improve repl and mvc structure

pom.xml

@@ -34,5 +34,15 @@
             <artifactId>logback-classic</artifactId>
             <version>1.5.25</version>
         </dependency>
+        <dependency>
+            <groupId>org.jline</groupId>
+            <artifactId>jline</artifactId>
+            <version>3.27.1</version>
+        </dependency>
+        <dependency>
+            <groupId>org.jline</groupId>
+            <artifactId>jline-terminal-jansi</artifactId>
+            <version>3.27.1</version>
+        </dependency>
     </dependencies>
 </project>

src/main/java/internal/hw/crawler/Main.java

@@ -20,7 +20,7 @@ public class Main {
         controller.registerCommand(new SaveCommand(repository, view));
         controller.registerCommand(new HelpCommand(controller.getCommands(), view));
 
-        view.printSuccess("Welcome to crawler. Type `help` for a list of available commands.");
+        view.success("Welcome to crawler. Type `help` for a list of available commands.");
         while (true) {
             try {
                 String line = view.readLine();
@@ -32,7 +32,7 @@ public class Main {
                 controller.handleInput(line);
             } catch (Exception e) {
                 log.error("Unhandled exception in REPL loop", e);
-                view.printError("Unexpected error: " + e.getMessage());
+                view.error("Unexpected error: " + e.getMessage());
             }
         }
     }

src/main/java/internal/hw/crawler/MainController.java

@@ -2,6 +2,7 @@ package internal.hw.crawler;
 
 import internal.hw.crawler.commands.Command;
 import internal.hw.crawler.commands.CommandArg;
+import internal.hw.crawler.commands.InputParser;
 import internal.hw.crawler.strategies.crawl.CrawlerException;
 import internal.hw.crawler.views.ConsoleView;
 import org.slf4j.Logger;
@@ -30,31 +31,29 @@ public class MainController {
     }
 
     public void handleInput(String input) {
-        String text = input == null ? "" : input.trim();
+        InputParser.ParsedInput parsed = InputParser.parse(input);
-        if (text.isEmpty()) {
+        if (parsed == null) {
             return;
         }
 
-        String[] args = text.split("\\s+");
+        Command command = commands.get(parsed.command());
-        String cmdName = args[0].toLowerCase();
-        Command command = commands.get(cmdName);
         if (command == null) {
-            view.printError("Unknown command: " + cmdName);
+            view.error("Unknown command: " + parsed.command());
             return;
         }
 
-        if (!validateArgs(command, args)) {
+        if (!validateArgs(command, parsed.args())) {
             return;
         }
 
         try {
-            command.execute(args);
+            command.execute(parsed.args());
         } catch (CrawlerException e) {
-            log.warn("Crawler error in command '{}'", cmdName, e);
+            log.warn("Crawler error in command '{}'", parsed.command(), e);
-            view.printError(e.getMessage());
+            view.error(e.getMessage());
         } catch (Exception e) {
-            log.error("Unexpected error in command '{}'", cmdName, e);
+            log.error("Unexpected error in command '{}'", parsed.command(), e);
-            view.printError("Internal error: " + e.getMessage());
+            view.error("Internal error: " + e.getMessage());
         }
     }
 
@@ -64,7 +63,7 @@ public class MainController {
         int provided = args.length - 1;
 
         if (provided < required) {
-            view.printError("Usage: " + command.getName() + " " + formatUsage(cmdArgs));
+            view.error("Usage: " + command.getName() + " " + formatUsage(cmdArgs));
             return false;
         }
         return true;

src/main/java/internal/hw/crawler/commands/Command.java

@@ -10,4 +10,8 @@ public interface Command {
     }
 
     void execute(String[] args) throws Exception;
+
+    default String getDescription() {
+        return "";
+    }
 }

src/main/java/internal/hw/crawler/commands/CrawlCommand.java

@@ -9,6 +9,7 @@ import internal.hw.crawler.strategies.crawl.CrawlNetworkException;
 import internal.hw.crawler.strategies.crawl.CrawlParseException;
 import internal.hw.crawler.strategies.crawl.CrawlUnsupportedException;
 import internal.hw.crawler.views.CommandOutput;
+import internal.hw.crawler.views.ProgressTracker;
 import org.jsoup.Jsoup;
 import org.jsoup.nodes.Document;
 import org.slf4j.Logger;
@@ -35,6 +36,11 @@ public class CrawlCommand implements Command {
         return "crawl";
     }
 
+    @Override
+    public String getDescription() {
+        return "Crawl articles from a supported news website";
+    }
+
     @Override
     public List<CommandArg> getArgs() {
         return List.of(new CommandArg("url", "The website to crawl", true));
@@ -47,10 +53,11 @@ public class CrawlCommand implements Command {
             URL url = new URL(urlRaw);
             CrawlStrategy strategy = crawlStrategyFactory.getStrategy(url);
             Document doc = Jsoup.connect(url.toString()).timeout(5000).get();
-            CrawlUtils.setProgressCallback(msg -> System.out.print("\r" + msg));
+            ProgressTracker tracker = new ProgressTracker(out);
+            CrawlUtils.setProgressCallback(tracker::update);
             try {
                 List<Article> articles = strategy.parse(url, doc);
-                System.out.println();
+                tracker.done();
                 articles.stream().filter(Objects::nonNull).forEach(repository::add);
                 out.success(String.format("Crawled %d articles from %s", articles.size(), urlRaw));
             } finally {

src/main/java/internal/hw/crawler/commands/ExitCommand.java

@@ -14,6 +14,11 @@ public class ExitCommand implements Command {
         return "exit";
     }
 
+    @Override
+    public String getDescription() {
+        return "Exit the application";
+    }
+
     @Override
     public void execute(String[] args) {
         out.info("Goodbye.");

src/main/java/internal/hw/crawler/commands/HelpCommand.java

@@ -19,6 +19,11 @@ public class HelpCommand implements Command {
         return "help";
     }
 
+    @Override
+    public String getDescription() {
+        return "Show available commands or detailed help for a specific command";
+    }
+
     @Override
     public List<CommandArg> getArgs() {
         return List.of(
@@ -37,10 +42,19 @@ public class HelpCommand implements Command {
 
     private void showAll() {
         out.info("Available commands:");
+        out.print("");
+        int nameWidth = commands.values().stream()
+                .mapToInt(c -> c.getName().length()).max().orElse(0) + 4;
         for (Command cmd : commands.values()) {
-            out.print("  " + cmd.getName());
+            String desc = cmd.getDescription();
+            if (desc.isEmpty()) {
+                out.print("  " + cmd.getName());
+            } else {
+                out.print(String.format("  %-" + nameWidth + "s %s", cmd.getName(), desc));
+            }
         }
-        out.info("Type `help <command>` to show detailed help for a specific command.");
+        out.print("");
+        out.info("Type `help <command>` for detailed usage of a specific command.");
     }
 
     private void showDetail(String name) {
@@ -50,18 +64,33 @@ public class HelpCommand implements Command {
             return;
         }
 
-        out.info("Command: " + cmd.getName());
+        out.info("Command:     " + cmd.getName());
+        String desc = cmd.getDescription();
+        if (!desc.isEmpty()) {
+            out.print("Description: " + desc);
+        }
+
         List<CommandArg> cmdArgs = cmd.getArgs();
         if (cmdArgs.isEmpty()) {
-            out.print("  No arguments.");
+            out.print("Usage:       " + cmd.getName());
             return;
         }
 
+        StringBuilder usage = new StringBuilder(cmd.getName());
+        for (CommandArg arg : cmdArgs) {
+            if (arg.required()) {
+                usage.append(" <").append(arg.name()).append(">");
+            } else {
+                usage.append(" [").append(arg.name()).append("]");
+            }
+        }
+        out.print("Usage:       " + usage);
+
         out.info("Arguments:");
         for (CommandArg arg : cmdArgs) {
-            out.print(String.format("  %s  %s  %s",
+            out.print(String.format("  %-12s %s%s",
-                    arg.required() ? "[Required]" : "   ",
                     arg.name(),
+                    arg.required() ? "(required) " : "(optional) ",
                     arg.description()));
         }
     }

src/main/java/internal/hw/crawler/commands/InputParser.java

@@ -0,0 +1,32 @@
+package internal.hw.crawler.commands;
+
+public class InputParser {
+    private InputParser() {}
+
+    public static ParsedInput parse(String input) {
+        String text = input == null ? "" : input.trim();
+        if (text.isEmpty()) {
+            return null;
+        }
+        String[] parts = text.split("\\s+");
+        return new ParsedInput(parts[0].toLowerCase(), parts);
+    }
+
+    public static class ParsedInput {
+        private final String command;
+        private final String[] args;
+
+        public ParsedInput(String command, String[] args) {
+            this.command = command;
+            this.args = args;
+        }
+
+        public String command() {
+            return command;
+        }
+
+        public String[] args() {
+            return args;
+        }
+    }
+}

src/main/java/internal/hw/crawler/commands/ListCommand.java

@@ -18,6 +18,11 @@ public class ListCommand implements Command {
         return "list";
     }
 
+    @Override
+    public String getDescription() {
+        return "List all crawled articles";
+    }
+
     @Override
     public void execute(String[] args) {
         for (Article article : articleRepository.getAll()) {

src/main/java/internal/hw/crawler/commands/SaveCommand.java

@@ -13,7 +13,7 @@ import java.util.function.Function;
 import java.util.stream.Collectors;
 
 public class SaveCommand implements Command {
-    Gson gson = new Gson();
+    private final Gson gson = new Gson();
     private final ArticleRepository articleRepository;
     private final CommandOutput out;
 
@@ -27,6 +27,11 @@ public class SaveCommand implements Command {
         return "save";
     }
 
+    @Override
+    public String getDescription() {
+        return "Save articles to JSON file";
+    }
+
     @Override
     public void execute(String[] args) throws IOException {
         String filename = "articles.output.json";

src/main/java/internal/hw/crawler/strategies/crawl/CrawlUtils.java

@@ -16,17 +16,17 @@ import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.function.BiConsumer;
 import java.util.function.BiFunction;
-import java.util.function.Consumer;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 
 public class CrawlUtils {
     private static final Logger log = LoggerFactory.getLogger(CrawlUtils.class);
     private static final int THREAD_POOL_SIZE = 4;
-    private static final ThreadLocal<Consumer<String>> progressCallback = new ThreadLocal<>();
+    private static final ThreadLocal<BiConsumer<Integer, Integer>> progressCallback = new ThreadLocal<>();
 
-    public static void setProgressCallback(Consumer<String> callback) {
+    public static void setProgressCallback(BiConsumer<Integer, Integer> callback) {
         progressCallback.set(callback);
     }
 
@@ -37,7 +37,7 @@ public class CrawlUtils {
     public static List<Article> parseHomepage(Document doc, Pattern idRegex,
                                                BiFunction<URL, Document, Article> singleParser) {
         HttpCrawler crawler = new HttpCrawler();
-        Consumer<String> callback = progressCallback.get();
+        BiConsumer<Integer, Integer> callback = progressCallback.get();
 
         List<String> hrefs = new ArrayList<>();
         for (Element link : doc.getElementsByTag("a")) {
@@ -70,7 +70,7 @@ public class CrawlUtils {
                 } finally {
                     int completed = done.incrementAndGet();
                     if (callback != null) {
-                        callback.accept("Progress: " + completed + "/" + total);
+                        callback.accept(completed, total);
                     }
                 }
             }, executor));

src/main/java/internal/hw/crawler/views/CommandOutput.java

@@ -5,4 +5,5 @@ public interface CommandOutput {
     void info(String msg);
     void success(String msg);
     void error(String msg);
+    void printInline(String msg);
 }

src/main/java/internal/hw/crawler/views/ConsoleView.java

@@ -1,7 +1,12 @@
 package internal.hw.crawler.views;
 
-import java.util.NoSuchElementException;
+import org.jline.reader.LineReader;
-import java.util.Scanner;
+import org.jline.reader.LineReaderBuilder;
+import org.jline.terminal.Terminal;
+import org.jline.terminal.TerminalBuilder;
+
+import java.io.IOException;
+import java.io.PrintWriter;
 
 public class ConsoleView implements CommandOutput {
     private static final String ANSI_RESET = "\u001B[0m";
@@ -9,46 +14,59 @@ public class ConsoleView implements CommandOutput {
     private static final String ANSI_RED = "\u001B[31m";
     private static final String ANSI_BLUE = "\u001B[34m";
 
-    private final Scanner scanner = new Scanner(System.in);
+    private final LineReader reader;
+    private final PrintWriter writer;
+
+    public ConsoleView() {
+        try {
+            Terminal terminal = TerminalBuilder.builder()
+                    .system(true)
+                    .build();
+            this.reader = LineReaderBuilder.builder()
+                    .terminal(terminal)
+                    .build();
+            this.writer = terminal.writer();
+        } catch (IOException e) {
+            throw new RuntimeException("Failed to initialize terminal", e);
+        }
+    }
 
     public String readLine() {
-        System.out.print("> ");
         try {
-            return scanner.nextLine();
+            String line = reader.readLine("> ");
-        } catch (NoSuchElementException | IllegalStateException e) {
+            return (line == null || line.isBlank()) ? null : line.trim();
+        } catch (org.jline.reader.UserInterruptException | org.jline.reader.EndOfFileException e) {
             return null;
         }
     }
 
     @Override
     public void print(String msg) {
-        System.out.println(msg);
+        writer.println(msg);
+        writer.flush();
     }
 
-    public void printSuccess(String msg) {
+    @Override
-        System.out.println(ANSI_GREEN + msg + ANSI_RESET);
+    public void printInline(String msg) {
-    }
+        writer.print("\r" + msg);
-
+        writer.flush();
-    public void printError(String msg) {
-        System.out.println(ANSI_RED + msg + ANSI_RESET);
-    }
-
-    public void printInfo(String msg) {
-        System.out.println(ANSI_BLUE + msg + ANSI_RESET);
     }
 
     @Override
     public void success(String msg) {
-        printSuccess(msg);
+        writer.println(ANSI_GREEN + msg + ANSI_RESET);
+        writer.flush();
     }
 
     @Override
     public void error(String msg) {
-        printError(msg);
+        writer.println(ANSI_RED + msg + ANSI_RESET);
+        writer.flush();
     }
 
     @Override
     public void info(String msg) {
-        printInfo(msg);
+        writer.println(ANSI_BLUE + msg + ANSI_RESET);
+        writer.flush();
     }
 }

src/main/java/internal/hw/crawler/views/ProgressTracker.java

@@ -0,0 +1,31 @@
+package internal.hw.crawler.views;
+
+public class ProgressTracker {
+    private static final int BAR_WIDTH = 30;
+    private final CommandOutput out;
+
+    public ProgressTracker(CommandOutput out) {
+        this.out = out;
+    }
+
+    public void update(int done, int total) {
+        if (total <= 0) return;
+        int filled = (int) ((double) done / total * BAR_WIDTH);
+        StringBuilder bar = new StringBuilder("[");
+        for (int i = 0; i < BAR_WIDTH; i++) {
+            if (i < filled) {
+                bar.append("=");
+            } else if (i == filled) {
+                bar.append(">");
+            } else {
+                bar.append(" ");
+            }
+        }
+        bar.append("] ").append(done).append("/").append(total);
+        out.printInline(bar.toString());
+    }
+
+    public void done() {
+        out.print("");
+    }
+}