using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.DependencyInjection.Extensions;
using Svrnty.CQRS.Altcha.Abstractions;

namespace Svrnty.CQRS.Altcha.Grpc;

public static class ServiceCollectionExtensions
{
    /// <summary>
    /// Registers the gRPC-backed <see cref="IAltchaVerifier"/> and
    /// <see cref="IAltchaChallengeProvider"/>. Configure the endpoint
    /// and optional service-auth token provider via the
    /// <paramref name="configure"/> delegate.
    /// </summary>
    /// <example>
    /// <code>
    /// services.AddSvrntyAltcha();
    /// services.AddSvrntyAltchaGrpcVerifier(opts =>
    /// {
    ///     opts.Endpoint = "http://altcha:9090";
    ///     opts.TokenProvider = async ct => await tokenIssuer.GetTokenAsync("altcha", ct);
    /// });
    /// </code>
    /// </example>
    public static IServiceCollection AddSvrntyAltchaGrpcVerifier(
        this IServiceCollection services,
        Action<AltchaGrpcOptions> configure)
    {
        services.Configure(configure);
        RegisterCore(services);
        return services;
    }

    /// <summary>
    /// Binds <see cref="AltchaGrpcOptions"/> from a configuration section
    /// (typically <c>"Altcha:Grpc"</c>) and registers the gRPC verifier
    /// and challenge provider.
    /// </summary>
    public static IServiceCollection AddSvrntyAltchaGrpcVerifier(
        this IServiceCollection services,
        IConfiguration configuration)
    {
        services.Configure<AltchaGrpcOptions>(configuration);
        RegisterCore(services);
        return services;
    }

    private static void RegisterCore(IServiceCollection services)
    {
        services.AddGrpcClient<AltchaService.AltchaServiceClient>((sp, client) =>
        {
            var opts = sp.GetRequiredService<Microsoft.Extensions.Options.IOptions<AltchaGrpcOptions>>().Value;
            if (string.IsNullOrWhiteSpace(opts.Endpoint))
                throw new InvalidOperationException(
                    "Altcha gRPC endpoint not configured. Set AltchaGrpcOptions.Endpoint " +
                    "(e.g. http://altcha:9090).");
            client.Address = new Uri(opts.Endpoint);
        });

        services.TryAddSingleton<IAltchaVerifier, AltchaGrpcVerifier>();
        services.TryAddSingleton<IAltchaChallengeProvider, AltchaGrpcChallengeProvider>();
    }
}