsync(startUtc, endUtc, filter: null, CancellationToken.None))
            {
                observed++;
                hasFirstEvent = true;
                _ = evt; // event identity intentionally NOT logged (sanitized)
            }
        }
        catch (Exception ex)
        {
            // Default: type name only (sanitized). Opt into messages for live binding/protocol debugging
            // via HISTORIAN_WCF_EVENT_VERBOSE=1 — binding/protocol errors may carry the endpoint host
            // (already known to the operator) but never credentials; still off by default.
            outcome = string.Equals(Environment.GetEnvironmentVariable("HISTORIAN_WCF_EVENT_VERBOSE"), "1", StringComparison.Ordinal)
                ? $"threw {ex.GetType().FullName} :: {ex.Message} | inner={ex.InnerException?.GetType().FullName} :: {ex.InnerException?.Message}"
                : $"threw {ex.GetType().Name}";
        }

        // Sanitized diagnostic dump — counts, native return codes, buffer lengths, sha256 ONLY.
        _output.WriteLine($"[C2 WCF spike] transport:                {options.Transport} (integratedSec={integrated}, allowUntrusted={allowUntrusted})");
        _output.WriteLine($"[C2 WCF spike] outcome:                  {outcome}");
        _output.WriteLine($"[C2 WCF spike] events observed:          {observed}");
        _output.WriteLine($"[C2 WCF spike] hasFirstEvent:            {hasFirstEvent}");
        _output.WriteLine($"[C2 WCF spike] LastUpdC3ReturnCode:      {HistorianWcfEventOrchestrator.LastUpdC3ReturnCode}");
        _output.WriteLine($"[C2 WCF spike] LastRTag2ReturnCode:      {HistorianWcfEventOrchestrator.LastRTag2ReturnCode}");
        _output.WriteLine($"[C2 WCF spike] LastAddReturnCode(EnsT2): {HistorianWcfEventOrchestrator.LastAddReturnCode}");
        _output.WriteLine($"[C2 WCF spike] LastAddOutputLength:      {HistorianWcfEventOrchestrator.LastAddOutputLength}");
        _output.WriteLine($"[C2 WCF spike] LastEnsT2PayloadSha256:   {HistorianWcfEventOrchestrator.LastEnsT2PayloadSha256}");
        _output.WriteLine($"[C2 WCF spike] LastResultBufferLength:   {orchestrator.LastResultBufferLength}");
        // Contract-safe: LastErrorBufferDescription is DescribeNativeError's STRUCTURED formatting of the
        // 5-byte native error buffer ("type=N code=M (0xHEX)" / "<short>") — never freeform server text,
        // FQDN, SPN, or credentials. The code value (e.g. 76 / 85) is the RED-case signal this spike exists
        // to capture, so it is dumped in full rather than reduced to a length.
        _output.WriteLine($"[C2 WCF spike] LastErrorBufferDescription: {orchestrator.LastErrorBufferDescription}");
        _output.WriteLine($"[C2 WCF spike] window days:              {days}");

        // Diagnostic: NEVER fails the suite. GREEN = observed > 0; RED = observed == 0 (read the output).
        Assert.True(observed >= 0, "diagnostic always passes; the GREEN/RED signal is the printed count");
    }
}