KonSoft.Clean/gateways/KonSoft.InternalGateway/ReverseProxyBuilderExtensions.cs

using KonSoft.InternalGateway.Aggregations.ApplicationConfiguration;
using KonSoft.InternalGateway.Aggregations.Localization;
using Yarp.ReverseProxy.Configuration;

namespace KonSoft.InternalGateway
{
    public static class ReverseProxyBuilderExtensions
    {
        public static ReverseProxyConventionBuilder MapReverseProxyWithLocalization(
            this IEndpointRouteBuilder endpoints)
        {
            return endpoints.MapReverseProxy(proxyBuilder =>
            {
                proxyBuilder.Use(async (context, next) =>
                {
                    var endpoint = context.GetEndpoint();

                    var localizationAggregation = context.RequestServices
                        .GetRequiredService<ILocalizationAggregation>();

                    var appConfigurationAggregation = context.RequestServices
                        .GetRequiredService<IAppConfigurationAggregation>();

                    // The "/api/abp/application-localization" endpoint
                    if (localizationAggregation.LocalizationRouteName == endpoint?.DisplayName)
                    {
                        var localizationRequestInput =
                            CreateLocalizationRequestInput(context, localizationAggregation.LocalizationEndpoint);

                        var result = await localizationAggregation.GetLocalizationAsync(localizationRequestInput);
                        await context.Response.WriteAsJsonAsync(result);
                        return;
                    }

                    // The "/api/abp/application-configuration" endpoint
                    if (appConfigurationAggregation.AppConfigRouteName == endpoint?.DisplayName)
                    {
                        var appConfigurationRequestInput =
                            CreateAppConfigurationRequestInput(context, appConfigurationAggregation.AppConfigEndpoint);

                        var result =
                            await appConfigurationAggregation.GetAppConfigurationAsync(appConfigurationRequestInput);
                        await context.Response.WriteAsJsonAsync(result);
                        return;
                    }

                    await next();
                });

                proxyBuilder.UseLoadBalancing();
            });
        }

        private static AppConfigurationRequest CreateAppConfigurationRequestInput(HttpContext context,
                string appConfigurationPath)
        {
            var proxyConfig = context.RequestServices.GetRequiredService<IProxyConfigProvider>();

            var input = new AppConfigurationRequest();
            string path = $"{appConfigurationPath}?includeLocalizationResources=false";

            var clusterList = GetClusters(proxyConfig);
            foreach (var cluster in clusterList)
            {
                var hostUrl = new Uri(cluster.Value.Address) + $"{path}";
                // CacheKey/Endpoint dictionary key -> ex: ("Administration_AppConfig")
                input.Endpoints.Add($"{cluster.Key}_AppConfig", hostUrl);
            }

            return input;
        }

        private static LocalizationRequest CreateLocalizationRequestInput(HttpContext context,
            string localizationPath)
        {
            var proxyConfig = context.RequestServices.GetRequiredService<IProxyConfigProvider>();

            context.Request.Query.TryGetValue("CultureName", out var cultureName);

            var input = new LocalizationRequest(cultureName);
            string path = $"{localizationPath}?cultureName={cultureName}&onlyDynamics=false";

            var clusterList = GetClusters(proxyConfig);
            foreach (var cluster in clusterList)
            {
                var hostUrl = new Uri(cluster.Value.Address) + $"{path}";
                // Endpoint dictionary key -> ex: ("Administration_en")
                input.Endpoints.Add($"{cluster.Key}_{cultureName}", hostUrl);
            }

            return input;
        }

        private static Dictionary<string, DestinationConfig> GetClusters(IProxyConfigProvider proxyConfig)
        {
            var yarpConfig = proxyConfig.GetConfig();

            var routedClusters = yarpConfig.Clusters
                .SelectMany(t => t.Destinations,
                    (clusterId, destination) => new { clusterId.ClusterId, destination.Value });

            return routedClusters
                .GroupBy(q => q.Value.Address)
                .Select(t => t.First())
                .Distinct()
                .ToDictionary(k => k.ClusterId, v => v.Value);
        }
    }
}