basic structure

.gitignore

@@ -0,0 +1,33 @@
+target/
+!.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+.kotlin
+
+### IntelliJ IDEA ###
+.idea/
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store

pom.xml

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>internal.hw.crawler</groupId>
+    <artifactId>homework-final</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <properties>
+        <maven.compiler.source>11</maven.compiler.source>
+        <maven.compiler.target>11</maven.compiler.target>
+    </properties>
+
+</project>

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

@@ -0,0 +1,24 @@
+package internal.hw.crawler;
+
+import internal.hw.crawler.commands.CrawlCommand;
+import internal.hw.crawler.commands.ExitCommand;
+import internal.hw.crawler.commands.HelpCommand;
+import internal.hw.crawler.repositories.ArticleRepository;
+import internal.hw.crawler.views.ConsoleView;
+
+public class Main {
+    public static void main(String[] args) {
+        ConsoleView view = new ConsoleView();
+        MainController controller = new MainController(view);
+        ArticleRepository repository = new ArticleRepository();
+
+        controller.registerCommand(new ExitCommand());
+        controller.registerCommand(new CrawlCommand(repository));
+        controller.registerCommand(new HelpCommand(controller.getCommands()));
+
+        view.printSuccess("Welcome to crawler. Type `help` for a list of available commands.");
+        while (true) {
+            controller.handleInput(view.readLine());
+        }
+    }
+}

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

@@ -0,0 +1,72 @@
+package internal.hw.crawler;
+
+import internal.hw.crawler.commands.Command;
+import internal.hw.crawler.commands.CommandArg;
+import internal.hw.crawler.views.ConsoleView;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class MainController {
+    private final Map<String, Command> commands = new HashMap<>();
+    private final ConsoleView view;
+
+    public MainController(ConsoleView view) {
+        this.view = view;
+    }
+
+    public Map<String, Command> getCommands() {
+        return Collections.unmodifiableMap(commands);
+    }
+
+    public void registerCommand(Command command) {
+        commands.put(command.getName(), command);
+    }
+
+    public void handleInput(String input) {
+        String text = input == null ? "" : input.trim();
+        if (text.isEmpty()) {
+            return;
+        }
+
+        String[] args = text.split("\\s+");
+        String cmdName = args[0].toLowerCase();
+        Command command = commands.get(cmdName);
+        if (command == null) {
+            view.printError("Unknown command: " + cmdName);
+            return;
+        }
+
+        if (!validateArgs(command, args)) {
+            return;
+        }
+
+        command.execute(args);
+    }
+
+    private boolean validateArgs(Command command, String[] args) {
+        List<CommandArg> cmdArgs = command.getArgs();
+        long required = cmdArgs.stream().filter(CommandArg::required).count();
+        int provided = args.length - 1;
+
+        if (provided < required) {
+            view.printError("Usage: " + command.getName() + " " + formatUsage(cmdArgs));
+            return false;
+        }
+        return true;
+    }
+
+    private String formatUsage(List<CommandArg> cmdArgs) {
+        StringBuilder sb = new StringBuilder();
+        for (CommandArg arg : cmdArgs) {
+            if (arg.required()) {
+                sb.append("<").append(arg.name()).append("> ");
+            } else {
+                sb.append("[").append(arg.name()).append("] ");
+            }
+        }
+        return sb.toString().trim();
+    }
+}

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

@@ -0,0 +1,13 @@
+package internal.hw.crawler.commands;
+
+import java.util.List;
+
+public interface Command {
+    String getName();
+
+    default List<CommandArg> getArgs() {
+        return List.of();
+    }
+
+    void execute(String[] args);
+}

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

@@ -0,0 +1,39 @@
+package internal.hw.crawler.commands;
+
+import java.util.Objects;
+
+public final class CommandArg {
+    private final String name;
+    private final String description;
+    private final boolean required;
+
+    public CommandArg(String name, String description, boolean required) {
+        this.name = Objects.requireNonNull(name);
+        this.description = Objects.requireNonNull(description);
+        this.required = required;
+    }
+
+    public String name() { return name; }
+    public String description() { return description; }
+    public boolean required() { return required; }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (!(o instanceof CommandArg)) return false;
+        CommandArg that = (CommandArg) o;
+        return required == that.required
+                && name.equals(that.name)
+                && description.equals(that.description);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(name, description, required);
+    }
+
+    @Override
+    public String toString() {
+        return "CommandArg[name=" + name + ", description=" + description + ", required=" + required + "]";
+    }
+}

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

@@ -0,0 +1,28 @@
+package internal.hw.crawler.commands;
+
+import internal.hw.crawler.repositories.ArticleRepository;
+
+import java.util.List;
+
+public class CrawlCommand implements Command {
+    private ArticleRepository repository;
+
+    public CrawlCommand(ArticleRepository repository) {
+        this.repository = repository;
+    }
+
+    @Override
+    public String getName() {
+        return "crawl";
+    }
+
+    @Override
+    public List<CommandArg> getArgs() {
+        return List.of(new CommandArg("url", "The website to crawl", true));
+    }
+
+    @Override
+    public void execute(String[] args) {
+        System.out.printf("Will crawl %s%n", args[1]);
+    }
+}

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

@@ -0,0 +1,13 @@
+package internal.hw.crawler.commands;
+
+public class ExitCommand implements Command {
+    @Override
+    public String getName() {
+        return "exit";
+    }
+
+    @Override
+    public void execute(String[] args) {
+        System.exit(0);
+    }
+}

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

@@ -0,0 +1,65 @@
+package internal.hw.crawler.commands;
+
+import java.util.List;
+import java.util.Map;
+
+public class HelpCommand implements Command {
+    private final Map<String, Command> commands;
+
+    public HelpCommand(Map<String, Command> commands) {
+        this.commands = commands;
+    }
+
+    @Override
+    public String getName() {
+        return "help";
+    }
+
+    @Override
+    public List<CommandArg> getArgs() {
+        return List.of(
+                new CommandArg("command", "Command name to show detailed help for", false)
+        );
+    }
+
+    @Override
+    public void execute(String[] args) {
+        if (args.length >= 2) {
+            showDetail(args[1]);
+        } else {
+            showAll();
+        }
+    }
+
+    private void showAll() {
+        System.out.println("Available commands:");
+        for (Command cmd : commands.values()) {
+            System.out.printf("  %s", cmd.getName());
+            System.out.println();
+        }
+        System.out.println("Type `help <command>` to show detailed help for a specific command.");
+    }
+
+    private void showDetail(String name) {
+        Command cmd = commands.get(name);
+        if (cmd == null) {
+            System.out.println("Unknown command: " + name);
+            return;
+        }
+
+        System.out.println("Command: " + cmd.getName());
+        List<CommandArg> cmdArgs = cmd.getArgs();
+        if (cmdArgs.isEmpty()) {
+            System.out.println("  No arguments.");
+            return;
+        }
+
+        System.out.println("Arguments:");
+        for (CommandArg arg : cmdArgs) {
+            System.out.printf("  %s  %s  %s%n",
+                    arg.required() ? "[R]" : "   ",
+                    arg.name(),
+                    arg.description());
+        }
+    }
+}

src/main/java/internal/hw/crawler/models/Article.java

@@ -0,0 +1,42 @@
+package internal.hw.crawler.models;
+
+public class Article {
+    private String url;
+    private String title;
+    private String content;
+
+    public Article(String url, String title, String content) {
+        this.url = url;
+        this.title = title;
+        this.content = content;
+    }
+
+    public String getUrl() {
+        return url;
+    }
+
+    public void setUrl(String url) {
+        this.url = url;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public void setTitle(String title) {
+        this.title = title;
+    }
+
+    public String getContent() {
+        return content;
+    }
+
+    public void setContent(String content) {
+        this.content = content;
+    }
+
+    @Override
+    public String toString() {
+        return String.format("Article{%s}", url);
+    }
+}

src/main/java/internal/hw/crawler/repositories/ArticleRepository.java

@@ -0,0 +1,30 @@
+package internal.hw.crawler.repositories;
+
+import internal.hw.crawler.models.Article;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public class ArticleRepository {
+    private final List<Article> articles = new ArrayList<>();
+
+    public void add(Article article) {
+        if (article == null) {
+            throw new IllegalArgumentException("Article cannot be null");
+        }
+        articles.add(article);
+    }
+
+    public List<Article> getAll() {
+        return Collections.unmodifiableList(articles);
+    }
+
+    public int size() {
+        return articles.size();
+    }
+
+    public void clear() {
+        articles.clear();
+    }
+}

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

@@ -0,0 +1,29 @@
+package internal.hw.crawler.views;
+
+import java.util.Scanner;
+
+public class ConsoleView {
+    private static final String ANSI_RESET = "\u001B[0m";
+    private static final String ANSI_GREEN = "\u001B[32m";
+    private static final String ANSI_RED = "\u001B[31m";
+    private static final String ANSI_BLUE = "\u001B[34m";
+
+    private final Scanner scanner = new Scanner(System.in);
+
+    public String readLine() {
+        System.out.print("> ");
+        return scanner.nextLine();
+    }
+
+    public void printSuccess(String msg) {
+        System.out.println(ANSI_GREEN + msg + ANSI_RESET);
+    }
+
+    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);
+    }
+}