[WIP] Communication should be working fine now.

Signed-off-by: Louis Vallat <louis@louis-vallat.xyz>

src/main/java/xyz/vallat/louis/MoviesQuoteBot.java

@@ -6,6 +6,8 @@ import org.slf4j.LoggerFactory;
 import xyz.vallat.louis.codes.ExitCodes;
 import xyz.vallat.louis.database.DBManager;
 import xyz.vallat.louis.discord.DiscordManager;
+import xyz.vallat.louis.sockets.CommandsClient;
+import xyz.vallat.louis.sockets.CommandsServer;
 import xyz.vallat.louis.subtitles.OpenSubtitles;
 
 import java.io.File;
@@ -42,6 +44,7 @@ public class MoviesQuoteBot {
         DBManager.initDatabase();
         OpenSubtitles.login();
         DiscordManager.login();
+        CommandsServer.start();
 
         Runtime.getRuntime().addShutdownHook(new Thread(() -> {
             logger.info("Received shut down signal. Bye!");
@@ -87,5 +90,8 @@ public class MoviesQuoteBot {
     }
 
     private static void reimportAllSubtitleLines() {
+        CommandsClient.checkVersions();
+        CommandsClient.setMaintenanceMode(true);
+        CommandsClient.setMaintenanceMode(false);
     }
 }

src/main/java/xyz/vallat/louis/codes/ExitCodes.java

@@ -6,7 +6,10 @@ public enum ExitCodes {
     CANNOT_INITIALIZE_LANGUAGES(3),
     CANNOT_GET_PROPERTY(4),
     CANNOT_START_SOCKET_SERVER(5),
-    URGENT_EXIT_REQUIRED(6);
+    SOCKET_SERVER_MISBEHAVED(6),
+    SOCKET_SERVER_AND_CLIENT_VERSION_MISMATCH(7),
+    SOCKET_SERVER_COMMUNICATION_FAILURE(8),
+    URGENT_EXIT_REQUIRED(9);
 
     private final int value;
 

src/main/java/xyz/vallat/louis/env/EnvironmentVariables.java

@@ -11,6 +11,7 @@ public enum EnvironmentVariables {
     OS_PASSWORD("OPEN_SUBTITLES_PASSWORD"),
     OS_USER_AGENT("OPEN_SUBTITLES_USER_AGENT"),
     SOCKET_PORT("SOCKET_PORT"),
+    SOCKET_HOST("SOCKET_HOST"),
     OMDB_API_KEY("OMDB_API_KEY");
 
     private final String value;

src/main/java/xyz/vallat/louis/sockets/Client.java

@@ -1,4 +0,0 @@
-package xyz.vallat.louis.sockets;
-
-public class Client {
-}

src/main/java/xyz/vallat/louis/sockets/CommandsClient.java

@@ -0,0 +1,67 @@
+package xyz.vallat.louis.sockets;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import xyz.vallat.louis.MoviesQuoteBot;
+import xyz.vallat.louis.codes.ExitCodes;
+import xyz.vallat.louis.env.EnvironmentVariables;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.PrintWriter;
+import java.net.Socket;
+
+import static xyz.vallat.louis.sockets.CommandsServer.PORT;
+
+public class CommandsClient {
+
+    private static final Logger logger = LoggerFactory.getLogger(CommandsClient.class.getCanonicalName());
+    private static final String SOCKET_HOST = System.getenv(EnvironmentVariables.SOCKET_HOST.getValue()) == null ?
+            "localhost" : System.getenv(EnvironmentVariables.SOCKET_HOST.getValue());
+
+    private static String sendMessage(String message) {
+        logger.debug("Sending message '{}'.", message);
+        try (Socket clientSocket = new Socket(SOCKET_HOST, PORT)) {
+            PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);
+            BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
+            out.println(message);
+            String response = in.readLine();
+            logger.debug("Received response '{}'.", response);
+            return response;
+        } catch (IOException e) {
+            logger.error("An error happened while trying to communicate with server.", e);
+        }
+        return null;
+    }
+
+    public static void checkVersions() {
+        String message = sendMessage(SocketsCommand.VERSION_REQUEST.getName());
+        if (message == null) cannotCommunicateWithServer();
+        else if (!message.equals(MoviesQuoteBot.VERSION)) {
+            logger.error("Version mismatch between server and client! Got answer '{}'. Exiting.", message);
+            System.exit(ExitCodes.SOCKET_SERVER_AND_CLIENT_VERSION_MISMATCH.getValue());
+        }
+    }
+
+    public static void setMaintenanceMode(boolean mode) {
+        String message = sendMessage(mode ?
+                SocketsCommand.MAINTENANCE_MODE_ON.getName() : SocketsCommand.MAINTENANCE_MODE_OFF.getName());
+        if (message == null) cannotCommunicateWithServer();
+        else if (!message.equals(SocketsCommand.OK.getName())) {
+            if (!message.equals(SocketsCommand.UNRECOGNIZED_COMMAND.getName()))
+                logger.error("Unrecognized answer: '{}'.", message);
+            serverIsMisbehaving();
+        }
+    }
+
+    private static void serverIsMisbehaving() {
+        logger.error("The server is misbehaving. Exiting.");
+        System.exit(ExitCodes.SOCKET_SERVER_MISBEHAVED.getValue());
+    }
+
+    private static void cannotCommunicateWithServer() {
+        logger.error("Cannot communicate with server. Exiting.");
+        System.exit(ExitCodes.SOCKET_SERVER_COMMUNICATION_FAILURE.getValue());
+    }
+}

src/main/java/xyz/vallat/louis/sockets/CommandsServer.java

@@ -6,19 +6,16 @@ import xyz.vallat.louis.MoviesQuoteBot;
 import xyz.vallat.louis.codes.ExitCodes;
 import xyz.vallat.louis.env.EnvironmentVariables;
 
-import java.io.BufferedReader;
+import java.io.*;
-import java.io.File;
-import java.io.IOException;
-import java.io.InputStreamReader;
 import java.net.ServerSocket;
 import java.net.Socket;
 
 import static xyz.vallat.louis.MoviesQuoteBot.KILL_SWITCH_FILE;
 
-public class Server {
+public class CommandsServer {
 
-    private static final Logger logger = LoggerFactory.getLogger(Server.class.getCanonicalName());
+    public static final int PORT;
-    private static final int PORT;
+    private static final Logger logger = LoggerFactory.getLogger(CommandsServer.class.getCanonicalName());
 
     static {
         int port = 8888;
@@ -30,7 +27,7 @@ public class Server {
         PORT = port;
     }
 
-    private Server() {
+    private CommandsServer() {
     }
 
     public static void start() {
@@ -41,15 +38,10 @@ public class Server {
                     logger.info("Waiting for connections on port '{}'...", PORT);
                     Socket socket = serverSocket.accept();
                     logger.info("Connected!");
-                    BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
+                    BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
-                    String message = reader.readLine();
+                    PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
-                    logger.debug("Received message '{}'.", message);
+                    String message = in.readLine();
-                    if (message.equals(SocketsCommand.KILL_SWITCH_URGENT.getName())) everythingIsOkay = false;
+                    everythingIsOkay = computeMessage(out, message);
-                    else if (message.equals(SocketsCommand.MAINTENANCE_MODE_ON.getName()))
-                        MoviesQuoteBot.switchToMaintenanceMode();
-                    else if (message.equals(SocketsCommand.MAINTENANCE_MODE_OFF.getName()))
-                        MoviesQuoteBot.switchToNormalOperations();
-                    else logger.warn("Be careful, I received a message that I don't understand: '{}'.", message);
                 } catch (IOException e) {
                     everythingIsOkay = false;
                     logger.error("Cannot start socket server.", e);
@@ -68,4 +60,24 @@ public class Server {
         });
     }
 
+    private static boolean computeMessage(PrintWriter out, String message) {
+        boolean everythingIsOkay = true;
+        logger.debug("Received message '{}'.", message);
+        if (message.equals(SocketsCommand.KILL_SWITCH_URGENT.getName())) {
+            everythingIsOkay = false;
+            out.println(SocketsCommand.OK.getName());
+        } else if (message.equals(SocketsCommand.MAINTENANCE_MODE_ON.getName())) {
+            MoviesQuoteBot.switchToMaintenanceMode();
+            out.println(SocketsCommand.OK.getName());
+        } else if (message.equals(SocketsCommand.MAINTENANCE_MODE_OFF.getName())) {
+            MoviesQuoteBot.switchToNormalOperations();
+            out.println(SocketsCommand.OK.getName());
+        } else if (message.equals(SocketsCommand.VERSION_REQUEST.getName())) out.println(MoviesQuoteBot.VERSION);
+        else {
+            logger.warn("Be careful, I received a message that I don't understand: '{}'.", message);
+            out.println(SocketsCommand.UNRECOGNIZED_COMMAND.getName());
+        }
+        return everythingIsOkay;
+    }
+
 }

src/main/java/xyz/vallat/louis/sockets/SocketsCommand.java

@@ -3,6 +3,9 @@ package xyz.vallat.louis.sockets;
 public enum SocketsCommand {
     MAINTENANCE_MODE_ON("maintenance_engaged"),
     MAINTENANCE_MODE_OFF("maintenance_disengaged"),
+    VERSION_REQUEST("papers_please"),
+    OK("okay"),
+    UNRECOGNIZED_COMMAND("i_dont_think_so"),
     KILL_SWITCH_URGENT("big_red_button_pressed");
 
     private final String name;