dragonfly/server: Implement hoppers (#911)

Co-authored-by: DaPigGuy <mcpepig123@gmail.com>

server/block/composter.go

@@ -22,6 +22,44 @@ type Composter struct {
 	Level int
 }
 
+// InsertItem ...
+func (c Composter) InsertItem(h Hopper, pos cube.Pos, w *world.World) bool {
+	if c.Level == 8 {
+		return false
+	}
+
+	for sourceSlot, sourceStack := range h.inventory.Slots() {
+		if sourceStack.Empty() {
+			continue
+		}
+
+		if c.fill(sourceStack, pos, w) {
+			_ = h.inventory.SetItem(sourceSlot, sourceStack.Grow(-1))
+			return true
+		}
+	}
+
+	return false
+}
+
+// ExtractItem ...
+func (c Composter) ExtractItem(h Hopper, pos cube.Pos, w *world.World) bool {
+	if c.Level == 8 {
+		_, err := h.inventory.AddItem(item.NewStack(item.BoneMeal{}, 1))
+		if err != nil {
+			// The hopper is full.
+			return false
+		}
+
+		c.Level = 0
+		w.SetBlock(pos.Side(cube.FaceUp), c, nil)
+		w.PlaySound(pos.Side(cube.FaceUp).Vec3(), sound.ComposterEmpty{})
+		return true
+	}
+
+	return false
+}
+
 // Model ...
 func (c Composter) Model() world.BlockModel {
 	return model.Composter{Level: c.Level}
@@ -63,11 +101,19 @@ func (c Composter) Activate(pos cube.Pos, _ cube.Face, w *world.World, u item.Us
 		return false
 	}
 	it, _ := u.HeldItems()
+	if c.fill(it, pos, w) {
+		ctx.SubtractFromCount(1)
+		return true
+	}
+	return false
+}
+
+// Fill fills up the composter.
+func (c Composter) fill(it item.Stack, pos cube.Pos, w *world.World) bool {
 	compostable, ok := it.Item().(item.Compostable)
 	if !ok {
 		return false
 	}
-	ctx.SubtractFromCount(1)
 	w.AddParticle(pos.Vec3(), particle.BoneMeal{})
 	if rand.Float64() > compostable.CompostChance() {
 		w.PlaySound(pos.Vec3(), sound.ComposterFill{})
@@ -79,6 +125,7 @@ func (c Composter) Activate(pos cube.Pos, _ cube.Face, w *world.World, u item.Us
 	if c.Level == 7 {
 		w.ScheduleBlockUpdate(pos, time.Second)
 	}
+
 	return true
 }
 

server/block/hopper.go

@@ -0,0 +1,281 @@
+package block
+
+import (
+	"fmt"
+	"github.com/df-mc/dragonfly/server/block/cube"
+	"github.com/df-mc/dragonfly/server/block/model"
+	"github.com/df-mc/dragonfly/server/internal/nbtconv"
+	"github.com/df-mc/dragonfly/server/item"
+	"github.com/df-mc/dragonfly/server/item/inventory"
+	"github.com/df-mc/dragonfly/server/world"
+	"github.com/go-gl/mathgl/mgl64"
+	"strings"
+	"sync"
+)
+
+// Hopper is a low-capacity storage block that can be used to collect item entities directly above it, as well as to
+// transfer items into and out of other containers.
+type Hopper struct {
+	transparent
+	sourceWaterDisplacer
+
+	// Facing is the direction the hopper is facing.
+	Facing cube.Face
+	// Powered is whether the hopper is powered or not. If the hopper is powered it will be locked and will stop
+	// moving items into or out of itself.
+	Powered bool
+	// CustomName is the custom name of the hopper. This name is displayed when the hopper is opened, and may include
+	// colour codes.
+	CustomName string
+
+	// LastTick is the last world tick that the hopper was ticked.
+	LastTick int64
+	// TransferCooldown is the duration in ticks until the hopper can transfer items again.
+	TransferCooldown int64
+	// CollectCooldown is the duration in ticks until the hopper can collect items again.
+	CollectCooldown int64
+
+	inventory *inventory.Inventory
+	viewerMu  *sync.RWMutex
+	viewers   map[ContainerViewer]struct{}
+}
+
+// NewHopper creates a new initialised hopper. The inventory is properly initialised.
+func NewHopper() Hopper {
+	m := new(sync.RWMutex)
+	v := make(map[ContainerViewer]struct{}, 1)
+	return Hopper{
+		inventory: inventory.New(5, func(slot int, _, item item.Stack) {
+			m.RLock()
+			defer m.RUnlock()
+			for viewer := range v {
+				viewer.ViewSlotChange(slot, item)
+			}
+		}),
+		viewerMu: m,
+		viewers:  v,
+	}
+}
+
+// Model ...
+func (Hopper) Model() world.BlockModel {
+	return model.Hopper{}
+}
+
+// SideClosed ...
+func (Hopper) SideClosed(cube.Pos, cube.Pos, *world.World) bool {
+	return false
+}
+
+// BreakInfo ...
+func (h Hopper) BreakInfo() BreakInfo {
+	return newBreakInfo(3, pickaxeHarvestable, pickaxeEffective, oneOf(h)).withBlastResistance(24).withBreakHandler(func(pos cube.Pos, w *world.World, u item.User) {
+		for _, i := range h.Inventory(w, pos).Clear() {
+			dropItem(w, i, pos.Vec3())
+		}
+	})
+}
+
+// Inventory returns the inventory of the hopper.
+func (h Hopper) Inventory(*world.World, cube.Pos) *inventory.Inventory {
+	return h.inventory
+}
+
+// WithName returns the hopper after applying a specific name to the block.
+func (h Hopper) WithName(a ...any) world.Item {
+	h.CustomName = strings.TrimSuffix(fmt.Sprintln(a...), "\n")
+	return h
+}
+
+// AddViewer adds a viewer to the hopper, so that it is updated whenever the inventory of the hopper is changed.
+func (h Hopper) AddViewer(v ContainerViewer, _ *world.World, _ cube.Pos) {
+	h.viewerMu.Lock()
+	defer h.viewerMu.Unlock()
+	h.viewers[v] = struct{}{}
+}
+
+// RemoveViewer removes a viewer from the hopper, so that slot updates in the inventory are no longer sent to it.
+func (h Hopper) RemoveViewer(v ContainerViewer, _ *world.World, _ cube.Pos) {
+	h.viewerMu.Lock()
+	defer h.viewerMu.Unlock()
+	delete(h.viewers, v)
+}
+
+// Activate ...
+func (Hopper) Activate(pos cube.Pos, _ cube.Face, _ *world.World, u item.User, _ *item.UseContext) bool {
+	if opener, ok := u.(ContainerOpener); ok {
+		opener.OpenBlockContainer(pos)
+		return true
+	}
+	return false
+}
+
+// UseOnBlock ...
+func (h Hopper) UseOnBlock(pos cube.Pos, face cube.Face, _ mgl64.Vec3, w *world.World, user item.User, ctx *item.UseContext) bool {
+	pos, _, used := firstReplaceable(w, pos, face, h)
+	if !used {
+		return false
+	}
+
+	//noinspection GoAssignmentToReceiver
+	h = NewHopper()
+	h.Facing = cube.FaceDown
+	if h.Facing != face {
+		h.Facing = face.Opposite()
+	}
+
+	place(w, pos, h, user, ctx)
+	return placed(ctx)
+}
+
+// Tick ...
+func (h Hopper) Tick(currentTick int64, pos cube.Pos, w *world.World) {
+	h.TransferCooldown--
+	h.CollectCooldown--
+	h.LastTick = currentTick
+
+	if !h.Powered && h.TransferCooldown <= 0 {
+		inserted := h.insertItem(pos, w)
+		extracted := h.extractItem(pos, w)
+		if inserted || extracted {
+			h.TransferCooldown = 8
+		}
+	}
+
+	w.SetBlock(pos, h, nil)
+}
+
+// HopperInsertable represents a block that can have its contents inserted into by a hopper.
+type HopperInsertable interface {
+	// InsertItem handles the insert logic for that block.
+	InsertItem(h Hopper, pos cube.Pos, w *world.World) bool
+}
+
+// insertItem inserts an item into a block that can receive contents from the hopper.
+func (h Hopper) insertItem(pos cube.Pos, w *world.World) bool {
+	destPos := pos.Side(h.Facing)
+	dest := w.Block(destPos)
+
+	if e, ok := dest.(HopperInsertable); ok {
+		return e.InsertItem(h, pos.Side(h.Facing), w)
+	}
+
+	if container, ok := dest.(Container); ok {
+		for sourceSlot, sourceStack := range h.inventory.Slots() {
+			if sourceStack.Empty() {
+				continue
+			}
+
+			_, err := container.Inventory(w, pos).AddItem(sourceStack.Grow(-sourceStack.Count() + 1))
+			if err != nil {
+				// The destination is full.
+				return false
+			}
+
+			_ = h.inventory.SetItem(sourceSlot, sourceStack.Grow(-1))
+
+			if hopper, ok := dest.(Hopper); ok {
+				hopper.TransferCooldown = 8
+				w.SetBlock(destPos, hopper, nil)
+			}
+
+			return true
+		}
+	}
+	return false
+}
+
+// HopperExtractable represents a block that can have its contents extracted by a hopper.
+type HopperExtractable interface {
+	// ExtractItem handles the extract logic for that block.
+	ExtractItem(h Hopper, pos cube.Pos, w *world.World) bool
+}
+
+// extractItem extracts an item from a container into the hopper.
+func (h Hopper) extractItem(pos cube.Pos, w *world.World) bool {
+	originPos := pos.Side(cube.FaceUp)
+	origin := w.Block(originPos)
+
+	if e, ok := origin.(HopperExtractable); ok {
+		return e.ExtractItem(h, pos, w)
+	}
+
+	if containerOrigin, ok := origin.(Container); ok {
+		for slot, stack := range containerOrigin.Inventory(w, originPos).Slots() {
+			if stack.Empty() {
+				// We don't have any items to extract.
+				continue
+			}
+
+			_, err := h.inventory.AddItem(stack.Grow(-stack.Count() + 1))
+			if err != nil {
+				// The hopper is full.
+				continue
+			}
+
+			_ = containerOrigin.Inventory(w, originPos).SetItem(slot, stack.Grow(-1))
+
+			if hopper, ok := origin.(Hopper); ok {
+				hopper.TransferCooldown = 8
+				w.SetBlock(originPos, hopper, nil)
+			}
+
+			return true
+		}
+	}
+	return false
+}
+
+// EncodeItem ...
+func (Hopper) EncodeItem() (name string, meta int16) {
+	return "minecraft:hopper", 0
+}
+
+// EncodeBlock ...
+func (h Hopper) EncodeBlock() (string, map[string]any) {
+	return "minecraft:hopper", map[string]any{
+		"facing_direction": int32(h.Facing),
+		"toggle_bit":       h.Powered,
+	}
+}
+
+// EncodeNBT ...
+func (h Hopper) EncodeNBT() map[string]any {
+	if h.inventory == nil {
+		facing, powered, customName := h.Facing, h.Powered, h.CustomName
+		//noinspection GoAssignmentToReceiver
+		h = NewHopper()
+		h.Facing, h.Powered, h.CustomName = facing, powered, customName
+	}
+	m := map[string]any{
+		"Items":            nbtconv.InvToNBT(h.inventory),
+		"TransferCooldown": int32(h.TransferCooldown),
+		"id":               "Hopper",
+	}
+	if h.CustomName != "" {
+		m["CustomName"] = h.CustomName
+	}
+	return m
+}
+
+// DecodeNBT ...
+func (h Hopper) DecodeNBT(data map[string]any) any {
+	facing, powered := h.Facing, h.Powered
+	//noinspection GoAssignmentToReceiver
+	h = NewHopper()
+	h.Facing = facing
+	h.Powered = powered
+	h.CustomName = nbtconv.String(data, "CustomName")
+	h.TransferCooldown = int64(nbtconv.Int32(data, "TransferCooldown"))
+	nbtconv.InvFromNBT(h.inventory, nbtconv.Slice(data, "Items"))
+	return h
+}
+
+// allHoppers ...
+func allHoppers() (hoppers []world.Block) {
+	for _, f := range cube.Faces() {
+		hoppers = append(hoppers, Hopper{Facing: f})
+		hoppers = append(hoppers, Hopper{Facing: f, Powered: true})
+	}
+	return hoppers
+}