using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;
using ZB.MOM.WW.Secrets.Replicator.Grpc.DependencyInjection;

namespace ZB.MOM.WW.Secrets.Replicator.Grpc.Tests;

/// <summary>
/// Registration-time validation for the hub server. A misconfigured hub must fail at startup with
/// a message naming the exact configuration key, not serve unauthenticated at runtime.
/// </summary>
public sealed class SecretsGrpcHubServerOptionsTests
{
    [Theory]
    [InlineData("")]
    [InlineData("   ")]
    [InlineData("\t\n")]
    public void Validate_throws_when_the_bearer_token_is_unset(string token)
    {
        var options = new SecretsGrpcHubServerOptions { BearerToken = token };

        InvalidOperationException error =
            Assert.Throws<InvalidOperationException>(() => options.Validate());

        Assert.Contains("Secrets:GrpcHub:BearerToken", error.Message, StringComparison.Ordinal);
    }

    [Fact]
    public void Validate_names_the_section_path_the_hub_was_registered_under()
    {
        var options = new SecretsGrpcHubServerOptions { BearerToken = string.Empty };
        options.SectionPath = "Central:Secrets:Hub";

        InvalidOperationException error =
            Assert.Throws<InvalidOperationException>(() => options.Validate());

        Assert.Contains("Central:Secrets:Hub:BearerToken", error.Message, StringComparison.Ordinal);
    }

    [Fact]
    public void Validate_accepts_a_configured_token()
    {
        var options = new SecretsGrpcHubServerOptions { BearerToken = "a-configured-hub-token" };

        options.Validate();
    }

    [Fact]
    public void Validate_never_echoes_the_configured_token()
    {
        // A token that is present but only whitespace-padded is still a real credential; the
        // failure message must never carry it.
        const string token = "  ";
        var options = new SecretsGrpcHubServerOptions { BearerToken = token };

        InvalidOperationException error =
            Assert.Throws<InvalidOperationException>(() => options.Validate());

        Assert.DoesNotContain($"'{token}'", error.Message, StringComparison.Ordinal);
        Assert.DoesNotContain("was ", error.Message, StringComparison.Ordinal);
    }

    [Fact]
    public void Bearer_token_defaults_to_empty_so_an_unconfigured_hub_cannot_serve()
    {
        var options = new SecretsGrpcHubServerOptions();

        Assert.Equal(string.Empty, options.BearerToken);
        Assert.Throws<InvalidOperationException>(() => options.Validate());
    }

    [Fact]
    public void Section_path_defaults_to_the_documented_convention()
    {
        var options = new SecretsGrpcHubServerOptions();

        Assert.Equal("Secrets:GrpcHub", options.SectionPath);
    }

    [Fact]
    public void Max_names_per_request_defaults_above_the_followers_own_fetch_chunk()
    {
        // The follower chunks at 500; the cap sits above that so a compliant sweep never meets it,
        // and meeting it therefore means something.
        var options = new SecretsGrpcHubServerOptions();

        Assert.Equal(1000, options.MaxNamesPerRequest);
    }

    [Theory]
    [InlineData(0)]
    [InlineData(-1)]
    [InlineData(int.MinValue)]
    public void Validate_rejects_a_nonpositive_request_cap(int cap)
    {
        var options = new SecretsGrpcHubServerOptions
        {
            BearerToken = "a-configured-hub-token",
            MaxNamesPerRequest = cap,
        };

        InvalidOperationException error =
            Assert.Throws<InvalidOperationException>(() => options.Validate());

        Assert.Contains("Secrets:GrpcHub:MaxNamesPerRequest", error.Message, StringComparison.Ordinal);
    }

    [Fact]
    public void Validate_accepts_a_cap_of_one()
    {
        var options = new SecretsGrpcHubServerOptions
        {
            BearerToken = "a-configured-hub-token",
            MaxNamesPerRequest = 1,
        };

        options.Validate();
    }

    [Fact]
    public void Validate_names_the_section_path_on_the_request_cap_too()
    {
        var options = new SecretsGrpcHubServerOptions
        {
            BearerToken = "a-configured-hub-token",
            MaxNamesPerRequest = 0,
        };
        options.SectionPath = "Central:Secrets:Hub";

        InvalidOperationException error =
            Assert.Throws<InvalidOperationException>(() => options.Validate());

        Assert.Contains("Central:Secrets:Hub:MaxNamesPerRequest", error.Message, StringComparison.Ordinal);
    }
}

/// <summary>
/// The registration extension itself, driven through a real <see cref="ServiceCollection"/> and a
/// real <see cref="IConfiguration"/>. What is pinned here is the coherence of what a host ends up
/// holding: the token it configured, bound from the section it named, reported under that same
/// section path — and the refusal of a second registration, which cannot deliver that coherence.
/// </summary>
public sealed class SecretsGrpcHubServerExtensionsTests
{
    private const string Token = "a-configured-hub-token";

    [Fact]
    public void Registration_binds_the_token_and_stamps_the_default_section_path()
    {
        var services = new ServiceCollection();

        services.AddZbSecretsGrpcHub(Configuration(("Secrets:GrpcHub:BearerToken", Token)));

        SecretsGrpcHubServerOptions options = Resolve(services);
        Assert.Equal(Token, options.BearerToken);
        Assert.Equal("Secrets:GrpcHub", options.SectionPath);
        Assert.Equal(1000, options.MaxNamesPerRequest);
    }

    [Fact]
    public void Registration_binds_the_request_cap_when_configured()
    {
        var services = new ServiceCollection();

        services.AddZbSecretsGrpcHub(Configuration(
            ("Secrets:GrpcHub:BearerToken", Token),
            ("Secrets:GrpcHub:MaxNamesPerRequest", "250")));

        Assert.Equal(250, Resolve(services).MaxNamesPerRequest);
    }

    [Fact]
    public void Registration_under_a_custom_section_path_binds_and_stamps_that_path()
    {
        var services = new ServiceCollection();

        services.AddZbSecretsGrpcHub(
            Configuration(("Central:Secrets:Hub:BearerToken", Token)),
            "Central:Secrets:Hub");

        SecretsGrpcHubServerOptions options = Resolve(services);
        Assert.Equal(Token, options.BearerToken);
        Assert.Equal("Central:Secrets:Hub", options.SectionPath);
    }

    [Fact]
    public void Registration_under_a_custom_section_path_names_that_path_when_the_token_is_missing()
    {
        // End to end: the operator is told the key THIS host reads, not the library's default.
        var services = new ServiceCollection();

        InvalidOperationException error = Assert.Throws<InvalidOperationException>(
            () => services.AddZbSecretsGrpcHub(
                Configuration(("Secrets:GrpcHub:BearerToken", Token)), "Central:Secrets:Hub"));

        Assert.Contains("Central:Secrets:Hub:BearerToken", error.Message, StringComparison.Ordinal);
    }

    [Fact]
    public void Registration_without_a_token_throws_naming_the_exact_key()
    {
        var services = new ServiceCollection();

        InvalidOperationException error = Assert.Throws<InvalidOperationException>(
            () => services.AddZbSecretsGrpcHub(Configuration()));

        Assert.Contains("Secrets:GrpcHub:BearerToken", error.Message, StringComparison.Ordinal);
    }

    [Fact]
    public void Registration_with_a_nonpositive_request_cap_throws()
    {
        var services = new ServiceCollection();

        InvalidOperationException error = Assert.Throws<InvalidOperationException>(
            () => services.AddZbSecretsGrpcHub(Configuration(
                ("Secrets:GrpcHub:BearerToken", Token),
                ("Secrets:GrpcHub:MaxNamesPerRequest", "0"))));

        Assert.Contains("Secrets:GrpcHub:MaxNamesPerRequest", error.Message, StringComparison.Ordinal);
    }

    [Fact]
    public void Registering_the_hub_twice_throws()
    {
        var services = new ServiceCollection();
        IConfiguration configuration = Configuration(("Secrets:GrpcHub:BearerToken", Token));

        services.AddZbSecretsGrpcHub(configuration);

        InvalidOperationException error = Assert.Throws<InvalidOperationException>(
            () => services.AddZbSecretsGrpcHub(configuration));

        Assert.Contains("once", error.Message, StringComparison.OrdinalIgnoreCase);
    }

    [Fact]
    public void Registering_the_hub_twice_under_different_sections_throws_rather_than_merging()
    {
        // This is the case the guard exists for: binding MERGES (the second section's absent
        // BearerToken leaves the first one's standing) while the SectionPath stamp is last-one-wins,
        // so the surviving options would report a section that did not supply the token they hold.
        var services = new ServiceCollection();
        IConfiguration configuration = Configuration(
            ("Secrets:GrpcHub:BearerToken", Token),
            ("Central:Secrets:Hub:MaxNamesPerRequest", "7"));

        services.AddZbSecretsGrpcHub(configuration);

        Assert.Throws<InvalidOperationException>(
            () => services.AddZbSecretsGrpcHub(configuration, "Central:Secrets:Hub"));

        SecretsGrpcHubServerOptions options = Resolve(services);
        Assert.Equal("Secrets:GrpcHub", options.SectionPath);
        Assert.Equal(Token, options.BearerToken);
        Assert.Equal(1000, options.MaxNamesPerRequest);
    }

    private static IConfiguration Configuration(params (string Key, string Value)[] entries) =>
        new ConfigurationBuilder()
            .AddInMemoryCollection(entries.Select(e => new KeyValuePair<string, string?>(e.Key, e.Value)))
            .Build();

    private static SecretsGrpcHubServerOptions Resolve(IServiceCollection services)
    {
        using ServiceProvider provider = services.BuildServiceProvider();
        return provider.GetRequiredService<IOptions<SecretsGrpcHubServerOptions>>().Value;
    }
}