feat(io): GameIO.choose numbered-menu primitive (console default)

Semesterprojekt/src/main/java/thb/jeanluc/adventure/io/GameIO.java

@@ -9,6 +9,8 @@ import thb.jeanluc.adventure.io.text.Renderings;
 import thb.jeanluc.adventure.io.text.RoomView;
 import thb.jeanluc.adventure.io.text.StyledText;
 
+import java.util.List;
+
 /**
  * Bidirectional channel between the engine and the player. Commands emit
  * semantic, role-styled output via {@link #print(StyledText)} (the primitive)
@@ -56,4 +58,38 @@ public interface GameIO {
     default void showQuests(QuestView view) {
         print(QuestText.render(view));
     }
+
+    /**
+     * Presents a titled list of options and returns the 0-based index of the
+     * player's choice. Default (console) prints a numbered list and reads a
+     * number, re-prompting on invalid input. EOF / empty input returns the
+     * LAST option (menus place the safe/cancel option last). Frontends with
+     * native widgets (e.g. buttons) may override.
+     *
+     * @param title   heading shown above the options
+     * @param options non-empty list of option labels
+     * @return 0-based index into {@code options}
+     */
+    default int choose(String title, List<String> options) {
+        StyledText.Builder b = StyledText.builder().heading(title).plain("\n");
+        for (int i = 0; i < options.size(); i++) {
+            b.plain("  " + (i + 1) + ") " + options.get(i) + "\n");
+        }
+        print(b.build());
+        while (true) {
+            String line = readLine();
+            if (line == null || line.isBlank()) {
+                return options.size() - 1;
+            }
+            try {
+                int n = Integer.parseInt(line.trim());
+                if (n >= 1 && n <= options.size()) {
+                    return n - 1;
+                }
+            } catch (NumberFormatException ignored) {
+                // fall through to re-prompt
+            }
+            write("Please enter a number between 1 and " + options.size() + ".");
+        }
+    }
 }

Semesterprojekt/src/test/java/thb/jeanluc/adventure/io/ChooseDefaultTest.java

@@ -0,0 +1,32 @@
+package thb.jeanluc.adventure.io;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class ChooseDefaultTest {
+
+    @Test
+    void returnsZeroBasedIndexOfValidChoice() {
+        TestIO io = new TestIO().enqueue("2");
+        int i = io.choose("Menu", List.of("A", "B", "C"));
+        assertThat(i).isEqualTo(1);
+    }
+
+    @Test
+    void rePromptsOnInvalidThenAccepts() {
+        TestIO io = new TestIO().enqueue("9").enqueue("x").enqueue("1");
+        int i = io.choose("Menu", List.of("A", "B"));
+        assertThat(i).isZero();
+        assertThat(io.allOutput()).contains("between 1 and 2");
+    }
+
+    @Test
+    void eofReturnsLastOption() {
+        TestIO io = new TestIO(); // empty queue → readLine() returns null
+        int i = io.choose("Menu", List.of("Play", "Quit"));
+        assertThat(i).isEqualTo(1);
+    }
+}