First bit of work on adding script support to NPCs

internal/game/game.go

@@ -127,9 +127,8 @@ func NewGame(opts Options) (*Game, error) {
 	logger.Infof("finished map warm-up in: %s", time.Now().Sub(start))
 
 	// add a dummy npc
-	npc := model.NewNPC()
+	npc := model.NewNPC(70, "turael")
 	npc.ID = 4200
-	npc.DefinitionID = 1
 	npc.GlobalPos = model.Vector3D{X: 3239, Y: 3429, Z: 0}
 	ne := newNPCEntity(npc)
 	g.mapManager.AddNPC(ne, util.GlobalToRegionGlobal(npc.GlobalPos))
@@ -1795,6 +1794,14 @@ func (g *Game) handleGameUpdate() error {
 		}
 	}
 
+	// process each npc on this game tick
+	for _, ne := range g.mapManager.RegionsWithNPCs() {
+		err := g.scripts.DoNPCOnTick(ne)
+		if err != nil {
+			logger.Errorf("failed to execute script for NPC ID %d: %v", ne.npc.ID, err)
+		}
+	}
+
 	// reconcile the map state now that players have taken their actions
 	mapUpdates := g.mapManager.Reconcile()
 

internal/game/map_manager.go

@@ -134,6 +134,20 @@ func (m *MapManager) RemoveNPC(ne *npcEntity, regionGlobal model.Vector3D) {
 	}
 }
 
+// RegionsWithNPCs returns a map of NPC IDs to their entities that are found on the map.
+func (m *MapManager) RegionsWithNPCs() map[int]*npcEntity {
+	npcs := map[int]*npcEntity{}
+
+	// TODO: can npc entities be separated by region?
+	for _, region := range m.regions {
+		for id, entity := range region.npcs {
+			npcs[id] = entity
+		}
+	}
+
+	return npcs
+}
+
 // FindSpectators returns a tuple of players and NPCs that are within visual distance to a player. The keys of the map
 // are the player's IDs and NPC IDs, respectively.
 func (m *MapManager) FindSpectators(pe *playerEntity) (map[int]*playerEntity, map[int]*npcEntity) {

internal/game/script_manager.go

@@ -15,6 +15,7 @@ import (
 )
 
 const luaTypePlayerEntity = "playerEntity"
+const luaTypeNPCEntity = "npcEntity"
 const luaTypeInterface = "interface"
 const luaTypeItem = "item"
 
@@ -117,6 +118,11 @@ func (s *ScriptManager) DoCastSpellOnItem(pe *playerEntity, item *model.Item, sl
 		s.interfaceType(spell, s.state))
 }
 
+// DoNPCOnTick executes an NPC's per-tick logic script.
+func (s *ScriptManager) DoNPCOnTick(ne *npcEntity) error {
+	return s.doFunctionVoid(fmt.Sprintf("npc_%s_on_tick", ne.npc.ScriptSlug), s.npcEntityType(ne, s.state))
+}
+
 // playerEntity creates a Lua user-defined data type for a playerEntity.
 func (s *ScriptManager) playerEntityType(pe *playerEntity, l *lua.LState) *lua.LUserData {
 	ud := l.NewUserData()
@@ -125,6 +131,14 @@ func (s *ScriptManager) playerEntityType(pe *playerEntity, l *lua.LState) *lua.L
 	return ud
 }
 
+// npcEntity creates a Lua user-defined data type for an npcEntity.
+func (s *ScriptManager) npcEntityType(ne *npcEntity, l *lua.LState) *lua.LUserData {
+	ud := l.NewUserData()
+	ud.Value = ne
+	ud.Metatable = l.GetTypeMetatable(luaTypeNPCEntity)
+	return ud
+}
+
 // itemType creates a Lua user-defined data type for a model.Item.
 func (s *ScriptManager) itemType(item *model.Item, l *lua.LState) *lua.LUserData {
 	ud := l.NewUserData()
@@ -147,6 +161,7 @@ func (s *ScriptManager) createState() (*lua.LState, error) {
 	s.registerInterfaceModel(l)
 	s.registerItemModel(l)
 	s.registerPlayerModel(l)
+	s.registerNPCModel(l)
 
 	err := s.registerFunctionProtos(l)
 	if err != nil {
@@ -683,6 +698,12 @@ func (s *ScriptManager) registerPlayerModel(l *lua.LState) {
 	}))
 }
 
+// registerNPCModel registers metadata for an npcEntity type.
+func (s *ScriptManager) registerNPCModel(l *lua.LState) {
+	mt := l.NewTypeMetatable(luaTypeNPCEntity)
+	l.SetGlobal(luaTypeNPCEntity, mt)
+}
+
 // registerFunctionProtos executes compiled functions into a Lua state.
 func (s *ScriptManager) registerFunctionProtos(l *lua.LState) error {
 	for _, proto := range s.protos {

internal/model/npc.go

@@ -5,11 +5,15 @@ type NPC struct {
 	*Entity
 	// DefinitionID is the identifier for the NPC's appearance.
 	DefinitionID int
+	// ScriptSlug is the slug for the game script to execute for this NPC.
+	ScriptSlug string
 }
 
 // NewNPC returns a new NPC model.
-func NewNPC() *NPC {
+func NewNPC(definitionID int, scriptSlug string) *NPC {
 	return &NPC{
-		Entity: &Entity{},
+		Entity:       &Entity{},
+		DefinitionID: definitionID,
+		ScriptSlug:   scriptSlug,
 	}
 }

scripts/npcs/turael.lua

@@ -0,0 +1,9 @@
+-------------------------------------
+-- Teleport spell library functions
+-------------------------------------
+
+--- Handler invoked when the next game tick has started.
+-- @param npc The NPC entity to update.
+function npc_turael_on_tick(npc)
+
+end