Add type constants to action.Syncable.

server/action/map.go

@@ -5,6 +5,10 @@ import (
 	"hexmap-server/state"
 )
 
+const (
+	CellColorType SyncableType = "CELL_COLOR"
+)
+
 // CellColor is the action sent when a cell of the map has been colored a different color.
 type CellColor struct {
 	// At is the location of the cell in storage coordinates.
@@ -14,11 +18,16 @@ type CellColor struct {
 }
 
 func (c CellColor) MarshalLogObject(encoder zapcore.ObjectEncoder) error {
+	encoder.AddString("type", string(CellColorType))
 	err := encoder.AddObject("at", c.At)
 	encoder.AddString("color", c.Color.String())
 	return err
 }
 
+func (c CellColor) Type() SyncableType {
+	return CellColorType
+}
+
 // Apply sets the target cell's color, or returns ErrNoOp if it can't.
 func (c CellColor) Apply(s *state.Synced) error {
 	if c.Color.A < 0xF {

server/action/syncable.go

@@ -6,11 +6,21 @@ import (
 	"hexmap-server/state"
 )
 
-var ErrNoOp error = errors.New("action's effects were already applied, or it's an empty action")
+var (
+	// ErrNoOp is returned when an action has no effect.
+	ErrNoOp = errors.New("action's effects were already applied, or it's an empty action")
+	// ErrNoTransparentColors is returned when a user tries to set their active color or a cell color to transparent.
+	// Transparent here is defined as having an alpha component of less than 15 (0xF).
+	ErrNoTransparentColors = errors.New("transparent colors not allowed")
+)
+
+type SyncableType string
 
-// Syncable is the interface for action that can be shared.
+// Syncable is the interface for actions that can be shared between clients.
 type Syncable interface {
 	zapcore.ObjectMarshaler
+	// Type gives the Javascript type that is sent over the wire.
+	Type() SyncableType
 	// Apply causes the action's effects to be applied to s, mutating it in place.
 	// All syncable.Actions must conform to the standard that if an action can't be correctly applied, or if it would
 	// have no effect, it returns an error without changing s.
@@ -18,3 +28,4 @@ type Syncable interface {
 	// If an action is correctly applied and has an effect, it should return nil.
 	Apply(s *state.Synced) error
 }
+type SyncableProducer func()

server/action/user.go

@@ -1,14 +1,13 @@
 package action
 
 import (
-	"errors"
 	"go.uber.org/zap/zapcore"
 	"hexmap-server/state"
 )
 
-// ErrNoTransparentColors is returned when a user tries to set their active color or a cell color to transparent.
-// Transparent here is defined as having an alpha component of less than 15 (0xF).
-var ErrNoTransparentColors error = errors.New("transparent colors not allowed")
+const (
+	UserActiveColorType = "USER_ACTIVE_COLOR"
+)
 
 // UserActiveColor is the action sent when the user's current color, the one being painted with, changes.
 type UserActiveColor struct {
@@ -16,6 +15,10 @@ type UserActiveColor struct {
 	Color state.HexColor `json:"color"`
 }
 
+func (c UserActiveColor) Type() SyncableType {
+	return UserActiveColorType
+}
+
 func (c UserActiveColor) MarshalLogObject(encoder zapcore.ObjectEncoder) error {
 	encoder.AddString("color", c.Color.String())
 	return nil