Building a .NET CLI Tool with .NET 8

using System.Net.Http;
using System.Net.Http.Json;

class Program
{
    static async Task Main(string[] args)
    {
        if (args.Length == 0)
        {
            Console.WriteLine("Usage: weathercli <city>");
            Console.WriteLine("Example: weathercli Tokyo");
            return;
        }

        string city = string.Join(" ", args);
        string? apiKey = Environment.GetEnvironmentVariable("OPENWEATHER_API_KEY");

        if (string.IsNullOrWhiteSpace(apiKey))
        {
            Console.WriteLine("❌ ERROR: OpenWeatherMap API key not found.");
            Console.WriteLine("Set it using: export OPENWEATHER_API_KEY=your_key");
            return;
        }

        string url = $"https://api.openweathermap.org/data/2.5/weather?q={city}&appid={apiKey}&units=metric";

        try
        {
            using HttpClient client = new();
            var weather = await client.GetFromJsonAsync<WeatherResponse>(url);

            if (weather is not null)
            {
                Console.WriteLine($"\n🌍 City: {weather.Name}");
                Console.WriteLine($"🌡 Temperature: {weather.Main.Temp}°C");
                Console.WriteLine($"🌦 Condition: {weather.Weather[0].Main} ({weather.Weather[0].Description})");
                Console.WriteLine($"💨 Wind: {weather.Wind.Speed} m/s\n");
            }
            else
            {
                Console.WriteLine("❌ Could not retrieve weather data.");
            }
        }
        catch (HttpRequestException)
        {
            Console.WriteLine("❌ Network error. Please check your internet connection.");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"❌ Unexpected error: {ex.Message}");
        }
    }
}

// API Response Models
public class WeatherResponse
{
    public string Name { get; set; }
    public MainWeather Main { get; set; }
    public List<WeatherInfo> Weather { get; set; }
    public Wind Wind { get; set; }
}

public class MainWeather
{
    public double Temp { get; set; }
}

public class WeatherInfo
{
    public string Main { get; set; }
    public string Description { get; set; }
}

public class Wind
{
    public double Speed { get; set; }
}