// SPDX-License-Identifier: MIT
// SPDX-FileCopyrightText: 2026 Martino Ferrari

#pragma once

#ifdef PLOT_PYRAMID_COUNT_MERGES

#include <atomic>

#include <plot/core/types.hpp>

namespace plot::data::detail {

/// Test-only instrumentation. Counts the bucket merges the append path has
/// performed since the counter was last reset: one for the bucket pushed at
/// level 0 when it completes, plus one for every parent bucket written above it.
///
/// The append path's *cost* is invisible in every answer -- a pyramid that walks
/// every live level per sample returns exactly the same min/max/sum as one that
/// stops at the first level that gained no entry -- so a test that wants to pin
/// "amortised O(1) per sample, independent of the number of live levels" has to
/// count merges. The counter exists only when PLOT_PYRAMID_COUNT_MERGES is
/// defined (the test build defines it), so every normal build carries no counter
/// and no increment on the append path.
///
/// Not part of the query surface and not meant for production use.
inline std::atomic<u64>& merge_count() {
  static std::atomic<u64> count{0};
  return count;
}

}  // namespace plot::data::detail

#endif  // PLOT_PYRAMID_COUNT_MERGES