Implementation of NPC Dialogues

server/player/dialogue/button.go

@@ -0,0 +1,29 @@
+package dialogue
+
+import "encoding/json"
+
+// Button represents a Button added to Menu. A button contains Name as well as an activation type and a general type.
+type Button struct {
+	// Name is the name of the button and is displayed to the user.
+	Name string
+	// Activation is the specific method of activation required by the button. CLICK = 0, CLOSE = 1, ENTER = 2.
+	Activation ActivationType
+	// Type is the type of button / action it takes.
+	Type ButtonType
+}
+
+// NewButton returns a new Button with the name, activationType, and buttonType passed.
+func NewButton(name string, activationType ActivationType, buttonType ButtonType) Button {
+	return Button{Name: name, Activation: activationType, Type: buttonType}
+}
+
+// MarshalJSON ...
+func (b Button) MarshalJSON() ([]byte, error) {
+	data := map[string]any{
+		"button_name": b.Name,
+		"text":        "", // Buttons don't work if this value isn't sent.
+		"mode":        b.Activation.Uint8(),
+		"type":        b.Type.Uint8(),
+	}
+	return json.Marshal(data)
+}

server/player/dialogue/button_type.go

@@ -0,0 +1,48 @@
+package dialogue
+
+type activation uint8
+
+// ActivationType represents a specific type of activation on a Button. The different types are Click, Close, and Enter.
+type ActivationType struct {
+	activation
+}
+
+func (a activation) Uint8() uint8 {
+	return uint8(a)
+}
+
+// ActivationClick specifies on activating a button when its clicked.
+func ActivationClick() ActivationType {
+	return ActivationType{0}
+}
+
+// ActivationClose is the close activation.
+func ActivationClose() ActivationType {
+	return ActivationType{1}
+}
+
+// ActivationEnter is the enter activation type.
+func ActivationEnter() ActivationType {
+	return ActivationType{2}
+}
+
+type button uint8
+
+// ButtonType represents the type of Button. URL, COMMAND, and UNKNOWN are all the button types.
+type ButtonType struct {
+	button
+}
+
+func (b button) Uint8() uint8 {
+	return uint8(b)
+}
+
+// CommandButton is a button meant to execute a command.
+func CommandButton() ButtonType {
+	return ButtonType{1}
+}
+
+// UnknownButton has unknown behaviour as of the moment.
+func UnknownButton() ButtonType {
+	return ButtonType{2}
+}

server/player/dialogue/dialogue.go

@@ -0,0 +1,9 @@
+package dialogue
+
+// Dialogue represents a singular dialog scene. Scenes are used to within NewMenu to create a new Dialog Menu. Submit is
+// called when a button is submitted by a Submitter.
+type Dialogue interface {
+	Menu() Menu
+	// Submit is called when a Submitter submits a Button on the specified Menu.
+	Submit(submitter Submitter, pressed Button)
+}

server/player/dialogue/menu.go

@@ -0,0 +1,75 @@
+package dialogue
+
+import (
+	"encoding/json"
+	"fmt"
+	"github.com/df-mc/dragonfly/server/world"
+	"strings"
+)
+
+// Menu represents a npc dialogue. It contains a title, body, entity, and a number of buttons no more than
+// 6.
+type Menu struct {
+	title, body string
+	// action represents the action this menu is executing. This value is either packet.NPCDialogueActionOpen or
+	// packet.NPCDialogueActionClose.
+	npc     world.NPC
+	buttons []Button
+}
+
+// NewMenu creates a new Menu with the Dialogue passed. Title is formatted with accordance to the rules of fmt.Sprintln.
+func NewMenu(npc world.NPC, title ...any) Menu {
+	return Menu{
+		title: format(title),
+		npc:   npc,
+	}
+}
+
+// WithButtons creates a copy of the dialogue Menu and appends the buttons passed to the existing buttons, after
+// which the new dialogue Menu is returned. If the count of the buttons passed and the buttons already within the Menu
+// pass the threshold of 6, it will return an empty Menu and an error.
+func (m Menu) WithButtons(buttons ...Button) (Menu, error) {
+	if len(m.buttons)+len(buttons) > 6 {
+		return Menu{}, fmt.Errorf("menu has %v buttons, an addition of %v will pass the 6 buttons threashold", len(m.buttons), len(buttons))
+	}
+	m.buttons = append(m.buttons, buttons...)
+	return m, nil
+}
+
+// WithBody creates a copy of the dialogue Menu and replaces the existing body with the body passed, after which the
+// new dialogue Menu is returned. The text is formatted following the rules of fmt.Sprintln.
+func (m Menu) WithBody(body ...any) Menu {
+	m.body = format(body)
+	return m
+}
+
+// NPC returns the entity associated with this Menu.
+func (m Menu) NPC() world.Entity {
+	return m.npc
+}
+
+// Body returns the formatted body passed to Menu by WithBody()
+func (m Menu) Body() string {
+	return m.body
+}
+
+// Buttons will return all the buttons passed to Menu by WithButtons().
+func (m Menu) Buttons() []Button {
+	return m.buttons
+}
+
+// Title returns the formatted body passed to Menu from NewMenu()
+func (m Menu) Title() string {
+	return m.title
+}
+
+// MarshalJSON ...
+func (m Menu) MarshalJSON() ([]byte, error) {
+	return json.Marshal(m.Buttons())
+}
+
+// format is a utility function to format a list of values to have spaces between them, but no newline at the
+// end.
+func format(a []any) string {
+	return strings.TrimSuffix(strings.TrimSuffix(fmt.Sprintln(a...), "\n"), "\n")
+}

server/player/dialogue/submit.go

@@ -0,0 +1,14 @@
+package dialogue
+
+// Submitter is an entity that is able to open a dialog and submit it by clicking a button. The entity can also have
+// a dialogue force closed upon it by the server.
+type Submitter interface {
+	SendDialogue(d Dialogue)
+	CloseDialogue(d Dialogue)
+}
+
+// Closer represents a scene that has special logic when the dialogue scene is closed.
+type Closer interface {
+	// Close gets called when a Submitter closes a dialogue.
+	Close(submitter Submitter)
+}

server/player/player.go

@@ -2,6 +2,7 @@ package player
 
 import (
 	"fmt"
+	"github.com/df-mc/dragonfly/server/player/dialogue"
 	"math"
 	"math/rand"
 	"net"
@@ -389,6 +390,20 @@ func (p *Player) SendForm(f form.Form) {
 	p.session().SendForm(f)
 }
 
+// SendDialogue sends a dialogue to the player for the client to fill out. Once the client fills it out, the Submit
+// method of the form will be called.
+// Note that the client may also close the form instead of filling it out, which will result in the Close method to be
+// called on the dialogue if it implements dialogue.Closer.
+func (p *Player) SendDialogue(d dialogue.Dialogue) {
+	p.session().SendDialogue(d)
+}
+
+// CloseDialogue closes any dialogue that may be open to a user. Note that when this method is closed, if the dialogue
+// implements dialogue.Closer the Close method will still execute.
+func (p *Player) CloseDialogue(d dialogue.Dialogue) {
+	p.session().CloseDialogue(d)
+}
+
 // ShowCoordinates enables the vanilla coordinates for the player.
 func (p *Player) ShowCoordinates() {
 	p.session().EnableCoordinates(true)

server/session/controllable.go

@@ -7,6 +7,7 @@ import (
 	"github.com/df-mc/dragonfly/server/item"
 	"github.com/df-mc/dragonfly/server/item/inventory"
 	"github.com/df-mc/dragonfly/server/player/chat"
+	"github.com/df-mc/dragonfly/server/player/dialogue"
 	"github.com/df-mc/dragonfly/server/player/form"
 	"github.com/df-mc/dragonfly/server/player/skin"
 	"github.com/df-mc/dragonfly/server/world"
@@ -22,6 +23,7 @@ type Controllable interface {
 	world.Entity
 	item.User
 	form.Submitter
+	dialogue.Submitter
 	cmd.Source
 	chat.Subscriber
 

server/session/entity_metadata.go

@@ -28,6 +28,9 @@ func (s *Session) parseEntityMetadata(e world.Entity) entityMetadata {
 
 	m.setFlag(dataKeyFlags, dataFlagAffectedByGravity)
 	m.setFlag(dataKeyFlags, dataFlagCanClimb)
+	if npc, ok := e.(world.NPC); ok && npc.NPC() {
+		m[dataKeyHasNpcComponent] = boolByte(npc.NPC())
+	}
 	if sn, ok := e.(sneaker); ok && sn.Sneaking() {
 		m.setFlag(dataKeyFlags, dataFlagSneaking)
 	}
@@ -175,6 +178,7 @@ const (
 	dataKeyCustomDisplay                       = 18
 	dataKeyPotionAuxValue                      = 36
 	dataKeyScale                               = 38
+	dataKeyHasNpcComponent                     = 39
 	dataKeyMaxAir                              = 42
 	dataKeyBoundingBoxWidth                    = 53
 	dataKeyBoundingBoxHeight                   = 54

server/session/handle_npc_request.go

@@ -0,0 +1,46 @@
+package session
+
+import (
+	"fmt"
+	"github.com/df-mc/dragonfly/server/player/dialogue"
+	"github.com/sandertv/gophertunnel/minecraft/protocol/packet"
+	"sync"
+)
+
+// NpcRequestHandler handles the NpcRequest packet.
+type NpcRequestHandler struct {
+	mu        sync.Mutex
+	dialogues map[string]dialogue.Dialogue
+}
+
+// Handle ...
+func (h *NpcRequestHandler) Handle(p packet.Packet, s *Session) error {
+	pk := p.(*packet.NPCRequest)
+	h.mu.Lock()
+	d, ok := h.dialogues[s.c.XUID()]
+	h.mu.Unlock()
+	if !ok {
+		return fmt.Errorf("no dialogue menu for player with xuid %v", s.c.XUID())
+	}
+	m := d.Menu()
+	switch pk.RequestType {
+	case packet.NPCRequestActionExecuteAction:
+		buttons := m.Buttons()
+		index := int(pk.ActionType)
+		if index >= len(buttons) {
+			return fmt.Errorf("error submitting dialogue, button index points to inexistent button: %v (only %v buttons present)", index, len(buttons))
+		}
+		d.Submit(s.Controllable(), buttons[index])
+		// We close the dialogue because if we don't close it here and the api implementor forgets to close it the
+		// client permanently stuck in the dialogue UI being unable to close it or submit a button.
+		s.Controllable().CloseDialogue(d)
+	case packet.NPCRequestActionExecuteClosingCommands:
+		if c, ok := d.(dialogue.Closer); ok {
+			c.Close(s.Controllable())
+		}
+		h.mu.Lock()
+		delete(h.dialogues, s.c.XUID())
+		h.mu.Unlock()
+	}
+	return nil
+}

server/session/player.go

@@ -12,6 +12,7 @@ import (
 	"github.com/df-mc/dragonfly/server/item/creative"
 	"github.com/df-mc/dragonfly/server/item/inventory"
 	"github.com/df-mc/dragonfly/server/item/recipe"
+	"github.com/df-mc/dragonfly/server/player/dialogue"
 	"github.com/df-mc/dragonfly/server/player/form"
 	"github.com/df-mc/dragonfly/server/player/skin"
 	"github.com/df-mc/dragonfly/server/world"
@@ -328,6 +329,57 @@ func (s *Session) SendForm(f form.Form) {
 	})
 }
 
+// SendDialogue shows a npc dialogue to the client of the connection. The Submit method of the dialogue is called when
+// the client clicks a button or closes the menu.
+func (s *Session) SendDialogue(d dialogue.Dialogue) {
+	h := s.handlers[packet.IDNPCRequest].(*NpcRequestHandler)
+
+	m := d.Menu()
+	h.mu.Lock()
+	h.dialogues[s.c.XUID()] = d
+	h.mu.Unlock()
+
+	s.entityMutex.Lock()
+	RID := s.entityRuntimeIDs[m.NPC()]
+	s.entityMutex.Unlock()
+
+	aj, _ := json.Marshal(m)
+	s.writePacket(&packet.NPCDialogue{
+		EntityUniqueID: RID,
+		ActionType:     packet.NPCDialogueActionOpen,
+		Dialogue:       m.Body(),
+		SceneName:      "default",
+		NPCName:        m.Title(),
+		ActionJSON:     string(aj),
+	})
+}
+
+// CloseDialogue forcefully closes the users current dialogue. The Close method of dialogue.Closer is called when the
+// form closes on the client.
+func (s *Session) CloseDialogue(d dialogue.Dialogue) {
+	h := s.handlers[packet.IDNPCRequest].(*NpcRequestHandler)
+
+	m := d.Menu()
+	s.entityMutex.Lock()
+	RID := s.entityRuntimeIDs[m.NPC()]
+	s.entityMutex.Unlock()
+
+	h.mu.Lock()
+	_, ok := h.dialogues[s.c.XUID()]
+	h.mu.Unlock()
+	if !ok {
+		return
+	}
+	s.writePacket(&packet.NPCDialogue{
+		EntityUniqueID: RID,
+		ActionType:     packet.NPCDialogueActionClose,
+		Dialogue:       m.Body(),
+		SceneName:      "default",
+		NPCName:        m.Title(),
+		ActionJSON:     "",
+	})
+}
+
 // Transfer transfers the player to a server with the IP and port passed.
 func (s *Session) Transfer(ip net.IP, port int) {
 	s.writePacket(&packet.Transfer{

server/session/session.go

@@ -12,6 +12,7 @@ import (
 	"github.com/df-mc/dragonfly/server/item/inventory"
 	"github.com/df-mc/dragonfly/server/item/recipe"
 	"github.com/df-mc/dragonfly/server/player/chat"
+	"github.com/df-mc/dragonfly/server/player/dialogue"
 	"github.com/df-mc/dragonfly/server/player/form"
 	"github.com/df-mc/dragonfly/server/world"
 	"github.com/go-gl/mathgl/mgl64"
@@ -446,6 +447,7 @@ func (s *Session) registerHandlers() {
 		packet.IDMobEquipment:          &MobEquipmentHandler{},
 		packet.IDModalFormResponse:     &ModalFormResponseHandler{forms: make(map[uint32]form.Form)},
 		packet.IDMovePlayer:            nil,
+		packet.IDNPCRequest:            &NpcRequestHandler{dialogues: make(map[string]dialogue.Dialogue)},
 		packet.IDPlayerAction:          &PlayerActionHandler{},
 		packet.IDPlayerAuthInput:       &PlayerAuthInputHandler{},
 		packet.IDPlayerSkin:            &PlayerSkinHandler{},

server/world/entity.go

@@ -33,6 +33,13 @@ type Entity interface {
 	World() *World
 }
 
+// NPC represents an entity can be seen within Npc Dialogues. Only entities that implement NPC can be used to create
+// dialogue forms.
+type NPC interface {
+	Entity
+	NPC() bool
+}
+
 // TickerEntity represents an entity that has a Tick method which should be called every time the entity is
 // ticked every 20th of a second.
 type TickerEntity interface {