added Venv query method and checks for existence of files/directories

Author: tg359

Python_Engine/Python_Engine.csproj

@@ -78,6 +78,7 @@
     <Compile Include="Convert\ToPython.cs" />
     <Compile Include="Modify\AddQuotesIfRequired.cs" />
     <Compile Include="Create\VirtualEnvironment.cs" />
+    <Compile Include="Query\VirtualEnv.cs" />
     <Compile Include="Query\VirtualEnvPythonExePath.cs" />
     <Compile Include="Query\VirtualEnvDirectory.cs" />
     <Compile Include="Query\ToString.cs" />

Python_Engine/Query/VirtualEnv.cs

@@ -0,0 +1,42 @@
+/*
+ * This file is part of the Buildings and Habitats object Model (BHoM)
+ * Copyright (c) 2015 - 2022, the respective contributors. All rights reserved.
+ *
+ * Each contributor holds copyright over their respective contributions.
+ * The project versioning (Git) records all such contribution source information.
+ *
+ *
+ * The BHoM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3.0 of the License, or
+ * (at your option) any later version.
+ *
+ * The BHoM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this code. If not, see <https://www.gnu.org/licenses/lgpl-3.0.html>.
+ */
+
+using BH.oM.Base.Attributes;
+using BH.oM.Python;
+using System.ComponentModel;
+using System.IO;
+using System.Xml.Linq;
+
+namespace BH.Engine.Python
+{
+    public static partial class Query
+    {
+        [Description("Get an installed environment without the overhead of attempting to install that environment.")]
+        [Input("envName","The virtual environment name to request.")]
+        [Output("The virtual environment, if it exists.")]
+        public static PythonEnvironment VirtualEnv(string envName)
+        {
+            return new PythonEnvironment() { Executable = VirtualEnvPythonExePath(envName), Name = envName };
+        }
+    }
+}
+

Python_Engine/Query/VirtualEnvDirectory.cs

@@ -35,7 +35,15 @@ public static partial class Query
         [Output("The location where any BHoM generated Python environments reside.")]
         public static string VirtualEnvDirectory(string envName)
         {
-            return Path.Combine(Query.EnvironmentsDirectory(), envName);
+            string directory = Path.Combine(Query.EnvironmentsDirectory(), envName);
+            
+            if (Directory.Exists(directory))
+            {
+                return directory;
+            }
+            
+            BH.Engine.Base.Compute.RecordError($"The virtual environment directory for \"{envName}\" does not exist at \"{directory}\".");
+            return null;
         }
     }
 }

Python_Engine/Query/VirtualEnvPythonExePath.cs

@@ -35,7 +35,15 @@ public static partial class Query
         [Output("The location where a Python virtual environment would reside.")]
         public static string VirtualEnvPythonExePath(string envName)
         {
-            return Path.Combine(VirtualEnvDirectory(envName), "Scripts", "python.exe");
+            string exePath = Path.Combine(VirtualEnvDirectory(envName), "Scripts", "python.exe");
+
+            if (File.Exists(exePath))
+            {
+                return exePath;
+            }
+
+            BH.Engine.Base.Compute.RecordError($"The executable for \"{envName}\" does not exist at \"{exePath}\".");
+            return null;
         }
     }
 }