--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/src/main/java/com/five_ten_sg/connectbot/service/PromptHelper.java	Thu Dec 03 11:23:55 2015 -0800
@@ -0,0 +1,184 @@
+/*
+ * ConnectBot: simple, powerful, open-source SSH client for Android
+ * Copyright 2007 Kenny Root, Jeffrey Sharkey
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.five_ten_sg.connectbot.service;
+
+import java.util.concurrent.Semaphore;
+
+import android.os.Handler;
+import android.os.Message;
+
+/**
+ * Helps provide a relay for prompts and responses between a possible user
+ * interface and some underlying service.
+ *
+ * @author jsharkey
+ */
+public class PromptHelper {
+    private final Object tag;
+
+    private Handler handler = null;
+
+    private Semaphore promptToken;
+    private Semaphore promptResponse;
+
+    public String promptInstructions = null;
+    public String promptHint = null;
+    public Object promptRequested = null;
+    public boolean passwordRequested = true;
+
+    private Object response = null;
+
+    public PromptHelper(Object tag) {
+        this.tag = tag;
+        // Threads must acquire this before they can send a prompt.
+        promptToken = new Semaphore(1);
+        // Responses will release this semaphore.
+        promptResponse = new Semaphore(0);
+    }
+
+
+    /**
+     * Register a user interface handler, if available.
+     */
+    public void setHandler(Handler handler) {
+        this.handler = handler;
+    }
+
+    /**
+     * Set an incoming value from an above user interface. Will automatically
+     * notify any waiting requests.
+     */
+    public void setResponse(Object value) {
+        response = value;
+        promptRequested = null;
+        promptInstructions = null;
+        promptHint = null;
+        promptResponse.release();
+    }
+
+    /**
+     * Return the internal response value just before erasing and returning it.
+     */
+    protected Object popResponse() {
+        Object value = response;
+        response = null;
+        return value;
+    }
+
+
+    /**
+     * Request a prompt response from parent. This is a blocking call until user
+     * interface returns a value.
+     * Only one thread can call this at a time. cancelPrompt() will force this to
+     * immediately return.
+     */
+    private Object requestPrompt(String instructions, String hint, Object type) throws InterruptedException {
+        Object response = null;
+        promptToken.acquire();
+
+        try {
+            promptInstructions = instructions;
+            promptHint = hint;
+            promptRequested = type;
+
+            // notify any parent watching for live events
+            if (handler != null)
+                Message.obtain(handler, -1, tag).sendToTarget();
+
+            // acquire lock until user passes back value
+            promptResponse.acquire();
+            response = popResponse();
+        }
+        finally {
+            promptToken.release();
+        }
+
+        return response;
+    }
+
+    /**
+     * Request a string response from parent. This is a blocking call until user
+     * interface returns a value.
+     * @param hint prompt hint for user to answer
+     * @return string user has entered
+     */
+    public String requestStringPrompt(String instructions, String hint) {
+        String value = null;
+        passwordRequested = false;
+
+        try {
+            value = (String)this.requestPrompt(instructions, hint, String.class);
+        }
+        catch (Exception e) {
+        }
+
+        return value;
+    }
+
+    /**
+     * Request a password response from parent. This is a blocking call until user
+     * interface returns a value.
+     * @param hint prompt hint for user to answer
+     * @return string user has entered
+     */
+    public String requestPasswordPrompt(String instructions, String hint) {
+        String value = null;
+        passwordRequested = true;
+
+        try {
+            value = (String)this.requestPrompt(instructions, hint, String.class);
+        }
+        catch (Exception e) {
+        }
+
+        return value;
+    }
+
+    /**
+     * Request a boolean response from parent. This is a blocking call until user
+     * interface returns a value.
+     * @param hint prompt hint for user to answer
+     * @return choice user has made (yes/no)
+     */
+    public Boolean requestBooleanPrompt(String instructions, String hint) {
+        Boolean value = null;
+
+        try {
+            value = (Boolean)this.requestPrompt(instructions, hint, Boolean.class);
+        }
+        catch (Exception e) {
+        }
+
+        return value;
+    }
+
+    /**
+     * Cancel an in-progress prompt.
+     */
+    public void cancelPrompt() {
+        if (!promptToken.tryAcquire()) {
+            // A thread has the token, so try to interrupt it
+            response = null;
+            promptResponse.release();
+        }
+        else {
+            // No threads have acquired the token
+            promptToken.release();
+        }
+    }
+}