Fixed VersionHandler and IOSResolver compatibility with Unity 4.

Unity 4 doesn't have the UnityEngine.PluginImporter class and
stores the Xcode DLL in a yet another location.

Since the PluginImporter is not available in Unity 4,
VersionHandler targetting is disabled as it's not possible
- without hacking .meta files - to enable / disable targeting
for plugins (DLLs).

As the Mono distribution is slightly different, the IOSResolver
has been modified to only call methods that use the Xcode
plugin in separate methods after the workaround for loading
the plugin has been installed.  In addition, since the Xcode DLL
seemingly moves with each Unity OSX release, a brute force file
search is now used to search for the Xcode DLL if it isn't in
the default location.

BUG=31336359

Change-Id: Ia45055abd460b10a018f3a1623833a558283e646

Author: Stewart Miles

exploded/Assets/PlayServicesResolver/Editor/Google.IOSResolver_v1.2.1.0.dll

@@ -22,7 +22,6 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Reflection;
-using UnityEditor.iOS.Xcode;
 using UnityEditor;
 using UnityEditor.Callbacks;
 using UnityEngine;
@@ -186,27 +185,27 @@ public static SortedDictionary<int, List<string>>
     private static string IOS_PLAYBACK_ENGINES_PATH =
         Path.Combine("PlaybackEngines", "iOSSupport");
 
-    // Search for a directory up to a maximum search depth stopping the
-    // depth first search each time the specified directory is found.
-    private static List<string> FindDirectory(
-            string searchPath, string directoryToFind, int maxDepth,
+    // Search for a file up to a maximum search depth stopping the
+    // depth first search each time the specified file is found.
+    private static List<string> FindFile(
+            string searchPath, string fileToFind, int maxDepth,
             int currentDepth = 0) {
-        if (Path.GetFileName(searchPath) == directoryToFind) {
+        if (Path.GetFileName(searchPath) == fileToFind) {
             return new List<string> { searchPath };
         } else if (maxDepth == currentDepth) {
             return new List<string>();
         }
-        var foundDirs = new List<string>();
-        foreach (var dir in Directory.GetDirectories(searchPath)) {
-            if (Path.GetFileName(dir) == directoryToFind) {
-                foundDirs.Add(dir);
-            } else {
-                foundDirs.AddRange(FindDirectory(
-                    dir, directoryToFind, maxDepth,
-                    currentDepth: currentDepth + 1));
+        var foundFiles = new List<string>();
+        foreach (var file in Directory.GetFiles(searchPath)) {
+            if (Path.GetFileName(file) == fileToFind) {
+                foundFiles.Add(file);
             }
         }
-        return foundDirs;
+        foreach (var dir in Directory.GetDirectories(searchPath)) {
+            foundFiles.AddRange(FindFile(dir, fileToFind, maxDepth,
+                                         currentDepth: currentDepth + 1));
+        }
+        return foundFiles;
     }
 
     // Try to load the Xcode editor extension.
@@ -218,47 +217,55 @@ private static Assembly ResolveUnityEditoriOSXcodeExtension(
         // Unity.iOS.Extensions.Xcode.  Catch this and redirect the load to
         // the UnityEditor.iOS.Extensions.Xcode.
         string assemblyName = (new AssemblyName(args.Name)).Name;
-        if (!assemblyName.Equals("Unity.iOS.Extensions.Xcode")) {
+        if (!(assemblyName.Equals("Unity.iOS.Extensions.Xcode") ||
+              assemblyName.Equals("UnityEditor.iOS.Extensions.Xcode"))) {
             return null;
         }
+        Log("Trying to load assembly: " + assemblyName, verbose: true);
         iOSXcodeExtensionLoaded = false;
         string fixedAssemblyName =
             assemblyName.Replace("Unity.", "UnityEditor.") + ".dll";
+        Log("Redirecting to assembly name: " + fixedAssemblyName,
+            verbose: true);
 
-        // Find the playback engines folder.
+        // Get the managed DLLs folder.
         string folderPath = Path.GetDirectoryName(
             Assembly.GetAssembly(
                 typeof(UnityEditor.AssetPostprocessor)).Location);
-        if (UnityEngine.RuntimePlatform.OSXEditor ==
-            UnityEngine.Application.platform) {
-            // Unity likes to move their DLLs around between releases to keep
-            // us on our toes, so search for the PlaybackEngines folder under
-            // the package path.
+        // Try searching a common install location.
+        folderPath = Path.Combine(
+            (new DirectoryInfo(folderPath)).Parent.FullName,
+            IOS_PLAYBACK_ENGINES_PATH);
+        string assemblyPath = Path.Combine(folderPath, fixedAssemblyName);
+        if (!File.Exists(assemblyPath)) {
             string searchPath = (new DirectoryInfo(folderPath)).FullName;
-            searchPath = Path.GetDirectoryName(
-                searchPath.Substring(0, searchPath.LastIndexOf(".app")));
-            foreach (var directory in
-                     FindDirectory(
-                         searchPath,
-                         Path.GetFileName(IOS_PLAYBACK_ENGINES_PATH), 3)) {
-                if (File.Exists(Path.Combine(directory, fixedAssemblyName))) {
-                    folderPath = directory;
-                    break;
-                }
+            if (UnityEngine.RuntimePlatform.OSXEditor ==
+                UnityEngine.Application.platform) {
+                // Unity likes to move their DLLs around between releases to
+                // keep us on our toes, so search for the DLL under the
+                // package path.
+                searchPath = Path.GetDirectoryName(
+                    searchPath.Substring(0, searchPath.LastIndexOf(".app")));
+            } else {
+                // Search under the Data directory.
+                searchPath = Path.GetDirectoryName(
+                    searchPath.Substring(
+                        0, searchPath.LastIndexOf(
+                            "Data" + Path.DirectorySeparatorChar.ToString())));
             }
-        } else {
-            folderPath = Path.Combine(
-                (new DirectoryInfo(folderPath)).Parent.FullName,
-                IOS_PLAYBACK_ENGINES_PATH);
+            Log("Searching for assembly under " + searchPath, verbose: true);
+            var files = FindFile(searchPath, fixedAssemblyName, 5);
+            if (files.Count > 0) assemblyPath = files.ToArray()[0];
         }
-
         // Try to load the assembly.
-        string assemblyPath = Path.Combine(folderPath, fixedAssemblyName);
         if (!File.Exists(assemblyPath)) {
-          return null;
+            Log(assemblyPath + " does not exist", verbose: true);
+            return null;
         }
+        Log("Loading " + assemblyPath, verbose: true);
         Assembly assembly = Assembly.LoadFrom(assemblyPath);
         if (assembly != null) {
+            Log("Load succeeded from " + assemblyPath, verbose: true);
             iOSXcodeExtensionLoaded = true;
         }
         return assembly;
@@ -268,10 +275,22 @@ private static Assembly ResolveUnityEditoriOSXcodeExtension(
     /// Initialize the module.
     /// </summary>
     static IOSResolver() {
+        // NOTE: We can't reference the UnityEditor.iOS.Xcode module in this
+        // method as the Mono runtime in Unity 4 and below requires all
+        // dependencies of a method are loaded before the method is executed
+        // so we install the DLL loader first then try using the Xcode module.
         RemapXcodeExtension();
+        InitializeTargetName();
+    }
+
+    /// <summary>
+    /// Initialize the TARGET_NAME property.
+    /// </summary>
+    private static void InitializeTargetName() {
         try {
-            TARGET_NAME = PBXProject.GetUnityTargetName();
+            TARGET_NAME = UnityEditor.iOS.Xcode.PBXProject.GetUnityTargetName();
         } catch (Exception exception) {
+            Debug.Log("Failed: " + exception.ToString());
             if (exception is FileNotFoundException ||
                 exception is TypeInitializationException ||
                 exception is TargetInvocationException) {
@@ -561,10 +580,9 @@ public static void OnPostProcessPatchProject(BuildTarget buildTarget,
                 String.Join(", ", podsWithoutBitcode.ToArray()) + ")",
                 level: LogLevel.Warning);
         }
-
         // Configure project settings for Cocoapods.
         string pbxprojPath = GetProjectPath(pathToBuiltProject);
-        PBXProject project = new PBXProject();
+        var project = new UnityEditor.iOS.Xcode.PBXProject();
         project.ReadFromString(File.ReadAllText(pbxprojPath));
         string target = project.TargetGuidByName(TARGET_NAME);
         project.SetBuildProperty(target, "CLANG_ENABLE_MODULES", "YES");
@@ -680,7 +698,7 @@ public static void OnPostProcessUpdateProjectDeps(
                                                "Resources"));
 
         string pbxprojPath = GetProjectPath(pathToBuiltProject);
-        PBXProject project = new PBXProject();
+        var project = new UnityEditor.iOS.Xcode.PBXProject();
         project.ReadFromString(File.ReadAllText(pbxprojPath));
         string target = project.TargetGuidByName(TARGET_NAME);
 
@@ -707,10 +725,11 @@ public static void OnPostProcessUpdateProjectDeps(
             PlayServicesSupport.DeleteExistingFileOrDirectory(
                 destFrameworkFullPath);
             Directory.Move(frameworkFullPath, destFrameworkFullPath);
-            project.AddFileToBuild(target,
-                                   project.AddFile(destFrameworkPath,
-                                                   destFrameworkPath,
-                                                   PBXSourceTree.Source));
+            project.AddFileToBuild(
+                target,
+                project.AddFile(destFrameworkPath,
+                                destFrameworkPath,
+                                UnityEditor.iOS.Xcode.PBXSourceTree.Source));
 
             string moduleMapPath =
                 Path.Combine(Path.Combine(destFrameworkFullPath, "Modules"),
@@ -752,8 +771,9 @@ public static void OnPostProcessUpdateProjectDeps(
                     File.Copy(resFile, Path.Combine(pathToBuiltProject,
                                                     destFile), true);
                     project.AddFileToBuild(
-                        target, project.AddFile(destFile, destFile,
-                                                PBXSourceTree.Source));
+                        target, project.AddFile(
+                            destFile, destFile,
+                            UnityEditor.iOS.Xcode.PBXSourceTree.Source));
                 }
                 foreach (var resFolder in resFolders) {
                     string destFolder =
@@ -765,8 +785,9 @@ public static void OnPostProcessUpdateProjectDeps(
                         destFolderFullPath);
                     Directory.Move(resFolder, destFolderFullPath);
                     project.AddFileToBuild(
-                        target, project.AddFile(destFolder, destFolder,
-                                                PBXSourceTree.Source));
+                        target, project.AddFile(
+                            destFolder, destFolder,
+                            UnityEditor.iOS.Xcode.PBXSourceTree.Source));
                 }
             }
         }

exploded/Assets/PlayServicesResolver/Editor/Google.IOSResolver_v1.2.1.0.dll.meta

@@ -437,6 +437,18 @@ public FileMetadata this[long version] {
             }
         }
 
+        /// <summary>
+        /// Determine whether the PluginImporter class is available in
+        /// UnityEditor. Unity 4 does not have this class in which case we
+        /// can't - without potentially dangerously - modify the .meta yaml
+        /// files to enable / disable plugin targeting.
+        /// </summary>
+        internal static bool PluginImporterAvailable {
+            get {
+                return FindClass("UnityEditor", "UnityEditor.PluginImporter") != null;
+            }
+        }
+
         /// <summary>
         /// Construct an instance.
         /// </summary>
@@ -635,6 +647,11 @@ public void Add(FileMetadata metadata) {
         /// AssetDatabase.Refresh(), false otherwise.</return>
         public bool EnableMostRecentPlugins() {
             bool modified = false;
+
+            // If PluginImporter isn't available it's not possible
+            // to enable / disable targeting.
+            if (!FileMetadataByVersion.PluginImporterAvailable) return false;
+
             foreach (var metadataByVersion in
                      metadataByCanonicalFilename.Values) {
                 modified |= metadataByVersion.EnableMostRecentPlugins();