SNote/Server/Program.cs

using System;
using System.IO;
using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using SNote.Server.Data;
using SNote.Server.Endpoints;
using SNote.Server.Security;

namespace SNote.Server;

public class Program
{
    public static void Main(string[] args)
    {
        var builder = WebApplication.CreateBuilder(args);

        // Add Configuration & DB Context (SQLite)
        var dbPath = Path.Combine(AppContext.BaseDirectory, "snote_server.db");
        builder.Services.AddDbContext<ServerDbContext>(options =>
            options.UseSqlite($"Data Source={dbPath}"));

        // Register custom security managers & HTTP utilities
        builder.Services.AddSingleton<CertificateManager>();
        builder.Services.AddSingleton<RsaKeyManager>();
        builder.Services.AddSingleton<PeerCache>();
        builder.Services.AddSingleton<HttpClient>();

        // Register OpenAPI explorer
        builder.Services.AddOpenApi();

        var app = builder.Build();

        // 1. Initialize SQLite Database Schema
        using (var scope = app.Services.CreateScope())
        {
            var db = scope.ServiceProvider.GetRequiredService<ServerDbContext>();
            db.Database.EnsureCreated();
        }

        // Configure Development Tools
        if (app.Environment.IsDevelopment())
        {
            app.MapOpenApi();
        }

        // 2. Map Modular API Endpoint Classes
        app.MapAuthEndpoints();
        app.MapNodeEndpoints();
        app.MapSyncEndpoints();

        // Welcome / Healthcheck root
        app.MapGet("/", () => Results.Ok(new
        {
            service = "SNote Server",
            status = "Online",
            time = DateTime.UtcNow
        }));

        // 3. Start Background Sync Runner
        var hostApplicationLifetime = app.Services.GetRequiredService<IHostApplicationLifetime>();
        var services = app.Services;
        
        var config = app.Configuration;

        // Dynamic Handshake & Bootstrapping: Connect to target destination server on startup, and optionally bootstrap
        var destUrl = config["Sync:DestinationServerUrl"];
        var localUrl = config["Sync:LocalServerUrl"];
        if (!string.IsNullOrEmpty(destUrl) && !string.IsNullOrEmpty(localUrl))
        {
            Task.Run(async () =>
            {
                // Wait briefly for server startup
                await Task.Delay(2000);
                using var scope = services.CreateScope();
                var rsaKeyManager = scope.ServiceProvider.GetRequiredService<RsaKeyManager>();
                var configuration = scope.ServiceProvider.GetRequiredService<IConfiguration>();
                var client = scope.ServiceProvider.GetRequiredService<HttpClient>();
                
                // 1. Perform handshake
                await SyncEndpoints.RegisterPeerWithDestinationAsync(destUrl, localUrl, rsaKeyManager, configuration, client);
                
                // 2. Check if we have successfully handshaked and obtained a token
                if (!string.IsNullOrEmpty(SyncEndpoints.UpstreamSessionToken))
                {
                    var bootstrapMode = configuration["Sync:BootstrapFromUpstream"] ?? "Never";
                    bool doBootstrap = false;
                    
                    if (string.Equals(bootstrapMode, "Always", StringComparison.OrdinalIgnoreCase))
                    {
                        doBootstrap = true;
                    }
                    else if (string.Equals(bootstrapMode, "FirstTime", StringComparison.OrdinalIgnoreCase))
                    {
                        var flagPath = Path.Combine(AppContext.BaseDirectory, "snote_bootstrapped.flag");
                        if (!File.Exists(flagPath))
                        {
                            doBootstrap = true;
                        }
                        else
                        {
                            Console.WriteLine("[Bootstrap] Skipped because BootstrapFromUpstream is set to FirstTime and server has bootstrapped before.");
                        }
                    }
                    
                    if (doBootstrap)
                    {
                        var db = scope.ServiceProvider.GetRequiredService<ServerDbContext>();
                        await SyncEndpoints.BootstrapFromPeerServerAsync(destUrl, localUrl, SyncEndpoints.UpstreamSessionToken, db, client);
                        
                        // If it's FirstTime, write the flag file
                        if (string.Equals(bootstrapMode, "FirstTime", StringComparison.OrdinalIgnoreCase))
                        {
                            try
                            {
                                var flagPath = Path.Combine(AppContext.BaseDirectory, "snote_bootstrapped.flag");
                                await File.WriteAllTextAsync(flagPath, DateTime.UtcNow.ToString("o"));
                                Console.WriteLine("[Bootstrap] Wrote bootstrap flag file.");
                            }
                            catch (Exception ex)
                            {
                                Console.WriteLine($"[Bootstrap] Warning: Could not write bootstrap flag file: {ex.Message}");
                            }
                        }
                    }
                }
                else
                {
                    Console.WriteLine("[Bootstrap] Skipped because handshake failed (no token obtained).");
                }
            });
        }

        // Heartbeat Loop: Periodic Downstream Heartbeat pinger pings downstream peers every 30 seconds
        Task.Run(async () =>
        {
            var token = hostApplicationLifetime.ApplicationStopping;
            using var scope = services.CreateScope();
            var peerCache = scope.ServiceProvider.GetRequiredService<PeerCache>();
            var rsaKeyManager = scope.ServiceProvider.GetRequiredService<RsaKeyManager>();
            var client = scope.ServiceProvider.GetRequiredService<HttpClient>();
            await SyncEndpoints.StartHeartbeatPingerAsync(peerCache, rsaKeyManager, client, token);
        });

        app.Run();
    }
}