Add project files.

Gateway/Data/SqlServer.cs

@@ -0,0 +1,92 @@
+using System.Data;
+using System.Diagnostics;
+using Microsoft.Data.SqlClient;
+
+namespace Gateway.Data;
+
+public class SqlService
+{
+    private readonly IConfiguration _config;
+    private readonly ILogger<SqlService> _logger;
+
+    public SqlService(IConfiguration config, ILogger<SqlService> logger)
+    {
+        _config = config;
+        _logger = logger;
+    }
+
+    private string GetConnectionString()
+    {
+        // expects env var: ConnectionStrings__Sql
+        var cs = _config.GetConnectionString("Sql");
+        if (string.IsNullOrWhiteSpace(cs))
+            throw new InvalidOperationException("Missing connection string: ConnectionStrings:Sql (env var ConnectionStrings__Sql).");
+        return cs;
+    }
+
+    /// <summary>
+    /// Executes a stored procedure using the standard signature:
+    ///   @action varchar(..),
+    ///   @rqst nvarchar(max),
+    ///   @resp nvarchar(max) OUTPUT
+    /// Returns the output JSON string (resp).
+    /// </summary>
+    public async Task<string> ExecProcAsync(
+        string procName,
+        string action,
+        string rqstJson,
+        int commandTimeoutSeconds = 60,
+        CancellationToken ct = default)
+    {
+        if (string.IsNullOrWhiteSpace(procName))
+            throw new ArgumentException("procName is required.", nameof(procName));
+        if (string.IsNullOrWhiteSpace(action))
+            throw new ArgumentException("action is required.", nameof(action));
+        if (string.IsNullOrWhiteSpace(rqstJson))
+            rqstJson = "{}";
+
+        var sw = Stopwatch.StartNew();
+
+        try
+        {
+            await using var conn = new SqlConnection(GetConnectionString());
+            await conn.OpenAsync(ct);
+
+            await using var cmd = new SqlCommand(procName, conn)
+            {
+                CommandType = CommandType.StoredProcedure,
+                CommandTimeout = commandTimeoutSeconds
+            };
+
+            cmd.Parameters.Add(new SqlParameter("@action", SqlDbType.VarChar, 50) { Value = action });
+            cmd.Parameters.Add(new SqlParameter("@rqst", SqlDbType.NVarChar, -1) { Value = rqstJson });
+
+            var pResp = new SqlParameter("@resp", SqlDbType.NVarChar, -1)
+            {
+                Direction = ParameterDirection.Output
+            };
+            cmd.Parameters.Add(pResp);
+
+            await cmd.ExecuteNonQueryAsync(ct);
+
+            var resp = pResp.Value as string ?? "";
+
+            sw.Stop();
+            _logger.LogInformation("SQL ok: {Proc} action={Action} ms={Ms}", procName, action, sw.ElapsedMilliseconds);
+
+            return resp;
+        }
+        catch (SqlException ex)
+        {
+            sw.Stop();
+            _logger.LogError(ex, "SQL error: {Proc} action={Action} ms={Ms}", procName, action, sw.ElapsedMilliseconds);
+            throw;
+        }
+        catch (Exception ex)
+        {
+            sw.Stop();
+            _logger.LogError(ex, "App error calling SQL: {Proc} action={Action} ms={Ms}", procName, action, sw.ElapsedMilliseconds);
+            throw;
+        }
+    }
+}