package logging

import (
	"bytes"
	"log/slog"
	"testing"
)

func TestRingHandler_KeepsErrorsNewestFirst(t *testing.T) {
	ring := NewErrorRing(3)
	var out bytes.Buffer
	log := slog.New(newRingHandler(slog.NewTextHandler(&out, nil), ring)).With("component", "scan")

	log.Info("fine")
	log.Warn("odd")
	for _, msg := range []string{"one", "two", "three", "four"} {
		log.WithGroup("job").Error(msg, "n", len(msg))
	}

	got, total := ring.Snapshot()
	if total != 4 {
		t.Errorf("total = %d, want 4 (info and warn are not errors)", total)
	}
	if len(got) != 3 {
		t.Fatalf("kept %d, want 3", len(got))
	}
	for i, want := range []string{"four", "three", "two"} {
		if got[i].Message != want {
			t.Errorf("kept[%d] = %q, want %q", i, got[i].Message, want)
		}
	}
	if got[0].Attrs != "component=scan job.n=4" {
		t.Errorf("attrs = %q", got[0].Attrs)
	}
	// Every record still reaches the log stream.
	if n := bytes.Count(out.Bytes(), []byte("\n")); n != 6 {
		t.Errorf("log lines = %d, want 6", n)
	}
}

func TestErrorRing_BeforeItFills(t *testing.T) {
	ring := NewErrorRing(5)
	ring.add(LoggedError{Message: "a"})
	ring.add(LoggedError{Message: "b"})
	got, total := ring.Snapshot()
	if total != 2 || len(got) != 2 || got[0].Message != "b" || got[1].Message != "a" {
		t.Errorf("got %+v total %d, want b, a", got, total)
	}
}