Implement enterprise architecture patterns (Clean Architecture, CQRS, Repository)

README.md

@@ -2,8 +2,14 @@
 
 A full-stack web application with .NET Web API backend and Angular frontend, featuring comprehensive observability with Grafana, Prometheus, Tempo, and Loki, plus fun Databricks integration for banana analytics! 🍌
 
+Built using enterprise architecture patterns including Clean Architecture, CQRS, and Repository Pattern for maintainability and scalability.
+
 > **🚀 [Quick Start Guide](QUICKSTART.md)** - Get up and running in minutes!
 > 
+> **🏛️ [Enterprise Architecture Patterns](docs/ENTERPRISE_ARCHITECTURE_PATTERNS.md)** - Clean Architecture, CQRS, Repository Pattern
+> 
+> **📊 [Architecture Visual Guide](docs/ARCHITECTURE_VISUAL_GUIDE.md)** - Diagrams and visual documentation
+> 
 > **🍌 [Databricks Integration](docs/DATABRICKS_INTEGRATION.md)** - Banana analytics powered by Databricks
 > 
 > **📊 [Observability Guide](observability/README.md)** - Complete monitoring and tracing documentation

backend/GrafanaBanana.Api/Application/DependencyInjection.cs

@@ -0,0 +1,28 @@
+using GrafanaBanana.Api.Domain.Repositories;
+using GrafanaBanana.Api.Infrastructure.Repositories;
+using System.Reflection;
+
+namespace GrafanaBanana.Api.Application;
+
+/// <summary>
+/// Extension methods for registering application layer services
+/// Implements Dependency Injection pattern for loose coupling
+/// </summary>
+public static class DependencyInjection
+{
+    /// <summary>
+    /// Registers all application layer services including MediatR, repositories, and handlers
+    /// Following the Dependency Inversion Principle - depending on abstractions, not concretions
+    /// </summary>
+    public static IServiceCollection AddApplicationServices(this IServiceCollection services)
+    {
+        // Register MediatR for CQRS pattern
+        services.AddMediatR(cfg => cfg.RegisterServicesFromAssembly(Assembly.GetExecutingAssembly()));
+
+        // Register repositories (Repository Pattern)
+        services.AddScoped<IWeatherForecastRepository, WeatherForecastRepository>();
+        services.AddScoped<IBananaAnalyticsRepository, BananaAnalyticsRepository>();
+
+        return services;
+    }
+}

backend/GrafanaBanana.Api/Application/Handlers/GetBananaAnalyticsQueryHandler.cs

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+using GrafanaBanana.Api.Application.Queries;
+using GrafanaBanana.Api.Databricks;
+using GrafanaBanana.Api.Domain.Repositories;
+using MediatR;
+
+namespace GrafanaBanana.Api.Application.Handlers;
+
+/// <summary>
+/// Handler for GetBananaAnalyticsQuery
+/// Implements the business logic for retrieving banana analytics
+/// Following CQRS and Mediator patterns
+/// </summary>
+public class GetBananaAnalyticsQueryHandler : IRequestHandler<GetBananaAnalyticsQuery, BananaAnalytics>
+{
+    private readonly IBananaAnalyticsRepository _repository;
+    private readonly ILogger<GetBananaAnalyticsQueryHandler> _logger;
+
+    public GetBananaAnalyticsQueryHandler(
+        IBananaAnalyticsRepository repository,
+        ILogger<GetBananaAnalyticsQueryHandler> logger)
+    {
+        _repository = repository;
+        _logger = logger;
+    }
+
+    public async Task<BananaAnalytics> Handle(GetBananaAnalyticsQuery request, CancellationToken cancellationToken)
+    {
+        _logger.LogInformation("Handling GetBananaAnalyticsQuery");
+
+        var analytics = await _repository.GetBananaAnalyticsAsync(cancellationToken);
+
+        _logger.LogInformation(
+            "Retrieved banana analytics: {ProductionTons} tons produced, {Revenue} revenue, {Countries} countries served",
+            analytics.Summary.TotalProductionTons,
+            analytics.Summary.TotalRevenue,
+            analytics.Summary.CountriesServed);
+
+        return analytics;
+    }
+}

backend/GrafanaBanana.Api/Application/Handlers/GetBananaProductionQueryHandler.cs

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+using GrafanaBanana.Api.Application.Queries;
+using GrafanaBanana.Api.Databricks;
+using GrafanaBanana.Api.Domain.Repositories;
+using MediatR;
+
+namespace GrafanaBanana.Api.Application.Handlers;
+
+/// <summary>
+/// Handler for GetBananaProductionQuery
+/// Implements the business logic for retrieving banana production data
+/// Following CQRS and Mediator patterns
+/// </summary>
+public class GetBananaProductionQueryHandler : IRequestHandler<GetBananaProductionQuery, List<BananaProduction>>
+{
+    private readonly IBananaAnalyticsRepository _repository;
+    private readonly ILogger<GetBananaProductionQueryHandler> _logger;
+
+    public GetBananaProductionQueryHandler(
+        IBananaAnalyticsRepository repository,
+        ILogger<GetBananaProductionQueryHandler> logger)
+    {
+        _repository = repository;
+        _logger = logger;
+    }
+
+    public async Task<List<BananaProduction>> Handle(GetBananaProductionQuery request, CancellationToken cancellationToken)
+    {
+        _logger.LogInformation("Handling GetBananaProductionQuery for year {Year}", request.Year);
+
+        var production = await _repository.GetProductionDataAsync(request.Year, cancellationToken);
+
+        _logger.LogInformation("Retrieved {Count} production records for year {Year}", production.Count, request.Year);
+
+        return production;
+    }
+}

backend/GrafanaBanana.Api/Application/Handlers/GetBananaSalesQueryHandler.cs

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+using GrafanaBanana.Api.Application.Queries;
+using GrafanaBanana.Api.Databricks;
+using GrafanaBanana.Api.Domain.Repositories;
+using MediatR;
+
+namespace GrafanaBanana.Api.Application.Handlers;
+
+/// <summary>
+/// Handler for GetBananaSalesQuery
+/// Implements the business logic for retrieving banana sales data
+/// Following CQRS and Mediator patterns
+/// </summary>
+public class GetBananaSalesQueryHandler : IRequestHandler<GetBananaSalesQuery, List<BananaSalesData>>
+{
+    private readonly IBananaAnalyticsRepository _repository;
+    private readonly ILogger<GetBananaSalesQueryHandler> _logger;
+
+    public GetBananaSalesQueryHandler(
+        IBananaAnalyticsRepository repository,
+        ILogger<GetBananaSalesQueryHandler> logger)
+    {
+        _repository = repository;
+        _logger = logger;
+    }
+
+    public async Task<List<BananaSalesData>> Handle(GetBananaSalesQuery request, CancellationToken cancellationToken)
+    {
+        // Sanitize region parameter for logging to prevent log forging
+        var sanitizedRegion = request.Region.Replace("\n", "").Replace("\r", "");
+        _logger.LogInformation("Handling GetBananaSalesQuery for region {Region}", sanitizedRegion);
+
+        var sales = await _repository.GetSalesDataAsync(request.Region, cancellationToken);
+
+        _logger.LogInformation("Retrieved {Count} sales records", sales.Count);
+
+        return sales;
+    }
+}

backend/GrafanaBanana.Api/Application/Handlers/GetWeatherForecastQueryHandler.cs

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+using GrafanaBanana.Api.Application.Queries;
+using GrafanaBanana.Api.Domain.Entities;
+using GrafanaBanana.Api.Domain.Repositories;
+using MediatR;
+
+namespace GrafanaBanana.Api.Application.Handlers;
+
+/// <summary>
+/// Handler for GetWeatherForecastQuery
+/// Implements the business logic for retrieving weather forecasts
+/// Following CQRS and Mediator patterns
+/// </summary>
+public class GetWeatherForecastQueryHandler : IRequestHandler<GetWeatherForecastQuery, IEnumerable<WeatherForecast>>
+{
+    private readonly IWeatherForecastRepository _repository;
+    private readonly ILogger<GetWeatherForecastQueryHandler> _logger;
+
+    public GetWeatherForecastQueryHandler(
+        IWeatherForecastRepository repository,
+        ILogger<GetWeatherForecastQueryHandler> logger)
+    {
+        _repository = repository;
+        _logger = logger;
+    }
+
+    public async Task<IEnumerable<WeatherForecast>> Handle(GetWeatherForecastQuery request, CancellationToken cancellationToken)
+    {
+        _logger.LogInformation("Handling GetWeatherForecastQuery for {Days} days", request.Days);
+
+        var forecasts = await _repository.GetForecastsAsync(request.Days, cancellationToken);
+
+        _logger.LogInformation("Successfully retrieved {Count} weather forecast entries", forecasts.Count());
+
+        return forecasts;
+    }
+}

backend/GrafanaBanana.Api/Application/Queries/GetBananaAnalyticsQuery.cs

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+using GrafanaBanana.Api.Databricks;
+using MediatR;
+
+namespace GrafanaBanana.Api.Application.Queries;
+
+/// <summary>
+/// Query to get banana analytics data
+/// Following CQRS pattern - read operation
+/// </summary>
+public record GetBananaAnalyticsQuery : IRequest<BananaAnalytics>;

backend/GrafanaBanana.Api/Application/Queries/GetBananaProductionQuery.cs

@@ -0,0 +1,10 @@
+using GrafanaBanana.Api.Databricks;
+using MediatR;
+
+namespace GrafanaBanana.Api.Application.Queries;
+
+/// <summary>
+/// Query to get banana production data by year
+/// Following CQRS pattern - read operation
+/// </summary>
+public record GetBananaProductionQuery(int Year) : IRequest<List<BananaProduction>>;

backend/GrafanaBanana.Api/Application/Queries/GetBananaSalesQuery.cs

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+using GrafanaBanana.Api.Databricks;
+using MediatR;
+
+namespace GrafanaBanana.Api.Application.Queries;
+
+/// <summary>
+/// Query to get banana sales data by region
+/// Following CQRS pattern - read operation
+/// </summary>
+public record GetBananaSalesQuery(string Region) : IRequest<List<BananaSalesData>>;

backend/GrafanaBanana.Api/Application/Queries/GetWeatherForecastQuery.cs

@@ -0,0 +1,10 @@
+using GrafanaBanana.Api.Domain.Entities;
+using MediatR;
+
+namespace GrafanaBanana.Api.Application.Queries;
+
+/// <summary>
+/// Query to get weather forecasts
+/// Following CQRS pattern - read operation
+/// </summary>
+public record GetWeatherForecastQuery(int Days = 5) : IRequest<IEnumerable<WeatherForecast>>;

backend/GrafanaBanana.Api/Domain/Entities/WeatherForecast.cs

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+namespace GrafanaBanana.Api.Domain.Entities;
+
+/// <summary>
+/// Domain entity representing a weather forecast
+/// </summary>
+public class WeatherForecast
+{
+    public DateOnly Date { get; private set; }
+    public int TemperatureC { get; private set; }
+    public string? Summary { get; private set; }
+
+    // Domain logic
+    public int TemperatureF => 32 + (int)(TemperatureC * 9.0 / 5.0);
+
+    public WeatherForecast(DateOnly date, int temperatureC, string? summary)
+    {
+        Date = date;
+        TemperatureC = temperatureC;
+        Summary = summary;
+    }
+
+    // Factory method for creating forecasts
+    public static WeatherForecast Create(DateOnly date, int temperatureC, string? summary)
+    {
+        // Domain validation
+        if (temperatureC < -273) // Absolute zero check
+            throw new ArgumentException("Temperature cannot be below absolute zero", nameof(temperatureC));
+
+        return new WeatherForecast(date, temperatureC, summary);
+    }
+}

backend/GrafanaBanana.Api/Domain/Repositories/IBananaAnalyticsRepository.cs

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+using GrafanaBanana.Api.Databricks;
+
+namespace GrafanaBanana.Api.Domain.Repositories;
+
+/// <summary>
+/// Repository interface for banana analytics data access
+/// Abstracts the Databricks service implementation
+/// </summary>
+public interface IBananaAnalyticsRepository
+{
+    Task<BananaAnalytics> GetBananaAnalyticsAsync(CancellationToken cancellationToken = default);
+    Task<List<BananaProduction>> GetProductionDataAsync(int year, CancellationToken cancellationToken = default);
+    Task<List<BananaSalesData>> GetSalesDataAsync(string region, CancellationToken cancellationToken = default);
+}

backend/GrafanaBanana.Api/Domain/Repositories/IWeatherForecastRepository.cs

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+using GrafanaBanana.Api.Domain.Entities;
+
+namespace GrafanaBanana.Api.Domain.Repositories;
+
+/// <summary>
+/// Repository interface for weather forecast data access
+/// Following Repository Pattern for abstraction of data access logic
+/// </summary>
+public interface IWeatherForecastRepository
+{
+    Task<IEnumerable<WeatherForecast>> GetForecastsAsync(int days, CancellationToken cancellationToken = default);
+}

backend/GrafanaBanana.Api/GrafanaBanana.Api.csproj

@@ -7,6 +7,7 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="MediatR" Version="12.4.1" />
     <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="9.0.10" />
 
     <!-- OpenTelemetry packages for comprehensive observability -->

backend/GrafanaBanana.Api/Infrastructure/Repositories/BananaAnalyticsRepository.cs

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+using GrafanaBanana.Api.Databricks;
+using GrafanaBanana.Api.Domain.Repositories;
+
+namespace GrafanaBanana.Api.Infrastructure.Repositories;
+
+/// <summary>
+/// Repository implementation for banana analytics data
+/// Delegates to the existing DatabricksService while providing a repository abstraction
+/// This follows the Adapter pattern to integrate legacy code with new architecture
+/// </summary>
+public class BananaAnalyticsRepository : IBananaAnalyticsRepository
+{
+    private readonly IDatabricksService _databricksService;
+    private readonly ILogger<BananaAnalyticsRepository> _logger;
+
+    public BananaAnalyticsRepository(
+        IDatabricksService databricksService,
+        ILogger<BananaAnalyticsRepository> logger)
+    {
+        _databricksService = databricksService;
+        _logger = logger;
+    }
+
+    public async Task<BananaAnalytics> GetBananaAnalyticsAsync(CancellationToken cancellationToken = default)
+    {
+        _logger.LogDebug("Fetching banana analytics from Databricks service");
+        return await _databricksService.GetBananaAnalyticsAsync(cancellationToken);
+    }
+
+    public async Task<List<BananaProduction>> GetProductionDataAsync(int year, CancellationToken cancellationToken = default)
+    {
+        _logger.LogDebug("Fetching banana production data for year {Year}", year);
+        return await _databricksService.GetProductionDataAsync(year, cancellationToken);
+    }
+
+    public async Task<List<BananaSalesData>> GetSalesDataAsync(string region, CancellationToken cancellationToken = default)
+    {
+        _logger.LogDebug("Fetching banana sales data for region {Region}", region);
+        return await _databricksService.GetSalesDataAsync(region, cancellationToken);
+    }
+}

backend/GrafanaBanana.Api/Infrastructure/Repositories/WeatherForecastRepository.cs

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+using GrafanaBanana.Api.Domain.Entities;
+using GrafanaBanana.Api.Domain.Repositories;
+
+namespace GrafanaBanana.Api.Infrastructure.Repositories;
+
+/// <summary>
+/// Repository implementation for weather forecast data
+/// Implements in-memory data generation for demonstration
+/// In a real application, this would connect to a database or external API
+/// </summary>
+public class WeatherForecastRepository : IWeatherForecastRepository
+{
+    private readonly ILogger<WeatherForecastRepository> _logger;
+    private static readonly string[] Summaries = new[]
+    {
+        "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
+    };
+
+    public WeatherForecastRepository(ILogger<WeatherForecastRepository> logger)
+    {
+        _logger = logger;
+    }
+
+    public Task<IEnumerable<WeatherForecast>> GetForecastsAsync(int days, CancellationToken cancellationToken = default)
+    {
+        _logger.LogDebug("Generating {Days} weather forecasts", days);
+
+        var forecasts = Enumerable.Range(1, days).Select(index =>
+            WeatherForecast.Create(
+                DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
+                Random.Shared.Next(-20, 55),
+                Summaries[Random.Shared.Next(Summaries.Length)]
+            ))
+            .ToList();
+
+        return Task.FromResult<IEnumerable<WeatherForecast>>(forecasts);
+    }
+}