Owin Bearer Token Not Working for WebApi

Question

I have gone through loads of documentation on this, My google search shows that I've visited all the links on the first page

Problem Token Generation works fine. I configured it with a custom provider as such:

    public void ConfigureOAuth(IAppBuilder app)
    {
        var usermanager = NinjectContainer.Resolve<UserManager>(); 
        app.UseOAuthAuthorizationServer(new OAuthAuthorizationServerOptions
        {
            AllowInsecureHttp = true,
            TokenEndpointPath = new PathString("/token"),
            AccessTokenExpireTimeSpan = TimeSpan.FromDays(1),
            Provider = new AppOAuthProvider(usermanager)
        });
        app.UseOAuthBearerAuthentication(new OAuthBearerAuthenticationOptions());
    }

However when I call a protected URL and pass the bearer token, I always get:

How do I diagnose or fix the problem. If possible, how can I do the token validation myself

UPDATE Here is my AppOAuthProvider. Both Methods are called when I'm trying to mint a token but not when I'm trying to access a protected resource

public class AppOAuthProvider : OAuthAuthorizationServerProvider
{
    private UserManager _user;
    public AppOAuthProvider(UserManager user)
    {
        _user = user;
    }
    public override async Task ValidateClientAuthentication(OAuthValidateClientAuthenticationContext context)
    {
        context.Validated();
    }

    public override Task GrantResourceOwnerCredentials(OAuthGrantResourceOwnerCredentialsContext context)
    {
        context.OwinContext.Response.Headers.Add("Access-Control-Allow-Origin", new[] { "*" });

        //Get User Information
        var getUser = _user.FindUser(context.UserName);
        if (getUser.Status == StatusCode.Failed)
        {
            context.SetError("invalid_grant", "The user name or password is incorrect.");
            return Task.FromResult<object>(null);
        }

        var user = getUser.Result;

        //Get Roles for User
        var getRoles = _user.GetRoles(user.UserID);
        if (getRoles.Status == StatusCode.Failed)
        {
            context.SetError("invalid_grant", "Could not determine Roles for the Specified User");
        }

        var roles = getRoles.Result;

        var identity = new ClaimsIdentity(context.Options.AuthenticationType);
        identity.AddClaim(new Claim("UserID", user.UserID.ToString()));
        identity.AddClaim(new Claim("UserName", user.UserName));

        foreach (var role in roles)
        {
            identity.AddClaim(new Claim(ClaimTypes.Role, role));
        }

        context.Validated(identity);

        return Task.FromResult<object>(null);
    }
}

UPDATE 2: Here is my Account Controller

[RoutePrefix("api/auth/account")]
public class AccountController : ApiController
{
    private UserManager _user;
    public AccountController(UserManager user)
    {
        _user = user;
    }

    [Authorize]
    [HttpGet]
    [Route("secret")]
    public IHttpActionResult Secret()
    {
        return Ok("Yay! Achievement Unlocked");
    }
}

UPDATE 3: Here is my Startup.cs

public partial class Startup
{
    public void Configuration(IAppBuilder app)
    {
        app.UseNinjectMiddleware(NinjectContainer.CreateKernel);
        app.UseNinjectWebApi(GlobalConfiguration.Configuration);
        GlobalConfiguration.Configure(WebApiConfig.Register);
        ConfigureOAuth(app);
        app.UseCors(Microsoft.Owin.Cors.CorsOptions.AllowAll);
        app.UseWebApi(GlobalConfiguration.Configuration);
        app.UseWelcomePage();
    }
}

Answer 1

You must configure the OAuth authorization server and OAuth bearer authentication before call UseWebApi on IAppBuilder. The following is from my program.

    public void Configuration(IAppBuilder app)
    {
        app.UseFileServer(new FileServerOptions()
        {
            RequestPath = PathString.Empty,
            FileSystem = new PhysicalFileSystem(@".\files")
        });

        // set the default page
        app.UseWelcomePage(@"/index.html");

        ConfigureAuth(app);

        HttpConfiguration config = new HttpConfiguration();

        config.Routes.MapHttpRoute
        (
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{id}",
            defaults: new { id = RouteParameter.Optional } 
        );

        config.Formatters.Clear();
        config.Formatters.Add(new JsonMediaTypeFormatter());
        config.Formatters.JsonFormatter.SerializerSettings =
        new JsonSerializerSettings
        {
            ContractResolver = new CamelCasePropertyNamesContractResolver()
        };

        app.UseCors(CorsOptions.AllowAll);
        app.UseWebApi(config);


    }

    public void ConfigureAuth(IAppBuilder app)
    {
        OAuthAuthorizationServerOptions oAuthServerOptions = new OAuthAuthorizationServerOptions()
        {
            AllowInsecureHttp = true,
            TokenEndpointPath = new PathString("/token"),
            AccessTokenExpireTimeSpan = TimeSpan.FromDays(1),
            Provider = new YourApplicationOAuthProvider()
        };

        app.UseOAuthAuthorizationServer(oAuthServerOptions);
        app.UseOAuthBearerAuthentication
        (
            new OAuthBearerAuthenticationOptions 
            {
                Provider = new OAuthBearerAuthenticationProvider()
            }
        );
    }