Andres Grobas - .NET Backend Task

.gitignore

@@ -21,3 +21,5 @@
 node_modules
 bower_components
 npm-debug.log
+/jobs/Backend/Task/.vs
+/.vs

jobs/Backend/Task/Dockerfile

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+FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
+WORKDIR /src
+
+COPY ["ExchangeRates.Api/ExchangeRates.Api.csproj", "ExchangeRates.Api/"]
+COPY ["ExchangeRates.Application/ExchangeRates.Application.csproj", "ExchangeRates.Application/"]
+COPY ["ExchangeRates.Domain/ExchangeRates.Domain.csproj", "ExchangeRates.Domain/"]
+COPY ["ExchangeRates.Infrastructure/ExchangeRates.Infrastructure.csproj", "ExchangeRates.Infrastructure/"]
+
+RUN dotnet restore "ExchangeRates.Api/ExchangeRates.Api.csproj"
+
+COPY . .
+WORKDIR "/src/ExchangeRates.Api"
+RUN dotnet publish "ExchangeRates.Api.csproj" -c Release -o /app/publish /p:UseAppHost=false
+
+FROM mcr.microsoft.com/dotnet/aspnet:8.0 AS runtime
+WORKDIR /app
+COPY --from=build /app/publish .
+
+EXPOSE 80
+ENTRYPOINT ["dotnet", "ExchangeRates.Api.dll"]

jobs/Backend/Task/ExchangeRates.Api/Controllers/ExchangeRatesController.cs

@@ -0,0 +1,30 @@
+using ExchangeRates.Api.DTOs;
+using ExchangeRates.Application.Providers;
+using ExchangeRates.Domain.Entities;
+using Microsoft.AspNetCore.Mvc;
+
+[ApiController]
+[Route("api/[controller]")]
+public class ExchangeRatesController : ControllerBase
+{
+    private readonly IExchangeRatesProvider _exchangeRatesProvider;
+
+    public ExchangeRatesController(IExchangeRatesProvider exchangeRatesProvider, ILogger<ExchangeRatesController> logger)
+    {
+        _exchangeRatesProvider = exchangeRatesProvider;
+    }
+
+    [HttpGet]
+    [ProducesResponseType(typeof(IEnumerable<ExchangeRate>), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(StatusCodes.Status500InternalServerError)]
+    public async Task<ActionResult<IEnumerable<ExchangeRate>>> Get([FromQuery] GetExchangeRatesRequest request, CancellationToken cancellationToken)
+    {
+        if (!ModelState.IsValid)
+            return BadRequest(ModelState);
+
+        var currencies = request.Currencies ?? Array.Empty<string>();
+        var rates = await _exchangeRatesProvider.GetExchangeRatesAsync(currencies, cancellationToken);
+        return Ok(rates);
+    }
+}

jobs/Backend/Task/ExchangeRates.Api/Dtos/GetExchangeRatesRequest.cs

@@ -0,0 +1,10 @@
+using ExchangeRates.Api.Dtos;
+
+namespace ExchangeRates.Api.DTOs
+{
+    public class GetExchangeRatesRequest
+    {
+        [ValidCurrencyCodes]
+        public IEnumerable<string>? Currencies { get; set; }
+    }
+}

jobs/Backend/Task/ExchangeRates.Api/Dtos/ValidCurrencyCodesAttribute.cs

@@ -0,0 +1,22 @@
+using System.ComponentModel.DataAnnotations;
+using System.Text.RegularExpressions;
+
+namespace ExchangeRates.Api.Dtos
+{
+    [AttributeUsage(AttributeTargets.Property | AttributeTargets.Parameter)]
+    public class ValidCurrencyCodesAttribute : ValidationAttribute
+    {
+        protected override ValidationResult? IsValid(object? value, ValidationContext validationContext)
+        {
+            if (value is IEnumerable<string> arr)
+            {
+                foreach (var c in arr)
+                {
+                    if (string.IsNullOrWhiteSpace(c) || !Regex.IsMatch(c, "^[A-Za-z]{3}$"))
+                        return new ValidationResult("All currency codes must be exactly 3 alphabetic characters.");
+                }
+            }
+            return ValidationResult.Success;
+        }
+    }
+}

jobs/Backend/Task/ExchangeRates.Api/ExchangeRates.Api.csproj

@@ -0,0 +1,20 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.Http.Polly" Version="9.0.10" />
+    <PackageReference Include="Swashbuckle.AspNetCore" Version="6.6.2" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\ExchangeRates.Application\ExchangeRates.Application.csproj" />
+    <ProjectReference Include="..\ExchangeRates.Domain\ExchangeRates.Domain.csproj" />
+    <ProjectReference Include="..\ExchangeRates.Infrastructure\ExchangeRates.Infrastructure.csproj" />
+  </ItemGroup>
+
+</Project>

jobs/Backend/Task/ExchangeRates.Api/Extensions/ApplicationBuilderExtensions.cs

@@ -0,0 +1,27 @@
+namespace ExchangeRates.Api.Extensions
+{
+    public static class ApplicationBuilderExtensions
+    {
+        public static WebApplication ConfigureApp(this WebApplication app, IHostEnvironment env)
+        {
+            app.UseExceptionHandler("/error");
+            app.UseCors("AllowAll");
+            app.UseRouting();
+
+            app.UseSwagger();
+            app.UseSwaggerUI(c =>
+            {
+                c.SwaggerEndpoint("/swagger/v1/swagger.json", "Exchange Rates API v1");
+                c.RoutePrefix = "swagger";
+            });
+
+            app.MapControllers();
+            app.Map("/error", (HttpContext httpContext) =>
+            {
+                return Results.Problem("An unexpected error occurred. Please try again later.");
+            });
+
+            return app;
+        }
+    }
+}

jobs/Backend/Task/ExchangeRates.Api/Extensions/ServiceCollectionExtensions.cs

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+using ExchangeRates.Application.Options;
+using ExchangeRates.Application.Providers;
+using ExchangeRates.Infrastructure.Clients.CNB;
+using Microsoft.OpenApi.Models;
+
+namespace ExchangeRates.Api.Extensions
+{
+    public static class ServiceCollectionExtensions
+    {
+        public static IServiceCollection AddExchangeRatesServices(this IServiceCollection services, IConfiguration configuration)
+        {
+            services.AddControllers();
+
+            services
+                .AddSwaggerDocumentation()
+                .AddCorsPolicy()
+                .AddCacheSupport()
+                .AddAppSettings(configuration)
+                .AddCNBClient(configuration)
+                .AddApplicationServices();
+
+            return services;
+        }
+
+        public static IServiceCollection AddAppSettings(this IServiceCollection services, IConfiguration configuration)
+        {
+            services.Configure<ExchangeRatesOptions>(configuration.GetSection("ExchangeRates"));
+            services.Configure<CnbHttpClientOptions>(configuration.GetSection("CNBApi:HttpClient"));
+            return services;
+        }
+
+        public static IServiceCollection AddSwaggerDocumentation(this IServiceCollection services)
+        {
+            services.AddSwaggerGen(options =>
+            {
+                options.SwaggerDoc("v1", new OpenApiInfo
+                {
+                    Version = "v1",
+                    Title = "Exchange Rates API",
+                    Description = "API that provides daily exchange rates from the Czech National Bank."
+                });
+            });
+            return services;
+        }
+
+        public static IServiceCollection AddCorsPolicy(this IServiceCollection services)
+        {
+            services.AddCors(options =>
+            {
+                options.AddPolicy("AllowAll", policy =>
+                {
+                    policy.AllowAnyOrigin()
+                          .AllowAnyMethod()
+                          .AllowAnyHeader();
+                });
+            });
+            return services;
+        }
+
+        public static IServiceCollection AddCacheSupport(this IServiceCollection services)
+        {
+            services.AddDistributedMemoryCache();
+            return services;
+        }
+
+        public static IServiceCollection AddCNBClient(this IServiceCollection services, IConfiguration configuration)
+        {
+            var options = configuration
+                .GetSection("CNBApi:HttpClient")
+                .Get<CnbHttpClientOptions>()
+                ?? new CnbHttpClientOptions();
+
+            if (options == null)
+                throw new InvalidOperationException("CNBApi configuration section is missing.");
+
+            if (string.IsNullOrWhiteSpace(options.BaseUrl))
+                throw new InvalidOperationException("CNBApi:HttpClient:BaseUrl configuration value is missing.");
+
+            services.AddHttpClient<ICnbHttpClient, CnbHttpClient>((serviceProvider, client) =>
+            {
+                client.BaseAddress = new Uri(options.BaseUrl);
+                client.DefaultRequestHeaders.Add("Accept", "application/json");
+            })
+            .AddPolicyHandler((serviceProvider, request) =>
+            {
+                return CnbHttpClientPolicies.TimeoutPolicy(options);
+            })
+            .AddPolicyHandler((serviceProvider, request) =>
+            {
+                var logger = serviceProvider.GetRequiredService<ILogger<CnbHttpClient>>();
+                return CnbHttpClientPolicies.RetryPolicy(options, logger);
+            });
+
+            return services;
+        }
+
+        public static IServiceCollection AddApplicationServices(this IServiceCollection services)
+        {
+            services.AddScoped<IExchangeRatesProvider, ExchangeRatesProvider>();
+            return services;
+        }
+    }
+}

jobs/Backend/Task/ExchangeRates.Api/Program.cs

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+using ExchangeRates.Api.Extensions;
+
+namespace ExchangeRates.Api
+{
+    public class Program
+    {
+        public static void Main(string[] args)
+        {
+            var builder = WebApplication.CreateBuilder(args);
+
+            builder.Logging.ClearProviders();
+            builder.Logging.AddConfiguration(builder.Configuration.GetSection("Logging"));
+            builder.Logging.AddConsole();
+
+            builder.Services.AddExchangeRatesServices(builder.Configuration);
+
+            var app = builder.Build();
+
+            app.ConfigureApp(builder.Environment);
+
+            app.Run();
+        }
+    }
+}

jobs/Backend/Task/ExchangeRates.Api/Properties/launchSettings.json

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+{
+  "$schema": "http://json.schemastore.org/launchsettings.json",
+  "iisSettings": {
+    "windowsAuthentication": false,
+    "anonymousAuthentication": true,
+    "iisExpress": {
+      "applicationUrl": "http://localhost:17427",
+      "sslPort": 44320
+    }
+  },
+  "profiles": {
+    "Development": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": true,
+      "launchUrl": "swagger",
+      "applicationUrl": "https://localhost:7253;http://localhost:5282",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    },
+    "IIS Express": {
+      "commandName": "IISExpress",
+      "launchBrowser": true,
+      "launchUrl": "swagger",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    }
+  }
+}

jobs/Backend/Task/ExchangeRates.Api/appsettings.Development.json

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+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Warning",
+      "Microsoft": "Warning",
+      "ExchangeRates": "Debug"
+    }
+  }
+}

jobs/Backend/Task/ExchangeRates.Api/appsettings.json

@@ -0,0 +1,23 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Error",
+      "Microsoft": "Error",
+      "System": "Error",
+      "ExchangeRates": "Information"
+    }
+  },
+  "AllowedHosts": "*",
+  "CNBApi": {
+    "HttpClient": {
+      "BaseUrl": "https://api.cnb.cz/",
+      "TimeoutSeconds": 10,
+      "RetryCount": 2,
+      "RetryBaseDelaySeconds": 2,
+      "DailyRefreshTimeCZ": "14:30:00"
+    }
+  },
+  "ExchangeRates": {
+    "DefaultCurrencies": [ "USD", "EUR", "CZK", "JPY", "KES", "RUB", "THB", "TRY", "XYZ" ]
+  }
+}