android - holder-based updater for certificate

If holder exsists, check string (version) of assets creation.
If it differs from current app version or null, try delete certificates forder contents
for unpacking new certificates.

android/src/org/purplei2p/i2pd/I2PDActivity.java

@@ -1,7 +1,9 @@
 package org.purplei2p.i2pd;
 
 import java.io.File;
+import java.io.FileReader;
 import java.io.FileWriter;
+import java.io.BufferedReader;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
@@ -35,6 +37,7 @@ public class I2PDActivity extends Activity {
 
 	private TextView textView;
 	private boolean assetsCopied;
+	private String i2pdpath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/i2pd/";
 
 	private static final DaemonSingleton daemon = DaemonSingleton.getInstance();
 
@@ -43,31 +46,7 @@ public class I2PDActivity extends Activity {
 		@Override
 		public void daemonStateUpdate()
 		{
-			try
-			{
-				// copy assets
-				if (!assetsCopied)
-				{
-					copyAsset("certificates");
-					copyAsset("i2pd.conf");
-					copyAsset("subscriptions.txt");
-					copyAsset("tunnels.conf");
-					assetsCopied = true;
-
-					// create holder file about successful copying
-					File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/i2pd/", "assets.ready");
-					FileWriter writer = new FileWriter(file);
-					String versionName = BuildConfig.VERSION_NAME; // here will be 2.XX.0
-					writer.append(versionName);
-					writer.flush();
-					writer.close();
-				}
-			}
-			catch (Throwable tr)
-			{
-				Log.e(TAG,"copy assets",tr);
-			};
-
+			processAssets();
 			runOnUiThread(new Runnable(){
 
 				@Override
@@ -343,7 +322,7 @@ public class I2PDActivity extends Activity {
 			throw new IOException();
 
 			// Make the directory.
-			File dir = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/i2pd/", path);
+			File dir = new File(i2pdpath, path);
 			dir.mkdirs();
 
 			// Recurse on the contents.
@@ -363,7 +342,7 @@ public class I2PDActivity extends Activity {
 		* Path to asset, relative to app's assets directory.
 	*/
 	private void copyFileAsset(String path) {
-		File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/i2pd/", path);
+		File file = new File(i2pdpath, path);
 		if(!file.exists()) try {
 			InputStream in = getAssets().open(path);
 			OutputStream out = new FileOutputStream(file);
@@ -379,4 +358,62 @@ public class I2PDActivity extends Activity {
 			Log.e(TAG, "", e);
 		}
 	}
+
+	private void deleteRecursive(File fileOrDirectory) {
+		if (fileOrDirectory.isDirectory()) {
+			for (File child : fileOrDirectory.listFiles()) {
+				deleteRecursive(child);
+			}
+		}
+		fileOrDirectory.delete();
+	}
+
+	private void processAssets() {
+		if (!assetsCopied) try {
+			assetsCopied = true; // prevent from running on every state update
+
+			File holderfile = new File(i2pdpath, "assets.ready");
+			String versionName = BuildConfig.VERSION_NAME; // here will be app version, like 2.XX.XX
+			StringBuilder text = new StringBuilder();
+
+			if (holderfile.exists()) try { // if holder file exists, read assets version string
+				BufferedReader br = new BufferedReader(new FileReader(holderfile));
+				String line;
+
+				while ((line = br.readLine()) != null) {
+					text.append(line);
+				}
+				br.close();
+			}
+			catch (IOException e) {
+				Log.e(TAG, "", e);
+			}
+
+			// if version differs from current app version or null, try to delete certificates folder
+			if (!text.toString().contains(versionName)) try {
+				holderfile.delete();
+				File certpath = new File(i2pdpath, "certificates");
+				deleteRecursive(certpath);
+			}
+			catch (Throwable tr) {
+				Log.e(TAG, "", tr);
+			}
+
+			// copy assets. If processed file exists, it won't be overwrited
+			copyAsset("certificates");
+			copyAsset("i2pd.conf");
+			copyAsset("subscriptions.txt");
+			copyAsset("tunnels.conf");
+
+			// update holder file about successful copying
+			FileWriter writer = new FileWriter(holderfile);
+			writer.append(versionName);
+			writer.flush();
+			writer.close();
+		}
+		catch (Throwable tr)
+		{
+			Log.e(TAG,"copy assets",tr);
+		}
+	}
 }