Implement controller for accessing database with airports with follow…

…ing middleware and filters:

- caching
- validation of input IATA code
- global exception handler
- invalid request to database filter
- URI disconitinuation filter
Use CQRS pattern to decouple any logic from controllers by using MediatR NuGet package.
Add Repository pattern to decouple access to database from CQRS pattern.

README.md

@@ -7,6 +7,15 @@
 - **CLI project** - it is responsible for scraping data from wikipedia page and exporting it to database file. This is done since IATA codes sholdn't be taken from resource that almost everyone can edit. This database file can afterwards be used on server side of application.
     - CLI application has clean decoupling of input received from CLI UI and business logic, which enables good testability.
     - SQLite is used as database because of simlicity. There is no need for separate server installation, it's stored in single file which simplifies deployment and enhances it's portability. It also has support for Entity Framework which will afterwards be used as database manager.
+- **Domain** - contains entities and abstractions for business services.
+- **Persistence** - implements communication to SQLite database.
+    - implements Repository pattern to decouple access to database from application logic.
+- **Application** - contains implementations for domain service abstractions, repositories, CQRS, caching...
+- **Web API** - used for communication with flight APIs by controllers, and for communication to client application.
+    - uses CQRS pattern for decoupling controllers from outer infrastructure code.
+    - uses Repository pattern for decoupling access to database.
+    - contains various middleware: caching, validation of input IATA code, invalid request oarameter to database filter, URI disconitinuation filter
 
 # Possible improvements
-- Implement deploymnet for CLI project so that database file is uploaded to git repo
+- Implement deploymnet for CLI project so that database file is uploaded to git repo
+- Use Infrastructure project to better decouple some logic like caching from Application

source/FlightScanner.Domain/Models/AirportEntity.cs → source/FlightScanner.Domain/Entities/AirportEntity.cs

@@ -1,8 +1,8 @@
-namespace FlightScanner.Domain.Models;
+namespace FlightScanner.Domain.Entities;
 
-public class Airport
+public class AirportEntity
 {
-    public Airport(string iataCode, string? airportName, string? location)
+    public AirportEntity(string iataCode, string? airportName, string? location)
     {
         IataCode = iataCode;
         AirportName = airportName;

source/FlightScanner.Domain/Exceptions/InvalidResponseException.cs

@@ -0,0 +1,8 @@
+namespace FlightScanner.Domain.Exceptions;
+
+public class InvalidResponseException : Exception
+{
+    public InvalidResponseException(string? message) : base(message)
+    {
+    }
+}

source/FlightScanner.Domain/Exceptions/NotFoundException.cs

@@ -0,0 +1,9 @@
+namespace FlightScanner.Domain.Exceptions;
+
+public class NotFoundException : Exception
+{
+    public NotFoundException(Type typeName, string objectId)
+        : base($"{typeName} with id {objectId} was not found!")
+    {
+    }
+}

source/FlightScanner.Domain/Repositories/IAirportRepository.cs

@@ -0,0 +1,9 @@
+
+using FlightScanner.Domain.Entities;
+
+namespace FlightScanner.Domain.Repositories;
+
+public interface IAirportRepository
+{
+    Task<AirportEntity> GetAirportWithIataCode(string iataCode, CancellationToken cancellationToken);
+}

source/FlightScanner.Persistence/Configurations/AirportEntityConfiguration.cs

@@ -1,12 +1,12 @@
 using Microsoft.EntityFrameworkCore.Metadata.Builders;
 using Microsoft.EntityFrameworkCore;
-using FlightScanner.Domain.Models;
+using FlightScanner.Domain.Entities;
 
 namespace FlightScanner.Persistence.Configurations;
 
-public class AirportEntityConfiguration : IEntityTypeConfiguration<Airport>
+public class AirportEntityConfiguration : IEntityTypeConfiguration<AirportEntity>
 {
-    public void Configure(EntityTypeBuilder<Airport> builder)
+    public void Configure(EntityTypeBuilder<AirportEntity> builder)
     {
         builder.HasKey(e => e.IataCode);
         builder.Property(e => e.IataCode)

source/FlightScanner.Persistence/Database/AirportsDbContext.cs

@@ -1,4 +1,4 @@
-using FlightScanner.Domain.Models;
+using FlightScanner.Domain.Entities;
 using Microsoft.EntityFrameworkCore;
 
 namespace FlightScanner.Persistence.Database;
@@ -12,7 +12,7 @@ public AirportsDbContext(DbContextOptions<AirportsDbContext> options)
 
     #region Properties
 
-    public DbSet<Airport> Airports { get; set; }
+    public DbSet<AirportEntity> Airports { get; set; }
 
     #endregion
 

source/FlightScanner.Persistence/PersistenceServiceExtensions.cs

@@ -1,4 +1,6 @@
-using FlightScanner.Persistence.Database;
+using FlightScanner.Domain.Repositories;
+using FlightScanner.Persistence.Database;
+using FlightScanner.Persistence.Repositories;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection;
 using System.Reflection;
@@ -15,6 +17,8 @@ public static class PersistenceServiceExtensions
 
     public static IServiceCollection AddInfrastructureProjectServices(this IServiceCollection services)
     {
+        services.AddScoped<IAirportRepository, AirportRepository>();
+
         services.AddDbContext<AirportsDbContext>(optionsBuilder =>
         {
             optionsBuilder.UseSqlite($"Data Source={s_databaseFilePath}");

source/FlightScanner.Persistence/Repositories/AirportRepository.cs

@@ -0,0 +1,35 @@
+using FlightScanner.Domain.Entities;
+using FlightScanner.Domain.Exceptions;
+using FlightScanner.Domain.Repositories;
+using FlightScanner.Persistence.Database;
+using Microsoft.EntityFrameworkCore;
+
+namespace FlightScanner.Persistence.Repositories;
+
+public class AirportRepository : IAirportRepository
+{
+    private readonly AirportsDbContext _airportsDbContext;
+
+    public AirportRepository(AirportsDbContext airportsDbContext)
+    {
+        _airportsDbContext = airportsDbContext;
+    }
+
+    public async Task<AirportEntity> GetAirportWithIataCode(string iataCode, CancellationToken cancellationToken)
+    {
+        var airport = await _airportsDbContext
+            .Airports
+            .AsNoTracking()
+            .AsQueryable()
+            .FirstOrDefaultAsync(
+                predicate: airport => string.Equals(airport.IataCode, iataCode.ToUpper()),
+                cancellationToken: cancellationToken);
+
+        if (airport == null)
+        {
+            throw new NotFoundException(typeof(AirportEntity), iataCode);
+        }
+
+        return airport;
+    }
+}

source/FlightScanner.WebApi/Controllers/AirportCodesController.cs

@@ -0,0 +1,38 @@
+using FlightScanner.Domain.Entities;
+using FlightScanner.WebApi.Filters;
+using FlightScanner.WebApi.Validation;
+using FlightsScanner.Application.Airports.Queries.GetAirport;
+using MediatR;
+using Microsoft.AspNetCore.Mvc;
+using System.Net.Mime;
+
+namespace FlightScanner.WebApi.Controllers;
+
+[ApiController]
+[Route("api/v2")]
+[AirportCodesVersionDiscontinuationResourceFilter]
+public class AirportCodesController : ControllerBase
+{
+    private readonly ISender _sender;
+
+    public AirportCodesController(ISender sender)
+    {
+        _sender = sender;
+    }
+
+    [Produces(MediaTypeNames.Application.Json)]
+    [ProducesResponseType(StatusCodes.Status201Created, Type = typeof(AirportEntity))]
+    [HttpGet]
+    [Route("airport")]
+    [CountriesWithClosedAirTrafficFilter]
+    public async Task<IActionResult> GetAirport(
+        [FromQuery][IataCodeValidation] string iataCode,
+        CancellationToken cancellationToken)
+    {
+        var response = await _sender.Send(
+            request: new GetAirportQuery(iataCode),
+            cancellationToken: cancellationToken);
+
+        return Ok(response);
+    }
+}

source/FlightScanner.WebApi/Filters/AirportCodesVersionDiscontinuationResourceFilter.cs

@@ -0,0 +1,32 @@
+using Microsoft.AspNetCore.Mvc.Filters;
+using Microsoft.AspNetCore.Mvc;
+
+namespace FlightScanner.WebApi.Filters;
+
+public class AirportCodesVersionDiscontinuationResourceFilter : Attribute, IResourceFilter
+{
+    private const string OUTDATED_API_VERSION = "v1";
+
+    public void OnResourceExecuted(ResourceExecutedContext context)
+    {
+
+    }
+
+    public void OnResourceExecuting(ResourceExecutingContext context)
+    {
+        var uriPath = context.HttpContext.Request.Path;
+
+        if (!string.IsNullOrEmpty(uriPath.Value) && uriPath.Value.Contains(OUTDATED_API_VERSION, StringComparison.CurrentCultureIgnoreCase))
+        {
+            var errorObject = new
+            {
+                Versioning = new[]
+                {
+                    $"API version {OUTDATED_API_VERSION} is expired. Please use the latest version."
+                }
+            };
+
+            context.Result = new BadRequestObjectResult(errorObject);
+        }
+    }
+}

source/FlightScanner.WebApi/Filters/CountriesWithClosedAirTrafficFilter.cs

@@ -0,0 +1,44 @@
+using Microsoft.AspNetCore.Mvc.Filters;
+using Microsoft.AspNetCore.Mvc;
+using FlightScanner.Domain.Entities;
+
+namespace FlightScanner.WebApi.Filters;
+
+public class CountriesWithClosedAirTrafficFilter : ActionFilterAttribute
+{
+    private readonly string[] _ukrainianAirportIataCodes = new string[]
+    {
+        "UCK",
+        "UDJ",
+        "UMY",
+    };
+
+    public override void OnActionExecuted(ActionExecutedContext context)
+    {
+        base.OnActionExecuted(context);
+
+        if (context.Result is not OkObjectResult result)
+        {
+            return;
+        }
+
+        if (result.Value is not AirportEntity airport)
+        {
+            return;
+        }
+
+        if (_ukrainianAirportIataCodes.Any(ukrainianAirportIataCode => string.Equals(ukrainianAirportIataCode, airport.IataCode, StringComparison.OrdinalIgnoreCase)))
+        {
+            context.ModelState.AddModelError(
+                key: "Forbidden IATA code",
+                errorMessage: $"Airport with IATA code {airport.IataCode} is currently closed due to war conditions!");
+
+            var problemDetails = new ValidationProblemDetails(context.ModelState)
+            {
+                Status = StatusCodes.Status406NotAcceptable
+            };
+
+            context.Result = new BadRequestObjectResult(problemDetails);
+        }
+    }
+}

source/FlightScanner.WebApi/FlightScanner.WebApi.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk.Web">
+<Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
     <TargetFramework>net8.0</TargetFramework>
@@ -7,8 +7,14 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="MediatR" Version="12.4.1" />
     <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="8.0.11" />
     <PackageReference Include="Swashbuckle.AspNetCore" Version="6.6.2" />
   </ItemGroup>
 
+  <ItemGroup>
+    <ProjectReference Include="..\FlightScanner.Persistence\FlightScanner.Persistence.csproj" />
+    <ProjectReference Include="..\FlightsScanner.Application\FlightsScanner.Application.csproj" />
+  </ItemGroup>
+
 </Project>

source/FlightScanner.WebApi/Program.cs

@@ -1,4 +1,10 @@
-internal class Program
+using FlightsScanner.Application.Constants;
+using FlightsScanner.Application.Infrastructure;
+using FlightsScanner.Application.Services.Contracts;
+using FlightScanner.Persistence;
+using FlightsScanner.Application.Airports.Queries.GetAirport;
+
+internal class Program
 {
     private static void Main(string[] args)
     {
@@ -17,6 +23,21 @@ private static void CreateWebBuilder(WebApplicationBuilder builder)
     {
         builder.Services.AddEndpointsApiExplorer();
         builder.Services.AddSwaggerGen();
+
+        builder.Services.AddControllers();
+
+        builder.Services.AddInfrastructureProjectServices();
+
+        builder.Services.AddMemoryCache(options =>
+        {
+            options.SizeLimit = CacheConstants.CACHE_LIMIT;
+        });
+        builder.Services.AddScoped<IInMemoryCacheService, InMemoryCacheService>();
+
+        builder.Services.AddMediatR(configuration =>
+        {
+            configuration.RegisterServicesFromAssemblies(typeof(GetAirportQuery).Assembly);
+        });
     }
 
     private static void ConfigureMiddleware(WebApplication app)
@@ -29,5 +50,7 @@ private static void ConfigureMiddleware(WebApplication app)
         }
 
         app.UseHttpsRedirection();
+
+        app.MapControllers();
     }
 }

source/FlightScanner.WebApi/Validation/IataCodeValidation.cs

@@ -0,0 +1,23 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace FlightScanner.WebApi.Validation;
+
+public class IataCodeValidation : ValidationAttribute
+{
+    private const int IATA_CODE_LENGTH = 3;
+
+    protected override ValidationResult? IsValid(object? value, ValidationContext validationContext)
+    {
+        if (value is not string iataCode)
+        {
+            return new ValidationResult($"Received input {value} is not text!");
+        }
+
+        if (iataCode.Length != IATA_CODE_LENGTH)
+        {
+            return new ValidationResult($"IATA code has invalid length of {iataCode.Length}. IATA code should have {IATA_CODE_LENGTH} text characters.");
+        }
+
+        return ValidationResult.Success;
+    }
+}

source/FlightScanner.sln

@@ -15,6 +15,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "FlightScanner.Domain", "Fli
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "FlightScanner.WebApi", "FlightScanner.WebApi\FlightScanner.WebApi.csproj", "{8A92404B-9967-4249-BE31-6C0760007B55}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "FlightsScanner.Application", "FlightsScanner.Application\FlightsScanner.Application.csproj", "{206F0DE9-7E35-4610-BC73-332324891C26}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -41,6 +43,10 @@ Global
 		{8A92404B-9967-4249-BE31-6C0760007B55}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{8A92404B-9967-4249-BE31-6C0760007B55}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{8A92404B-9967-4249-BE31-6C0760007B55}.Release|Any CPU.Build.0 = Release|Any CPU
+		{206F0DE9-7E35-4610-BC73-332324891C26}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{206F0DE9-7E35-4610-BC73-332324891C26}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{206F0DE9-7E35-4610-BC73-332324891C26}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{206F0DE9-7E35-4610-BC73-332324891C26}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE