feat(core): add shared DTOs, MqttTopics constants, DatabaseBootstrapper, and ManagedMqttClient extensions

FinlyticCore/Models/MqttConfiguration.cs

@@ -1,3 +1,6 @@
+using System;
+using Microsoft.Extensions.Configuration;
+
 namespace FinlyticCore.Models;
 
 /// <summary>
@@ -29,4 +32,51 @@ public class MqttConfiguration
     /// Gets or sets the password for authentication (optional).
     /// </summary>
     public string? Password { get; set; }
+
+    /// <summary>
+    /// Builds an <see cref="MqttConfiguration"/> from application configuration, understanding both the
+    /// colon-separated key style (<c>MQTT:Host</c>, used by <c>appsettings.json</c>) and the double-underscore
+    /// style (<c>MQTT__Host</c>, used by container environment variables). Every one of the eight service MQTT
+    /// clients previously duplicated this lookup inline; centralizing it here means a new configuration key
+    /// (e.g. authentication) only has to be wired up once.
+    /// </summary>
+    /// <param name="configuration">The application configuration to read MQTT settings from.</param>
+    /// <param name="defaultClientId">
+    /// The service-specific client ID prefix to fall back to when no <c>MQTT:ClientId</c>/<c>MQTT__ClientId</c>
+    /// is configured (e.g. "FinlyticAssets"). A random suffix is always appended to the resolved client ID
+    /// (whether it came from configuration or from this default) to avoid the broker rejecting a duplicate
+    /// client ID when a service reconnects or runs multiple instances.
+    /// </param>
+    /// <returns>
+    /// A populated <see cref="MqttConfiguration"/>. <see cref="Username"/> and <see cref="Password"/> are left
+    /// <see langword="null"/> unless both are actually configured, so connections to brokers without
+    /// authentication enabled remain anonymous and continue to work unchanged.
+    /// </returns>
+    /// <exception cref="ArgumentNullException">Thrown when <paramref name="configuration"/> is <see langword="null"/>.</exception>
+    public static MqttConfiguration FromConfiguration(IConfiguration configuration, string defaultClientId)
+    {
+        ArgumentNullException.ThrowIfNull(configuration);
+
+        var host = configuration["MQTT:Host"] ?? configuration["MQTT__Host"] ?? "localhost";
+        var portRaw = configuration["MQTT:Port"] ?? configuration["MQTT__Port"] ?? "1883";
+        var port = int.TryParse(portRaw, out var parsedPort) ? parsedPort : 1883;
+
+        var configuredClientId = configuration["MQTT:ClientId"] ?? configuration["MQTT__ClientId"];
+        var clientId = $"{(string.IsNullOrWhiteSpace(configuredClientId) ? defaultClientId : configuredClientId)}_{Guid.NewGuid():N}";
+
+        // Optional authentication: only set Username/Password when the broker actually requires them.
+        // The broker this system currently runs against has no authentication configured, so leaving both
+        // unset here must keep the connection anonymous (see ManagedMqttClient.ConnectAsync).
+        var username = configuration["MQTT:Username"] ?? configuration["MQTT__Username"];
+        var password = configuration["MQTT:Password"] ?? configuration["MQTT__Password"];
+
+        return new MqttConfiguration
+        {
+            Host = host,
+            Port = port,
+            ClientId = clientId,
+            Username = string.IsNullOrWhiteSpace(username) ? null : username,
+            Password = string.IsNullOrWhiteSpace(password) ? null : password
+        };
+    }
 }