package events

import (
	"io"
	"log/slog"
	"sync"
	"testing"
)

func TestStoreBoundsCopiesAndConcurrentCounters(t *testing.T) {
	s := NewStore(4, slog.New(slog.NewTextHandler(io.Discard, nil)))
	var wg sync.WaitGroup
	for i := 0; i < 10; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			for n := 0; n < 10; n++ {
				s.Add(Event{Kind: MessageReceived, Properties: Properties{CorrelationData: []byte("id")}})
				s.Snapshot()
			}
		}()
	}
	wg.Wait()
	history, counts := s.Snapshot()
	if len(history) != 4 || counts[MessageReceived] != 100 {
		t.Fatal("history/counter bound incorrect")
	}
	for i := 1; i < len(history); i++ {
		if history[i].ID <= history[i-1].ID {
			t.Fatal("history IDs out of order")
		}
	}
	history[0].Properties.CorrelationData[0] = 'X'
	again, _ := s.Snapshot()
	if string(again[0].Properties.CorrelationData) != "id" {
		t.Fatal("snapshot mutated internal history")
	}
}

func TestSubscribeReplayGapLiveFanoutAndCleanup(t *testing.T) {
	s := NewStore(3, slog.New(slog.NewTextHandler(io.Discard, nil)))
	for i := 0; i < 5; i++ {
		s.Add(Event{Kind: MessageReceived})
	}
	replay, gap, stream, unsubscribe := s.Subscribe(0, 1, 1)
	if gap == nil || gap.ResetID != 4 || gap.Gap != 4 || len(replay) != 1 || replay[0].ID != 5 {
		t.Fatalf("bounded replay gap: %#v %#v", gap, replay)
	}
	s.Add(Event{Kind: MessageReceived})
	if n := <-stream; n.Event == nil || n.Event.ID != 6 {
		t.Fatal("live event fanout failed")
	}
	unsubscribe()
	unsubscribe()
	if len(s.subs) != 0 {
		t.Fatal("subscriber cleanup failed")
	}
	_, gap, _, closeSub := s.Subscribe(999, 1, 1)
	defer closeSub()
	if gap == nil || gap.ResetID != 6 {
		t.Fatal("future cursor did not request reset")
	}
}
func TestSlowViewerGetsGapWithoutBlockingEvents(t *testing.T) {
	s := NewStore(8, slog.New(slog.NewTextHandler(io.Discard, nil)))
	s.Add(Event{Kind: MessageReceived})
	_, _, stream, unsubscribe := s.Subscribe(1, 1, 8)
	defer unsubscribe()
	s.Add(Event{Kind: MessageReceived})
	s.Add(Event{Kind: MessageReceived})
	if n := <-stream; n.Event == nil || n.Event.ID != 2 {
		t.Fatal("first bounded event missing")
	}
	s.Add(Event{Kind: MessageReceived})
	if n := <-stream; n.Gap != 2 || n.ResetID != 4 {
		t.Fatalf("missing explicit overflow gap: %#v", n)
	}
	s.Add(Event{Kind: MessageReceived})
	if n := <-stream; n.Event == nil || n.Event.ID != 5 {
		t.Fatalf("unexpected event after overflow gap: %#v", n)
	}
}