Mono: Editor and export template dependencies and fixes

- Bundle editor dependencies:
    - 'GodotSharp': Root data directory for the editor
        - 'Tools': Editor dependencies. Only GodotSharp.dll for now.
        - 'Api': Prebuilt GodotSharp and GodotSharpEditor API assemblies.
        - 'Mono': Mono files to bundle with the editor.
            - 'bin': (Optional, not used for now) Mono bin directory.
            - 'etc': Mono configuration files.
            - 'lib': Mono dependency shared libraries.
            - 'lib/mono/4.5': Framework assemblies.
    - Added build option to copy the required files from the mono installation to 'GodotSharp/Mono'. Enable with 'copy_mono_root=yes'. Disabled by default.

- Export template dependencies:
    - 'data_AppName'/'data_Godot':
        - 'Mono': Mono files to bundle with the game.
            - 'etc': Mono configuration files.
            - 'lib': Mono dependency shared libraries.
    - The data directory is generated when compiling and must be bundled with the export templates. In the case of OSX, the data directory must be placed inside the 'osx.zip' export template.
    - In OSX, alternative location for directories (needed for app bundles) are:
        - 'data_AppName/Mono/etc' --> '../Resources/GodotSharp/Mono/etc'
        - 'data_AppName/Mono/lib' --> '../Frameworks/GodotSharp/Mono/lib'

- The editor can bundle prebuilt API assemblies.
    - Generate them with a tools build by running: `--generate-cs-core-api <GodotSharp_OutputDir> --generate-cs-editor-api <GodotSharpEditor_OutputDir> <GodotSharp_OutputDir>/bin/Release/GodotSharp.dll` (This command will be simplified in the future and both projects will be in the same solution)
    - Build the solutions and copy the output files to '#bin/GodotSharp/Api'.
- Fixed API assembly being added twice during the export process.

2 files changed, 73 insertions, 0 deletions

diff --git a/modules/mono/editor/GodotSharpTools/Editor/GodotSharpExport.cs b/modules/mono/editor/GodotSharpTools/Editor/GodotSharpExport.cs
new file mode 100644
index 0000000000..9f0d562ef7
--- /dev/null
+++ b/modules/mono/editor/GodotSharpTools/Editor/GodotSharpExport.cs
@@ -0,0 +1,72 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Runtime.CompilerServices;
+
+namespace GodotSharpTools.Editor
+{
+    public static class GodotSharpExport
+    {
+        public static void _ExportBegin(string[] features, bool debug, string path, int flags)
+        {
+            var featureSet = new HashSet<string>(features);
+
+            if (PlatformHasTemplateDir(featureSet))
+            {
+                string templateDirName = "data.mono";
+
+                if (featureSet.Contains("Windows"))
+                {
+                    templateDirName += ".windows";
+                    templateDirName += featureSet.Contains("64") ? ".64" : ".32";
+                }
+                else if (featureSet.Contains("X11"))
+                {
+                    templateDirName += ".x11";
+                    templateDirName += featureSet.Contains("64") ? ".64" : ".32";
+                }
+                else
+                {
+                    throw new NotSupportedException("Target platform not supported");
+                }
+
+                templateDirName += debug ? ".debug" : ".release";
+
+                string templateDirPath = Path.Combine(GetTemplatesDir(), templateDirName);
+
+                if (!Directory.Exists(templateDirPath))
+                    throw new FileNotFoundException("Data template directory not found");
+
+                string outputDir = new FileInfo(path).Directory.FullName;
+
+                string outputDataDir = Path.Combine(outputDir, GetDataDirName());
+
+                Directory.Delete(outputDataDir, recursive: true); // Clean first
+                Directory.CreateDirectory(outputDataDir);
+                
+                foreach (string dir in Directory.GetDirectories(templateDirPath, "*", SearchOption.AllDirectories))
+                {
+                    Directory.CreateDirectory(Path.Combine(outputDataDir, dir.Substring(templateDirPath.Length + 1)));
+                }
+
+                foreach (string file in Directory.GetFiles(templateDirPath, "*", SearchOption.AllDirectories))
+                {
+                    File.Copy(file, Path.Combine(outputDataDir, file.Substring(templateDirPath.Length + 1)));
+                }
+            }
+        }
+
+        public static bool PlatformHasTemplateDir(HashSet<string> featureSet)
+        {
+            // OSX export templates are contained in a zip, so we place
+            // our custom template inside it and let Godot do the rest.
+            return !featureSet.Contains("OSX");
+        }
+
+        [MethodImpl(MethodImplOptions.InternalCall)]
+        extern static string GetTemplatesDir();
+
+        [MethodImpl(MethodImplOptions.InternalCall)]
+        extern static string GetDataDirName();
+    }
+}
diff --git a/modules/mono/editor/GodotSharpTools/GodotSharpTools.csproj b/modules/mono/editor/GodotSharpTools/GodotSharpTools.csproj
index 773e8196f7..fceb732426 100644
--- a/modules/mono/editor/GodotSharpTools/GodotSharpTools.csproj
+++ b/modules/mono/editor/GodotSharpTools/GodotSharpTools.csproj
@@ -41,6 +41,7 @@
     <Compile Include="Project\ProjectUtils.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="Utils\OS.cs" />
+    <Compile Include="Editor\GodotSharpExport.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
 </Project>
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