package attesto

import (
	"context"
	"testing"
)

func TestIteratorDrainsThreePagesInOrder(t *testing.T) {
	pages := map[int][]M{
		0: {{"seqNo": 1}, {"seqNo": 2}, {"seqNo": 3}},
		3: {{"seqNo": 4}, {"seqNo": 5}, {"seqNo": 6}},
		6: {{"seqNo": 7}},
	}
	calls := 0
	it := NewIterator(func(_ context.Context, limit, offset int) ([]M, error) {
		calls++
		if limit != 3 {
			t.Fatalf("limit = %d, want 3", limit)
		}
		return pages[offset], nil
	}, 3)

	var seqs []int
	for {
		item, err := it.Next(context.Background())
		if err != nil {
			t.Fatal(err)
		}
		if item == nil {
			break
		}
		seqs = append(seqs, item["seqNo"].(int))
	}
	want := []int{1, 2, 3, 4, 5, 6, 7}
	if len(seqs) != len(want) {
		t.Fatalf("seqs = %v", seqs)
	}
	for i, v := range want {
		if seqs[i] != v {
			t.Fatalf("seqs = %v, want %v", seqs, want)
		}
	}
	if calls != 3 {
		t.Errorf("calls = %d, want 3", calls)
	}
}

func TestIteratorStopsCleanlyOnShortFirstPage(t *testing.T) {
	calls := 0
	it := NewIterator(func(_ context.Context, _, _ int) ([]M, error) {
		calls++
		return []M{{"streamId": "str_only"}}, nil
	}, 100)
	first, err := it.Next(context.Background())
	if err != nil || first == nil {
		t.Fatalf("first = %v err = %v", first, err)
	}
	second, err := it.Next(context.Background())
	if err != nil || second != nil {
		t.Fatalf("second = %v err = %v", second, err)
	}
	if calls != 1 {
		t.Errorf("calls = %d, want 1 (short page must end iteration)", calls)
	}
}