[ModuleDependency(typeof(ServiceContainerInitialization))]
[InitializableModule]
public class WebApiInitializer : IConfigurableModule
{
    public void ConfigureContainer(ServiceConfigurationContext context)
    {
        // Resolver for Web API
        GlobalConfiguration.Configuration.DependencyResolver = new StructureMapWebApiDependencyResolver(context.Container);
    }

    public void Initialize(InitializationEngine context)
    {
        // Configure Web API as a whole in one configurator class
        GlobalConfiguration.Configure(WebApiConfig.ConfigureWebApi);
    }
    
    public void Uninitialize(InitializationEngine context) { }
}

public static class WebApiConfig
{
    public static void ConfigureWebApi(HttpConfiguration config)
    {
        // "Best-practice" setup for a typical project 
        AllowAttributeRouting(config);
        AddRoutes(config);
        ReturnJsonOnly(config);
        IndentJson(config);
        
        // Set EpiserverWebApiErrorHandler as default error handler
        SetCustomErrorHandler(config);
    }
    
    private static void AllowAttributeRouting(HttpConfiguration config)
    {
        config.MapHttpAttributeRoutes();
    }

    private static void AddRoutes(HttpConfiguration config)
    {
        /* Episerver Find defines this route already. Uncomment if Find is not used.
        config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{language}/{controller}/{id}",
            defaults: new { id = RouteParameter.Optional });
         * */
    }

    private static void ReturnJsonOnly(HttpConfiguration config)
    {
        // Web API returns xml or json depending on the request http headers (accept).
        // When you debug the method with a browser it defaults to xml.
        // In a typical use case we need json only, thus this feature is counterproductive. 
        // By removing the xml supported media types the method will always default to json.
        config.Formatters.XmlFormatter.SupportedMediaTypes.Clear();
    }

    private static void IndentJson(HttpConfiguration config)
    {
        config.Formatters.JsonFormatter.SerializerSettings.Formatting = Formatting.Indented;
    }

    private static void SetCustomErrorHandler(HttpConfiguration config)
    {
        // Log errors and display full exception for admins/editors/localhost
        config.Services.Replace(typeof(IExceptionHandler), new EpiserverWebApiErrorHandler());
    }
}  

[EpiserverWebApiOutputCache(60 * 60)]
public class StoreApiController : ApiController
{
    [HttpGet]
    [Route("api/stores")]
    public IList<Store> GetStores(int count)
    {
        // Result is cached for each unique url for 60 minutes or until Episerver content is modified.
    }        
}

[WebApiLanguage]
public class SearchApiController : ApiController
{
    [HttpGet]
    [Route("api/search")]
    public SearchResult Search(string query, string language)
    {
        // PreferredCulture, CurrentCulture and CurrentUICulture are set to language's culture.
        // All Episerver interfaces now use "language" as the default language.
        // In essence, this makes language issues with Episerver API as easy as with PageControllers.
    }        
}

public class CommentApiController : ApiController
{
    [HttpPost]
    [Route("api/comment")]
    [ValidateWebApiModel]
    public CommentModel PostComment(CommentModel model)
    {
        // Method is only executed when model is not null and its state is valid.
        // Otherwise HttpStatusCode.BadRequest is returned with a exception about the errors.
    }
    
    public class CommentModel
    {
        [Required]
        public string Username { get; set; }
        [Required]
        [MaxLength(4000)]
        public string Message { get; set; }
    }
}