package service

import (
	"sync"
	"testing"
	"time"
)

func TestOpsLogBroadcaster_FanOutDeliversToMatchingSubscribers(t *testing.T) {
	b := NewOpsLogBroadcaster(16)

	chHigh, unHigh := b.Subscribe(OpsLogFilter{MinStatus: 500}, 8)
	defer unHigh()
	chAll, unAll := b.Subscribe(OpsLogFilter{}, 8)
	defer unAll()

	b.Publish(OpsLogEntry{Status: 200, Model: "claude-sonnet-4.6"})
	b.Publish(OpsLogEntry{Status: 503, Model: "kimi-k2.5"})

	got200 := receiveOrTimeout(t, chAll, 200*time.Millisecond)
	got503 := receiveOrTimeout(t, chAll, 200*time.Millisecond)
	if got200.Status != 200 || got503.Status != 503 {
		t.Fatalf("unexpected fan-out: %d / %d", got200.Status, got503.Status)
	}

	gotHigh := receiveOrTimeout(t, chHigh, 200*time.Millisecond)
	if gotHigh.Status != 503 {
		t.Fatalf("filter MinStatus=500 should drop 200, got %d", gotHigh.Status)
	}
	expectNoMessage(t, chHigh, 50*time.Millisecond)
}

func TestOpsLogBroadcaster_FilterByModelAndAccount(t *testing.T) {
	b := NewOpsLogBroadcaster(0)

	chKimi, unKimi := b.Subscribe(OpsLogFilter{Model: "kimi-k2.5"}, 4)
	defer unKimi()
	chAcct, unAcct := b.Subscribe(OpsLogFilter{AccountID: 42}, 4)
	defer unAcct()

	b.Publish(OpsLogEntry{Status: 200, Model: "claude-sonnet-4.6", AccountID: 1})
	b.Publish(OpsLogEntry{Status: 200, Model: "kimi-k2.5", AccountID: 42})

	got := receiveOrTimeout(t, chKimi, 200*time.Millisecond)
	if got.Model != "kimi-k2.5" {
		t.Fatalf("expected kimi entry, got %+v", got)
	}
	expectNoMessage(t, chKimi, 50*time.Millisecond)

	gotA := receiveOrTimeout(t, chAcct, 200*time.Millisecond)
	if gotA.AccountID != 42 {
		t.Fatalf("expected account 42, got %d", gotA.AccountID)
	}
}

func TestOpsLogBroadcaster_NeverBlocksOnSlowSubscriber(t *testing.T) {
	b := NewOpsLogBroadcaster(0)

	// Subscriber with buffer=1, never reads. After the second Publish,
	// the entry must be dropped instead of blocking the publisher.
	_, unsub := b.Subscribe(OpsLogFilter{}, 1)
	defer unsub()

	done := make(chan struct{})
	go func() {
		for i := 0; i < 100; i++ {
			b.Publish(OpsLogEntry{Status: 200})
		}
		close(done)
	}()

	select {
	case <-done:
	case <-time.After(2 * time.Second):
		t.Fatal("publisher blocked on slow subscriber")
	}

	_, dropped, _ := b.Stats()
	if dropped == 0 {
		t.Fatal("expected dropped count > 0 when subscriber buffer overflows")
	}
}

func TestOpsLogBroadcaster_HistorySnapshot(t *testing.T) {
	b := NewOpsLogBroadcaster(3)

	for i := 1; i <= 5; i++ {
		b.Publish(OpsLogEntry{Status: 200 + i})
	}

	got := b.Snapshot(OpsLogFilter{}, 0)
	if len(got) != 3 {
		t.Fatalf("expected ring of 3, got %d", len(got))
	}
	// Oldest → newest
	if got[0].Status != 203 || got[1].Status != 204 || got[2].Status != 205 {
		t.Fatalf("expected 203/204/205, got %d/%d/%d", got[0].Status, got[1].Status, got[2].Status)
	}
}

func TestOpsLogBroadcaster_HistoryAppliesFilter(t *testing.T) {
	b := NewOpsLogBroadcaster(8)

	b.Publish(OpsLogEntry{Status: 200})
	b.Publish(OpsLogEntry{Status: 500})
	b.Publish(OpsLogEntry{Status: 503})

	got := b.Snapshot(OpsLogFilter{MinStatus: 500}, 0)
	if len(got) != 2 {
		t.Fatalf("expected 2 high-status entries, got %d: %+v", len(got), got)
	}
}

func TestOpsLogBroadcaster_UnsubscribeIdempotent(t *testing.T) {
	b := NewOpsLogBroadcaster(0)
	_, unsub := b.Subscribe(OpsLogFilter{}, 1)
	unsub()
	unsub() // second call must not panic
	unsub() // and a third
}

func TestOpsLogBroadcaster_ZeroTimeFilledIn(t *testing.T) {
	b := NewOpsLogBroadcaster(2)

	b.Publish(OpsLogEntry{Status: 200}) // Time intentionally zero
	got := b.Snapshot(OpsLogFilter{}, 0)
	if len(got) != 1 {
		t.Fatalf("expected 1 entry, got %d", len(got))
	}
	if got[0].Time.IsZero() {
		t.Fatal("Publish should populate zero Time with time.Now()")
	}
}

func TestOpsLogBroadcaster_ConcurrentSafe(t *testing.T) {
	b := NewOpsLogBroadcaster(64)

	// Spin a few subscribers and producers; rely on -race to surface
	// any concurrency bugs in the fan-out path.
	var wg sync.WaitGroup
	for i := 0; i < 4; i++ {
		ch, unsub := b.Subscribe(OpsLogFilter{}, 32)
		wg.Add(1)
		go func() {
			defer wg.Done()
			defer unsub()
			deadline := time.Now().Add(200 * time.Millisecond)
			for time.Now().Before(deadline) {
				select {
				case <-ch:
				case <-time.After(5 * time.Millisecond):
				}
			}
		}()
	}

	for i := 0; i < 4; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			for j := 0; j < 200; j++ {
				b.Publish(OpsLogEntry{Status: 200, Model: "x"})
			}
		}()
	}

	wg.Wait()
	pub, _, _ := b.Stats()
	if pub != 800 {
		t.Fatalf("expected 800 publishes, got %d", pub)
	}
}

// TestOpsLogBroadcaster_ConcurrentUnsubscribeNoPanic exercises the exact
// race the audit identified: a Publish goroutine has snapped a subscription
// pointer while another goroutine unsubscribes (close(ch)) the moment before
// the send. Without the closed-flag guard in Publish, this races into
// "send on closed channel" and panics. With the guard, Publish observes
// closed=true and skips the send. Run with -race.
func TestOpsLogBroadcaster_ConcurrentUnsubscribeNoPanic(t *testing.T) {
	b := NewOpsLogBroadcaster(0)

	var wg sync.WaitGroup
	for i := 0; i < 8; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			for j := 0; j < 200; j++ {
				ch, unsub := b.Subscribe(OpsLogFilter{}, 1)
				// Drain non-blockingly until the next publish lands.
				done := make(chan struct{})
				go func() {
					defer close(done)
					timer := time.NewTimer(50 * time.Millisecond)
					defer timer.Stop()
					for {
						select {
						case <-ch:
						case <-timer.C:
							return
						}
					}
				}()
				b.Publish(OpsLogEntry{Status: 200})
				unsub()
				b.Publish(OpsLogEntry{Status: 200}) // post-unsub publish must not panic
				<-done
			}
		}()
	}
	wg.Wait()
}

// TestOpsLogBroadcaster_SnapshotConcurrentWithPublish ensures Snapshot is
// safe under concurrent Publish (verifies subsMu vs historyMu coexistence).
func TestOpsLogBroadcaster_SnapshotConcurrentWithPublish(t *testing.T) {
	b := NewOpsLogBroadcaster(32)

	stop := make(chan struct{})
	var wg sync.WaitGroup
	wg.Add(2)

	go func() {
		defer wg.Done()
		for {
			select {
			case <-stop:
				return
			default:
				b.Publish(OpsLogEntry{Status: 200})
			}
		}
	}()

	go func() {
		defer wg.Done()
		for i := 0; i < 200; i++ {
			_ = b.Snapshot(OpsLogFilter{}, 0)
		}
	}()

	time.Sleep(50 * time.Millisecond)
	close(stop)
	wg.Wait()
}

// helpers --------------------------------------------------------------

func receiveOrTimeout(t *testing.T, ch <-chan OpsLogEntry, d time.Duration) OpsLogEntry {
	t.Helper()
	select {
	case e := <-ch:
		return e
	case <-time.After(d):
		t.Fatalf("timeout waiting for entry after %s", d)
	}
	return OpsLogEntry{}
}

func expectNoMessage(t *testing.T, ch <-chan OpsLogEntry, d time.Duration) {
	t.Helper()
	select {
	case e := <-ch:
		t.Fatalf("unexpected message: %+v", e)
	case <-time.After(d):
	}
}