Incorporate all functions.txt

refactor this code to meet all common code standards:
public class CountryService : ICountryService
{
    private readonly HttpClient _httpClient;
    private readonly string _apiBaseUrl;

    public CountryService(IConfiguration configuration)
    {
        _httpClient = new HttpClient();
        _apiBaseUrl = configuration.GetValue<string>("CountryApiBaseUrl");
    }

    public async Task<IEnumerable<Country>> GetAllCountriesAsync()
    {
        var response = await _httpClient.GetAsync(_apiBaseUrl);
        response.EnsureSuccessStatusCode();

        var responseData = await response.Content.ReadAsStringAsync();
        var countries = JsonConvert.DeserializeObject<IEnumerable<Country>>(responseData);

        return countries;
    }

    public async Task<IEnumerable<Country>> GetFilteredCountriesAsync(RequestModel model)
    {
        var allCountries = await GetAllCountriesAsync();

        if (!string.IsNullOrWhiteSpace(model.Name))
            allCountries = allCountries?.Where(x => x.Name.Common.ToLower().Contains(model.Name.ToLower()));

        if (model.Population.HasValue)
        {
            var populationExact = model.Population.Value * 1000000; // Convert input from millions to the exact number
            allCountries = allCountries?.Where(x => x.Population < populationExact);
        }

        if (!string.IsNullOrWhiteSpace(model.Sort))
        {
            allCountries = model.Sort?.ToLower() switch
            {
                "ascend" => allCountries.OrderBy(item => item.Name.Common).ToList(),
                "descend" => allCountries.OrderByDescending(item => item.Name.Common).ToList(),
                _ => allCountries // If sort parameter is not provided or invalid, return items as is.
            };
        }

        return model.Limit.HasValue ? allCountries.Take(model.Limit.Value) : allCountries;
    }
}

ChatGPT
Certainly, there are a few common coding standards that can be applied to your code. These standards include:

Consistent Naming: Use meaningful and consistent names.
Separation of Concerns: Methods should have a single responsibility.
Code Comments: Comment the code for readability and maintainability.
Error Handling: Handle potential errors gracefully.
Null Checks: Include null checks for method parameters or variables that can be null.
Here is a refactored version of your code:

csharp
Copy code
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Threading.Tasks;
using Microsoft.Extensions.Configuration;
using Newtonsoft.Json;

public class CountryService : ICountryService
{
    private readonly HttpClient _httpClient;
    private readonly string _apiBaseUrl;

    public CountryService(IConfiguration configuration)
    {
        _httpClient = new HttpClient();
        _apiBaseUrl = configuration.GetValue<string>("CountryApiBaseUrl") 
                     ?? throw new ArgumentNullException("CountryApiBaseUrl is not defined in configuration.");
    }

    public async Task<IEnumerable<Country>> GetAllCountriesAsync()
    {
        try
        {
            var response = await _httpClient.GetAsync(_apiBaseUrl);
            response.EnsureSuccessStatusCode();
            
            var responseData = await response.Content.ReadAsStringAsync();
            return DeserializeCountries(responseData);
        }
        catch (Exception ex)
        {
            // Log the exception here (logging code omitted)
            throw; // Re-throw the exception or handle it as required
        }
    }

    public async Task<IEnumerable<Country>> GetFilteredCountriesAsync(RequestModel model)
    {
        var allCountries = await GetAllCountriesAsync() ?? Enumerable.Empty<Country>();

        allCountries = FilterCountriesByName(allCountries, model.Name);
        allCountries = FilterCountriesByPopulation(allCountries, model.Population);
        allCountries = SortCountries(allCountries, model.Sort);

        return LimitCountries(allCountries, model.Limit);
    }

    private IEnumerable<Country> DeserializeCountries(string responseData)
    {
        return JsonConvert.DeserializeObject<IEnumerable<Country>>(responseData);
    }

    private IEnumerable<Country> FilterCountriesByName(IEnumerable<Country> countries, string name)
    {
        return string.IsNullOrWhiteSpace(name) 
            ? countries 
            : countries.Where(x => x.Name.Common.ToLower().Contains(name.ToLower()));
    }

    private IEnumerable<Country> FilterCountriesByPopulation(IEnumerable<Country> countries, long? populationInMillions)
    {
        if (!populationInMillions.HasValue)
        {
            return countries;
        }

        var populationExact = populationInMillions.Value * 1000000;
        return countries.Where(x => x.Population < populationExact);
    }

    private IEnumerable<Country> SortCountries(IEnumerable<Country> countries, string sort)
    {
        return sort?.ToLower() switch
        {
            "ascend" => countries.OrderBy(item => item.Name.Common),
            "descend" => countries.OrderByDescending(item => item.Name.Common),
            _ => countries
        };
    }

    private IEnumerable<Country> LimitCountries(IEnumerable<Country> countries, int? limit)
    {
        return limit.HasValue ? countries.Take(limit.Value) : countries;
    }
}
In this refactored version, I've split the tasks into multiple smaller methods, each focusing on a specific aspect (separation of concerns). I've also included a null check for the configuration, added comments for readability, and used try-catch for error handling.




User
inject logger into this service
ChatGPT
To inject a logger into the service, you'll need to make a few changes:

Add a constructor parameter for the ILogger<CountryService> type.
Initialize a private read-only field for the logger.
Utilize the logger in your methods.
Here's how your class would look after these changes:

csharp
Copy code
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Threading.Tasks;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json;

public class CountryService : ICountryService
{
    private readonly HttpClient _httpClient;
    private readonly string _apiBaseUrl;
    private readonly ILogger<CountryService> _logger;

    public CountryService(IConfiguration configuration, ILogger<CountryService> logger)
    {
        _httpClient = new HttpClient();
        _apiBaseUrl = configuration.GetValue<string>("CountryApiBaseUrl") 
                     ?? throw new ArgumentNullException("CountryApiBaseUrl is not defined in configuration.");
        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
    }

    public async Task<IEnumerable<Country>> GetAllCountriesAsync()
    {
        try
        {
            var response = await _httpClient.GetAsync(_apiBaseUrl);
            response.EnsureSuccessStatusCode();
            
            var responseData = await response.Content.ReadAsStringAsync();
            return DeserializeCountries(responseData);
        }
        catch (Exception ex)
        {
            _logger.LogError($"An error occurred while fetching all countries: {ex.Message}");
            throw; // Re-throw the exception or handle it as required
        }
    }

    public async Task<IEnumerable<Country>> GetFilteredCountriesAsync(RequestModel model)
    {
        try
        {
            var allCountries = await GetAllCountriesAsync() ?? Enumerable.Empty<Country>();

            allCountries = FilterCountriesByName(allCountries, model.Name);
            allCountries = FilterCountriesByPopulation(allCountries, model.Population);
            allCountries = SortCountries(allCountries, model.Sort);

            return LimitCountries(allCountries, model.Limit);
        }
        catch (Exception ex)
        {
            _logger.LogError($"An error occurred while fetching filtered countries: {ex.Message}");
            throw; // Re-throw the exception or handle it as required
        }
    }

    private IEnumerable<Country> DeserializeCountries(string responseData)
    {
        return JsonConvert.DeserializeObject<IEnumerable<Country>>(responseData);
    }

    private IEnumerable<Country> FilterCountriesByName(IEnumerable<Country> countries, string name)
    {
        return string.IsNullOrWhiteSpace(name) 
            ? countries 
            : countries.Where(x => x.Name.Common.ToLower().Contains(name.ToLower()));
    }

    private IEnumerable<Country> FilterCountriesByPopulation(IEnumerable<Country> countries, long? populationInMillions)
    {
        if (!populationInMillions.HasValue)
        {
            return countries;
        }

        var populationExact = populationInMillions.Value * 1000000;
        return countries.Where(x => x.Population < populationExact);
    }

    private IEnumerable<Country> SortCountries(IEnumerable<Country> countries, string sort)
    {
        return sort?.ToLower() switch
        {
            "ascend" => countries.OrderBy(item => item.Name.Common),
            "descend" => countries.OrderByDescending(item => item.Name.Common),
            _ => countries
        };
    }

    private IEnumerable<Country> LimitCountries(IEnumerable<Country> countries, int? limit)
    {
        return limit.HasValue ? countries.Take(limit.Value) : countries;
    }
}
With this setup, you can log errors and other important events. The ILogger<CountryService> interface provides various logging methods such as LogInformation, LogWarning, LogError, etc., which can be used throughout the service to log necessary information and exceptions.