Function GetTwoLatestSnapshotsForASource

internal/diff/diff.go:444–462

GetTwoLatestSnapshotsForASource fetches two latest snapshot manifests for a given source if they exist.

(ctx context.Context, rep repo.Repository, source snapshot.SourceInfo)

// GetTwoLatestSnapshotsForASource fetches two latest snapshot manifests for a given source if they exist.
func GetTwoLatestSnapshotsForASource(ctx context.Context, rep repo.Repository, source snapshot.SourceInfo) (secondLast, last *snapshot.Manifest, err error) {
	snapshots, err := snapshot.ListSnapshots(ctx, rep, source)
	if err != nil {
		return nil, nil, errors.Wrap(err, "failed to list all snapshots")
	}

	const minimumReqSnapshots = 2

	sizeSnapshots := len(snapshots)
	if sizeSnapshots < minimumReqSnapshots {
		return nil, nil, errors.New("snapshot source has less than two snapshots")
	}

	sort.Slice(snapshots, func(i, j int) bool {
		return snapshots[i].StartTime.Before(snapshots[j].StartTime)
	})

	return snapshots[sizeSnapshots-2], snapshots[sizeSnapshots-1], nil
}