using Moq;
using Opc.Ua;
using Opc.Ua.Client;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient;
using ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.Browser;

namespace ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.Browser.Tests;

/// <summary>
///     Unit-only coverage of <see cref="OpcUaClientDriverBrowser"/>'s pre-connect
///     validation. These tests do not require a live OPC UA endpoint and are safe to
///     run without the opc-plc Docker fixture.
/// </summary>
[Trait("Category", "Unit")]
public sealed class OpcUaClientDriverBrowserTests
{
    private readonly OpcUaClientDriverBrowser _sut = new();

    /// <summary>The DriverType key must match the AdminUI's persisted value.</summary>
    [Fact]
    public void DriverType_is_OpcUaClient() => _sut.DriverType.ShouldBe("OpcUaClient");

    /// <summary>An empty endpoint must fail fast with a clear EndpointUrl-mentioning message.</summary>
    [Fact]
    public async Task OpenAsync_with_empty_endpoint_throws()
    {
        var json = """{"EndpointUrl":"","EndpointUrls":[]}""";
        var ex = await Should.ThrowAsync<InvalidOperationException>(
            () => _sut.OpenAsync(json, TestContext.Current.CancellationToken));
        ex.Message.ShouldContain("EndpointUrl");
    }

    /// <summary>A JSON literal that deserializes to null must fail fast.</summary>
    [Fact]
    public async Task OpenAsync_with_null_json_throws()
    {
        var ex = await Should.ThrowAsync<InvalidOperationException>(
            () => _sut.OpenAsync("null", TestContext.Current.CancellationToken));
        ex.Message.ShouldContain("null");
    }

    /// <summary>Certificate auth is not supported by the browser; the failure message
    /// must say so explicitly rather than surfacing a downstream COM/SDK error.
    /// <c>OpcUaAuthType.Certificate</c> serializes as the numeric value 2 under the
    /// browser's default System.Text.Json options (no string-enum converter).</summary>
    [Fact]
    public async Task OpenAsync_with_certificate_auth_throws_clear_message()
    {
        var json = """{"EndpointUrl":"opc.tcp://127.0.0.1:1","AuthType":2}""";
        var ex = await Should.ThrowAsync<InvalidOperationException>(
            () => _sut.OpenAsync(json, TestContext.Current.CancellationToken));
        ex.Message.ShouldContain("Certificate");
    }

    // ---- Driver.OpcUaClient.Browser-001: AttributesAsync must refresh LastUsedUtc ----

    /// <summary>
    ///     <see cref="IBrowseSession.LastUsedUtc"/> must be updated on every call
    ///     including <see cref="OpcUaClientBrowseSession.AttributesAsync"/>, which the
    ///     <see cref="BrowseSessionReaper"/> uses for idle eviction. Before the fix
    ///     the method returned immediately without touching the property, causing a
    ///     session that only received <c>AttributesAsync</c> calls to be evicted early.
    /// </summary>
    [Fact]
    public async Task AttributesAsync_updates_LastUsedUtc()
    {
        var ct = TestContext.Current.CancellationToken;

        // Arrange: build a minimal OpcUaClientBrowseSession without a live server.
        // AttributesAsync does not call ISession — MockBehavior.Loose is safe.
        var mockSession = new Mock<ISession>(MockBehavior.Loose);
        var nsMap = NamespaceMap.FromTable(new NamespaceTable());
        var sut = new OpcUaClientBrowseSession(mockSession.Object, nsMap, ObjectIds.ObjectsFolder);

        var before = sut.LastUsedUtc;

        // Introduce a small delay so clock advances at least one tick.
        await Task.Delay(5, ct);

        // Act
        var attrs = await sut.AttributesAsync("nsu=http://opcfoundation.org/UA/;i=85", ct);

        // Assert: LastUsedUtc must have been refreshed, and the result must be empty
        // (OPC UA picker treats variables as leaves, no attribute side-panel).
        attrs.ShouldBeEmpty();
        sut.LastUsedUtc.ShouldBeGreaterThan(before,
            "AttributesAsync must refresh LastUsedUtc to satisfy the IBrowseSession contract");
    }
}