Exchange Rate Provider - Backend Task - Fernando Álvarez Naval

jobs/Backend/Task/ExchangeRateUpdater/.gitignore

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+# Archivos de sistema operativo
+.DS_Store
+Thumbs.db
+
+# Configuración de Visual Studio
+.vs/
+*.vcxproj.user
+*.suo
+*.user
+*.sln.docstates
+
+# Carpetas de compilación y temporales
+[Bb]in/
+[Oo]bj/
+[Ll]og/
+[Dd]ebug*/
+[Rr]elease*/
+x64/
+x86/
+[Aa]rm/
+[Aa]rm64/
+*.log
+*.tmp
+
+# Archivos de paquetes y dependencias
+packages/
+*.nupkg
+project.lock.json
+project.fragment.lock.json
+
+# Archivos de publicación
+*.publishsettings
+*.azurePubxml
+*.azurePubxml.user
+
+# Configuración de IDEs
+.idea/
+.vscode/
+
+# Archivos de pruebas
+TestResults/
+*.trx
+*.coverage
+
+# Archivos sensibles
+*.config
+*.env
+*.key
+*.pem

jobs/Backend/Task/ExchangeRateUpdater/ExchangeRateUpdater.Business/ExchangeRateUpdater.Business.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.Logging" Version="9.0.1" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\ExchangeRateUpdater.Data\ExchangeRateUpdater.Data.csproj" />
+    <ProjectReference Include="..\ExchangeRateUpdater.Models\ExchangeRateUpdater.Models.csproj" />
+  </ItemGroup>
+
+</Project>

jobs/Backend/Task/ExchangeRateUpdater/ExchangeRateUpdater.Business/Interfaces/IExchangeRateService.cs

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+using ExchangeRateUpdater.Data.Responses;
+using ExchangeRateUpdater.Models.Requests;
+
+namespace ExchangeRateUpdater.Business.Interfaces;
+public interface IExchangeRateService
+{
+    Task<List<ExchangeRateResultDto>> GetExchangeRates(IEnumerable<ExchangeRateRequest> currencies, DateTime date, CancellationToken cancellationToken);
+}

jobs/Backend/Task/ExchangeRateUpdater/ExchangeRateUpdater.Business/Services/ExchangeRateService.cs

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+using ExchangeRateUpdater.Models.Requests;
+using ExchangeRateUpdater.Data.Interfaces;
+using ExchangeRateUpdater.Data.Responses;
+using ExchangeRateUpdater.Business.Interfaces;
+using ExchangeRateUpdater.Models.Models;
+using Microsoft.Extensions.Logging;
+
+namespace ExchangeRateUpdater.Business.Services;
+public class ExchangeRateService : IExchangeRateService
+{
+    private readonly IExchangeRateRepository _exchangeRatesRepository;
+    private readonly ILogger<ExchangeRateService> _logger;
+    public ExchangeRateService(IExchangeRateRepository exchangeRatesRepository, ILogger<ExchangeRateService> logger)
+    {
+        _exchangeRatesRepository = exchangeRatesRepository;
+        _logger = logger;
+    }
+    public async Task<List<ExchangeRateResultDto>> GetExchangeRates(IEnumerable<ExchangeRateRequest> currencies, DateTime date, CancellationToken cancellationToken)
+    {
+        var exchangeRatesByCurrency = new List<ExchangeRate>();
+
+        //Get all the rates for a specified date
+        var exchangeRates = await _exchangeRatesRepository.GetExchangeRatesByDateAsync(date, cancellationToken);
+
+        //Get only the requested ones
+        var requestedExchangeRates = exchangeRates.Where(p => currencies
+                            .Any(e => e.ToString() == p.ToString()))
+                            .ToList();
+
+        _logger.LogInformation($"{requestedExchangeRates.Count}/{currencies.ToList().Count} exchange rate(s) have been obtained.");
+        //Map to a new object that simplifies reading the response
+        return requestedExchangeRates.Select(rate => MapToResult(rate)).ToList();
+    }
+
+    private ExchangeRateResultDto MapToResult(ExchangeRate rate)
+    {
+        return new ExchangeRateResultDto(
+           new Currency(rate.SourceCurrency.Code),
+           new Currency(rate.TargetCurrency.Code),
+           rate.Value,
+           rate.Date);
+    }
+}

jobs/Backend/Task/ExchangeRateUpdater/ExchangeRateUpdater.Data/ExchangeRateUpdater.Data.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Flurl" Version="4.0.0" />
+    <PackageReference Include="Flurl.Http" Version="4.0.2" />
+    <PackageReference Include="Flurl.Http.Newtonsoft" Version="0.9.1" />
+    <PackageReference Include="Microsoft.Extensions.Caching.Abstractions" Version="9.0.1" />
+    <PackageReference Include="Microsoft.Extensions.Configuration.Abstractions" Version="9.0.1" />
+    <PackageReference Include="Microsoft.Extensions.Logging" Version="9.0.1" />
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\ExchangeRateUpdater.Models\ExchangeRateUpdater.Models.csproj" />
+  </ItemGroup>
+
+</Project>

jobs/Backend/Task/ExchangeRateUpdater/ExchangeRateUpdater.Data/Interfaces/IExchangeRateCacheRepository.cs

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+
+using ExchangeRateUpdater.Data.Responses;
+
+namespace ExchangeRateUpdater.Data.Interfaces;
+public interface IExchangeRateCacheRepository
+{
+    ExchangeRatesResponseDto GetExchangeRates(DateTime date);
+    void SetExchangeRates(ExchangeRatesResponseDto rates);
+}

jobs/Backend/Task/ExchangeRateUpdater/ExchangeRateUpdater.Data/Interfaces/IExchangeRateRepository.cs

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+
+using ExchangeRateUpdater.Data.Responses;
+
+namespace ExchangeRateUpdater.Data.Interfaces;
+public interface IExchangeRateRepository
+{
+    Task<List<ExchangeRate>> GetExchangeRatesByDateAsync(DateTime date, CancellationToken cancellationToken);
+}

jobs/Backend/Task/ExchangeRateUpdater/ExchangeRateUpdater.Data/Repositories/ExchangeRateCacheRepository.cs

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+using ExchangeRateUpdater.Data.Interfaces;
+using ExchangeRateUpdater.Data.Responses;
+using Microsoft.Extensions.Caching.Memory;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.Logging;
+
+
+namespace ExchangeRateUpdater.Data.Repositories;
+public class ExchangeRateCacheRepository : IExchangeRateCacheRepository
+{   
+    private readonly IMemoryCache _cache;
+    private readonly ILogger<ExchangeRateCacheRepository> _logger;
+
+    public ExchangeRateCacheRepository(IMemoryCache cache, ILogger<ExchangeRateCacheRepository> logger)
+    {        
+        _cache = cache;
+        _logger = logger;
+    }
+
+    public ExchangeRatesResponseDto GetExchangeRates(DateTime date)
+    {
+        var result = new ExchangeRatesResponseDto() { Rates = new List<ExchangeRateDto>()};
+        var key = date.ToString("yyyy-MM-dd");
+
+        if (_cache.TryGetValue(key, out ExchangeRatesResponseDto ratesCached))
+        {
+            _logger.LogInformation($"{ratesCached.Rates.Count} retrieved from cache");
+            result.Rates = ratesCached.Rates.Where(t => t.ValidFor == date).ToList();
+        }             
+
+        return result;
+    }
+
+    public void SetExchangeRates(ExchangeRatesResponseDto rates)
+    {
+        try
+        {
+            var cacheEntryOptions = new MemoryCacheEntryOptions()
+                .SetAbsoluteExpiration(TimeSpan.FromDays(1)); //Keep cache for 1 day max
+
+            //Since weekends there's no rates and the api always returns the las data avaiable,
+            //the rates in cache have the actual date and not the requested
+            var key = rates.Rates[0].ValidFor.ToString("yyyy-MM-dd");
+
+            if (!_cache.TryGetValue(key, out _))
+            {
+                _logger.LogInformation($"{rates.Rates.Count} have been saved on cache");
+                _cache.Set(key, rates, cacheEntryOptions);
+            }
+
+
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex.Message);
+            throw new Exception($"There was an error while saving in cache. Error: {ex.Message}");
+        }        
+    }
+}
+