up3

server/item/enchantment.go

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+package item
+
+import (
+	"github.com/df-mc/dragonfly/server/world"
+	"maps"
+	"slices"
+	"sort"
+)
+
+// Enchantment is an enchantment that can be applied to a Stack. It holds an EnchantmentType and level that influences
+// the power of the enchantment.
+type Enchantment struct {
+	t   EnchantmentType
+	lvl int
+}
+
+// NewEnchantment creates and returns an Enchantment with a specific EnchantmentType and level. If the level passed
+// exceeds EnchantmentType.MaxLevel, NewEnchantment panics.
+func NewEnchantment(t EnchantmentType, lvl int) Enchantment {
+	if lvl < 1 {
+		panic("enchantment level must never be below 1")
+	}
+	return Enchantment{t: t, lvl: lvl}
+}
+
+// Level returns the current level of the Enchantment as passed to NewEnchantment upon construction.
+func (e Enchantment) Level() int {
+	return e.lvl
+}
+
+// Type returns the EnchantmentType of the Enchantment as passed to NewEnchantment upon construction.
+func (e Enchantment) Type() EnchantmentType {
+	return e.t
+}
+
+// EnchantmentType represents an enchantment type that can be applied to a Stack, with specific behaviour that modifies
+// the Stack's behaviour.
+// An instance of an EnchantmentType may be created using NewEnchantment.
+type EnchantmentType interface {
+	// Name returns the name of the enchantment.
+	Name() string
+	// MaxLevel returns the maximum level the enchantment should be able to have.
+	MaxLevel() int
+	// Cost returns the minimum and maximum cost the enchantment may inhibit. The higher this range is, the more likely
+	// better enchantments are to be selected.
+	Cost(level int) (int, int)
+	// Rarity returns the enchantment's rarity.
+	Rarity() EnchantmentRarity
+	// CompatibleWithEnchantment is called when an enchantment is added to an item. It can be used to check if
+	// the enchantment is compatible with other enchantments.
+	CompatibleWithEnchantment(t EnchantmentType) bool
+	// CompatibleWithItem is also called when an enchantment is added to an item. It can be used to check if
+	// the enchantment is compatible with the item type.
+	CompatibleWithItem(i world.Item) bool
+}
+
+// Enchantable is an interface that can be implemented by items that can be enchanted through an enchanting table.
+type Enchantable interface {
+	// EnchantmentValue returns the value the item may inhibit on possible enchantments.
+	EnchantmentValue() int
+}
+
+// RegisterEnchantment registers an enchantment with the ID passed. Once registered, enchantments may be received
+// by instantiating an EnchantmentType struct (e.g. enchantment.Protection{})
+func RegisterEnchantment(id int, enchantment EnchantmentType) {
+	enchantmentsMap[id] = enchantment
+	enchantmentIDs[enchantment] = id
+}
+
+var (
+	enchantmentsMap = map[int]EnchantmentType{}
+	enchantmentIDs  = map[EnchantmentType]int{}
+)
+
+// EnchantmentByID attempts to return an enchantment by the ID it was registered with. If found, the enchantment found
+// is returned and the bool true.
+func EnchantmentByID(id int) (EnchantmentType, bool) {
+	e, ok := enchantmentsMap[id]
+	return e, ok
+}
+
+// EnchantmentID attempts to return the ID the enchantment was registered with. If found, the id is returned and
+// the bool true.
+func EnchantmentID(e EnchantmentType) (int, bool) {
+	id, ok := enchantmentIDs[e]
+	return id, ok
+}
+
+// Enchantments returns a slice of all registered enchantments.
+func Enchantments() []EnchantmentType {
+	e := slices.Collect(maps.Values(enchantmentsMap))
+	sort.Slice(e, func(i, j int) bool {
+		id1, _ := EnchantmentID(e[i])
+		id2, _ := EnchantmentID(e[j])
+		return id1 < id2
+	})
+	return e
+}