feat: add stature potions and tiny-player launchers

src/main/java/games/dmg/spigotheights/HeightMath.java

@@ -0,0 +1,40 @@
+package games.dmg.spigotheights;
+
+import java.util.function.IntUnaryOperator;
+
+public final class HeightMath {
+    private HeightMath() {
+    }
+
+    public static double randomScale(HeightSettings settings, IntUnaryOperator randomIndex) {
+        int outcomes = settings.randomStepCount() + 1;
+        int index = randomIndex.applyAsInt(outcomes);
+        if (index < 0 || index >= outcomes) {
+            throw new IllegalArgumentException("random index is outside the requested bound");
+        }
+        return normalize(settings.minimum() + index * settings.adjustmentStep());
+    }
+
+    public static double grow(double current, HeightSettings settings) {
+        return clamp(current + settings.adjustmentStep(), settings);
+    }
+
+    public static double shrink(double current, HeightSettings settings) {
+        return clamp(current - settings.adjustmentStep(), settings);
+    }
+
+    public static double safeStoredScale(Double stored, HeightSettings settings) {
+        if (stored == null || !Double.isFinite(stored)) {
+            return clamp(1.0, settings);
+        }
+        return clamp(stored, settings);
+    }
+
+    public static double clamp(double value, HeightSettings settings) {
+        return normalize(Math.max(settings.minimum(), Math.min(settings.maximum(), value)));
+    }
+
+    private static double normalize(double value) {
+        return Math.rint(value * 1_000_000.0) / 1_000_000.0;
+    }
+}

src/main/java/games/dmg/spigotheights/HeightSettings.java

@@ -0,0 +1,40 @@
+package games.dmg.spigotheights;
+
+public record HeightSettings(
+        double minimum,
+        double maximum,
+        double adjustmentStep,
+        double launcherThreshold,
+        double launcherSpeed,
+        int launcherCooldownTicks) {
+
+    public HeightSettings {
+        requirePositiveFinite("height.minimum", minimum);
+        requirePositiveFinite("height.maximum", maximum);
+        requirePositiveFinite("height.adjustment-step", adjustmentStep);
+        requirePositiveFinite("launcher.maximum-player-scale-exclusive", launcherThreshold);
+        requirePositiveFinite("launcher.speed", launcherSpeed);
+        if (minimum > maximum) {
+            throw new IllegalArgumentException("height.minimum must not exceed height.maximum");
+        }
+        if (minimum < 0.0625 || maximum > 16.0) {
+            throw new IllegalArgumentException("height range must stay within Minecraft's 0.0625 to 16.0 scale range");
+        }
+        if (launcherThreshold < minimum || launcherThreshold > maximum) {
+            throw new IllegalArgumentException("launcher threshold must be within the height range");
+        }
+        if (launcherCooldownTicks < 0) {
+            throw new IllegalArgumentException("launcher.cooldown-ticks must not be negative");
+        }
+    }
+
+    public int randomStepCount() {
+        return (int) Math.floor((maximum - minimum) / adjustmentStep + 1.0e-9);
+    }
+
+    private static void requirePositiveFinite(String key, double value) {
+        if (!Double.isFinite(value) || value <= 0.0) {
+            throw new IllegalArgumentException(key + " must be a finite positive number");
+        }
+    }
+}

src/main/java/games/dmg/spigotheights/HeightStore.java

@@ -0,0 +1,43 @@
+package games.dmg.spigotheights;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.AtomicMoveNotSupportedException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
+import java.util.UUID;
+import org.bukkit.configuration.file.YamlConfiguration;
+
+public final class HeightStore {
+    private final Path statePath;
+    private final YamlConfiguration state;
+
+    public HeightStore(File dataFolder) {
+        statePath = dataFolder.toPath().resolve("state.yml");
+        state = YamlConfiguration.loadConfiguration(statePath.toFile());
+    }
+
+    public synchronized Double find(UUID playerId) {
+        String path = path(playerId);
+        return state.contains(path) ? state.getDouble(path) : null;
+    }
+
+    public synchronized void save(UUID playerId, double scale) throws IOException {
+        state.set(path(playerId), scale);
+        Files.createDirectories(statePath.getParent());
+        Path temporary = statePath.resolveSibling("state.yml.tmp");
+        Files.writeString(temporary, state.saveToString(), StandardCharsets.UTF_8);
+        try {
+            Files.move(temporary, statePath, StandardCopyOption.ATOMIC_MOVE,
+                    StandardCopyOption.REPLACE_EXISTING);
+        } catch (AtomicMoveNotSupportedException exception) {
+            Files.move(temporary, statePath, StandardCopyOption.REPLACE_EXISTING);
+        }
+    }
+
+    private static String path(UUID playerId) {
+        return "players." + playerId + ".scale";
+    }
+}

src/main/java/games/dmg/spigotheights/LaunchVector.java

@@ -0,0 +1,11 @@
+package games.dmg.spigotheights;
+
+public record LaunchVector(double x, double y, double z) {
+    public static LaunchVector fromDirection(int x, int y, int z, double speed) {
+        double length = Math.sqrt((double) x * x + (double) y * y + (double) z * z);
+        if (length == 0.0) {
+            throw new IllegalArgumentException("launch direction must not be stationary");
+        }
+        return new LaunchVector(x / length * speed, y / length * speed, z / length * speed);
+    }
+}

src/main/java/games/dmg/spigotheights/LauncherPolicy.java

@@ -0,0 +1,18 @@
+package games.dmg.spigotheights;
+
+public final class LauncherPolicy {
+    private LauncherPolicy() {
+    }
+
+    public static boolean isSmallEnough(double scale, double exclusiveThreshold) {
+        return scale < exclusiveThreshold;
+    }
+
+    public static boolean cooldownExpired(Long previousTick, long currentTick, int cooldownTicks) {
+        return previousTick == null || currentTick - previousTick >= cooldownTicks;
+    }
+
+    public static boolean isSafeExit(boolean empty) {
+        return empty;
+    }
+}

src/main/java/games/dmg/spigotheights/PotionRecipes.java

@@ -0,0 +1,106 @@
+package games.dmg.spigotheights;
+
+import net.kyori.adventure.text.Component;
+import net.kyori.adventure.text.format.NamedTextColor;
+import org.bukkit.Color;
+import org.bukkit.Material;
+import org.bukkit.NamespacedKey;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.RecipeChoice;
+import org.bukkit.inventory.ShapedRecipe;
+import org.bukkit.inventory.meta.PotionMeta;
+import org.bukkit.persistence.PersistentDataType;
+import org.bukkit.plugin.java.JavaPlugin;
+import org.bukkit.potion.PotionType;
+
+public final class PotionRecipes {
+    static final String[] SHIFTING_SHAPE = {"ACA", "AWA", "ACA"};
+    static final String[] GROWTH_SHAPE = {"GAG", "ASA", "GRG"};
+    static final String[] DIMINUTION_SHAPE = {"GAG", "ASA", "GFG"};
+
+    private final JavaPlugin plugin;
+    private final NamespacedKey potionKindKey;
+
+    public PotionRecipes(JavaPlugin plugin) {
+        this.plugin = plugin;
+        potionKindKey = new NamespacedKey(plugin, "stature_potion");
+    }
+
+    public void register() {
+        registerShifting();
+        registerGrowth();
+        registerDiminution();
+    }
+
+    public ItemStack create(StaturePotion kind) {
+        ItemStack item = new ItemStack(Material.POTION);
+        PotionMeta meta = (PotionMeta) item.getItemMeta();
+        meta.displayName(Component.text(kind.displayName(), NamedTextColor.LIGHT_PURPLE));
+        meta.getPersistentDataContainer().set(potionKindKey, PersistentDataType.STRING, kind.name());
+        meta.setColor(color(kind));
+        item.setItemMeta(meta);
+        return item;
+    }
+
+    public StaturePotion identify(ItemStack item) {
+        if (item == null || item.getType() != Material.POTION || !(item.getItemMeta() instanceof PotionMeta meta)) {
+            return null;
+        }
+        String value = meta.getPersistentDataContainer().get(potionKindKey, PersistentDataType.STRING);
+        if (value == null) {
+            return null;
+        }
+        try {
+            return StaturePotion.valueOf(value);
+        } catch (IllegalArgumentException exception) {
+            return null;
+        }
+    }
+
+    public boolean isAwkwardPotion(ItemStack item) {
+        return item != null && item.getItemMeta() instanceof PotionMeta meta
+                && meta.getBasePotionType() == PotionType.AWKWARD;
+    }
+
+    public NamespacedKey shiftingKey() {
+        return new NamespacedKey(plugin, "shifting_stature");
+    }
+
+    private void registerShifting() {
+        ShapedRecipe recipe = new ShapedRecipe(shiftingKey(), create(StaturePotion.SHIFTING));
+        recipe.shape(SHIFTING_SHAPE);
+        recipe.setIngredient('A', Material.AMETHYST_SHARD);
+        recipe.setIngredient('C', Material.CHORUS_FRUIT);
+        recipe.setIngredient('W', Material.POTION);
+        plugin.getServer().addRecipe(recipe);
+    }
+
+    private void registerGrowth() {
+        ShapedRecipe recipe = new ShapedRecipe(new NamespacedKey(plugin, "growth"), create(StaturePotion.GROWTH));
+        recipe.shape(GROWTH_SHAPE);
+        recipe.setIngredient('G', Material.GOLD_INGOT);
+        recipe.setIngredient('A', Material.AMETHYST_SHARD);
+        recipe.setIngredient('S', new RecipeChoice.ExactChoice(create(StaturePotion.SHIFTING)));
+        recipe.setIngredient('R', Material.RABBIT_FOOT);
+        plugin.getServer().addRecipe(recipe);
+    }
+
+    private void registerDiminution() {
+        ShapedRecipe recipe = new ShapedRecipe(new NamespacedKey(plugin, "diminution"),
+                create(StaturePotion.DIMINUTION));
+        recipe.shape(DIMINUTION_SHAPE);
+        recipe.setIngredient('G', Material.GOLD_INGOT);
+        recipe.setIngredient('A', Material.AMETHYST_SHARD);
+        recipe.setIngredient('S', new RecipeChoice.ExactChoice(create(StaturePotion.SHIFTING)));
+        recipe.setIngredient('F', Material.FERMENTED_SPIDER_EYE);
+        plugin.getServer().addRecipe(recipe);
+    }
+
+    private static Color color(StaturePotion kind) {
+        return switch (kind) {
+            case SHIFTING -> Color.PURPLE;
+            case GROWTH -> Color.LIME;
+            case DIMINUTION -> Color.FUCHSIA;
+        };
+    }
+}

src/main/java/games/dmg/spigotheights/SpigotHeightsPlugin.java

@@ -0,0 +1,37 @@
+package games.dmg.spigotheights;
+
+import org.bukkit.configuration.file.FileConfiguration;
+import org.bukkit.plugin.java.JavaPlugin;
+
+public final class SpigotHeightsPlugin extends JavaPlugin {
+    @Override
+    public void onEnable() {
+        saveDefaultConfig();
+        HeightSettings settings;
+        try {
+            settings = loadSettings(getConfig());
+        } catch (IllegalArgumentException exception) {
+            getLogger().severe("Invalid configuration: " + exception.getMessage());
+            getServer().getPluginManager().disablePlugin(this);
+            return;
+        }
+
+        HeightStore store = new HeightStore(getDataFolder());
+        PotionRecipes potions = new PotionRecipes(this);
+        potions.register();
+        getServer().getPluginManager().registerEvents(
+                new StatureListener(this, settings, store, potions), this);
+        getServer().getPluginManager().registerEvents(new TinyPlayerLauncher(settings), this);
+        getLogger().info("Spigot Heights enabled.");
+    }
+
+    static HeightSettings loadSettings(FileConfiguration config) {
+        return new HeightSettings(
+                config.getDouble("height.minimum"),
+                config.getDouble("height.maximum"),
+                config.getDouble("height.adjustment-step"),
+                config.getDouble("launcher.maximum-player-scale-exclusive"),
+                config.getDouble("launcher.speed"),
+                config.getInt("launcher.cooldown-ticks"));
+    }
+}

src/main/java/games/dmg/spigotheights/StatureListener.java

@@ -0,0 +1,97 @@
+package games.dmg.spigotheights;
+
+import java.io.IOException;
+import java.util.concurrent.ThreadLocalRandom;
+import org.bukkit.attribute.Attribute;
+import org.bukkit.attribute.AttributeInstance;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.EventPriority;
+import org.bukkit.event.Listener;
+import org.bukkit.event.inventory.PrepareItemCraftEvent;
+import org.bukkit.event.player.PlayerItemConsumeEvent;
+import org.bukkit.event.player.PlayerJoinEvent;
+import org.bukkit.event.player.PlayerRespawnEvent;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.Recipe;
+import org.bukkit.Keyed;
+import org.bukkit.plugin.java.JavaPlugin;
+
+public final class StatureListener implements Listener {
+    private final JavaPlugin plugin;
+    private final HeightSettings settings;
+    private final HeightStore store;
+    private final PotionRecipes potions;
+
+    public StatureListener(JavaPlugin plugin, HeightSettings settings, HeightStore store, PotionRecipes potions) {
+        this.plugin = plugin;
+        this.settings = settings;
+        this.store = store;
+        this.potions = potions;
+    }
+
+    @EventHandler
+    public void onCraftPrepare(PrepareItemCraftEvent event) {
+        Recipe recipe = event.getRecipe();
+        if (!(recipe instanceof Keyed keyed) || !keyed.getKey().equals(potions.shiftingKey())) {
+            return;
+        }
+        ItemStack[] matrix = event.getInventory().getMatrix();
+        if (matrix.length < 5 || !potions.isAwkwardPotion(matrix[4])) {
+            event.getInventory().setResult(null);
+        }
+    }
+
+    @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true)
+    public void onConsume(PlayerItemConsumeEvent event) {
+        StaturePotion kind = potions.identify(event.getItem());
+        if (kind == null) {
+            return;
+        }
+        Player player = event.getPlayer();
+        double current = currentScale(player);
+        double scale = switch (kind) {
+            case SHIFTING -> HeightMath.randomScale(settings,
+                    bound -> ThreadLocalRandom.current().nextInt(bound));
+            case GROWTH -> HeightMath.grow(current, settings);
+            case DIMINUTION -> HeightMath.shrink(current, settings);
+        };
+        applyAndSave(player, scale);
+        player.sendMessage("Your scale is now " + scale + ".");
+    }
+
+    @EventHandler
+    public void onJoin(PlayerJoinEvent event) {
+        apply(event.getPlayer(), HeightMath.safeStoredScale(store.find(event.getPlayer().getUniqueId()), settings));
+    }
+
+    @EventHandler
+    public void onRespawn(PlayerRespawnEvent event) {
+        plugin.getServer().getScheduler().runTask(plugin, () -> {
+            Player player = event.getPlayer();
+            apply(player, HeightMath.safeStoredScale(store.find(player.getUniqueId()), settings));
+        });
+    }
+
+    private void applyAndSave(Player player, double scale) {
+        apply(player, scale);
+        try {
+            store.save(player.getUniqueId(), scale);
+        } catch (IOException exception) {
+            plugin.getLogger().severe("Could not save scale for " + player.getUniqueId() + ": "
+                    + exception.getMessage());
+        }
+    }
+
+    private static void apply(Player player, double scale) {
+        AttributeInstance attribute = player.getAttribute(Attribute.SCALE);
+        if (attribute != null) {
+            attribute.setBaseValue(scale);
+        }
+    }
+
+    private static double currentScale(Player player) {
+        AttributeInstance attribute = player.getAttribute(Attribute.SCALE);
+        return attribute == null ? 1.0 : attribute.getBaseValue();
+    }
+}

src/main/java/games/dmg/spigotheights/StaturePotion.java

@@ -0,0 +1,17 @@
+package games.dmg.spigotheights;
+
+public enum StaturePotion {
+    SHIFTING("Potion of Shifting Stature"),
+    GROWTH("Potion of Growth"),
+    DIMINUTION("Potion of Diminution");
+
+    private final String displayName;
+
+    StaturePotion(String displayName) {
+        this.displayName = displayName;
+    }
+
+    public String displayName() {
+        return displayName;
+    }
+}

src/main/java/games/dmg/spigotheights/TinyPlayerLauncher.java

@@ -0,0 +1,82 @@
+package games.dmg.spigotheights;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.UUID;
+import org.bukkit.Bukkit;
+import org.bukkit.Location;
+import org.bukkit.Material;
+import org.bukkit.attribute.Attribute;
+import org.bukkit.attribute.AttributeInstance;
+import org.bukkit.block.Block;
+import org.bukkit.block.BlockFace;
+import org.bukkit.block.data.Directional;
+import org.bukkit.block.data.type.Hopper;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+import org.bukkit.event.player.PlayerMoveEvent;
+import org.bukkit.util.Vector;
+
+public final class TinyPlayerLauncher implements Listener {
+    private final HeightSettings settings;
+    private final Map<UUID, Long> lastLaunchTicks = new HashMap<>();
+
+    public TinyPlayerLauncher(HeightSettings settings) {
+        this.settings = settings;
+    }
+
+    @EventHandler(ignoreCancelled = true)
+    public void onMove(PlayerMoveEvent event) {
+        Location destination = event.getTo();
+        if (destination == null || sameBlock(event.getFrom(), destination)) {
+            return;
+        }
+        Player player = event.getPlayer();
+        if (!LauncherPolicy.isSmallEnough(scale(player), settings.launcherThreshold())) {
+            return;
+        }
+        long tick = Bukkit.getCurrentTick();
+        Long lastTick = lastLaunchTicks.get(player.getUniqueId());
+        if (!LauncherPolicy.cooldownExpired(lastTick, tick, settings.launcherCooldownTicks())) {
+            return;
+        }
+        Block hopperBlock = destination.clone().subtract(0.0, 0.1, 0.0).getBlock();
+        if (!(hopperBlock.getBlockData() instanceof Hopper hopper)) {
+            return;
+        }
+        Block dispenser = hopperBlock.getRelative(hopper.getFacing());
+        if (dispenser.getType() != Material.DISPENSER
+                || !(dispenser.getBlockData() instanceof Directional directional)) {
+            return;
+        }
+        BlockFace facing = directional.getFacing();
+        Block exit = dispenser.getRelative(facing);
+        if (!LauncherPolicy.isSafeExit(exit.isEmpty())) {
+            return;
+        }
+        Location exitLocation = exit.getLocation().add(0.5, 0.1, 0.5);
+        exitLocation.setYaw(player.getLocation().getYaw());
+        exitLocation.setPitch(player.getLocation().getPitch());
+        if (!player.teleport(exitLocation)) {
+            return;
+        }
+        Vector direction = facing.getDirection();
+        LaunchVector launch = LaunchVector.fromDirection(
+                direction.getBlockX(), direction.getBlockY(), direction.getBlockZ(), settings.launcherSpeed());
+        player.setVelocity(new Vector(launch.x(), launch.y(), launch.z()));
+        lastLaunchTicks.put(player.getUniqueId(), tick);
+    }
+
+    private static boolean sameBlock(Location first, Location second) {
+        return first.getWorld().equals(second.getWorld())
+                && first.getBlockX() == second.getBlockX()
+                && first.getBlockY() == second.getBlockY()
+                && first.getBlockZ() == second.getBlockZ();
+    }
+
+    private static double scale(Player player) {
+        AttributeInstance attribute = player.getAttribute(Attribute.SCALE);
+        return attribute == null ? 1.0 : attribute.getValue();
+    }
+}