using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.DependencyInjection.Extensions;
using StellaOps.Signer.Core;
using System;

namespace StellaOps.Signer.Infrastructure.Signing;

/// <summary>
/// Extension methods for registering signing services with dependency injection.
/// </summary>
public static class SigningServiceCollectionExtensions
{
    /// <summary>
    /// Adds the DSSE signing services to the service collection.
    /// </summary>
    /// <param name="services">The service collection.</param>
    /// <param name="configure">Optional configuration action for signer options.</param>
    /// <returns>The service collection for chaining.</returns>
    public static IServiceCollection AddDsseSigning(
        this IServiceCollection services,
        Action<DsseSignerOptions>? configure = null)
    {
        ArgumentNullException.ThrowIfNull(services);

        // Register options
        var optionsBuilder = services.AddOptions<DsseSignerOptions>();
        if (configure is not null)
        {
            optionsBuilder.Configure(configure);
        }

        // Register time provider if not already registered
        services.TryAddSingleton(TimeProvider.System);

        // Register signing key resolver
        services.TryAddSingleton<ISigningKeyResolver, DefaultSigningKeyResolver>();

        // Register DSSE signer
        services.TryAddSingleton<IDsseSigner, CryptoDsseSigner>();

        return services;
    }

    /// <summary>
    /// Adds the DSSE signing services with KMS configuration.
    /// </summary>
    /// <param name="services">The service collection.</param>
    /// <param name="defaultKmsKeyId">The default KMS key identifier.</param>
    /// <param name="configure">Additional configuration action.</param>
    /// <returns>The service collection for chaining.</returns>
    public static IServiceCollection AddDsseSigningWithKms(
        this IServiceCollection services,
        string defaultKmsKeyId,
        Action<DsseSignerOptions>? configure = null)
    {
        ArgumentNullException.ThrowIfNull(services);
        ArgumentException.ThrowIfNullOrWhiteSpace(defaultKmsKeyId);

        return services.AddDsseSigning(options =>
        {
            options.DefaultKmsKeyId = defaultKmsKeyId;
            configure?.Invoke(options);
        });
    }

    /// <summary>
    /// Adds the DSSE signing services configured for keyless (ephemeral) signing only.
    /// </summary>
    /// <param name="services">The service collection.</param>
    /// <param name="issuer">The issuer URL for keyless certificates.</param>
    /// <returns>The service collection for chaining.</returns>
    public static IServiceCollection AddDsseSigningKeyless(
        this IServiceCollection services,
        string issuer = "https://stellaops.io")
    {
        ArgumentNullException.ThrowIfNull(services);

        return services.AddDsseSigning(options =>
        {
            options.DefaultIssuer = issuer;
        });
    }
}