feat(core): declare item id enum and item stack definitions interface

core/include/vf/Item.h

@@ -0,0 +1,108 @@
+#pragma once
+
+#include <cstdint>
+#include "Block.h"
+
+namespace vf {
+
+enum class ItemId : uint16_t {
+    None = 0,
+
+    Grass, Dirt, Stone, Sand, Wood, Leaves, Snow,
+    CoalOre, IronOre, GoldOre, Gravel, Glowstone,
+    Cobblestone, Planks, Sandstone, Ice, Obsidian,
+    DiamondOre, RedstoneOre, EmeraldOre, LapisOre,
+    CraftingTable, Furnace, Chest, Torch,
+    RedstoneWire, RedstoneTorch, RedstoneLamp,
+    Lever, Button, RedstoneBlock, Repeater, Comparator,
+    Piston, PistonSticky, Tnt, Ladder,
+
+    Stick, Gunpowder,
+    CoalLump, IronIngot, GoldIngot, DiamondGem, EmeraldGem, RedstoneDust, LapisLazuli,
+
+    WoodPickaxe, WoodAxe, WoodShovel, WoodSword, WoodHoe,
+    StonePickaxe, StoneAxe, StoneShovel, StoneSword, StoneHoe,
+    IronPickaxe, IronAxe, IronShovel, IronSword, IronHoe,
+    GoldPickaxe, GoldAxe, GoldShovel, GoldSword, GoldHoe,
+    DiamondPickaxe, DiamondAxe, DiamondShovel, DiamondSword, DiamondHoe,
+
+    Apple, Bread,
+    RawPorkchop, CookedPorkchop,
+    RawBeef, CookedBeef,
+    RawMutton, CookedMutton,
+    RottenFlesh,
+
+    Count
+};
+
+enum class ItemKind : uint8_t { Block, Material, Tool, Food };
+enum class ToolType : uint8_t { None, Pickaxe, Axe, Shovel, Sword, Hoe };
+enum class ToolTier : uint8_t { None, Wood, Stone, Iron, Gold, Diamond };
+
+constexpr int defaultStackSize = 64;
+
+struct ItemInfo {
+    ItemKind kind = ItemKind::Material;
+    int maxStack = defaultStackSize;
+    ToolType toolType = ToolType::None;
+    ToolTier toolTier = ToolTier::None;
+    int foodHunger = 0;
+    float foodSaturation = 0.0f;
+};
+
+const ItemInfo& itemInfo(ItemId id);
+
+bool isBlockItem(ItemId id);
+bool isTool(ItemId id);
+bool isFood(ItemId id);
+
+int maxStackSize(ItemId id);
+int toolMaxDurability(ItemId id);
+
+// Bidirectional mapping between placeable/obtainable blocks and their item form.
+// blockForItem returns Block::Air and itemForBlock returns ItemId::None when the
+// given side has no counterpart.
+Block blockForItem(ItemId id);
+ItemId itemForBlock(Block block);
+
+// The tool type that is efficient against a block, or ToolType::None when no
+// tool gives a bonus (bare hands are as fast as any tool).
+ToolType correctToolFor(Block block);
+
+// Base multiplier for a tool tier regardless of block, 1.0 for bare hands.
+float toolTierSpeedMultiplier(ToolTier tier);
+
+// Combines correctToolFor and toolTierSpeedMultiplier: 1.0 unless toolItem is a
+// tool whose type matches the block's preferred class.
+float miningSpeedMultiplier(ItemId toolItem, Block block);
+
+struct FoodValue {
+    int hunger = 0;
+    float saturation = 0.0f;
+};
+
+FoodValue foodValue(ItemId id);
+
+struct ItemSlot {
+    ItemId item = ItemId::None;
+    int count = 0;
+    int durability = 0;
+
+    bool empty() const { return count <= 0 || item == ItemId::None; }
+};
+
+ItemSlot makeToolStack(ItemId toolItem);
+
+// Moves as many items as possible from `from` into `into` (same item, same
+// durability, respecting the item's max stack). Returns the amount moved.
+int mergeStacks(ItemSlot& into, ItemSlot& from);
+
+// Removes up to `amount` items from `stack` and returns them as a new stack.
+ItemSlot splitStack(ItemSlot& stack, int amount);
+
+// Reduces a tool's durability by `amount`. Clears the slot to empty and
+// returns true when durability reaches zero. No-op (returns false) on
+// non-tool stacks.
+bool damageTool(ItemSlot& stack, int amount = 1);
+
+} // namespace vf