diff --git a/mobile/src/main/java/com/github/shadowsocks/utils/Commandline.java b/mobile/src/main/java/com/github/shadowsocks/utils/Commandline.java
new file mode 100644
index 00000000..112df2d5
--- /dev/null
+++ b/mobile/src/main/java/com/github/shadowsocks/utils/Commandline.java
@@ -0,0 +1,146 @@
+package com.github.shadowsocks.utils;
+
+import java.util.ArrayList;
+import java.util.StringTokenizer;
+
+/**
+ * Commandline objects help handling command lines specifying processes to
+ * execute.
+ *
+ * The class can be used to define a command line as nested elements or as a
+ * helper to define a command line by an application.
+ * <p>
+ * <code>
+ * &lt;someelement&gt;<br>
+ * &nbsp;&nbsp;&lt;acommandline executable="/executable/to/run"&gt;<br>
+ * &nbsp;&nbsp;&nbsp;&nbsp;&lt;argument value="argument 1" /&gt;<br>
+ * &nbsp;&nbsp;&nbsp;&nbsp;&lt;argument line="argument_1 argument_2 argument_3" /&gt;<br>
+ * &nbsp;&nbsp;&nbsp;&nbsp;&lt;argument value="argument 4" /&gt;<br>
+ * &nbsp;&nbsp;&lt;/acommandline&gt;<br>
+ * &lt;/someelement&gt;<br>
+ * </code>
+ *
+ * Based on: https://github.com/apache/ant/blob/588ce1f/src/main/org/apache/tools/ant/types/Commandline.java
+ *
+ * Adds support for escape character '\'.
+ *
+ * @author Mygod
+ */
+public final class Commandline {
+    private Commandline() { }
+
+    /**
+     * Quote the parts of the given array in way that makes them
+     * usable as command line arguments.
+     * @param line the list of arguments to quote.
+     * @return empty string for null or no command, else every argument split
+     * by spaces and quoted by quoting rules.
+     */
+    public static String toString(String[] line) {
+        // empty path return empty string
+        if (line == null || line.length == 0) {
+            return "";
+        }
+        // path containing one or more elements
+        final StringBuilder result = new StringBuilder();
+        for (int i = 0; i < line.length; i++) {
+            if (i > 0) {
+                result.append(' ');
+            }
+            for (int j = 0; j < line[i].length(); ++j) {
+                char ch = line[i].charAt(j);
+                switch (ch) {
+                    case ' ': case '\\': case '"': case '\'': result.append('\\');  // intentionally no break
+                    default: result.append(ch);
+                }
+            }
+        }
+        return result.toString();
+    }
+
+    /**
+     * Crack a command line.
+     * @param toProcess the command line to process.
+     * @return the command line broken into strings.
+     * An empty or null toProcess parameter results in a zero sized array.
+     */
+    public static String[] translateCommandline(String toProcess) {
+        if (toProcess == null || toProcess.length() == 0) {
+            //no command? no string
+            return new String[0];
+        }
+        // parse with a simple finite state machine
+
+        final int normal = 0;
+        final int inQuote = 1;
+        final int inDoubleQuote = 2;
+        int state = normal;
+        final StringTokenizer tok = new StringTokenizer(toProcess, "\\\"\' ", true);
+        final ArrayList<String> result = new ArrayList<>();
+        final StringBuilder current = new StringBuilder();
+        boolean lastTokenHasBeenQuoted = false;
+        boolean lastTokenIsSlash = false;
+
+        while (tok.hasMoreTokens()) {
+            String nextTok = tok.nextToken();
+            switch (state) {
+                case inQuote:
+                    if ("\'".equals(nextTok)) {
+                        lastTokenHasBeenQuoted = true;
+                        state = normal;
+                    } else {
+                        current.append(nextTok);
+                    }
+                    break;
+                case inDoubleQuote:
+                    if ("\"".equals(nextTok)) {
+                        if (lastTokenIsSlash) {
+                            current.append(nextTok);
+                            lastTokenIsSlash = false;
+                        } else {
+                            lastTokenHasBeenQuoted = true;
+                            state = normal;
+                        }
+                    } else if ("\\".equals(nextTok)) {
+                        if (lastTokenIsSlash) {
+                            current.append(nextTok);
+                            lastTokenIsSlash = false;
+                        } else lastTokenIsSlash = true;
+                    } else {
+                        if (lastTokenIsSlash) {
+                            current.append("\\");   // unescaped
+                            lastTokenIsSlash = false;
+                        }
+                        current.append(nextTok);
+                    }
+                    break;
+                default:
+                    if (lastTokenIsSlash) {
+                        current.append(nextTok);
+                        lastTokenIsSlash = false;
+                    } else if ("\\".equals(nextTok)) lastTokenIsSlash = true; else if ("\'".equals(nextTok)) {
+                        state = inQuote;
+                    } else if ("\"".equals(nextTok)) {
+                        state = inDoubleQuote;
+                    } else if (" ".equals(nextTok)) {
+                        if (lastTokenHasBeenQuoted || current.length() != 0) {
+                            result.add(current.toString());
+                            current.setLength(0);
+                        }
+                    } else {
+                        current.append(nextTok);
+                    }
+                    lastTokenHasBeenQuoted = false;
+                    break;
+            }
+        }
+        if (lastTokenHasBeenQuoted || current.length() != 0) {
+            result.add(current.toString());
+        }
+        if (state == inQuote || state == inDoubleQuote) {
+            throw new IllegalArgumentException("unbalanced quotes in " + toProcess);
+        }
+        if (lastTokenIsSlash) throw new IllegalArgumentException("escape character following nothing in " + toProcess);
+        return result.toArray(new String[result.size()]);
+    }
+}
diff --git a/mobile/src/main/scala/com/github/shadowsocks/utils/Utils.scala b/mobile/src/main/scala/com/github/shadowsocks/utils/Utils.scala
index 348fc6a4..4937adfd 100644
--- a/mobile/src/main/scala/com/github/shadowsocks/utils/Utils.scala
+++ b/mobile/src/main/scala/com/github/shadowsocks/utils/Utils.scala
@@ -23,9 +23,8 @@ package com.github.shadowsocks.utils
 import java.io.File
 import java.net._
 import java.security.MessageDigest
-import java.util.{Scanner, StringTokenizer}
+import java.util.Scanner
 
-import android.animation.{Animator, AnimatorListenerAdapter}
 import android.content.pm.PackageManager
 import android.content.{Context, Intent}
 import android.graphics._
@@ -39,7 +38,6 @@ import com.github.shadowsocks.{BuildConfig, ShadowsocksRunnerService}
 import org.xbill.DNS._
 
 import scala.collection.JavaConversions._
-import scala.collection.mutable.ArrayBuffer
 import scala.concurrent.ExecutionContext.Implicits.global
 import scala.concurrent.Future
 import scala.util.{Failure, Try}
@@ -98,48 +96,6 @@ object Utils {
     }
   }
 
-  /**
-    * Crack a command line.
-    * Based on: https://github.com/apache/ant/blob/588ce1f/src/main/org/apache/tools/ant/types/Commandline.java#L471
-    * @param toProcess the command line to process.
-    * @return the command line broken into strings.
-    * An empty or null toProcess parameter results in a zero sized ArrayBuffer.
-    */
-  def translateCommandline(toProcess: String): ArrayBuffer[String] = {
-    if (toProcess == null || toProcess.length == 0) return ArrayBuffer[String]()
-    val tok = new StringTokenizer(toProcess, "\"' ", true)
-    val result = ArrayBuffer[String]()
-    val current = new StringBuilder()
-    var quote = ' '
-    var last = " "
-    while (tok.hasMoreTokens) {
-      val nextTok = tok.nextToken
-      quote match {
-        case '\'' => nextTok match {
-          case "'" => quote = ' '
-          case _ => current.append(nextTok)
-        }
-        case '"' => nextTok match {
-          case "\"" => quote = ' '
-          case _ => current.append(nextTok)
-        }
-        case _ => nextTok match {
-          case "'" => quote = '\''
-          case "\"" => quote = '"'
-          case " " => if (last != " ") {
-            result.append(current.toString)
-            current.setLength(0)
-          }
-          case _ => current.append(nextTok)
-        }
-      }
-      last = nextTok
-    }
-    if (current.nonEmpty) result.append(current.toString)
-    if (quote == '\'' || quote == '"') throw new Exception("Unbalanced quotes in " + toProcess)
-    result
-  }
-
   def resolve(host: String, addrType: Int): Option[String] = {
     try {
       val lookup = new Lookup(host, addrType)
diff --git a/plugin/src/main/java/com/github/shadowsocks/plugin/PluginInterface.java b/plugin/src/main/java/com/github/shadowsocks/plugin/PluginInterface.java
new file mode 100644
index 00000000..480de520
--- /dev/null
+++ b/plugin/src/main/java/com/github/shadowsocks/plugin/PluginInterface.java
@@ -0,0 +1,82 @@
+package com.github.shadowsocks.plugin;
+
+/**
+ * This class provides String constants that will be used in plugin interfaces.
+ *
+ * This class is written in Java to keep Java interoperability.
+ *
+ * @author Mygod
+ */
+public final class PluginInterface {
+    private PluginInterface() { }
+
+    /**
+     * Should be a NativePluginProvider.
+     *
+     * Constant Value: "com.github.shadowsocks.plugin.CATEGORY_NATIVE_PLUGIN"
+     */
+    public static final String CATEGORY_NATIVE_PLUGIN = "com.github.shadowsocks.plugin.CATEGORY_NATIVE_PLUGIN";
+
+    /**
+     * The lookup key for a string that provides the whole command as a string.
+     *
+     * Example: "obfs=http;obfs-host=www.baidu.com"
+     *
+     * Constant Value: "com.github.shadowsocks.plugin.EXTRA_OPTIONS"
+     */
+    public static final String EXTRA_OPTIONS = "com.github.shadowsocks.plugin.EXTRA_OPTIONS";
+    /**
+     * The lookup key for a CharSequence that provides user relevant help message.
+     *
+     * Example: "obfs=<http|tls>            Enable obfuscating: HTTP or TLS (Experimental).
+     *           obfs-host=<host_name>      Hostname for obfuscating (Experimental)."
+     *
+     * Constant Value: "com.github.shadowsocks.plugin.EXTRA_HELP_MESSAGE"
+     */
+    public static final String EXTRA_HELP_MESSAGE = "com.github.shadowsocks.plugin.EXTRA_HELP_MESSAGE";
+
+    /**
+     * The metadata key to retrieve default configuration. Default value is empty.
+     *
+     * Constant Value: "com.github.shadowsocks.plugin.default_config"
+     */
+    public static final String METADATA_KEY_DEFAULT_CONFIG = "com.github.shadowsocks.plugin.default_config";
+
+    /**
+     * Relative to the file to be copied. This column is required.
+     *
+     * Example: "kcptun", "doc/help.txt"
+     *
+     * Type: String
+     */
+    public static final String COLUMN_PATH = "path";
+
+    /**
+     * Authority to use for native plugin ContentProvider.
+     *
+     * @param pluginId Plugin ID.
+     * @return com.github.shadowsocks.plugin.$PLUGIN_ID
+     */
+    public static String getAuthority(String pluginId) {
+        return "com.github.shadowsocks.plugin." + pluginId;
+    }
+
+    /**
+     * Activity Action: Used for ConfigurationActivity.
+     *
+     * @param pluginId Plugin ID.
+     * @return com.github.shadowsocks.plugin.$PLUGIN_ID.ACTION_CONFIGURE
+     */
+    public static String ACTION_CONFIGURE(String pluginId) {
+        return getAuthority(pluginId) + ".ACTION_CONFIGURE";
+    }
+    /**
+     * Activity Action: Used for HelpActivity or HelpCallback.
+     *
+     * @param pluginId Plugin ID.
+     * @return com.github.shadowsocks.plugin.$PLUGIN_ID.ACTION_HELP
+     */
+    public static String ACTION_HELP(String pluginId) {
+        return getAuthority(pluginId) + ".ACTION_HELP";
+    }
+}
diff --git a/plugin/src/main/java/com/github/shadowsocks/plugin/PluginOptions.java b/plugin/src/main/java/com/github/shadowsocks/plugin/PluginOptions.java
new file mode 100644
index 00000000..de76ac71
--- /dev/null
+++ b/plugin/src/main/java/com/github/shadowsocks/plugin/PluginOptions.java
@@ -0,0 +1,78 @@
+package com.github.shadowsocks.plugin;
+
+import android.text.TextUtils;
+
+import java.util.HashMap;
+import java.util.StringTokenizer;
+
+/**
+ * Helper class for processing plugin options.
+ *
+ * Based on: https://github.com/apache/ant/blob/588ce1f/src/main/org/apache/tools/ant/types/Commandline.java
+ *
+ * @author Mygod
+ */
+public final class PluginOptions extends HashMap<String, String> {
+    public PluginOptions() {
+        super();
+    }
+    public PluginOptions(int initialCapacity) {
+        super(initialCapacity);
+    }
+    public PluginOptions(int initialCapacity, float loadFactor) {
+        super(initialCapacity, loadFactor);
+    }
+
+    public PluginOptions(String options) throws IllegalArgumentException {
+        if (TextUtils.isEmpty(options)) return;
+        final StringTokenizer tokenizer = new StringTokenizer(options, "\\=;", true);
+        final StringBuilder current = new StringBuilder();
+        String key = null;
+        boolean firstEntry = true;
+        while (tokenizer.hasMoreTokens()) {
+            String nextToken = tokenizer.nextToken();
+            if ("\\".equals(nextToken)) current.append(tokenizer.nextToken());
+            else if ("=".equals(nextToken)) {
+                if (key != null) throw new IllegalArgumentException("Duplicate keys in " + options);
+                key = current.toString();
+                current.setLength(0);
+            } else if (";".equals(nextToken)) {
+                if (current.length() > 0) put(key, current.toString());
+                else if (firstEntry) id = key;
+                else throw new IllegalArgumentException("Value missing in " + options);
+                firstEntry = false;
+            }
+        }
+    }
+    public PluginOptions(String id, String options) throws IllegalArgumentException {
+        this(options);
+        this.id = id;
+    }
+
+    public String id;
+
+    private static void append(StringBuilder result, String str) {
+        for (int i = 0; i < str.length(); ++i) {
+            char ch = str.charAt(i);
+            switch (ch) {
+                case '\\': case '=': case ';': result.append('\\'); // intentionally no break
+                default: result.append(ch);
+            }
+        }
+    }
+    public String toString(boolean trimId) {
+        final StringBuilder result = new StringBuilder();
+        if (!trimId && !TextUtils.isEmpty(id)) append(result, id);
+        for (Entry<String, String> entry : entrySet()) if (entry.getValue() != null) {
+            if (result.length() > 0) result.append(';');
+            append(result, entry.getKey());
+            result.append('=');
+            append(result, entry.getValue());
+        }
+        return result.toString();
+    }
+    @Override
+    public String toString() {
+        return toString(false);
+    }
+}
diff --git a/mobile/src/main/res/layout/toolbar_light_dark.xml b/plugin/src/main/res/layout/toolbar_light_dark.xml
similarity index 100%
rename from mobile/src/main/res/layout/toolbar_light_dark.xml
rename to plugin/src/main/res/layout/toolbar_light_dark.xml
diff --git a/plugin/src/main/scala/com/github/shadowsocks/plugin/ConfigurationActivity.scala b/plugin/src/main/scala/com/github/shadowsocks/plugin/ConfigurationActivity.scala
new file mode 100644
index 00000000..2200d79f
--- /dev/null
+++ b/plugin/src/main/scala/com/github/shadowsocks/plugin/ConfigurationActivity.scala
@@ -0,0 +1,39 @@
+package com.github.shadowsocks.plugin
+
+import android.app.Activity
+import android.content.Intent
+
+/**
+  * Base class for configuration activity. A configuration activity is started when user wishes to configure the
+  * selected plugin. To create a configuration activity, extend this class, implement abstract methods, invoke
+  * `saveChanges(options)` and `discardChanges()` when appropriate, and add it to your manifest like this:
+  *
+  * <pre class="prettyprint">&lt;manifest&gt;
+  *    ...
+  *    &lt;application&gt;
+  *        ...
+  *        &lt;activity android:name="com.github.shadowsocks.$PLUGIN_ID.ConfigureActivity"&gt;
+  *            &lt;intent-filter&gt;
+  *                &lt;action android:name="com.github.shadowsocks.plugin.$PLUGIN_ID.ACTION_CONFIGURE" /&gt;
+  *            &lt;/intent-filter&gt;
+  *        &lt;/activity&gt;
+  *        ...
+  *    &lt;/application&gt;
+  *&lt;/manifest&gt;</pre>
+  *
+  * @author Mygod
+  */
+trait ConfigurationActivity extends OptionsCapableActivity {
+  /**
+    * Equivalent to setResult(RESULT_CANCELED).
+    */
+  final def discardChanges(): Unit = setResult(Activity.RESULT_CANCELED)
+
+  /**
+    * Equivalent to setResult(RESULT_OK, args_with_correct_format).
+    *
+    * @param options PluginOptions to save.
+    */
+  final def saveChanges(options: PluginOptions): Unit =
+    setResult(Activity.RESULT_OK, new Intent().putExtra(PluginInterface.EXTRA_OPTIONS, options.toString))
+}
diff --git a/plugin/src/main/scala/com/github/shadowsocks/plugin/HelpActivity.scala b/plugin/src/main/scala/com/github/shadowsocks/plugin/HelpActivity.scala
new file mode 100644
index 00000000..40288b8c
--- /dev/null
+++ b/plugin/src/main/scala/com/github/shadowsocks/plugin/HelpActivity.scala
@@ -0,0 +1,25 @@
+package com.github.shadowsocks.plugin
+
+/**
+  * Base class for a help activity. A help activity is started when user taps help when configuring options for your
+  * plugin. To create a help activity, just extend this class, and add it to your manifest like this:
+  *
+  * <pre class="prettyprint">&lt;manifest&gt;
+  *    ...
+  *    &lt;application&gt;
+  *        ...
+  *        &lt;activity android:name="com.github.shadowsocks.$PLUGIN_ID.HelpActivity"&gt;
+  *            &lt;intent-filter&gt;
+  *                &lt;action android:name="com.github.shadowsocks.plugin.$PLUGIN_ID.ACTION_HELP" /&gt;
+  *            &lt;/intent-filter&gt;
+  *        &lt;/activity&gt;
+  *        ...
+  *    &lt;/application&gt;
+  *&lt;/manifest&gt;</pre>
+  *
+  * @author Mygod
+  */
+trait HelpActivity extends OptionsCapableActivity {
+  // HelpActivity can choose to ignore options
+  override protected def onInitializePluginOptions(options: PluginOptions): Unit = ()
+}
diff --git a/plugin/src/main/scala/com/github/shadowsocks/plugin/HelpCallback.scala b/plugin/src/main/scala/com/github/shadowsocks/plugin/HelpCallback.scala
new file mode 100644
index 00000000..1babb814
--- /dev/null
+++ b/plugin/src/main/scala/com/github/shadowsocks/plugin/HelpCallback.scala
@@ -0,0 +1,18 @@
+package com.github.shadowsocks.plugin
+
+import android.app.Activity
+import android.content.Intent
+
+/**
+  * HelpCallback is an HelpActivity but you just need to produce a CharSequence help message instead of having to
+  * provide UI. To create a help callback, just extend this class, implement abstract methods, and add it to your
+  * manifest following the same procedure as adding a HelpActivity.
+  *
+  * @author Mygod
+  */
+trait HelpCallback extends HelpActivity {
+  def produceHelpMessage(options: PluginOptions): CharSequence
+
+  override protected def onInitializePluginOptions(options: PluginOptions): Unit = setResult(Activity.RESULT_OK,
+    new Intent().putExtra(PluginInterface.EXTRA_HELP_MESSAGE, produceHelpMessage(options)))
+}
diff --git a/plugin/src/main/scala/com/github/shadowsocks/plugin/NativePluginProvider.scala b/plugin/src/main/scala/com/github/shadowsocks/plugin/NativePluginProvider.scala
new file mode 100644
index 00000000..1fdc7845
--- /dev/null
+++ b/plugin/src/main/scala/com/github/shadowsocks/plugin/NativePluginProvider.scala
@@ -0,0 +1,65 @@
+package com.github.shadowsocks.plugin
+
+import android.content.{ContentProvider, ContentValues}
+import android.database.{Cursor, MatrixCursor}
+import android.net.Uri
+import android.os.ParcelFileDescriptor
+
+/**
+  * Base class for a native plugin provider. A native plugin provider offers read-only access to files that are required
+  * to run a plugin, such as binary files and other configuration files. To create a native plugin provider, extend this
+  * class, implement the abstract methods, and add it to your manifest like this:
+  *
+  * <pre class="prettyprint">&lt;manifest&gt;
+  *    ...
+  *    &lt;application&gt;
+  *        ...
+  *        &lt;provider android:name="com.github.shadowsocks.$PLUGIN_ID.PluginProvider"
+  *                     android:authorities="com.github.shadowsocks.$PLUGIN_ID"&gt;
+  *            &lt;intent-filter&gt;
+  *                &lt;category android:name="com.github.shadowsocks.plugin.CATEGORY_NATIVE_PLUGIN" /&gt;
+  *            &lt;/intent-filter&gt;
+  *        &lt;/provider&gt;
+  *        ...
+  *    &lt;/application&gt;
+  *&lt;/manifest&gt;</pre>
+  *
+  * @author Mygod
+  */
+abstract class NativePluginProvider extends ContentProvider {
+  /**
+    * @inheritdoc
+    *
+    * NativePluginProvider returns application/x-elf by default. It's implementer's responsibility to change this to
+    * correct type.
+    */
+  override def getType(uri: Uri): String = "application/x-elf"
+
+  override def onCreate(): Boolean = true
+
+  /**
+    * Provide all files needed for native plugin.
+    *
+    * @param provider A helper object to use to add files.
+    */
+  protected def populateFiles(provider: PathProvider)
+
+  override def query(uri: Uri, projection: Array[String], selection: String, selectionArgs: Array[String],
+                     sortOrder: String): Cursor = {
+    if (selection != null || selectionArgs != null || sortOrder != null) ???
+    val result = new MatrixCursor(projection.filter(_ == PluginInterface.COLUMN_PATH))
+    populateFiles(new PathProvider(uri, result))
+    result
+  }
+
+  def openFile(uri: Uri): ParcelFileDescriptor
+  override def openFile(uri: Uri, mode: String): ParcelFileDescriptor = {
+    if (mode != "r") ???
+    openFile(uri)
+  }
+
+  // Methods that should not be used
+  override def update(uri: Uri, values: ContentValues, selection: String, selectionArgs: Array[String]): Int = ???
+  override def insert(uri: Uri, values: ContentValues): Uri = ???
+  override def delete(uri: Uri, selection: String, selectionArgs: Array[String]): Int = ???
+}
diff --git a/plugin/src/main/scala/com/github/shadowsocks/plugin/OptionsCapableActivity.scala b/plugin/src/main/scala/com/github/shadowsocks/plugin/OptionsCapableActivity.scala
new file mode 100644
index 00000000..40dbd96a
--- /dev/null
+++ b/plugin/src/main/scala/com/github/shadowsocks/plugin/OptionsCapableActivity.scala
@@ -0,0 +1,32 @@
+package com.github.shadowsocks.plugin
+
+import android.app.Activity
+import android.content.Intent
+import android.os.Bundle
+import android.widget.Toast
+
+/**
+  * Activity that's capable of getting EXTRA_OPTIONS input.
+  *
+  * @author Mygod
+  */
+trait OptionsCapableActivity extends Activity {
+  protected def pluginOptions(intent: Intent = getIntent): PluginOptions =
+    try new PluginOptions(intent.getStringExtra(PluginInterface.EXTRA_OPTIONS)) catch {
+      case exc: IllegalArgumentException =>
+        Toast.makeText(this, exc.getMessage, Toast.LENGTH_SHORT).show()
+        null
+    }
+
+  /**
+    * Populate args to your user interface.
+    *
+    * @param options PluginOptions parsed.
+    */
+  protected def onInitializePluginOptions(options: PluginOptions = pluginOptions()): Unit
+
+  override protected def onPostCreate(savedInstanceState: Bundle) {
+    super.onPostCreate(savedInstanceState)
+    if (savedInstanceState == null) onInitializePluginOptions()
+  }
+}
diff --git a/plugin/src/main/scala/com/github/shadowsocks/plugin/PathProvider.scala b/plugin/src/main/scala/com/github/shadowsocks/plugin/PathProvider.scala
new file mode 100644
index 00000000..4eddf6d6
--- /dev/null
+++ b/plugin/src/main/scala/com/github/shadowsocks/plugin/PathProvider.scala
@@ -0,0 +1,36 @@
+package com.github.shadowsocks.plugin
+
+import java.io.File
+
+import android.database.MatrixCursor
+import android.net.Uri
+
+/**
+  * Helper class to provide relative paths of files to copy.
+  *
+  * @author Mygod
+  */
+final class PathProvider private[plugin](baseUri: Uri, cursor: MatrixCursor) {
+  private val basePath = baseUri.getPath match {
+    case null => ""
+    case p => p.stripPrefix("/").stripSuffix("/")
+  }
+
+  def addPath(path: String): PathProvider = {
+    val stripped = path.stripPrefix("/").stripSuffix("/")
+    if (stripped.startsWith(basePath)) cursor.newRow().add(PluginInterface.COLUMN_PATH, stripped)
+    this
+  }
+  def addTo(file: File, to: String = ""): PathProvider = {
+    var sub = to + file.getName
+    if (basePath.startsWith(sub)) if (file.isDirectory) {
+      sub += '/'
+      file.listFiles().foreach(addTo(_, sub))
+    } else addPath(sub)
+    this
+  }
+  def addAt(file: File, at: String = ""): PathProvider = {
+    if (basePath.startsWith(at)) if (file.isDirectory) file.listFiles().foreach(addTo(_, at)) else addPath(at)
+    this
+  }
+}