#pragma once
#include <cstdint>
#include <vector>
#include <atomic>
#include <mutex>

struct CalibrationData;  // forward declare

class ProximityAlgorithm
{
public:
    explicit ProximityAlgorithm(int avgLength = 8);

    // Configure with calibration data (called from reader thread on connect/reconnect)
    void Reset(const CalibrationData& cal);

    // Process one HID sample (already cal-subtracted by firmware)
    void ProcessSample(uint16_t hid_distance);

    // Lock-free read (called from RunFrame on main thread)
    bool GetPersonDetected() const;

    // Diagnostic snapshot (called from HandlePipeCommand)
    struct DiagState {
        uint32_t averaged_prox;
        bool detected;
        uint16_t effective_threshold;
        uint32_t total_samples;
    };
    DiagState GetDiagState() const;

private:
    int m_averageLength;

    // Calibration (set on Reset, used only from reader thread)
    uint16_t m_trimmedThreshold = 0;
    uint16_t m_hysteresis = 100;

    // Circular buffer (reader thread only)
    std::vector<uint16_t> m_buffer;
    int m_writeIndex = 0;

    // Output (atomic for cross-thread reads)
    std::atomic<bool> m_personDetected{false};

    // Diagnostics (mutex-protected for multi-field consistency)
    mutable std::mutex m_diagMutex;
    uint32_t m_averagedProx = 0;
    uint32_t m_totalSamples = 0;
};