using IdentityServer.Wrapper;
using Microsoft.AspNetCore.Authentication;
using Microsoft.Extensions.DependencyInjection;
using NDB.Security.Authentication.Identity.Abstractions;
using System;

namespace NDB.Security.Authentication.Identity
{
    public static class AuthenticationExtensions
    {
        public static IServiceCollection AddAuthentication(this IServiceCollection services, string identityServerBaseAddress)
        {
            services.AddAuthentication(identityServerBaseAddress, new Services.AuthenticationOptions());
            return services;
        }

        public static IServiceCollection AddAuthentication(this IServiceCollection services, string identityServerBaseAddress, IAuthenticationOptions authenticationOptions)
        {
            Validate(identityServerBaseAddress, authenticationOptions);

            // Identity server
            services.UseIdentityServices(identityServerBaseAddress);
            services.AddSingleton(authenticationOptions);

            // configure authentication 
            AuthenticationServiceCollectionExtensions.AddAuthentication(services, "IdentityAuthentication")
                .AddScheme<AuthenticationSchemeOptions, IdentityAuthenticationHandler>("IdentityAuthentication", null);

            return services;
        }

        private static void Validate(string identityServerBaseAddress, IAuthenticationOptions authenticationOptions)
        {
            if (string.IsNullOrEmpty(identityServerBaseAddress))
                throw new ArgumentException("Identity server base address must be provided.");

            var guestFuncDefined = authenticationOptions.AuthenticateAsGuest != null;
            if (guestFuncDefined && string.IsNullOrEmpty(authenticationOptions.GuestUserName))
                throw new ArgumentException("Guest function is defined, but guest user name is not set.");
        }
    }
}