Created
September 20, 2016 01:47
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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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