using System;

using System.Linq;

using Microsoft.Extensions.DependencyInjection;

using Microsoft.Extensions.Logging;

using Polly;

using Polly.Extensions.Http;

using System.Net.Http;

using System.Net.Http.Headers;

using System.Text;

using System.Text.Json;

using System.Text.Json.Serialization;

using System.Threading.Tasks;

​

public class Program

{

    public static async Task Main()

    {

        var services = new ServiceCollection();

        services.AddLogging(b => b.AddConsole());

        services.AddHttpClient<MyService>()

                .SetHandlerLifetime(TimeSpan.FromMinutes(5))  //Set lifetime to five minutes

                .AddPolicyHandler(GetRetryPolicy());

        services.AddScoped<MyService>();

​

        using (var scope = services.BuildServiceProvider().CreateScope())

        {

            var sp = scope.ServiceProvider;

            var service = sp.GetRequiredService<MyService>();

            await service.MakeRequestCallsAsync();

        }

    }

    static IAsyncPolicy<HttpResponseMessage> GetRetryPolicy()

    {

        return HttpPolicyExtensions

            .HandleTransientHttpError()

            .WaitAndRetryAsync(3, retryAttempt => TimeSpan.FromSeconds(Math.Pow(2, retryAttempt)));

    }

}

​

class MyService

{

    private readonly ILogger _logger;

    private readonly string _username = "";

    private readonly string _password = "";

    private readonly HttpClient _client;

​

    public MyService(HttpClient client, ILogger<MyService> logger)

    {

        _client = client;

        _logger = logger;

​

        // Setup your credentials & headers

        _client.DefaultRequestHeaders.Accept.Clear();

        _client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

        _client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", Convert.ToBase64String(Encoding.ASCII.GetBytes(_username + ":" + _password)));

    }

​

    public async Task MakeRequestCallsAsync()

    {

        // Do your first request 

        var request1 = await ExecuteNextRequestAsync<object, ResponseObject>(null!, (input) =>

        {

            return "https://dummyjson.com/products";

        });

​

        // Do your second request with the result of your first one

        var request2 = await ExecuteNextRequestAsync<ResponseObject, ResponseProduct>(request1, (input) =>

        {

            return "https://dummyjson.com/products/" + input.Products.ElementAt(0).Id;

        });

        // And so on just by using the response of a previous request...

    }

​

    private async Task<TOut> ExecuteNextRequestAsync<TIn, TOut>(TIn lastResponse, Func<TIn, string> factory)

    {

        var url = factory(lastResponse);

        var response = await _client.GetAsync(url);

        if (response.IsSuccessStatusCode)

        {

            var responseJson = await response.Content.ReadAsStringAsync();

​

            _logger.LogInformation($"{responseJson}");

​

            var responseObj = JsonSerializer.Deserialize<TOut>(responseJson);

            return responseObj;

        }

        else

        {

            _logger.LogError($"{response.StatusCode}");

            return default;

        }

    }

}

​

class ResponseObject

{

    [JsonPropertyName("products")]

    public ResponseProduct[] Products { get; set; }

}

​

class ResponseProduct

{

    [JsonPropertyName("id")]

    public int Id { get; set; }

    [JsonPropertyName("title")]

    public string Title { get; set; }

    [JsonPropertyName("brand")]

    public string Brand { get; set; }

}