Add terminal

This is some functionality based on the way that MVS/other IBM OSes
handle their UI

4 files changed, 267 insertions, 0 deletions

diff --git a/base/src/main/java/bjc/utils/cli/StreamTerminal.java b/base/src/main/java/bjc/utils/cli/StreamTerminal.java
new file mode 100644
index 0000000..a45a22e
--- /dev/null
+++ b/base/src/main/java/bjc/utils/cli/StreamTerminal.java
@@ -0,0 +1,152 @@
+package bjc.utils.cli;
+
+import static bjc.utils.cli.TerminalCodes.*;
+
+import java.io.*;
+import java.util.*;
+import java.util.concurrent.*;
+import java.util.concurrent.locks.*;
+
+public class StreamTerminal implements Terminal, Runnable {
+	private SortedSet<Long> pendingRequests;
+	private ConcurrentMap<Long, String> pendingReplies;
+
+	private Lock replyLock;
+	private Condition replyCondition;
+
+	private Queue<String> pendingOutput;
+
+	private boolean running;
+
+	private Scanner inputScanner;
+	private Writer output;
+
+	private long currentRequest = -1;
+
+	public StreamTerminal(Reader input, Writer output) {
+		this.inputScanner = new Scanner(input);
+		this.output = output;
+
+		this.pendingRequests = new TreeSet<>();
+		this.pendingReplies = new ConcurrentHashMap<>();
+		this.pendingOutput = new ArrayDeque<>();
+
+		this.replyLock = new ReentrantLock();
+		this.replyCondition = replyLock.newCondition();
+	}
+
+	@Override
+	public void run() {
+		running = true;
+		try {
+			output.write(INFO_STARTCOMPROC.toString() + "\n");
+		} catch (IOException e) {
+			// TODO Consider if there is some better way to handle these
+			throw new RuntimeException(e);
+		}
+
+		overall: while (running && inputScanner.hasNextLine()) {
+			try {
+				while (!pendingOutput.isEmpty())
+					output.write(pendingOutput.remove());
+
+				String ln = inputScanner.nextLine();
+				String com = "";
+				int spcIdx = ln.indexOf(' ');
+				if (spcIdx == -1) {
+					com = ln;
+				} else {
+					com = ln.substring(0, spcIdx);
+					ln = ln.substring(spcIdx + 1);
+				}
+				comswt: switch (com) {
+				case "r": {
+					// General command format is 'r <request no.>,<reply>
+					String subRep = ln.substring(2);
+					// Process a reply
+					int comIndex = subRep.indexOf(',');
+					long repNo = 0;
+					if (comIndex == -1) {
+						// Reply to the oldest message by default
+						repNo = pendingRequests.first();
+					} else {
+						String repStr = subRep.substring(0, comIndex);
+						try {
+							repNo = Long.parseLong(repStr);
+						} catch (NumberFormatException nfex) {
+							output.write(ERROR_INVREPNO.toString() + "\n");
+							continue overall;
+						}
+						// Skip over the comma
+						subRep = subRep.substring(comIndex + 1);
+					}
+
+					if (!pendingRequests.contains(repNo)) {
+						output.write(ERROR_UNKREPNO.toString() + "\n");
+						continue overall;
+					}
+
+					pendingRequests.remove(repNo);
+					pendingReplies.put(repNo, subRep);
+
+					replyLock.lock();
+					replyCondition.signalAll();
+					replyLock.unlock();
+					break comswt;
+				}
+				case "q":
+					running = false;
+					break comswt;
+				default:
+					output.write(ERROR_UNRECCOM.toString() + "\n");
+				}
+			} catch (IOException ioex) {
+				throw new RuntimeException(ioex);
+			}
+		}
+
+		running = false;
+		try {
+			output.write(INFO_ENDCOMPROC.toString() + "\n");
+		} catch (IOException e) {
+			throw new RuntimeException(e);
+		}
+	}
+
+	@Override
+	public long submitRequest(String req) {
+		long reqNo = currentRequest + 1;
+		currentRequest += 1;
+
+		pendingOutput.add(reqNo + " " + req + "\n");
+		pendingRequests.add(reqNo);
+		return reqNo;
+	}
+
+	@Override
+	public String awaitReply(long id) throws InterruptedException {
+		if (pendingReplies.containsKey(id))
+			return pendingReplies.get(id);
+		while (true) {
+			replyLock.lock();
+			replyCondition.await();
+			replyLock.unlock();
+			// Explanation: Since the reply map is add-only, the lock isn't actually
+			// protecting anything. We just want to wait until a response is received.
+			if (pendingReplies.containsKey(id))
+				return pendingReplies.get(id);
+		}
+	}
+
+	@Override
+	public Optional<String> checkReply(long id) {
+		return Optional.ofNullable(pendingReplies.get(id));
+	}
+
+	@Override
+	public String submitRequestSync(String req) throws InterruptedException {
+		return awaitReply(submitRequest(req));
+	}
+	
+	// TODO add variants of the two blocking methods above with timeout support
+}
\ No newline at end of file
diff --git a/base/src/main/java/bjc/utils/cli/Terminal.java b/base/src/main/java/bjc/utils/cli/Terminal.java
new file mode 100644
index 0000000..a10d82e
--- /dev/null
+++ b/base/src/main/java/bjc/utils/cli/Terminal.java
@@ -0,0 +1,51 @@
+package bjc.utils.cli;
+
+import java.util.*;
+
+/**
+ * A terminal with support for asking multiple questions, and retrieving the
+ * results piecemeal.
+ * 
+ * This class is heavily inspired by the way that the old IBM MVS terminal
+ * worked, where the terminal would send you a series of requests and you would
+ * reply to them in whatever order you wanted.
+ * 
+ * @author bjcul
+ */
+public interface Terminal {
+	/**
+	 * Submit a request to the terminal
+	 * 
+	 * @param req The body of the request
+	 * @return The ID of the request
+	 */
+	long submitRequest(String req);
+
+	/**
+	 * Await a reply for a given request. Will block the current thread until a
+	 * response is available.
+	 * 
+	 * @param id The ID of the request
+	 * @return The response to that request
+	 * @throws InterruptedException If we are interrupted waiting for the reply
+	 */
+	String awaitReply(long id) throws InterruptedException;
+
+	/**
+	 * Check if a reply for a request is available, without blocking.
+	 * 
+	 * @param id The ID of the request
+	 * @return The reply to the request if one is available, and empty otherwise
+	 */
+	Optional<String> checkReply(long id);
+
+	/**
+	 * Submit a request and await the reply to it. Will block the current thread
+	 * until a response is received.
+	 * 
+	 * @param req The request to submit
+	 * @return The reply to the request
+	 * @throws InterruptedException If we are interrupted waiting for the reply
+	 */
+	String submitRequestSync(String req) throws InterruptedException;;
+}
\ No newline at end of file
diff --git a/base/src/main/java/bjc/utils/cli/TerminalCodes.java b/base/src/main/java/bjc/utils/cli/TerminalCodes.java
new file mode 100644
index 0000000..c1d7dfc
--- /dev/null
+++ b/base/src/main/java/bjc/utils/cli/TerminalCodes.java
@@ -0,0 +1,36 @@
+package bjc.utils.cli;
+
+/**
+ * Status codes output by {@link Terminal}.
+ * 
+ * Format is a two-letter system code, a two letter subsystem code, a severity
+ * letter and a five digit error code.
+ * 
+ * @author bjcul
+ *
+ */
+public enum TerminalCodes {
+	// TODO convert these into a class, and add an ability to read from the file
+	// The general idea of the format would be a tab-separated value file, with the
+	// first value being a command, and then the rest being the body of that command.
+	// Would also have the line-continuation feature
+	INFO_STARTCOMPROC("IOLPI00001", "STARTING PROCESSING"),
+	INFO_ENDCOMPROC("IOLPI00002", "ENDING PROCESSING"),
+	
+	ERROR_UNRECCOM("IOINE00001", "UNRECOGNIZED COMMAND"),
+	ERROR_INVREPNO("IOINE00002", "INVALID REPLY NUMBER FORMAT"),
+	ERROR_UNKREPNO("IOINE00002", "UNKNOWN REPLY NUMBER"),
+	;
+	public final String code;
+	public final String message;
+
+	private TerminalCodes(String code, String message) {
+		this.code = code;
+		this.message = message;
+	}
+	
+	@Override
+	public String toString() {
+		return code + " " + message;
+	}
+}
diff --git a/base/src/main/java/bjc/utils/funcutils/StringUtils.java b/base/src/main/java/bjc/utils/funcutils/StringUtils.java
index 0b57e18..2d86083 100644
--- a/base/src/main/java/bjc/utils/funcutils/StringUtils.java
+++ b/base/src/main/java/bjc/utils/funcutils/StringUtils.java
@@ -312,4 +312,32 @@ public class StringUtils {
 			String... splits) {
 		return LevelSplitter.def.levelSplit(phrase, keepDelims, splits);
 	}
+	
+	/**
+	 * Convert a string into a pseudorandom anagram.
+	 * 
+	 * Works by swapping each character in the string with a random one.
+	 * 
+	 * @param s The string to convert.
+	 * 
+	 * @return A pseudo-random anagram
+	 */
+	public static String strfry(String s) {
+		char[] chars = s.toCharArray();
+		
+		int strlen = chars.length;
+		Random rng = new Random();
+
+		for (int i = 0; i < strlen; i++) {
+			int randIdx = rng.nextInt(strlen);
+
+			char source = chars[i];
+			char dest = chars[randIdx];
+			
+			chars[i] = dest;
+			chars[randIdx] = source;
+		}
+		
+		return String.valueOf(chars);
+	}
 }
\ No newline at end of file