Simplify structure of command messages

The first byte of a input message shows the type of that message.
0: normal keystrokes
1: resize window command

app/app.go

@@ -158,7 +158,7 @@ func (app *App) generateHandler() func(w http.ResponseWriter, r *http.Request) {
 				}
 
 				switch data[0] {
-				case '0':
+				case Input:
 					if !app.options.PermitWrite {
 						break
 					}
@@ -168,41 +168,22 @@ func (app *App) generateHandler() func(w http.ResponseWriter, r *http.Request) {
 						return
 					}
 
-				case '1':
+				case ResizeTerminal:
-					var remoteCmd command
+					var args argResizeTerminal
-					err = json.Unmarshal(data[1:], &remoteCmd)
+					err = json.Unmarshal(data[1:], &args)
 					if err != nil {
 						log.Print("Malformed remote command")
 						return
 					}
 
-					switch remoteCmd.Name {
-					case "resize_terminal":
-
-						rows := remoteCmd.Arguments["rows"]
-						switch rows.(type) {
-						case float64:
-						default:
-							log.Print("Malformed remote command")
-							return
-						}
-
-						cols := remoteCmd.Arguments["columns"]
-						switch cols.(type) {
-						case float64:
-						default:
-							log.Print("Malformed remote command")
-							return
-						}
-
 					window := struct {
 						row uint16
 						col uint16
 						x   uint16
 						y   uint16
 					}{
-							uint16(rows.(float64)),
+						uint16(args.Rows),
-							uint16(cols.(float64)),
+						uint16(args.Columns),
 						0,
 						0,
 					}
@@ -212,7 +193,6 @@ func (app *App) generateHandler() func(w http.ResponseWriter, r *http.Request) {
 						syscall.TIOCSWINSZ,
 						uintptr(unsafe.Pointer(&window)),
 					)
-					}
 
 				default:
 					log.Print("Unknown message type")
@@ -230,9 +210,14 @@ func (app *App) generateHandler() func(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
-type command struct {
+const (
-	Name      string                 `json:"name"`
+	Input          = '0'
-	Arguments map[string]interface{} `json:"arguments"`
+	ResizeTerminal = '1'
+)
+
+type argResizeTerminal struct {
+	Columns float64
+	Rows    float64
 }
 
 func generateRandomString(length int) string {

resources/gotty.js

@@ -24,11 +24,8 @@
                 ws.send(
                     "1" + JSON.stringify(
                         {
-                            name: "resize_terminal",
-                            arguments: {
                             columns: columns,
                             rows: rows,
-                            },
                         }
                     )
                 )