Add writing ink and baseline link panel preparation

src/main/java/net/dnorberg/rivencraft/config/RivencraftConfig.java

@@ -15,6 +15,8 @@ public final class RivencraftConfig {
 
     public static final ModConfigSpec SPEC;
     private static final ModConfigSpec.EnumValue<ReturnLinkMode> RETURN_LINK_MODE;
+    private static final ModConfigSpec.IntValue SYMBOL_INK_COST;
+    private static final ModConfigSpec.IntValue LINK_PANEL_INK_COST;
 
     static {
         ModConfigSpec.Builder builder = new ModConfigSpec.Builder();
@@ -25,6 +27,12 @@ public final class RivencraftConfig {
                 )
                 .defineEnum("return_link_mode", ReturnLinkMode.ON_CREATION);
         builder.pop();
+        builder.push("writing");
+        SYMBOL_INK_COST = builder.comment("Ink units consumed when the Writing Desk copies one symbol page.")
+                .defineInRange("symbol_ink_cost", 1, 1, 16);
+        LINK_PANEL_INK_COST = builder.comment("Ink units consumed when preparing one baseline link-panel page.")
+                .defineInRange("link_panel_ink_cost", 2, 1, 16);
+        builder.pop();
         SPEC = builder.build();
     }
 
@@ -34,4 +42,12 @@ public final class RivencraftConfig {
     public static ReturnLinkMode returnLinkMode() {
         return RETURN_LINK_MODE.get();
     }
+
+    public static int symbolInkCost() {
+        return SYMBOL_INK_COST.get();
+    }
+
+    public static int linkPanelInkCost() {
+        return LINK_PANEL_INK_COST.get();
+    }
 }

src/main/java/net/dnorberg/rivencraft/gametest/WritingDataGameTests.java

@@ -11,6 +11,8 @@ import net.dnorberg.rivencraft.writing.SymbolReference;
 import net.dnorberg.rivencraft.writing.WritingEntry;
 import net.dnorberg.rivencraft.writing.NotebookContents;
 import net.dnorberg.rivencraft.item.PageItem;
+import net.dnorberg.rivencraft.item.InkVialItem;
+import net.dnorberg.rivencraft.writing.WritingInkService;
 import net.dnorberg.rivencraft.registry.ModDataComponents;
 import net.dnorberg.rivencraft.registry.ModItems;
 import net.dnorberg.rivencraft.menu.NotebookMenu;
@@ -200,6 +202,95 @@ public final class WritingDataGameTests {
         helper.succeed();
     }
 
+    @GameTest(template = "empty")
+    public static void inkVialsPersistAndOnlyStackWithMatchingContents(GameTestHelper helper) {
+        ItemStack vial = new ItemStack(ModItems.INK_VIAL.get());
+        vial.set(ModDataComponents.INK_REMAINING.get(), 7);
+        CompoundTag serialized = (CompoundTag) vial.saveOptional(helper.getLevel().registryAccess());
+        ItemStack restored = ItemStack.parseOptional(helper.getLevel().registryAccess(), serialized);
+        helper.assertValueEqual(InkVialItem.remaining(restored), 7,
+                "Remaining ink must survive ItemStack persistence");
+        helper.assertTrue(ItemStack.isSameItemSameComponents(vial, restored),
+                "Vials with equal ink contents must be eligible to stack");
+        helper.assertFalse(ItemStack.isSameItemSameComponents(vial, new ItemStack(ModItems.INK_VIAL.get())),
+                "Vials with different ink contents must not stack");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void linkPanelPreparationConsumesOnePageAndConfiguredInkOnlyOnSuccess(GameTestHelper helper) {
+        var player = helper.makeMockServerPlayerInLevel();
+        ItemStack pages = new ItemStack(ModItems.PAGE.get(), 2);
+        ItemStack vial = new ItemStack(ModItems.INK_VIAL.get());
+        player.setItemInHand(InteractionHand.MAIN_HAND, vial);
+        player.setItemInHand(InteractionHand.OFF_HAND, pages);
+
+        helper.assertTrue(WritingInkService.prepareLinkPanel(player, InteractionHand.MAIN_HAND),
+                "A blank Page and sufficient ink must prepare one link panel");
+        helper.assertValueEqual(pages.getCount(), 1, "Preparation must consume exactly one blank Page");
+        helper.assertValueEqual(InkVialItem.remaining(player.getMainHandItem()),
+                InkVialItem.CAPACITY - WritingInkService.linkPanelCost(),
+                "Preparation must consume exactly the server-configured ink cost");
+        long panels = player.getInventory().items.stream()
+                .filter(stack -> stack.is(ModItems.PAGE.get())
+                        && PageItem.content(stack).kind() == PageContent.Kind.LINK_PANEL)
+                .mapToInt(ItemStack::getCount).sum();
+        helper.assertValueEqual(panels, 1L, "Preparation must output exactly one link panel");
+
+        ItemStack written = PageItem.createSymbolPage(reference("rivencraft:terrain/standard"));
+        player.setItemInHand(InteractionHand.OFF_HAND, written);
+        int inkBefore = InkVialItem.remaining(player.getMainHandItem());
+        helper.assertFalse(WritingInkService.prepareLinkPanel(player, InteractionHand.MAIN_HAND),
+                "A written Page must not be overwritten as a link panel");
+        helper.assertValueEqual(InkVialItem.remaining(player.getMainHandItem()), inkBefore,
+                "Rejected writing must not consume ink");
+        helper.assertValueEqual(PageItem.content(written).kind(), PageContent.Kind.SYMBOL,
+                "Rejected writing must not modify the input Page");
+
+        ItemStack lowInk = new ItemStack(ModItems.INK_VIAL.get());
+        lowInk.set(ModDataComponents.INK_REMAINING.get(), WritingInkService.linkPanelCost() - 1);
+        player.setItemInHand(InteractionHand.MAIN_HAND, lowInk);
+        player.setItemInHand(InteractionHand.OFF_HAND, new ItemStack(ModItems.PAGE.get()));
+        helper.assertFalse(WritingInkService.prepareLinkPanel(player, InteractionHand.MAIN_HAND),
+                "Insufficient ink must reject link-panel preparation");
+        helper.assertValueEqual(InkVialItem.remaining(player.getMainHandItem()),
+                WritingInkService.linkPanelCost() - 1,
+                "Insufficient ink must remain untouched");
+        helper.assertValueEqual(PageItem.content(player.getOffhandItem()).kind(), PageContent.Kind.BLANK,
+                "Insufficient ink must leave the Page blank");
+
+        lowInk.set(ModDataComponents.INK_REMAINING.get(), WritingInkService.linkPanelCost());
+        helper.assertTrue(WritingInkService.prepareLinkPanel(player, InteractionHand.MAIN_HAND),
+                "Exact remaining ink must be usable");
+        helper.assertTrue(player.getMainHandItem().is(Items.GLASS_BOTTLE),
+                "A depleted Ink Vial must return a reusable glass bottle");
+        helper.assertValueEqual(PageItem.content(player.getOffhandItem()).kind(),
+                PageContent.Kind.LINK_PANEL,
+                "A single blank Page must be replaced by one Link Panel Page");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void stackedInkVialsSplitWithoutChangingTheOtherVials(GameTestHelper helper) {
+        var player = helper.makeMockServerPlayerInLevel();
+        player.setItemInHand(InteractionHand.MAIN_HAND, new ItemStack(ModItems.INK_VIAL.get(), 2));
+        player.setItemInHand(InteractionHand.OFF_HAND, new ItemStack(ModItems.PAGE.get()));
+
+        helper.assertTrue(WritingInkService.prepareLinkPanel(player, InteractionHand.MAIN_HAND),
+                "A stack of full vials must support preparing one panel");
+        helper.assertValueEqual(player.getMainHandItem().getCount(), 1,
+                "Using one vial must leave the other full vial in hand");
+        helper.assertValueEqual(InkVialItem.remaining(player.getMainHandItem()), InkVialItem.CAPACITY,
+                "The unconsumed vial must remain full");
+        long partialVials = player.getInventory().items.stream()
+                .filter(stack -> stack.is(ModItems.INK_VIAL.get())
+                        && InkVialItem.remaining(stack) == InkVialItem.CAPACITY - WritingInkService.linkPanelCost())
+                .mapToInt(ItemStack::getCount).sum();
+        helper.assertValueEqual(partialVials, 1L,
+                "The used vial must reappear with only its own ink reduced");
+        helper.succeed();
+    }
+
     private static SymbolReference reference(String id) {
         return new SymbolReference(ResourceLocation.parse(id));
     }

src/main/java/net/dnorberg/rivencraft/item/InkVialItem.java

@@ -0,0 +1,47 @@
+package net.dnorberg.rivencraft.item;
+
+import java.util.List;
+import net.dnorberg.rivencraft.registry.ModDataComponents;
+import net.dnorberg.rivencraft.writing.WritingInkService;
+import net.minecraft.ChatFormatting;
+import net.minecraft.network.chat.Component;
+import net.minecraft.world.InteractionHand;
+import net.minecraft.world.InteractionResultHolder;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.item.Item;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.TooltipFlag;
+import net.minecraft.world.level.Level;
+
+/** A stackable vial; the ink component is per vial, not shared across a stack. */
+public final class InkVialItem extends Item {
+    public static final int CAPACITY = 16;
+
+    public InkVialItem(Properties properties) {
+        super(properties);
+    }
+
+    public static int remaining(ItemStack vial) {
+        return vial.getOrDefault(ModDataComponents.INK_REMAINING.get(), CAPACITY);
+    }
+
+    @Override
+    public InteractionResultHolder<ItemStack> use(Level level, Player player, InteractionHand hand) {
+        if (!WritingInkService.canPrepareLinkPanel(player, hand)) {
+            return InteractionResultHolder.pass(player.getItemInHand(hand));
+        }
+        if (!level.isClientSide) {
+            WritingInkService.prepareLinkPanel(player, hand);
+        }
+        return InteractionResultHolder.sidedSuccess(player.getItemInHand(hand), level.isClientSide);
+    }
+
+    @Override
+    public void appendHoverText(ItemStack stack, TooltipContext context,
+                                List<Component> tooltip, TooltipFlag flag) {
+        tooltip.add(Component.translatable("item.rivencraft.ink_vial.remaining",
+                remaining(stack), CAPACITY).withStyle(ChatFormatting.GRAY));
+        tooltip.add(Component.translatable("item.rivencraft.ink_vial.usage")
+                .withStyle(ChatFormatting.GRAY));
+    }
+}

src/main/java/net/dnorberg/rivencraft/registry/ModCreativeTabs.java

@@ -21,6 +21,7 @@ public final class ModCreativeTabs {
                         output.accept(ModItems.LINKING_BOOK.get());
                         output.accept(ModItems.PAGE.get());
                         output.accept(ModItems.NOTEBOOK.get());
+                        output.accept(ModItems.INK_VIAL.get());
                     })
                     .build());
 

src/main/java/net/dnorberg/rivencraft/registry/ModDataComponents.java

@@ -6,6 +6,7 @@ import net.dnorberg.rivencraft.book.AgeReference;
 import net.dnorberg.rivencraft.writing.PageContent;
 import net.dnorberg.rivencraft.writing.NotebookContents;
 import net.dnorberg.rivencraft.writing.SymbolDisplayMetadata;
+import com.mojang.serialization.Codec;
 import net.minecraft.core.component.DataComponentType;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceLocation;
@@ -60,6 +61,12 @@ public final class ModDataComponents {
                     .networkSynchronized(NotebookContents.STREAM_CODEC)
                     .cacheEncoding()
                     .build());
+    public static final DeferredHolder<DataComponentType<?>, DataComponentType<Integer>> INK_REMAINING =
+            DATA_COMPONENTS.register("ink_remaining", () -> DataComponentType.<Integer>builder()
+                    .persistent(Codec.intRange(0, 16))
+                    .networkSynchronized(ByteBufCodecs.VAR_INT)
+                    .cacheEncoding()
+                    .build());
 
     private ModDataComponents() {
     }

src/main/java/net/dnorberg/rivencraft/registry/ModItems.java

@@ -5,6 +5,7 @@ import net.dnorberg.rivencraft.item.DescriptiveBookItem;
 import net.dnorberg.rivencraft.item.LinkingBookItem;
 import net.dnorberg.rivencraft.item.PageItem;
 import net.dnorberg.rivencraft.item.NotebookItem;
+import net.dnorberg.rivencraft.item.InkVialItem;
 import net.minecraft.world.item.Item;
 import net.neoforged.bus.api.IEventBus;
 import net.neoforged.neoforge.registries.DeferredItem;
@@ -33,6 +34,11 @@ public final class ModItems {
             NotebookItem::new,
             new Item.Properties().stacksTo(1)
     );
+    public static final DeferredItem<InkVialItem> INK_VIAL = ITEMS.registerItem(
+            "ink_vial",
+            InkVialItem::new,
+            new Item.Properties().stacksTo(16)
+    );
 
     private ModItems() {
     }

src/main/java/net/dnorberg/rivencraft/writing/WritingInkService.java

@@ -0,0 +1,77 @@
+package net.dnorberg.rivencraft.writing;
+
+import net.dnorberg.rivencraft.config.RivencraftConfig;
+import net.dnorberg.rivencraft.item.InkVialItem;
+import net.dnorberg.rivencraft.item.PageItem;
+import net.dnorberg.rivencraft.registry.ModDataComponents;
+import net.dnorberg.rivencraft.registry.ModItems;
+import net.minecraft.world.InteractionHand;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.Items;
+
+/** Server-owned costs and the baseline blank-page-to-link-panel transaction. */
+public final class WritingInkService {
+    private WritingInkService() {
+    }
+
+    public static int symbolCopyCost() {
+        return RivencraftConfig.symbolInkCost();
+    }
+
+    public static int linkPanelCost() {
+        return RivencraftConfig.linkPanelInkCost();
+    }
+
+    public static boolean canPrepareLinkPanel(Player player, InteractionHand vialHand) {
+        ItemStack vial = player.getItemInHand(vialHand);
+        ItemStack page = player.getItemInHand(other(vialHand));
+        int remaining = InkVialItem.remaining(vial);
+        return vial.is(ModItems.INK_VIAL.get()) && remaining >= linkPanelCost()
+                && remaining <= InkVialItem.CAPACITY
+                && page.is(ModItems.PAGE.get()) && PageItem.content(page).kind() == PageContent.Kind.BLANK;
+    }
+
+    public static boolean prepareLinkPanel(Player player, InteractionHand vialHand) {
+        if (player.level().isClientSide || !canPrepareLinkPanel(player, vialHand)) {
+            return false;
+        }
+
+        InteractionHand pageHand = other(vialHand);
+        ItemStack page = player.getItemInHand(pageHand);
+        ItemStack vial = player.getItemInHand(vialHand);
+        int newInk = InkVialItem.remaining(vial) - linkPanelCost();
+        ItemStack panel = PageItem.createLinkPanelPage();
+        ItemStack spentVial = newInk == 0
+                ? new ItemStack(Items.GLASS_BOTTLE)
+                : new ItemStack(ModItems.INK_VIAL.get());
+        if (newInk > 0) {
+            spentVial.set(ModDataComponents.INK_REMAINING.get(), newInk);
+        }
+
+        // All validation and output construction is complete before changing either input.
+        if (page.getCount() == 1) {
+            player.setItemInHand(pageHand, panel);
+        } else {
+            page.shrink(1);
+            giveOrDrop(player, panel);
+        }
+        if (vial.getCount() == 1) {
+            player.setItemInHand(vialHand, spentVial);
+        } else {
+            vial.shrink(1);
+            giveOrDrop(player, spentVial);
+        }
+        return true;
+    }
+
+    private static InteractionHand other(InteractionHand hand) {
+        return hand == InteractionHand.MAIN_HAND ? InteractionHand.OFF_HAND : InteractionHand.MAIN_HAND;
+    }
+
+    private static void giveOrDrop(Player player, ItemStack stack) {
+        if (!player.getInventory().add(stack)) {
+            player.drop(stack, false);
+        }
+    }
+}

src/main/resources/assets/rivencraft/lang/en_us.json

@@ -15,6 +15,9 @@
   "item.rivencraft.notebook": "Notebook",
   "item.rivencraft.notebook.pages": "Pages: %s/%s",
   "item.rivencraft.notebook.unresolved": "Unresolved pages: %s",
+  "item.rivencraft.ink_vial": "Ink Vial",
+  "item.rivencraft.ink_vial.remaining": "Ink: %s/%s",
+  "item.rivencraft.ink_vial.usage": "Use with a blank Page in the other hand to prepare a Link Panel.",
   "screen.rivencraft.notebook.rename": "Rename selected page",
   "screen.rivencraft.notebook.search": "Search pages",
   "screen.rivencraft.notebook.rename_toggle": "Rename selected page (R); use left/right arrows to reorder",

src/main/resources/assets/rivencraft/models/item/ink_vial.json

@@ -0,0 +1,6 @@
+{
+  "parent": "minecraft:item/generated",
+  "textures": {
+    "layer0": "rivencraft:item/ink_vial"
+  }
+}

src/main/resources/assets/rivencraft/textures/item/ink_vial.png.mcmeta

@@ -0,0 +1,3 @@
+{
+  "animation": {}
+}

src/main/resources/data/rivencraft/recipe/ink_vial.json

@@ -0,0 +1,14 @@
+{
+  "type": "minecraft:crafting_shapeless",
+  "category": "misc",
+  "ingredients": [
+    { "item": "minecraft:black_dye" },
+    { "item": "minecraft:black_dye" },
+    { "item": "minecraft:glass_bottle" },
+    { "item": "minecraft:water_bucket" }
+  ],
+  "result": {
+    "count": 1,
+    "id": "rivencraft:ink_vial"
+  }
+}