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using System;
using System.Collections.Generic;
using System.Net.Http;
using Newtonsoft.Json;
namespace LazyCache.Demo
{
class Program
{
private static IAppCache _cache;
private static HttpClient _httpClient;
static void Main(string[] args)
{
_cache = new CachingService();
_httpClient = new HttpClient();
while (true)
{
Console.WriteLine("Please enter a Date [yyyy-mm-dd]: ");
var dateStr = Console.ReadLine();
DateTime date;
if (DateTime.TryParse(dateStr, out date) == false)
{
Console.WriteLine($"{DateTime.UtcNow}: Invalid Date.");
continue;
}
if (date.Date > DateTime.UtcNow.Date)
{
Console.WriteLine($"{DateTime.UtcNow}: Cannot specify a date in the future.");
continue;
}
var exchange = GetCurrencyRate(date);
decimal canadian;
exchange.Rates.TryGetValue("CAD", out canadian);
Console.WriteLine($"{DateTime.UtcNow}: USD to CAD = {canadian}");
}
}
private static CurrencyExchange GetCurrencyRate(DateTime date)
{
var key = date.Date.ToString("yyyy-MM-dd");
return _cache.GetOrAdd(key, () =>
{
Console.WriteLine($"{DateTime.UtcNow}: Fetching from service");
var response = _httpClient.GetAsync("http://api.fixer.io/" + key + "?base=USD").Result;
var json = response.Content.ReadAsStringAsync().Result;
return JsonConvert.DeserializeObject<CurrencyExchange>(json);
}, new TimeSpan(0, 0, 0, 30));
}
}
public class CurrencyExchange
{
public string Base { get; set; }
public DateTime Date { get; set; }
public Dictionary<string, decimal> Rates { get; set; }
}
}
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