Fix parse error caused by missing dsc module

One solution to solve this is to download the missing modules to a temporary path and then add that temporary path to PSModulePath when isa is run and remove the temp path when isa is finished running. But at this iteration this approach doesn't seem to work and needs further investigation.

The solution, that we pursue, is to download the missing module to a temp path. This temp path and its data is persistent in the sense that the temp path information is stored in $LOCALAPPDATA/PSScriptAnalyzer (pssaappdata). Whenver isa in invoked, it checks the temp path pointed in pssaappdata, checks if the modules are present in the temp directory and if so, copies them to the user psmodule path, which is typcially $HOME/Documents/WindowsPowerShell/Modules. And, when isa is finished running we remove those copied modues from the user psmodule path.

Author: Kapil Borle

Engine/Generic/ModuleDependencyHandler.cs

@@ -18,10 +18,15 @@ public class ModuleDependencyHandler : IDisposable
         private Runspace runspace;
         private readonly string moduleRepository;
         private string tempDirPath;
+        private string localPSModulePath;
         Dictionary<string, PSObject> modulesFound;
-        HashSet<string> modulesSaved;
-        private string oldPSModulePath;
-        private string currentModulePath;
+        HashSet<string> modulesSavedInModulePath;
+        HashSet<string> modulesSavedInTempPath;
+        private string localAppdataPath;
+        private string pssaAppdataPath;
+        private const string symLinkName = "TempModuleDir";
+        private const string tempPrefix = "PSSAModules-";
+        private string symLinkPath;
 
         #endregion Private Variables
 
@@ -36,7 +41,7 @@ public Runspace Runspace
             get { return runspace; }
         }
 
-        #endregion
+        #endregion Properties
 
         #region Private Methods
         private static void ThrowIfNull<T>(T obj, string name)
@@ -46,44 +51,96 @@ private static void ThrowIfNull<T>(T obj, string name)
                 throw new ArgumentNullException(name);
             }            
         }
+
+        private void SetupCache()
+        {
+            // check if pssa exists in local appdata
+            if (Directory.Exists(pssaAppdataPath))
+            {
+                // check if there is a link
+                if (File.Exists(symLinkPath))
+                {
+                    tempDirPath = GetTempDirPath(symLinkPath);
+                    
+                    // check if the temp dir exists
+                    if (tempDirPath != null
+                        && Directory.Exists(tempDirPath))
+                    {
+                        SetModulesInTempPath();
+                        return;
+                    }
+                }
+                SetupTempDir();                
+            }
+            else
+            {
+                Directory.CreateDirectory(pssaAppdataPath);
+                SetupTempDir();
+            }           
+        }
+
+        private void SetModulesInTempPath()
+        {
+            // we assume the modules have not been tampered with
+            foreach (var dir in Directory.EnumerateDirectories(tempDirPath))
+            {
+                modulesSavedInTempPath.Add(Path.GetFileName(dir));
+            }
+        }
+
         private void SetupTempDir()
         {
-            //var tempPath = Path.GetTempPath();
-            //do
-            //{
-            //    tempDirPath = Path.Combine(
-            //        tempPath, 
-            //        Path.GetFileNameWithoutExtension(Path.GetRandomFileName()));
-            //} while (Directory.Exists(tempDirPath));
-            //Directory.CreateDirectory(tempDirPath);
-            tempDirPath = "C:\\Users\\kabawany\\tmp\\modules\\";
+            CreateTempDir();
+            UpdateSymLinkFile();            
         }
 
-        private void RemoveTempDir()
+        private void UpdateSymLinkFile()
         {
-            //Directory.Delete(tempDirPath, true);
+            File.WriteAllLines(symLinkPath, new string[] { tempDirPath });
         }
 
-        private void SetupPSModulePath()
+        private void CreateTempDir()
         {
-            oldPSModulePath = Environment.GetEnvironmentVariable("PSModulePath", EnvironmentVariableTarget.Process);
-            var sb = new StringBuilder();
-            sb.Append(oldPSModulePath)
-                .Append(Path.DirectorySeparatorChar)
-                .Append(tempDirPath);
-            currentModulePath = sb.ToString();
+            tempDirPath = GetTempDirPath();
+            Directory.CreateDirectory(tempDirPath);
+        }
+
+        private string GetTempDirPath()
+        {
+            var tempPathRoot = Path.GetTempPath();
+            string tempPath;
+            do
+            {
+                tempPath = Path.Combine(
+                    tempPathRoot,
+                    tempPrefix + Path.GetFileNameWithoutExtension(Path.GetRandomFileName()));
+            } while (Directory.Exists(tempPath));
+            return tempPath;
+        }
+
+        // Return the first line of the file
+        private string GetTempDirPath(string symLinkPath)
+        {
+            var symLinkLines = File.ReadAllLines(symLinkPath);
+            if(symLinkLines.Length != 1)
+            {
+                return null;
+            }
+            return symLinkLines[0];
         }
 
         private void CleanUp()
         {
             runspace.Dispose();
-            RemoveTempDir();            
-            RestorePSModulePath();
-        }
 
-        private void RestorePSModulePath()
-        {
-            Environment.SetEnvironmentVariable("PSModulePath", oldPSModulePath, EnvironmentVariableTarget.Process);
+            // remove the modules from local psmodule path            
+            foreach (var dir in Directory.EnumerateDirectories(localPSModulePath))
+            {
+                if (modulesSavedInModulePath.Contains(Path.GetFileName(dir)))
+                {
+                    Directory.Delete(dir, true);
+                }
+            }
         }
 
         private void SaveModule(PSObject module)
@@ -98,6 +155,33 @@ private void SaveModule(PSObject module)
             ps.Invoke();
         }
 
+        // TODO Use powershell copy-item
+        private void CopyDir(string srcParentPath,
+            string srcName,
+            string dstParentPath,
+            string dstName = null,
+            bool recurse = false)
+        {
+            if (dstName == null)
+            {
+                dstName = srcName;
+            }
+            var srcPath = Path.Combine(srcParentPath, srcName);
+            var dstPath = Path.Combine(dstParentPath, dstName);
+            Directory.CreateDirectory(dstPath);
+            foreach (var file in Directory.EnumerateFiles(srcPath))
+            {
+                File.Copy(file, Path.Combine(dstPath, Path.GetFileName(file)));
+            }
+            foreach (var dir in Directory.EnumerateDirectories(srcPath))
+            {
+                CopyDir(srcPath,
+                    Path.GetFileName(dir),
+                    dstPath,
+                    recurse: true);
+            }
+        }
+
         #endregion Private Methods
 
         #region Public Methods
@@ -106,10 +190,21 @@ public ModuleDependencyHandler()
         {
             runspace = null;
             moduleRepository = "PSGallery";
-            modulesSaved = new HashSet<string>();
+            modulesSavedInModulePath = new HashSet<string>();
+            modulesSavedInTempPath = new HashSet<string>();
             modulesFound = new Dictionary<string, PSObject>();
-            SetupTempDir();
-            //SetupPSModulePath();           
+
+            // TODO search it in the $psmodulepath instead of constructing it
+            localPSModulePath = Path.Combine(
+                Environment.GetEnvironmentVariable("USERPROFILE"),
+                "Documents\\WindowsPowerShell\\Modules");
+            localAppdataPath = Environment.GetEnvironmentVariable("LOCALAPPDATA");
+
+            // TODO Add PSSA Version in the path
+            pssaAppdataPath = Path.Combine(localAppdataPath, "PSScriptAnalyzer");
+            symLinkPath = Path.Combine(pssaAppdataPath, symLinkName);
+
+            SetupCache();
         }
 
         public ModuleDependencyHandler(Runspace runspace) : this()
@@ -163,13 +258,28 @@ public PSObject FindModule(string moduleName)
             return module;
         }
 
+
+        public bool ModuleExists(string moduleName)
+        {
+            throw new NotImplementedException();
+        }
+
+
         public void SaveModule(string moduleName)
         {
             ThrowIfNull(moduleName, "moduleName");
-            if (modulesSaved.Contains(moduleName))
+            if (modulesSavedInModulePath.Contains(moduleName))
+            {
+                return;
+            }
+            if (modulesSavedInTempPath.Contains(moduleName))
             {
+                // copy to local ps module path
+                CopyDir(tempDirPath, moduleName, localPSModulePath, recurse: true);
+                modulesSavedInModulePath.Add(moduleName);
                 return;
             }
+
             var module = FindModule(moduleName);
             if (module == null)
             {
@@ -180,7 +290,11 @@ public void SaveModule(string moduleName)
                         moduleRepository));
             }            
             SaveModule(module);
-            modulesSaved.Add(moduleName);
+            modulesSavedInTempPath.Add(moduleName);
+
+            // copy to local ps module path
+            CopyDir(tempDirPath, moduleName, localPSModulePath, recurse: true);
+            modulesSavedInModulePath.Add(moduleName);
         }
 
         public static string GetModuleNameFromErrorExtent(ParseError error, ScriptBlockAst ast)
@@ -229,4 +343,4 @@ public void Dispose()
 
         #endregion Public Methods
     }
-}
+}