♻️ refactor: make it simple, put logic in one class

Author: hsayed21

Class/MarkerFinder.cs

@@ -89,20 +89,10 @@ private void ProcessBakFile(string filePath)
         {
             lblDragDrop.Text = Path.GetFileName(filePath);
 
-            string output = string.Empty;
-            if (string.IsNullOrEmpty(filePath) || !File.Exists(filePath))
-                output = "Please select a valid .bak file.";
-            else
-                output = sqlVersion.GetVersion(filePath);
-
-            lblVersion.Text = output;
-            if (output.StartsWith("SQL"))
-                lblVersion.ForeColor = Color.LightGreen;
-            else
-                lblVersion.ForeColor = Color.Red;
-
-            if (!lblVersion.Visible)
-                lblVersion.Visible = true;
+            string versionInfo = File.Exists(filePath) ? sqlVersion.GetVersion(filePath) : "File not found";
+            lblVersion.Text = versionInfo;
+            lblVersion.ForeColor = versionInfo.StartsWith("SQL") ? Color.LightGreen : Color.Red;
+            lblVersion.Visible = true;
         }
     }
 }

Class/SQLVersion.cs

@@ -49,10 +49,7 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
-    <Compile Include="Class\MarkerFinder.cs" />
-    <Compile Include="Class\SQLVersion.cs" />
-    <Compile Include="Class\TapeHeaderValidator.cs" />
-    <Compile Include="Class\VersionDeterminer.cs" />
+    <Compile Include="SQLVersion.cs" />
     <Compile Include="Main.cs">
       <SubType>Form</SubType>
     </Compile>

Class/TapeHeaderValidator.cs

@@ -0,0 +1,130 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+
+namespace SQLBakVersion.Class
+{
+    /// <summary>
+    /// Main class for SQL Server version detection from BAK files
+    /// </summary>
+    public class SQLVersion
+    {
+        private const int TapeHeaderStart = 0x45504154; // "TAPE" in little endian
+        private const int MsciMarker = 0x4943534D;      // "MSCI" in little endian
+
+        private static readonly Dictionary<int, string> VersionMap = new Dictionary<int, string>
+        {
+            // SQL Server 2005
+            { 611, "SQL Server 2005" },
+            { 612, "SQL Server 2005" },
+
+            // SQL Server 2008/R2
+            { 655, "SQL Server 2008" },
+            { 660, "SQL Server 2008" },
+            { 661, "SQL Server 2008" },
+
+            // SQL Server 2012
+            { 684, "SQL Server 2012" },
+            { 706, "SQL Server 2012" },
+
+            // SQL Server 2014
+            { 782, "SQL Server 2014" },
+
+            // SQL Server 2016
+            { 852, "SQL Server 2016" },
+
+            // SQL Server 2017
+            { 868, "SQL Server 2017" },
+            { 869, "SQL Server 2017" },
+
+            // SQL Server 2019
+            { 895, "SQL Server 2019" },
+            { 896, "SQL Server 2019" },
+            { 897, "SQL Server 2019" },
+            { 902, "SQL Server 2019" },
+            { 904, "SQL Server 2019" },
+
+            // SQL Server 2022
+            { 950, "SQL Server 2022" },
+            { 957, "SQL Server 2022" }
+        };
+
+        /// <summary>
+        /// Get SQL Server version from a BAK file
+        /// </summary>
+        /// <param name="filePath">Path to the .bak file</param>
+        /// <returns>SQL Server version or error message</returns>
+        public string GetVersion(string filePath)
+        {
+            try
+            {
+                using (FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read))
+                {
+                    // Step 1: Validate the BAK file header
+                    if (!ValidateTapeHeader(fs))
+                    {
+                        return "Not a valid SQL Server backup file";
+                    }
+
+                    // Step 2: Find the version marker
+                    if (!FindVersionMarker(fs))
+                    {
+                        return "SQL version information not found";
+                    }
+
+                    // Step 3: Read the version number
+                    return DetermineVersion(fs);
+                }
+            }
+            catch (IOException ex)
+            {
+                return $"Cannot access file: {ex.Message}";
+            }
+            catch (Exception ex)
+            {
+                return $"Error: {ex.Message}";
+            }
+        }
+
+        /// <summary>
+        /// Validates if the file has a valid SQL BAK header
+        /// </summary>
+        private bool ValidateTapeHeader(FileStream fs)
+        {
+            byte[] headerBytes = new byte[4];
+            if (fs.Read(headerBytes, 0, 4) != 4)
+                return false;
+
+            return BitConverter.ToInt32(headerBytes, 0) == TapeHeaderStart;
+        }
+
+        /// <summary>
+        /// Finds the MSCI marker that precedes version info
+        /// </summary>
+        private bool FindVersionMarker(FileStream fs)
+        {
+            byte[] markerBytes = new byte[4];
+            while (fs.Read(markerBytes, 0, 4) == 4)
+            {
+                if (BitConverter.ToInt32(markerBytes, 0) == MsciMarker)
+                {
+                    return true;
+                }
+            }
+            return false;
+        }
+
+        /// <summary>
+        /// Reads and interprets the SQL Server version number
+        /// </summary>
+        private string DetermineVersion(FileStream fs)
+        {
+            byte[] versionBytes = new byte[2];
+            fs.Seek(168, SeekOrigin.Current);
+            fs.Read(versionBytes, 0, 2);
+            int dbVersion = BitConverter.ToInt16(versionBytes, 0);
+
+            return VersionMap.TryGetValue(dbVersion, out string version) ? version : $"Unknown SQL Server version (code: {dbVersion})";
+        }
+    }
+}