felt/internal/clock/ticker.go

package clock

import (
	"context"
	"encoding/json"
	"time"
)

// StartTicker runs the clock ticker for the given engine.
// It ticks every 100ms and broadcasts clock snapshots:
//   - 1/sec during normal play
//   - 10/sec (every 100ms) during the final 10 seconds
//
// The ticker stops when the context is cancelled.
func StartTicker(ctx context.Context, engine *ClockEngine) {
	ticker := time.NewTicker(100 * time.Millisecond)
	defer ticker.Stop()

	var lastBroadcastSecond int64 = -1

	for {
		select {
		case <-ctx.Done():
			return
		case <-ticker.C:
			shouldBroadcast, snapshot := engine.Tick()
			if !shouldBroadcast {
				continue
			}

			// Determine broadcast rate:
			// - Final 10 seconds: broadcast every tick (10/sec)
			// - Normal: broadcast once per second (1/sec)
			currentSecond := snapshot.RemainingMs / 1000
			isFinalSeconds := snapshot.RemainingMs <= 10000

			if isFinalSeconds {
				// Broadcast every 100ms tick in final 10 seconds
				broadcastSnapshot(engine, snapshot)
				lastBroadcastSecond = currentSecond
			} else if currentSecond != lastBroadcastSecond {
				// Broadcast once per second change
				broadcastSnapshot(engine, snapshot)
				lastBroadcastSecond = currentSecond
			}
		}
	}
}

// broadcastSnapshot sends a clock snapshot to all WebSocket clients.
func broadcastSnapshot(engine *ClockEngine, snapshot ClockSnapshot) {
	engine.mu.RLock()
	hub := engine.hub
	tournamentID := engine.tournamentID
	engine.mu.RUnlock()

	if hub == nil {
		return
	}

	data, err := json.Marshal(snapshot)
	if err != nil {
		return
	}

	hub.Broadcast(tournamentID, "clock.tick", data)
}