Update database handling code (#247)

web/backend/Database/Database.Connection/SqlConnectionStringHelper.cs

@@ -0,0 +1,102 @@
+using Microsoft.Data.SqlClient;
+using Microsoft.Extensions.Configuration;
+
+namespace Database.Connection;
+
+/// <summary>
+///     Helper for building SQL Server connection strings from configuration
+///     (backed by the <c>DB_*</c> environment variables).
+/// </summary>
+public static class SqlConnectionStringHelper
+{
+    private static SqlConnectionStringBuilder MakeConfiguredConnectionBuilder(
+        IConfiguration configuration
+    ) =>
+        new()
+        {
+            DataSource = ConfigurationHelpers.GetKeyOrThrow(configuration, "DB_SERVER"),
+            UserID = ConfigurationHelpers.GetKeyOrThrow(configuration, "DB_USER"),
+            Password = ConfigurationHelpers.GetKeyOrThrow(configuration, "DB_PASSWORD"),
+            TrustServerCertificate = ResolveTrustServerCertificate(configuration),
+            Encrypt = true,
+        };
+
+    /// <summary>
+    ///     Builds a SQL Server connection string from configuration.
+    /// </summary>
+    /// <remarks>
+    ///     Returns <c>false</c> if DB_SERVER, DB_NAME, DB_USER, or DB_PASSWORD is unset.
+    /// </remarks>
+    /// <param name="configuration">The configuration to read the <c>DB_*</c> values from.</param>
+    /// <param name="connectionString">The resolved connection string, if successful.</param>
+    public static bool TryGetStandardDbConnectionString(
+        IConfiguration configuration,
+        out string connectionString
+    )
+    {
+        connectionString = string.Empty;
+        try
+        {
+            SqlConnectionStringBuilder builder = MakeConfiguredConnectionBuilder(configuration);
+            builder.InitialCatalog = ConfigurationHelpers.GetKeyOrThrow(configuration, "DB_NAME");
+            connectionString = builder.ConnectionString;
+            return true;
+        }
+        catch
+        {
+            return false;
+        }
+    }
+
+    public static bool TryGetMasterConnectionString(
+        IConfiguration configuration,
+        out string connectionString
+    )
+    {
+        connectionString = string.Empty;
+        try
+        {
+            var builder = MakeConfiguredConnectionBuilder(configuration);
+            builder.InitialCatalog = "master";
+
+            connectionString = builder.ConnectionString;
+
+            return true;
+        }
+        catch
+        {
+            return false;
+        }
+    }
+
+    public static bool TryGetDatabaseNameFromConnectionString(
+        string connectionString,
+        out string databaseName
+    )
+    {
+        databaseName = string.Empty;
+
+        try
+        {
+            var builder = new SqlConnectionStringBuilder(connectionString);
+            databaseName = builder.InitialCatalog;
+            return true;
+        }
+        catch
+        {
+            return false;
+        }
+    }
+
+    /// <summary>
+    ///     Resolves the <c>DB_TRUST_SERVER_CERTIFICATE</c> configuration value, defaulting to
+    ///     <c>true</c> when it is unset or not a valid boolean.
+    /// </summary>
+    private static bool ResolveTrustServerCertificate(IConfiguration configuration)
+    {
+        return !bool.TryParse(
+                configuration["DB_TRUST_SERVER_CERTIFICATE"],
+                out bool trustServerCertificate
+            ) || trustServerCertificate;
+    }
+}