Merge go to <room> pathfinding into develop

BFS auto-walk over visited rooms (respecting locked exits + darkness), routed
through GoCommand (go to <room> vs go <direction>). Console: silent traversal +
a start/middle/destination summary line. GUI: the minimap animates the player
moving room-by-room via a new GameIO.travelStep hook (SwingIO override, ~300ms;
console no-op). New stateless Pathfinder BFS in the game package. Trie
autocomplete deferred.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Semesterprojekt/docs/enhancement-ideas.md

@@ -195,8 +195,11 @@ vorerst puzzle-fokussiert ohne Survival-Druck.
 
 ## Festgelegte Erweiterungs-Entscheidungen
 
-> **Pathfinding** (BFS `go to <raum>`, Trie-Autocomplete) bleibt für eine
-> spätere Runde im Scope.
+> ✅ **Pathfinding** umgesetzt (Branch `feature/pathfinding-go-to`): `go to <raum>`
+> per BFS über besuchte Räume (Locks + Licht beachtet), via `GoCommand`
+> (Richtung vs. Raumziel). Konsole still + Zusammenfassung (Start/Mitte/Ziel),
+> GUI-Minikarte animiert pro Schritt (`GameIO.travelStep`, ~300 ms).
+> **Trie-Autocomplete** weiterhin für eine spätere Runde zurückgestellt.
 
 | Entscheidung | Wert |
 |---|---|

Semesterprojekt/src/main/java/thb/jeanluc/adventure/command/impl/GoCommand.java

@@ -4,38 +4,48 @@ import thb.jeanluc.adventure.command.Command;
 import thb.jeanluc.adventure.game.Conditions;
 import thb.jeanluc.adventure.game.GameContext;
 import thb.jeanluc.adventure.game.Light;
+import thb.jeanluc.adventure.game.Pathfinder;
+import thb.jeanluc.adventure.map.MapLayout;
 import thb.jeanluc.adventure.model.Direction;
 import thb.jeanluc.adventure.model.ExitLock;
 import thb.jeanluc.adventure.model.Room;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
 
 /**
- * Moves the player into the room reachable in a given direction.
- * Usage: {@code go <direction>}.
+ * Moves the player. {@code go <direction>} steps once to a connected room.
+ * {@code go to <room>} auto-walks the shortest path (BFS) over already-visited
+ * rooms, honouring locked exits and darkness. Usage: {@code go <direction>} or
+ * {@code go to <room>}. The parser strips the filler word "to", so "go to
+ * &lt;room&gt;" and "go &lt;room&gt;" are equivalent.
  */
 public class GoCommand implements Command {
 
     @Override
     public void execute(GameContext ctx, List<String> args) {
         if (args.isEmpty()) {
-            ctx.getIo().write("Go where? Try 'go north'.");
+            ctx.getIo().write("Go where? Try 'go north' or 'go to <room>'.");
             return;
         }
-        Direction dir;
         try {
-            dir = Direction.fromString(args.getFirst());
-        } catch (IllegalArgumentException e) {
-            ctx.getIo().write("I don't know which way '" + args.getFirst() + "' is.");
-            return;
+            Direction dir = Direction.fromString(args.getFirst());
+            moveDirection(ctx, dir);
+        } catch (IllegalArgumentException notADirection) {
+            goToRoom(ctx, args);
         }
-        Optional<Room> next = ctx.getPlayer().getCurrentRoom().getExit(dir);
+    }
+
+    /** Single-step move in a compass direction (the original behaviour). */
+    private void moveDirection(GameContext ctx, Direction dir) {
+        Room here = ctx.getPlayer().getCurrentRoom();
+        Optional<Room> next = here.getExit(dir);
         if (next.isEmpty()) {
             ctx.getIo().write("You can't go " + dir.getLabel() + " from here.");
             return;
         }
-        ExitLock lock = ctx.getPlayer().getCurrentRoom().getExitLocks().get(dir);
+        ExitLock lock = here.getExitLocks().get(dir);
         if (lock != null && !Conditions.all(lock.requires(), ctx)) {
             ctx.getIo().write(lock.blocked());
             return;
@@ -49,8 +59,70 @@ public class GoCommand implements Command {
         new LookCommand().execute(ctx, List.of());
     }
 
+    /** Resolve a visited room by id/name and auto-walk the BFS path to it. */
+    private void goToRoom(GameContext ctx, List<String> args) {
+        String name = String.join(" ", args).toLowerCase();
+        Room target = resolveVisited(ctx, name);
+        if (target == null) {
+            ctx.getIo().write("You don't know any direction or place called '" + name + "'.");
+            return;
+        }
+        Room start = ctx.getPlayer().getCurrentRoom();
+        if (target == start) {
+            ctx.getIo().write("You're already in the " + target.getName() + ".");
+            return;
+        }
+        List<Room> path = Pathfinder.findPath(ctx, target);
+        if (path.isEmpty()) {
+            ctx.getIo().write("You can't find a way there right now.");
+            return;
+        }
+        List<Room> route = new ArrayList<>();
+        route.add(start);
+        route.addAll(path);
+        for (Room step : path) {
+            ctx.getPlayer().setCurrentRoom(step);
+            ctx.getIo().travelStep(MapLayout.compute(
+                    ctx.getWorld(), ctx.getPlayer().getVisitedRoomIds(), step));
+        }
+        ctx.getIo().write(summary(route));
+        new LookCommand().execute(ctx, List.of());
+    }
+
+    /** Finds a visited room whose id or display name matches {@code name}. */
+    private Room resolveVisited(GameContext ctx, String name) {
+        // the command test harness (CommandTestSupport) uses a null world; production always has one
+        if (ctx.getWorld() == null) {
+            return null;
+        }
+        for (String id : ctx.getPlayer().getVisitedRoomIds()) {
+            Room r = ctx.getWorld().getRooms().get(id);
+            if (r == null) {
+                continue;
+            }
+            if (id.equalsIgnoreCase(name) || r.getName().equalsIgnoreCase(name)) {
+                return r;
+            }
+        }
+        return null;
+    }
+
+    /** Names start, destination, and at most one middle waypoint. */
+    private String summary(List<Room> route) {
+        int n = route.size();
+        String start = route.get(0).getName();
+        String dest = route.get(n - 1).getName();
+        if (n >= 3) {
+            String middle = route.get(n / 2).getName();
+            return "You make your way from the " + start + ", through the " + middle
+                    + ", to the " + dest + ".";
+        }
+        return "You make your way from the " + start + " to the " + dest + ".";
+    }
+
     @Override
     public String help() {
-        return "go <direction>  -  move to the connected room (north/south/east/west)";
+        return "go <direction>  -  move one room (north/south/east/west); "
+                + "or  go to <room>  to travel to a known room";
     }
 }

Semesterprojekt/src/main/java/thb/jeanluc/adventure/game/Pathfinder.java

@@ -0,0 +1,76 @@
+package thb.jeanluc.adventure.game;
+
+import thb.jeanluc.adventure.model.Direction;
+import thb.jeanluc.adventure.model.ExitLock;
+import thb.jeanluc.adventure.model.Room;
+
+import java.util.ArrayDeque;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Queue;
+import java.util.Set;
+
+/**
+ * Breadth-first shortest-path search over the rooms the player has already
+ * visited, honouring the same gates as a manual move: locked exits and
+ * darkness. Stateless utility, alongside {@link Conditions}/{@link Effects}/
+ * {@link Light}.
+ */
+public final class Pathfinder {
+
+    private Pathfinder() {
+    }
+
+    /**
+     * Finds the shortest path from the player's current room to {@code target}.
+     *
+     * @param ctx    active game context
+     * @param target destination room (expected to be a visited room)
+     * @return the rooms to step through, excluding the start and ending at
+     *         {@code target}; empty if there is no currently-passable path
+     *         (or {@code target} is the current room)
+     */
+    public static List<Room> findPath(GameContext ctx, Room target) {
+        Room start = ctx.getPlayer().getCurrentRoom();
+        Set<String> visited = ctx.getPlayer().getVisitedRoomIds();
+
+        Queue<Room> queue = new ArrayDeque<>();
+        Map<Room, Room> cameFrom = new HashMap<>();
+        queue.add(start);
+        cameFrom.put(start, null);
+
+        while (!queue.isEmpty()) {
+            Room current = queue.poll();
+            if (current == target) {
+                return reconstruct(cameFrom, target);
+            }
+            for (Map.Entry<Direction, Room> exit : current.getExits().entrySet()) {
+                Room next = exit.getValue();
+                if (cameFrom.containsKey(next) || !visited.contains(next.getId())) {
+                    continue;
+                }
+                ExitLock lock = current.getExitLocks().get(exit.getKey());
+                if (lock != null && !Conditions.all(lock.requires(), ctx)) {
+                    continue;
+                }
+                if (!Light.isLit(ctx, next)) {
+                    continue;
+                }
+                cameFrom.put(next, current);
+                queue.add(next);
+            }
+        }
+        return List.of();
+    }
+
+    /** Walks predecessors back from target to start; returns steps after start. */
+    private static List<Room> reconstruct(Map<Room, Room> cameFrom, Room target) {
+        LinkedList<Room> path = new LinkedList<>();
+        for (Room r = target; r != null && cameFrom.get(r) != null; r = cameFrom.get(r)) {
+            path.addFirst(r);
+        }
+        return path;
+    }
+}

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

@@ -44,6 +44,17 @@ public interface GameIO {
         // no-op
     }
 
+    /**
+     * One frame of an auto-walk (the {@code go to} command), as the player moves
+     * through a room en route. Default is a no-op: text mode travels silently.
+     * The GUI overrides this to repaint the map and pace the animation.
+     *
+     * @param view the map snapshot at this step
+     */
+    default void travelStep(MapView view) {
+        // no animation in text mode
+    }
+
     /** On-demand map (the 'map' command). Default renders ASCII (Unicode frames). */
     default void showMap(MapView view) {
         print(AsciiMap.render(view, true));

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

@@ -66,6 +66,9 @@ public class SwingIO implements GameIO {
     /** Unscaled size for the HUD and side-panel font, in points. */
     private static final float SMALL_SIZE = 12.5f;
 
+    /** Delay between rooms while animating a go-to auto-walk, in milliseconds. */
+    private static final long TRAVEL_STEP_MS = 300L;
+
     /** Side-panel width as a fraction of the window width, clamped by the bounds below. */
     private static final double SIDE_RATIO = 0.28;
     private static final int SIDE_MIN = 180;
@@ -335,6 +338,16 @@ public class SwingIO implements GameIO {
         map.show(view);
     }
 
+    @Override
+    public void travelStep(MapView view) {
+        setMap(view);
+        try {
+            Thread.sleep(TRAVEL_STEP_MS);
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+        }
+    }
+
     @Override
     public void setQuests(QuestView view) {
         quests.show(view);

Semesterprojekt/src/test/java/thb/jeanluc/adventure/command/impl/GoCommandPathTest.java

@@ -0,0 +1,103 @@
+package thb.jeanluc.adventure.command.impl;
+
+import org.junit.jupiter.api.Test;
+import thb.jeanluc.adventure.game.GameContext;
+import thb.jeanluc.adventure.io.TestIO;
+import thb.jeanluc.adventure.model.Condition;
+import thb.jeanluc.adventure.model.Direction;
+import thb.jeanluc.adventure.model.ExitLock;
+import thb.jeanluc.adventure.model.Player;
+import thb.jeanluc.adventure.model.Room;
+import thb.jeanluc.adventure.model.World;
+
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class GoCommandPathTest {
+
+    /** kitchen --N--> hallway --N--> library (all lit). Optional lock on kitchen->hallway. */
+    private GameContext world(boolean lockHallway, String libraryName) {
+        Room kitchen = new Room("kitchen", "Kitchen", "d");
+        Room hallway = new Room("hallway", "Hallway", "d");
+        Room library = new Room("library", libraryName, "d");
+        kitchen.addExit(Direction.NORTH, hallway);
+        hallway.addExit(Direction.SOUTH, kitchen);
+        hallway.addExit(Direction.NORTH, library);
+        library.addExit(Direction.SOUTH, hallway);
+        if (lockHallway) {
+            kitchen.addExitLock(Direction.NORTH,
+                    new ExitLock(List.of(new Condition(Condition.Type.FLAG, "open")), "It's locked."));
+        }
+        Map<String, Room> rooms = new LinkedHashMap<>();
+        rooms.put("kitchen", kitchen);
+        rooms.put("hallway", hallway);
+        rooms.put("library", library);
+        World w = new World(rooms, Map.of(), Map.of(), "t", "w");
+        Player p = new Player(kitchen, 0);
+        p.getVisitedRoomIds().addAll(List.of("kitchen", "hallway", "library"));
+        return new GameContext(w, p, new TestIO());
+    }
+
+    private String out(GameContext ctx) {
+        return ((TestIO) ctx.getIo()).allOutput();
+    }
+
+    @Test
+    void goToWalksToVisitedRoomById() {
+        GameContext ctx = world(false, "Library");
+        new GoCommand().execute(ctx, List.of("library"));
+        assertThat(ctx.getPlayer().getCurrentRoom().getId()).isEqualTo("library");
+        assertThat(out(ctx)).contains("make your way");
+        assertThat(out(ctx)).contains("through the Hallway");
+    }
+
+    @Test
+    void resolvesByRoomName() {
+        // id "library" but type the display name (lower-cased) — still resolves
+        GameContext ctx = world(false, "Grand Library");
+        new GoCommand().execute(ctx, List.of("grand", "library"));
+        assertThat(ctx.getPlayer().getCurrentRoom().getId()).isEqualTo("library");
+    }
+
+    @Test
+    void unknownPlaceReportsSo() {
+        GameContext ctx = world(false, "Library");
+        new GoCommand().execute(ctx, List.of("dungeon"));
+        assertThat(ctx.getPlayer().getCurrentRoom().getId()).isEqualTo("kitchen");
+        assertThat(out(ctx)).contains("don't know any direction or place called 'dungeon'");
+    }
+
+    @Test
+    void alreadyThere() {
+        GameContext ctx = world(false, "Library");
+        new GoCommand().execute(ctx, List.of("kitchen"));
+        assertThat(out(ctx)).contains("already in the Kitchen");
+    }
+
+    @Test
+    void noPassablePathReportsSo() {
+        GameContext ctx = world(true, "Library"); // kitchen->hallway locked, flag unset
+        new GoCommand().execute(ctx, List.of("library"));
+        assertThat(ctx.getPlayer().getCurrentRoom().getId()).isEqualTo("kitchen");
+        assertThat(out(ctx)).contains("can't find a way there");
+    }
+
+    @Test
+    void directionalMoveStillWorks() {
+        GameContext ctx = world(false, "Library");
+        new GoCommand().execute(ctx, List.of("north"));
+        assertThat(ctx.getPlayer().getCurrentRoom().getId()).isEqualTo("hallway");
+    }
+
+    @Test
+    void adjacentWalkUsesShortSummary() {
+        GameContext ctx = world(false, "Library");
+        new GoCommand().execute(ctx, List.of("hallway"));
+        assertThat(ctx.getPlayer().getCurrentRoom().getId()).isEqualTo("hallway");
+        assertThat(out(ctx)).contains("make your way from the Kitchen to the Hallway");
+        assertThat(out(ctx)).doesNotContain("through");
+    }
+}

Semesterprojekt/src/test/java/thb/jeanluc/adventure/game/PathfinderTest.java

@@ -0,0 +1,88 @@
+package thb.jeanluc.adventure.game;
+
+import org.junit.jupiter.api.Test;
+import thb.jeanluc.adventure.io.TestIO;
+import thb.jeanluc.adventure.model.Condition;
+import thb.jeanluc.adventure.model.Direction;
+import thb.jeanluc.adventure.model.ExitLock;
+import thb.jeanluc.adventure.model.Player;
+import thb.jeanluc.adventure.model.Room;
+import thb.jeanluc.adventure.model.World;
+import thb.jeanluc.adventure.model.item.Item;
+import thb.jeanluc.adventure.model.item.PlainItem;
+
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class PathfinderTest {
+
+    private Room room(String id) {
+        return new Room(id, id, "d");
+    }
+
+    private GameContext ctx(Room start, List<Room> all, Set<String> visited) {
+        Map<String, Room> rooms = new LinkedHashMap<>();
+        for (Room r : all) {
+            rooms.put(r.getId(), r);
+        }
+        World w = new World(rooms, Map.of(), Map.of(), "t", "w");
+        Player p = new Player(start, 0);
+        p.getVisitedRoomIds().addAll(visited);
+        return new GameContext(w, p, new TestIO());
+    }
+
+    @Test
+    void findsShortestPathOverVisitedRooms() {
+        Room a = room("a"), b = room("b"), c = room("c");
+        a.addExit(Direction.NORTH, b);
+        b.addExit(Direction.NORTH, c);
+        GameContext ctx = ctx(a, List.of(a, b, c), Set.of("a", "b", "c"));
+        assertThat(Pathfinder.findPath(ctx, c)).containsExactly(b, c);
+    }
+
+    @Test
+    void willNotRouteThroughUnvisitedRoom() {
+        Room a = room("a"), b = room("b"), c = room("c");
+        a.addExit(Direction.NORTH, b);
+        b.addExit(Direction.NORTH, c);
+        GameContext ctx = ctx(a, List.of(a, b, c), Set.of("a", "c")); // b not visited
+        assertThat(Pathfinder.findPath(ctx, c)).isEmpty();
+    }
+
+    @Test
+    void respectsLockedExit() {
+        Room a = room("a"), b = room("b");
+        a.addExit(Direction.NORTH, b);
+        a.addExitLock(Direction.NORTH,
+                new ExitLock(List.of(new Condition(Condition.Type.FLAG, "open")), "locked"));
+        GameContext ctx = ctx(a, List.of(a, b), Set.of("a", "b"));
+        assertThat(Pathfinder.findPath(ctx, b)).isEmpty();
+        ctx.getState().set("open");
+        assertThat(Pathfinder.findPath(ctx, b)).containsExactly(b);
+    }
+
+    @Test
+    void respectsDarkness() {
+        Room a = room("a");
+        Room dark = room("dark");
+        dark.setDark(true);
+        a.addExit(Direction.NORTH, dark);
+        GameContext ctx = ctx(a, List.of(a, dark), Set.of("a", "dark"));
+        assertThat(Pathfinder.findPath(ctx, dark)).isEmpty();
+        Item torch = PlainItem.builder().id("lit").name("Lit").description("d").light(true).build();
+        ctx.getPlayer().addItem(torch);
+        assertThat(Pathfinder.findPath(ctx, dark)).containsExactly(dark);
+    }
+
+    @Test
+    void unreachableTargetReturnsEmpty() {
+        Room a = room("a");
+        Room island = room("island"); // no connecting exits
+        GameContext ctx = ctx(a, List.of(a, island), Set.of("a", "island"));
+        assertThat(Pathfinder.findPath(ctx, island)).isEmpty();
+    }
+}

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

@@ -0,0 +1,19 @@
+package thb.jeanluc.adventure.io;
+
+import org.junit.jupiter.api.Test;
+import thb.jeanluc.adventure.io.text.MapView;
+
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class TravelStepDefaultTest {
+
+    @Test
+    void defaultTravelStepIsSilentNoOp() {
+        TestIO io = new TestIO();
+        // An empty map view is fine; the default must not print or throw.
+        io.travelStep(new MapView(List.of(), List.of()));
+        assertThat(io.outputs()).isEmpty();
+    }
+}