dotnet-cqrs/OpenHarbor.CQRS.Abstractions/ServiceCollectionExtensions.cs

using Microsoft.Extensions.DependencyInjection;
using OpenHarbor.CQRS.Abstractions.Discovery;

namespace OpenHarbor.CQRS.Abstractions;

public static class ServiceCollectionExtensions
{
    public static IServiceCollection AddQuery<TQuery, TQueryResult, TQueryHandler>(this IServiceCollection services)
        where TQuery : class
        where TQueryHandler : class, IQueryHandler<TQuery, TQueryResult>
    {
        // add handler to DI.
        services.AddTransient<IQueryHandler<TQuery, TQueryResult>, TQueryHandler>();

        // add for discovery purposes.
        var queryMeta = new QueryMeta(typeof(TQuery), typeof(IQueryHandler<TQuery, TQueryResult>), typeof(TQueryResult));
        services.AddSingleton<IQueryMeta>(queryMeta);

        return services;
    }

    public static IServiceCollection AddCommand<TCommand, TCommandResult, TCommandHandler>(this IServiceCollection services)
        where TCommand : class
        where TCommandHandler : class, ICommandHandler<TCommand, TCommandResult>
    {
        // add handler to DI.
        services.AddTransient<ICommandHandler<TCommand, TCommandResult>, TCommandHandler>();

        // add for discovery purposes.
        var commandMeta = new CommandMeta(typeof(TCommand), typeof(ICommandHandler<TCommand>), typeof(TCommandResult));
        services.AddSingleton<ICommandMeta>(commandMeta);

        return services;
    }

    public static IServiceCollection AddCommand<TCommand, TCommandHandler>(this IServiceCollection services)
        where TCommand : class
        where TCommandHandler : class, ICommandHandler<TCommand>
    {
        // add handler to DI.
        services.AddTransient<ICommandHandler<TCommand>, TCommandHandler>();

        // add for discovery purposes.
        var commandMeta = new CommandMeta(typeof(TCommand), typeof(ICommandHandler<TCommand>));
        services.AddSingleton<ICommandMeta>(commandMeta);

        return services;
    }
}