Add the concept of commands to the world and executing them

pkg/game/world.go

@@ -8,10 +8,8 @@ import (
 
 // World describes a self contained universe and everything in it
 type World struct {
+	// Instances is a map of all the instances in the game
 	Instances map[uuid.UUID]Instance `json:"instances"`
-
-	// dataPath is the location for the data to be stored
-	dataPath string
 }
 
 // Instance describes a single entity or instance of an entity in the world
@@ -20,7 +18,7 @@ type Instance struct {
 	id uuid.UUID
 
 	// pos represents where this instance is in the world
-	pos Position
+	pos Vector
 }
 
 const kWorldFileName = "rove-world.json"
@@ -32,9 +30,11 @@ func NewWorld() *World {
 	}
 }
 
-// Adds an instance to the game
-func (w *World) CreateInstance() uuid.UUID {
-	id := uuid.New()
+// Spawn adds an instance to the game
+func (w *World) Spawn(id uuid.UUID) error {
+	if _, ok := w.Instances[id]; ok {
+		return fmt.Errorf("instance with id %s already exists in world", id)
+	}
 
 	// Initialise the instance
 	instance := Instance{
@@ -44,7 +44,7 @@ func (w *World) CreateInstance() uuid.UUID {
 	// Append the instance to the list
 	w.Instances[id] = instance
 
-	return id
+	return nil
 }
 
 // Removes an instance from the game
@@ -58,10 +58,42 @@ func (w *World) DestroyInstance(id uuid.UUID) error {
 }
 
 // GetPosition returns the position of a given instance
-func (w World) GetPosition(id uuid.UUID) (Position, error) {
+func (w World) GetPosition(id uuid.UUID) (Vector, error) {
 	if i, ok := w.Instances[id]; ok {
 		return i.pos, nil
 	} else {
-		return Position{}, fmt.Errorf("no instance matching id")
+		return Vector{}, fmt.Errorf("no instance matching id")
 	}
 }
+
+// SetPosition sets an instances position
+func (w *World) SetPosition(id uuid.UUID, pos Vector) error {
+	if i, ok := w.Instances[id]; ok {
+		i.pos = pos
+		w.Instances[id] = i
+		return nil
+	} else {
+		return fmt.Errorf("no instance matching id")
+	}
+}
+
+// SetPosition sets an instances position
+func (w *World) MovePosition(id uuid.UUID, vec Vector) (Vector, error) {
+	if i, ok := w.Instances[id]; ok {
+		i.pos.Add(vec)
+		w.Instances[id] = i
+		return i.pos, nil
+	} else {
+		return Vector{}, fmt.Errorf("no instance matching id")
+	}
+}
+
+// Execute will run the commands given
+func (w *World) Execute(commands ...Command) error {
+	for _, c := range commands {
+		if err := c(); err != nil {
+			return err
+		}
+	}
+	return nil
+}