using Polly;
using System;
using System.Net.Http;
using System.Threading.Tasks;

class Program
{
    static async Task Main(string[] args)
    {
        var retryPolicy = Policy
            .Handle<HttpRequestException>()
            .WaitAndRetryAsync(3, retryAttempt => TimeSpan.FromSeconds(Math.Pow(2, retryAttempt)),
                (exception, timeSpan, retryCount, context) =>
                {
                    Console.WriteLine($"Retry {retryCount} sau {timeSpan.TotalSeconds}s do lỗi: {exception.Message}");
                });

        HttpClient client = new HttpClient();

        await retryPolicy.ExecuteAsync(async () =>
        {
            Console.WriteLine("Thử gửi yêu cầu HTTP...");
            HttpResponseMessage response = await client.GetAsync("https://example.com");
            response.EnsureSuccessStatusCode();
            Console.WriteLine("Yêu cầu thành công!");
        });
    }
}

using Polly;
using System;
using System.Net.Http;
using System.Threading.Tasks;

class Program
{
    static async Task Main(string[] args)
    {
        var circuitBreakerPolicy = Policy
            .Handle<HttpRequestException>()
            .CircuitBreakerAsync(2, TimeSpan.FromSeconds(10),
                onBreak: (exception, duration) =>
                {
                    Console.WriteLine($"Circuit mở! Chặn gọi trong {duration.TotalSeconds}s do lỗi: {exception.Message}");
                },
                onReset: () =>
                {
                    Console.WriteLine("Circuit đã đóng lại! Cho phép gọi tiếp.");
                });

        HttpClient client = new HttpClient();

        for (int i = 0; i < 5; i++)
        {
            try
            {
                await circuitBreakerPolicy.ExecuteAsync(async () =>
                {
                    Console.WriteLine("Thử gửi yêu cầu HTTP...");
                    HttpResponseMessage response = await client.GetAsync("https://example.com");
                    response.EnsureSuccessStatusCode();
                    Console.WriteLine("Yêu cầu thành công!");
                });
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Yêu cầu thất bại: {ex.Message}");
            }
        }
    }
}

using Polly;
using System;
using System.Net.Http;
using System.Threading.Tasks;

class Program
{
    static async Task Main(string[] args)
    {
        var fallbackPolicy = Policy<string>
            .Handle<HttpRequestException>()
            .FallbackAsync("Phản hồi mặc định", onFallback: (exception, context) =>
            {
                Console.WriteLine($"Fallback được kích hoạt vì: {exception.Message}");
                return Task.CompletedTask;
            });

        HttpClient client = new HttpClient();

        string result = await fallbackPolicy.ExecuteAsync(async () =>
        {
            Console.WriteLine("Thử gửi yêu cầu HTTP...");
            HttpResponseMessage response = await client.GetAsync("https://example.com");
            response.EnsureSuccessStatusCode();
            return await response.Content.ReadAsStringAsync();
        });

        Console.WriteLine($"Kết quả: {result}");
    }
}