OptixServe/OptixServe.Api/Program.cs

using System.CommandLine;
using OptixServe.Api.Endpoints;
using OptixServe.Core.Services;

class Program
{
    /// <summary>
    /// Main method that configures and runs the application
    /// </summary>
    /// <param name="args">Command line arguments</param>
    /// <returns>A Task representing the asynchronous operation</returns>
    static async Task Main(string[] args)
    {
        var rootCommand = new RootCommand("OptixServe API");

        // Configure the --config/-c command line option
        var configOption = new Option<FileInfo?>("--config", "-c")
        {
            Description = "Config file path",
            CustomParser = arg =>
            {
                if (!arg.Tokens.Any()) return null;

                var filePath = arg.Tokens.Single().Value;
                if (!File.Exists(filePath))
                {
                    arg.AddError($"Configuration file not found: {filePath}");
                    return null;
                }
                return new FileInfo(filePath);
            }
        };
        rootCommand.Add(configOption);

        // Set handle for rootCommand
        // The handle prototype and way of parsing arguments
        // is changed in System.CommandLine 2.0.0-beta5
        rootCommand.SetAction((ParseResult parseResult) =>
        {
            var builder = WebApplication.CreateSlimBuilder(args);

            var configFile = parseResult.GetValue(configOption);
            builder.AddConfigurationWithCommand(configFile);

            builder.RegisterServices();
            builder.RegiserJsonContext();

            var app = builder.Build();
            var apiGroup = app.MapGroup("api/v1");
            ExtensionMethods.RegisterEndpoints(apiGroup);

            app.Run();
        });

        // Parse arguments then invoke the command
        var parseResult = rootCommand.Parse(args);
        await parseResult.InvokeAsync();
    }
}


/// <summary>
/// Contains extension methods for WebApplicationBuilder and WebApplication
/// </summary>
static class ExtensionMethods
{
    /// <summary>
    /// Adds configuration sources to the application builder
    /// </summary>
    /// <param name="builder">WebApplicationBuilder instance</param>
    /// <param name="file">Optional configuration file specified via command line</param>
    public static void AddConfigurationWithCommand(this WebApplicationBuilder builder, FileInfo? file)
    {
        // Configure configuration sources in specified order
        var configurationBuilder = new ConfigurationBuilder()
            .SetBasePath(Directory.GetCurrentDirectory())
            .AddJsonFile("appsettings.json", optional: true)
            .AddJsonFile($"appsettings.{builder.Environment.EnvironmentName}.json", optional: true)
            .AddJsonFile("config.json", optional: true)
            .AddJsonFile($"config.{builder.Environment.EnvironmentName}.json", optional: true);

        // Add command-line specified config file if provided
        if (file != null)
        {
            configurationBuilder.AddJsonFile(file.FullName, optional: false);
        }

        builder.Configuration.AddConfiguration(configurationBuilder.Build());
    }

    /// <summary>
    /// Configures JSON serialization options with custom context
    /// </summary>
    /// <param name="builder">WebApplicationBuilder instance</param>
    public static void RegiserJsonContext(this WebApplicationBuilder builder)
    {
        builder.Services.ConfigureHttpJsonOptions(options =>
        {
            options.SerializerOptions.TypeInfoResolverChain.Add(UserJsonContext.Default);
        });
    }

    /// <summary>
    /// Configures services for DI
    /// </summary>
    /// <param name="builder"></param>
    public static void RegisterServices(this WebApplicationBuilder builder)
    {
        // Application services
        builder.Services.AddScoped<IUserService, UserService>();
    }

    /// <summary>
    /// Registers all API endpoints
    /// </summary>
    /// <param name="app">WebApplication instance</param>
    public static void RegisterEndpoints(RouteGroupBuilder rootGroup)
    {
        UserEndpoint.Register(rootGroup);
    }

}