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

namespace AVEVA.Historian.Client.Tests;

/// <remarks>
/// Live verification of the RemoteTcpIntegrated and RemoteTcpCertificate transports
/// per <c>docs/plans/tcp-connection-validation.md</c>. Gated by env vars:
/// <list type="bullet">
///   <item><c>HISTORIAN_REMOTE_TCP_HOST</c> — hostname or IP of a reachable remote Historian.</item>
///   <item><c>HISTORIAN_REMOTE_TCP_TAG</c> — tag with non-zero history rows.</item>
///   <item><c>HISTORIAN_REMOTE_TCP_SPN</c> — optional Kerberos SPN override (default per <c>HistorianClientOptions.TargetSpn</c>).</item>
///   <item><c>HISTORIAN_REMOTE_TCPCERT_HOST</c> + <c>HISTORIAN_REMOTE_TCPCERT_DNS</c> — for the certificate transport variant.</item>
/// </list>
/// All tests skip cleanly if the gating env var isn't set.
/// </remarks>
[SupportedOSPlatform("windows")]
public sealed class RemoteTcpIntegrationTests
{
    private readonly ITestOutputHelper _output;

    public RemoteTcpIntegrationTests(ITestOutputHelper output)
    {
        _output = output;
    }

    [Fact]
    public async Task ProbeAsync_RemoteTcpIntegrated_ReturnsTrue()
    {
        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_HOST");
        if (string.IsNullOrWhiteSpace(host) || !OperatingSystem.IsWindows())
        {
            return;
        }

        HistorianClient client = new(BuildIntegratedOptions(host));
        bool reachable = await client.ProbeAsync(CancellationToken.None);
        Assert.True(reachable, "ProbeAsync against remote-TCP host returned false");
    }

    [Fact]
    public async Task ReadRawAsync_RemoteTcpIntegrated_ReturnsAtLeastOneRow()
    {
        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_HOST");
        string? testTag = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_TAG");
        if (string.IsNullOrWhiteSpace(host) || string.IsNullOrWhiteSpace(testTag) || !OperatingSystem.IsWindows())
        {
            return;
        }

        HistorianClient client = new(BuildIntegratedOptions(host));
        DateTime endUtc = DateTime.UtcNow;
        DateTime startUtc = endUtc - TimeSpan.FromDays(7);

        List<HistorianSample> samples = [];
        await foreach (HistorianSample sample in client.ReadRawAsync(testTag, startUtc, endUtc, maxValues: 8, CancellationToken.None))
        {
            samples.Add(sample);
        }

        _output.WriteLine($"Returned {samples.Count} samples for {testTag}");
        Assert.NotEmpty(samples);
        Assert.All(samples, s => Assert.Equal(testTag, s.TagName));
    }

    [Fact]
    public async Task GetTagMetadataAsync_RemoteTcpIntegrated_PopulatesFields()
    {
        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_HOST");
        string? testTag = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_TAG");
        if (string.IsNullOrWhiteSpace(host) || string.IsNullOrWhiteSpace(testTag) || !OperatingSystem.IsWindows())
        {
            return;
        }

        HistorianClient client = new(BuildIntegratedOptions(host));
        HistorianTagMetadata? metadata = await client.GetTagMetadataAsync(testTag, CancellationToken.None);
        Assert.NotNull(metadata);
        Assert.Equal(testTag, metadata.Name);
    }

    [Fact]
    public async Task GetSystemParameterAsync_RemoteTcpIntegrated_ReturnsHistorianVersion()
    {
        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_HOST");
        if (string.IsNullOrWhiteSpace(host) || !OperatingSystem.IsWindows())
        {
            return;
        }

        HistorianClient client = new(BuildIntegratedOptions(host));
        string? value = await client.GetSystemParameterAsync("HistorianVersion", CancellationToken.None);
        _output.WriteLine($"HistorianVersion: {value}");
        Assert.False(string.IsNullOrWhiteSpace(value));
    }

    [Fact]
    public async Task ReadAggregateAsync_RemoteTcpIntegrated_ReturnsTimeWeightedRows()
    {
        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_HOST");
        string? testTag = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_TAG");
        if (string.IsNullOrWhiteSpace(host) || string.IsNullOrWhiteSpace(testTag) || !OperatingSystem.IsWindows())
        {
            return;
        }

        HistorianClient client = new(BuildIntegratedOptions(host));
        DateTime endUtc = DateTime.UtcNow;
        DateTime startUtc = endUtc - TimeSpan.FromMinutes(10);

        List<HistorianAggregateSample> samples = [];
        await foreach (HistorianAggregateSample sample in client.ReadAggregateAsync(
            testTag, startUtc, endUtc, RetrievalMode.TimeWeightedAverage, TimeSpan.FromMinutes(1), CancellationToken.None))
        {
            samples.Add(sample);
        }

        Assert.NotEmpty(samples);
        Assert.All(samples, s => Assert.Equal(testTag, s.TagName));
    }

    [Fact]
    public async Task ReadAtTimeAsync_RemoteTcpIntegrated_ReturnsTimestamps()
    {
        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_HOST");
        string? testTag = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_TAG");
        if (string.IsNullOrWhiteSpace(host) || string.IsNullOrWhiteSpace(testTag) || !OperatingSystem.IsWindows())
        {
            return;
        }

        HistorianClient client = new(BuildIntegratedOptions(host));
        DateTime now = DateTime.UtcNow;
        DateTime[] timestamps = [now - TimeSpan.FromMinutes(5), now - TimeSpan.FromMinutes(2), now - TimeSpan.FromMinutes(1)];
        IReadOnlyList<HistorianSample> samples = await client.ReadAtTimeAsync(testTag, timestamps, CancellationToken.None);
        Assert.NotEmpty(samples);
        Assert.All(samples, s => Assert.Equal(testTag, s.TagName));
    }

    [Fact]
    public async Task BrowseTagNamesAsync_RemoteTcpIntegrated_FindsTestTag()
    {
        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_HOST");
        string? testTag = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_TAG");
        if (string.IsNullOrWhiteSpace(host) || string.IsNullOrWhiteSpace(testTag) || !OperatingSystem.IsWindows())
        {
            return;
        }

        HistorianClient client = new(BuildIntegratedOptions(host));
        List<string> names = [];
        await foreach (string name in client.BrowseTagNamesAsync(testTag, CancellationToken.None))
        {
            names.Add(name);
        }
        Assert.Contains(testTag, names);
    }

    [Fact]
    public async Task ReadEventsAsync_RemoteTcpIntegrated_DoesNotThrow()
    {
        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_HOST");
        if (string.IsNullOrWhiteSpace(host) || !OperatingSystem.IsWindows())
        {
            return;
        }

        HistorianClient client = new(BuildIntegratedOptions(host));
        DateTime endUtc = DateTime.UtcNow;
        DateTime startUtc = endUtc - TimeSpan.FromDays(1);

        // Empty result is acceptable — we're just verifying the chain doesn't throw over TCP.
        List<HistorianEvent> events = [];
        await foreach (HistorianEvent evt in client.ReadEventsAsync(startUtc, endUtc, CancellationToken.None))
        {
            events.Add(evt);
        }
        Assert.NotNull(events);
    }

    [Fact]
    public async Task GetConnectionStatusAsync_RemoteTcpIntegrated_ReportsConnectedToServer()
    {
        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_HOST");
        if (string.IsNullOrWhiteSpace(host) || !OperatingSystem.IsWindows())
        {
            return;
        }

        HistorianClient client = new(BuildIntegratedOptions(host));
        HistorianConnectionStatus status = await client.GetConnectionStatusAsync(CancellationToken.None);
        Assert.True(status.ConnectedToServer);
        Assert.False(status.ErrorOccurred);
        Assert.Equal(host, status.ServerName);
    }

    [Fact]
    public async Task ProbeAsync_RemoteTcpCertificate_ReturnsTrue()
    {
        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCPCERT_HOST");
        if (string.IsNullOrWhiteSpace(host) || !OperatingSystem.IsWindows())
        {
            return;
        }

        HistorianClient client = new(new HistorianClientOptions
        {
            Host = host,
            Port = HistorianClientOptions.DefaultPort,
            IntegratedSecurity = false,
            Transport = HistorianTransport.RemoteTcpCertificate,
        });

        bool reachable = await client.ProbeAsync(CancellationToken.None);
        Assert.True(reachable, "ProbeAsync over RemoteTcpCertificate returned false");
    }

    private static HistorianClientOptions BuildIntegratedOptions(string host)
    {
        string? spn = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_SPN");
        return new HistorianClientOptions
        {
            Host = host,
            Port = HistorianClientOptions.DefaultPort,
            IntegratedSecurity = true,
            Transport = HistorianTransport.RemoteTcpIntegrated,
            // SPN default in HistorianClientOptions is "NT SERVICE\aahClientAccessPoint" which is the
            // LocalPipe service identity; for remote TCP, override via env var if needed.
            TargetSpn = string.IsNullOrWhiteSpace(spn) ? "NT SERVICE\\aahClientAccessPoint" : spn,
        };
    }
}