using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;

namespace StellaOps.DependencyInjection.Validation;

public static partial class FailFastOptionsExtensions
{
    /// <summary>
    /// Adds options with data annotation validation and configures fail-fast startup validation.
    /// </summary>
    /// <typeparam name="TOptions">The options type to configure. Must have DataAnnotations attributes.</typeparam>
    /// <param name="services">The service collection.</param>
    /// <param name="sectionName">The configuration section name.</param>
    /// <returns>The service collection for chaining.</returns>
    public static IServiceCollection AddOptionsWithDataAnnotations<TOptions>(
        this IServiceCollection services,
        string sectionName)
        where TOptions : class
    {
        services.AddOptions<TOptions>()
            .BindConfiguration(sectionName)
            .ValidateDataAnnotations()
            .ValidateOnStart();

        return services;
    }

    /// <summary>
    /// Registers an existing options configuration to validate on start.
    /// Use when options are already registered but need fail-fast validation added.
    /// </summary>
    /// <typeparam name="TOptions">The options type.</typeparam>
    /// <param name="services">The service collection.</param>
    /// <returns>The service collection for chaining.</returns>
    public static IServiceCollection ValidateOptionsOnStart<TOptions>(this IServiceCollection services)
        where TOptions : class
    {
        // Force options validation at startup by resolving IOptions<TOptions>
        services.AddHostedService<OptionsValidationHostedService<TOptions>>();
        return services;
    }
}