lobby can parse, marshal player join, leave events

src/state/lobby/event.go

@@ -0,0 +1,63 @@
+package lobby
+
+import (
+	"encoding/json"
+	"fmt"
+)
+
+type Event interface {
+	LobbyEvent()
+}
+
+type PlayerJoin struct {
+	ID int
+}
+
+func (PlayerJoin) LobbyEvent() {}
+
+type PlayerLeave struct {
+	ID int
+}
+
+func (PlayerLeave) LobbyEvent() {}
+
+func ParseEvent(b []byte) (Event, error) {
+	var wrapper struct {
+		Type    string          `json:"type"`
+		Package string          `json:"package"`
+		Payload json.RawMessage `json:"payload"`
+	}
+	if err := json.Unmarshal(b, &wrapper); err != nil {
+		return nil, err
+	} else if wrapper.Package != "lobby" {
+		return nil, nil
+	}
+
+	var e Event
+	var err error
+	switch wrapper.Type {
+	case "lobby.PlayerJoin":
+		v := PlayerJoin{}
+		err = json.Unmarshal(wrapper.Payload, &v)
+		e = v
+	case "lobby.PlayerLeave":
+		v := PlayerLeave{}
+		err = json.Unmarshal(wrapper.Payload, &v)
+		e = v
+	default:
+		return nil, fmt.Errorf("failed to parse event %q", wrapper.Type)
+	}
+	return e, err
+}
+
+func MarshalEvent(e Event) ([]byte, error) {
+	var marshalme struct {
+		Payload Event  `json:"payload"`
+		Type    string `json:"type"`
+		Package string `json:"package"`
+	}
+	marshalme.Payload = e
+	marshalme.Type = fmt.Sprintf("%T", e)
+	marshalme.Package = "lobby"
+	return json.Marshal(marshalme)
+}

src/state/lobby/event_test.go

@@ -0,0 +1,36 @@
+package lobby_test
+
+import (
+	"gitea/price-is-wrong/src/state/lobby"
+	"testing"
+)
+
+func TestMarshalUnmarshal(t *testing.T) {
+	cases := map[string]struct {
+		e lobby.Event
+	}{
+		"PlayerJoin":  {e: lobby.PlayerJoin{ID: 1}},
+		"PlayerLeave": {e: lobby.PlayerLeave{ID: 1}},
+	}
+
+	for name, d := range cases {
+		c := d
+		t.Run(name, func(t *testing.T) {
+			b, err := lobby.MarshalEvent(c.e)
+			if err != nil {
+				t.Fatal(err)
+			}
+			t.Logf("marshalled: %s", b)
+
+			e, err := lobby.ParseEvent(b)
+			if err != nil {
+				t.Fatal(err)
+			}
+			t.Logf("unmarshalled: %+v", e)
+
+			if c.e != e {
+				t.Errorf("expected %+v but got %+v", c.e, e)
+			}
+		})
+	}
+}

src/state/lobby/internal/event.go

@@ -1,17 +0,0 @@
-package lobby
-
-type event interface {
-	lobbyEvent()
-}
-
-type playerJoin struct {
-	ID int
-}
-
-func (playerJoin) LobbyEvent() {}
-
-type playerLeave struct {
-	ID int
-}
-
-func (playerLeave) LobbyEvent() {}

src/state/lobby/internal/storage.go

@@ -1,16 +0,0 @@
-package lobby
-
-import (
-	"context"
-	"io"
-)
-
-type storage interface {
-	playerIDs(context.Context) ([]int, error)
-}
-
-type DB struct{}
-
-func (db DB) playerIDs(ctx context.Context) ([]int, error) {
-	return nil, io.EOF
-}

src/state/lobby/storage.go

@@ -0,0 +1,16 @@
+package lobby
+
+import (
+	"context"
+	"io"
+)
+
+type Storage interface {
+	PlayerIDs(context.Context) ([]int, error)
+}
+
+type DB struct{}
+
+func (db DB) PlayerIDs(ctx context.Context) ([]int, error) {
+	return nil, io.EOF
+}