package backend

import (
	"context"
	"sync/atomic"
	"testing"
	"time"
)

func TestSetHeartbeatInterval_ValidValue(t *testing.T) {
	atomic.StoreInt32(&heartbeatIntervalSecs, 30)
	SetHeartbeatInterval(60)
	if got := atomic.LoadInt32(&heartbeatIntervalSecs); got != 60 {
		t.Errorf("heartbeatIntervalSecs = %d, want 60", got)
	}
}

func TestSetHeartbeatInterval_ZeroIgnored(t *testing.T) {
	atomic.StoreInt32(&heartbeatIntervalSecs, 30)
	SetHeartbeatInterval(0)
	if got := atomic.LoadInt32(&heartbeatIntervalSecs); got != 30 {
		t.Errorf("heartbeatIntervalSecs = %d, want 30 (zero should be ignored)", got)
	}
}

func TestSetHeartbeatInterval_NegativeIgnored(t *testing.T) {
	atomic.StoreInt32(&heartbeatIntervalSecs, 30)
	SetHeartbeatInterval(-1)
	if got := atomic.LoadInt32(&heartbeatIntervalSecs); got != 30 {
		t.Errorf("heartbeatIntervalSecs = %d, want 30 (negative should be ignored)", got)
	}
}

func TestRunHeartbeat_CallsFunction(t *testing.T) {
	atomic.StoreInt32(&heartbeatIntervalSecs, 1)

	var callCount int64
	fn := func(_ int) { atomic.AddInt64(&callCount, 1) }

	ctx, cancel := context.WithCancel(context.Background())
	done := make(chan struct{})
	go func() {
		runHeartbeat(ctx, fn)
		close(done)
	}()

	time.Sleep(1500 * time.Millisecond)
	cancel()
	<-done // wait for goroutine to exit before the test returns

	if got := atomic.LoadInt64(&callCount); got < 1 {
		t.Errorf("fn was called %d times, want at least 1", got)
	}
}

func TestRunHeartbeat_CancelsOnContext(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	cancel() // already cancelled

	var callCount int64
	fn := func(_ int) {
		atomic.AddInt64(&callCount, 1)
	}

	done := make(chan struct{})
	go func() {
		runHeartbeat(ctx, fn)
		close(done)
	}()

	select {
	case <-done:
		// returned quickly as expected
	case <-time.After(100 * time.Millisecond):
		t.Error("runHeartbeat did not return promptly after context cancellation")
	}

	if got := atomic.LoadInt64(&callCount); got != 0 {
		t.Errorf("fn was called %d times, want 0 for already-cancelled context", got)
	}
}