Improve sync error handling.

1) Show warning during one second then resume game.
2) Don't update cookie during simultaneous turns.

When playing SoT live, discarding cards at the same time leads to many
harmless in-flight action collision errors, which don't really matter.
If we stop updating the cookie during simultaneous turns, we can
avoid this.

2 files changed, 21 insertions, 5 deletions

diff --git a/public/common/play.js b/public/common/play.js
index cf4bcad..e34f42c 100644
--- a/public/common/play.js
+++ b/public/common/play.js
@@ -442,6 +442,15 @@ function connect_play() {
 		let arg = msg_data[1]
 		console.log("MESSAGE", cmd)
 		switch (cmd) {
+		case "warning":
+			document.getElementById("prompt").textContent = arg
+			document.querySelector("header").classList.add("disconnected")
+			setTimeout(() => {
+				document.querySelector("header").classList.remove("disconnected")
+				on_update_header()
+			}, 1000)
+			break
+
 		case "error":
 			document.getElementById("prompt").textContent = arg
 			if (view) {
diff --git a/server.js b/server.js
index d0b55cf..c3487e1 100644
--- a/server.js
+++ b/server.js
@@ -2211,19 +2211,26 @@ function on_action(socket, action, args, cookie) {
 	else
 		SLOG(socket, "ACTION", action)
 
-	if (typeof cookie === "number") // TODO: for backwards compatibility only, remove later!
-	if (game_cookies[socket.game_id] !== cookie)
-		return send_message(socket, 'error', "Synchronization error!")
-	game_cookies[socket.game_id] ++
+	if (game_cookies[socket.game_id] !== cookie) {
+		send_state(socket, get_game_state(socket.game_id))
+		send_message(socket, "warning", "Synchronization error!")
+		return
+	}
 
 	try {
 		let state = get_game_state(socket.game_id)
 		let old_active = state.active
+
+		// Don't update cookie during simultaneous turns, as it results
+		// in many in-flight collisions.
+		if (old_active !== "Both")
+			game_cookies[socket.game_id] ++
+
 		state = socket.rules.action(state, socket.role, action, args)
 		put_new_state(socket.game_id, state, old_active, socket.role, action, args)
 	} catch (err) {
 		console.log(err)
-		return send_message(socket, 'error', err.toString())
+		return send_message(socket, "error", err.toString())
 	}
 }