Serialise the World as well

pkg/game/world.go

@@ -1,14 +1,21 @@
 package game
 
 import (
+	"encoding/json"
 	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
 
 	"github.com/google/uuid"
 )
 
 // World describes a self contained universe and everything in it
 type World struct {
-	instances map[uuid.UUID]Instance
+	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
@@ -20,13 +27,50 @@ type Instance struct {
 	pos Position
 }
 
+const kWorldFileName = "rove-world.json"
+
 // NewWorld creates a new world object
-func NewWorld() *World {
+func NewWorld(data string) *World {
 	return &World{
-		instances: make(map[uuid.UUID]Instance),
+		Instances: make(map[uuid.UUID]Instance),
+		dataPath:  data,
 	}
 }
 
+// path returns the full path to the data file
+func (w *World) path() string {
+	return path.Join(w.dataPath, kWorldFileName)
+}
+
+// Load will load the accountant from data
+func (w *World) Load() error {
+	// Don't load anything if the file doesn't exist
+	_, err := os.Stat(w.path())
+	if os.IsNotExist(err) {
+		fmt.Printf("File %s didn't exist, loading with fresh world data\n", w.path())
+		return nil
+	}
+
+	if b, err := ioutil.ReadFile(w.path()); err != nil {
+		return err
+	} else if err := json.Unmarshal(b, &w); err != nil {
+		return err
+	}
+	return nil
+}
+
+// Save will save the accountant data out
+func (w *World) Save() error {
+	if b, err := json.MarshalIndent(w, "", "\t"); err != nil {
+		return err
+	} else {
+		if err := ioutil.WriteFile(w.path(), b, os.ModePerm); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // Adds an instance to the game
 func (w *World) CreateInstance() uuid.UUID {
 	id := uuid.New()
@@ -37,14 +81,14 @@ func (w *World) CreateInstance() uuid.UUID {
 	}
 
 	// Append the instance to the list
-	w.instances[id] = instance
+	w.Instances[id] = instance
 
 	return id
 }
 
 // GetPosition returns the position of a given instance
 func (w World) GetPosition(id uuid.UUID) (Position, error) {
-	if i, ok := w.instances[id]; ok {
+	if i, ok := w.Instances[id]; ok {
 		return i.pos, nil
 	} else {
 		return Position{}, fmt.Errorf("no instance matching id")

pkg/game/world_test.go

@@ -1,26 +1,27 @@
 package game
 
 import (
+	"os"
 	"testing"
 )
 
 func TestNewWorld(t *testing.T) {
 	// Very basic for now, nothing to verify
-	world := NewWorld()
+	world := NewWorld(os.TempDir())
 	if world == nil {
 		t.Error("Failed to create world")
 	}
 }
 
 func TestWorld_CreateInstance(t *testing.T) {
-	world := NewWorld()
+	world := NewWorld(os.TempDir())
 	a := world.CreateInstance()
 	b := world.CreateInstance()
 
 	// Basic duplicate check
 	if a == b {
 		t.Errorf("Created identical instances")
-	} else if len(world.instances) != 2 {
+	} else if len(world.Instances) != 2 {
 		t.Errorf("Incorrect number of instances created")
 	}
 }