using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;
using Shouldly;
using Xunit;
using ZB.MOM.WW.Configuration;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Core.Hosting;
using ZB.MOM.WW.OtOpcUa.Driver.AbCip;
using ZB.MOM.WW.OtOpcUa.Host.Configuration;
using ZB.MOM.WW.OtOpcUa.Host.Drivers;
using ZB.MOM.WW.Secrets.Abstractions;

namespace ZB.MOM.WW.OtOpcUa.Host.Tests.Configuration;

/// <summary>
///     Final review I1 — the node-level <c>Drivers:AbCip:DefaultTransport</c>: binding (appsettings and the
///     <c>__</c> env-var form), precedence (explicit per-driver key &gt; node default &gt; compiled Native), the
///     probe agreeing with the driver factory, and fail-fast validation. Every precedence test runs a pinned
///     node (Libplctag) against the compiled default (Native), so a wiring that ignores the node value goes red.
/// </summary>
[Trait("Category", "Unit")]
[Collection(AbTransportSharedPoolCollection.Name)] // resolves the registry, which configures the shared pool
public sealed class AbCipDriverDefaultsOptionsTests
{
    private const string NoKey = """{"devices":[{"hostAddress":"ab://10.0.0.1/1,0"}],"probe":{"enabled":false}}""";
    private const string ExplicitNative =
        """{"transport":"Native","devices":[{"hostAddress":"ab://10.0.0.1/1,0"}],"probe":{"enabled":false}}""";

    private static ServiceProvider Build(IConfiguration configuration)
    {
        var services = new ServiceCollection();
        services.AddLogging();
        services.AddSingleton<ISecretResolver>(new StubSecretResolver());
        services.AddAbCipDriverDefaults(configuration);
        services.AddOtOpcUaDriverFactories();
        return services.BuildServiceProvider();
    }

    private static IConfiguration Config(string? value) =>
        new ConfigurationBuilder()
            .AddInMemoryCollection(value is null
                ? []
                : new Dictionary<string, string?> { ["Drivers:AbCip:DefaultTransport"] = value })
            .Build();

    private static AbCipDriver Create(ServiceProvider sp, string json) =>
        (AbCipDriver)sp.GetRequiredService<DriverFactoryRegistry>().TryGet(DriverTypeNames.AbCip)!("drv-i1", json);

    /// <summary>
    ///     #585 composition-root pin: <c>Program.cs</c> is top-level statements and cannot be booted in a unit test, so
    ///     the registration lives in <see cref="AbCipDriverDefaultsRegistration.AddAbCipDriverDefaults"/> (which every
    ///     test here builds through) and this asserts Program.cs still CALLS it. Deleting the call silently ignores an
    ///     operator's <c>Drivers:AbCip:DefaultTransport</c> pin — every behaviour test above would stay green.
    /// </summary>
    [Fact]
    public void Program_registers_the_node_default_transport()
    {
        var dir = new DirectoryInfo(AppContext.BaseDirectory);
        while (dir is not null && !File.Exists(Path.Combine(dir.FullName, "ZB.MOM.WW.OtOpcUa.slnx"))) dir = dir.Parent;
        dir.ShouldNotBeNull();
        var program = File.ReadAllText(Path.Combine(dir.FullName, "src", "Server", "ZB.MOM.WW.OtOpcUa.Host", "Program.cs"));

        System.Text.RegularExpressions.Regex.IsMatch(
                program, @"^builder\.Services\s*\.\s*AddAbCipDriverDefaults\(\s*builder\.Configuration\s*\)\s*;",
                System.Text.RegularExpressions.RegexOptions.Multiline)
            .ShouldBeTrue("Program.cs must call builder.Services.AddAbCipDriverDefaults(builder.Configuration), unconditionally " +
                          "(at top level, not inside an if (hasDriver/hasAdmin) block — the probe on admin nodes needs it too)");
    }

    [Fact]
    public void Absent_section_defaults_to_Native()
    {
        using var sp = Build(Config(null));
        sp.GetRequiredService<IOptions<AbCipDriverDefaultsOptions>>().Value.ResolveDefaultTransport()
            .ShouldBe(AbCipTransport.Native);
        Create(sp, NoKey).EffectiveTransport.ShouldBe(AbCipTransport.Native);
    }

    [Theory]
    [InlineData("Libplctag", AbCipTransport.Libplctag)]
    [InlineData("libplctag", AbCipTransport.Libplctag)]
    [InlineData("NATIVE", AbCipTransport.Native)]
    [InlineData("", AbCipTransport.Native)]
    public void The_appsettings_key_binds(string value, AbCipTransport expected)
    {
        using var sp = Build(Config(value));
        sp.GetRequiredService<IOptions<AbCipDriverDefaultsOptions>>().Value.ResolveDefaultTransport()
            .ShouldBe(expected);
    }

    /// <summary>The documented env-var override form, <c>Drivers__AbCip__DefaultTransport</c>.</summary>
    [Fact]
    public void The_double_underscore_environment_variable_binds()
    {
        const string prefix = "OTOPCUA_I1_TEST_";
        Environment.SetEnvironmentVariable(prefix + "Drivers__AbCip__DefaultTransport", "Libplctag");
        try
        {
            var configuration = new ConfigurationBuilder().AddEnvironmentVariables(prefix).Build();
            using var sp = Build(configuration);
            Create(sp, NoKey).EffectiveTransport.ShouldBe(AbCipTransport.Libplctag);
        }
        finally
        {
            Environment.SetEnvironmentVariable(prefix + "Drivers__AbCip__DefaultTransport", null);
        }
    }

    /// <summary>A pinned node moves no-key drivers; an explicit per-driver key still wins over the pin.</summary>
    [Fact]
    public void Node_default_applies_only_to_drivers_without_a_key()
    {
        using var sp = Build(Config("Libplctag"));
        Create(sp, NoKey).EffectiveTransport.ShouldBe(AbCipTransport.Libplctag);
        Create(sp, ExplicitNative).EffectiveTransport.ShouldBe(AbCipTransport.Native);
    }

    /// <summary>The Test Connect probe resolves an absent key to the SAME node default the driver does.</summary>
    [Theory]
    [InlineData("Libplctag", AbCipTransport.Libplctag)]
    [InlineData(null, AbCipTransport.Native)]
    public void The_probe_uses_the_node_default(string? value, AbCipTransport expected)
    {
        using var sp = Build(Config(value));
        var probe = sp.GetServices<IDriverProbe>().OfType<AbCipDriverProbe>().ShouldHaveSingleItem();
        probe.DefaultTransport.ShouldBe(expected);
        Create(sp, NoKey).EffectiveTransport.ShouldBe(expected); // driver and probe agree
    }

    /// <summary>The probe stays registered exactly once on a fused node (driver path + admin path).</summary>
    [Fact]
    public void The_factory_built_probe_is_still_deduplicated()
    {
        var services = new ServiceCollection();
        services.AddOtOpcUaDriverProbes();
        services.AddOtOpcUaDriverProbes();
        using var sp = services.BuildServiceProvider();
        sp.GetServices<IDriverProbe>().OfType<AbCipDriverProbe>().Count().ShouldBe(1);
    }

    [Theory]
    [InlineData("Bogus")]
    [InlineData("1")]
    [InlineData("7")]
    [InlineData("Native,Libplctag")]
    public void A_bad_value_fails_validation_with_a_named_message(string value)
    {
        var result = new AbCipDriverDefaultsOptionsValidator().Validate(
            null, new AbCipDriverDefaultsOptions { DefaultTransport = value });
        result.Failed.ShouldBeTrue();
        result.Failures.ShouldContain(f => f.Contains("Drivers:AbCip:DefaultTransport") && f.Contains(value));

        using var sp = Build(Config(value));
        Should.Throw<OptionsValidationException>(
            () => sp.GetRequiredService<IOptions<AbCipDriverDefaultsOptions>>().Value)
            .Message.ShouldContain("Drivers:AbCip:DefaultTransport");
    }

    [Theory]
    [InlineData("Native")]
    [InlineData("libplctag")]
    [InlineData(null)]
    [InlineData("  ")]
    public void A_good_or_blank_value_validates(string? value) =>
        new AbCipDriverDefaultsOptionsValidator()
            .Validate(null, new AbCipDriverDefaultsOptions { DefaultTransport = value })
            .Succeeded.ShouldBeTrue();

    private sealed class StubSecretResolver : ISecretResolver
    {
        public Task<string?> GetAsync(SecretName name, CancellationToken ct) => Task.FromResult<string?>(null);
    }
}