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

namespace ZB.MOM.WW.OtOpcUa.Driver.Galaxy.ParityTests;

/// <summary>
///     PR 5.8 — Per-platform <c>ScanState</c> probe parity. The legacy backend's
///     <c>GalaxyRuntimeProbeManager</c> and the in-process backend's
///     <c>PerPlatformProbeWatcher</c> (PR 4.7) must surface the same per-host
///     <see cref="HostConnectivityStatus"/> stream after Discover: same host name
///     set, matching <see cref="HostState"/> per host.
/// </summary>
[Trait("Category", "ParityE2E")]
[Collection(nameof(ParityCollection))]
public sealed class ScanStateProbeParityTests
{
    private readonly ParityHarness _h;
    public ScanStateProbeParityTests(ParityHarness h) => _h = h;

    [Fact]
    public async Task GetHostStatuses_emits_same_host_set_after_Discover()
    {
        _h.RequireBoth();

        // Probe-watcher membership only refreshes after a Discover pass — drive that
        // first so both backends have populated their per-platform tracker.
        var snapshots = await _h.RunOnAvailableAsync(async (driver, ct) =>
        {
            var b = new RecordingAddressSpaceBuilder();
            await ((ITagDiscovery)driver).DiscoverAsync(b, ct);
            // Give the probe watcher a beat to land its initial ScanState reads —
            // PR 4.7 subscribes per platform with bufferedUpdateIntervalMs=0 so the
            // first push lands within ~publishingInterval (1s default).
            await Task.Delay(1_500, ct);
            return ((IHostConnectivityProbe)driver).GetHostStatuses();
        }, CancellationToken.None);

        var legacy = snapshots[ParityHarness.Backend.LegacyHost];
        var mxgw = snapshots[ParityHarness.Backend.MxGateway];

        // Legacy reports: client-name transport entry + every $WinPlatform/$AppEngine
        // probe. Mxgw reports the same shape (PR 4.7). The host-name set must agree
        // case-insensitively.
        var legacyHosts = legacy.Select(s => s.HostName).ToHashSet(StringComparer.OrdinalIgnoreCase);
        var mxgwHosts = mxgw.Select(s => s.HostName).ToHashSet(StringComparer.OrdinalIgnoreCase);

        if (legacyHosts.Count == 0)
        {
            Assert.Skip("legacy backend reported no host probes — dev Galaxy may not be a multi-platform deployment");
        }

        // The transport-entry host names differ by design — legacy uses the legacy
        // host's process-level identity, mxgw uses MxAccess.ClientName. Compare
        // only the platform-host subset (anything that's NOT either side's transport).
        var legacyPlatformHosts = legacyHosts.Where(h => !h.Contains("Galaxy.Host", StringComparison.OrdinalIgnoreCase)).ToHashSet(StringComparer.OrdinalIgnoreCase);
        var mxgwPlatformHosts = mxgwHosts.Where(h => !h.Contains("OtOpcUa-Parity", StringComparison.OrdinalIgnoreCase)).ToHashSet(StringComparer.OrdinalIgnoreCase);

        legacyPlatformHosts.Except(mxgwPlatformHosts, StringComparer.OrdinalIgnoreCase).ShouldBeEmpty(
            "every $WinPlatform / $AppEngine probed by the legacy backend must appear in the mxgw probe set");
        mxgwPlatformHosts.Except(legacyPlatformHosts, StringComparer.OrdinalIgnoreCase).ShouldBeEmpty(
            "every $WinPlatform / $AppEngine probed by the mxgw backend must appear in the legacy probe set");
    }

    [Fact]
    public async Task GetHostStatuses_state_per_platform_matches_across_backends()
    {
        _h.RequireBoth();

        var snapshots = await _h.RunOnAvailableAsync(async (driver, ct) =>
        {
            var b = new RecordingAddressSpaceBuilder();
            await ((ITagDiscovery)driver).DiscoverAsync(b, ct);
            await Task.Delay(1_500, ct);
            return ((IHostConnectivityProbe)driver).GetHostStatuses()
                .ToDictionary(s => s.HostName, s => s.State, StringComparer.OrdinalIgnoreCase);
        }, CancellationToken.None);

        var legacy = snapshots[ParityHarness.Backend.LegacyHost];
        var mxgw = snapshots[ParityHarness.Backend.MxGateway];

        if (legacy.Count == 0 || mxgw.Count == 0)
        {
            Assert.Skip("one or both backends reported no host probes");
        }

        // Skip the transport entry per backend (different by design); compare the
        // platform-host overlap.
        var commonHosts = legacy.Keys.Intersect(mxgw.Keys, StringComparer.OrdinalIgnoreCase).ToArray();
        if (commonHosts.Length == 0)
        {
            Assert.Skip("no overlapping platform hosts between backends — likely the transport names differ but no $WinPlatform was discovered");
        }

        foreach (var host in commonHosts)
        {
            mxgw[host].ShouldBe(legacy[host], $"HostState parity for '{host}'");
        }
    }
}