android add google diff-match-patch

Author: lisong

android/app/src/main/java/com/microsoft/codepush/react/CodePushUpdateManager.java

@@ -226,6 +226,7 @@ public void downloadPackage(JSONObject updatePackage, String expectedBundleFileN
             if (isDiffUpdate) {
                 String currentPackageFolderPath = getCurrentPackageFolderPath();
                 CodePushUpdateUtils.copyNecessaryFilesFromCurrentPackage(diffManifestFilePath, currentPackageFolderPath, newUpdateFolderPath);
+                CodePushUpdateUtils.diffPatchApplyNecessaryFilesFromCurrentPackage(diffManifestFilePath, currentPackageFolderPath, unzippedFolderPath);
                 File diffManifestFile = new File(diffManifestFilePath);
                 diffManifestFile.delete();
             }

android/app/src/main/java/com/microsoft/codepush/react/CodePushUpdateUtils.java

@@ -29,6 +29,8 @@
 import java.util.Collections;
 import java.util.Map;
 
+import name.fraser.neil.plaintext.diff_match_patch;
+
 public class CodePushUpdateUtils {
 
     public static final String NEW_LINE = System.getProperty("line.separator");
@@ -113,6 +115,26 @@ public static void copyNecessaryFilesFromCurrentPackage(String diffManifestFileP
         }
     }
 
+    public static void diffPatchApplyNecessaryFilesFromCurrentPackage(String diffManifestFilePath, String currentPackageFolderPath, String unzippedFolderPath) throws IOException {
+        diff_match_patch dmp = new diff_match_patch();
+        JSONObject diffManifest = CodePushUtils.getJsonObjectFromFile(diffManifestFilePath);
+        try {
+            JSONArray patchedFiles = diffManifest.getJSONArray("patchedFiles");
+            for (int i = 0; i < patchedFiles.length(); i++) {
+                String fileNameToPatch = patchedFiles.getString(i);
+                File fileToPatch = new File(currentPackageFolderPath, fileNameToPatch);
+                File patchFile = new File(unzippedFolderPath, fileNameToPatch);
+                if (fileToPatch.exists() && patchFile.exists()) {
+                    List<diff_match_patch.Patch> patches = dmp.patch_fromText(FileUtils.readFileToString(patchFile.getAbsolutePath()));
+                    Object[] results = dmp.patch_apply((LinkedList<diff_match_patch.Patch>) patches, FileUtils.readFileToString(fileToPatch.getAbsolutePath()));
+                    FileUtils.writeStringToFile((String) results[0], patchFile.getAbsolutePath());
+                }
+            }
+        } catch (JSONException e) {
+            throw new CodePushUnknownException("Unable to diff-patch-apply files from current package during diff update", e);
+        }
+    }
+
     public static String findJSBundleInUpdateContents(String folderPath, String expectedFileName) {
         File folder = new File(folderPath);
         File[] folderFiles = folder.listFiles();