// SampleBuffer.h
#pragma once
#include "../core/DataTypes.h"
#include <deque>
#include <vector>
#include <shared_mutex>
#include <chrono>

enum class RetainMode {
    ByCount,        // °´Ñù±¾ÊýÉÏÏÞ
    ByRollingAge,   // °´¹ö¶¯Ê±¼ä´°¿Ú£¨maxAge£©
    ByAbsoluteRange // °´¾ø¶Ôʱ¼ä¶Î [absFrom, absTo]
};

struct RetentionPolicy {
    RetainMode mode = RetainMode::ByCount;
    size_t maxSamples = 100000;                         // ByCount ÓÃ
    std::chrono::milliseconds maxAge{ std::chrono::hours(1) }; // ByRollingAge ÓÃ
    int64_t absFrom = 0;                                // ByAbsoluteRange ÓÃ
    int64_t absTo = 0;                                // ByAbsoluteRange Óã¨absTo>=absFrom ÓÐЧ£©
};

class SampleBuffer {
public:
    explicit SampleBuffer(RetentionPolicy policy = {}) : policy_(policy) {}

    // д£º°´Ê±¼ä´ÁµÝÔöÍÆÈ루ÂÒÐò»á±»¼òµ¥¾ÀÕýΪ·ÇµÝ¼õ£©
    void push(int64_t ts_ms, double v);

    // ¶Á£º°´¡°tsExclusive Ö®ºó¡±µÄÐÂÊý¾Ý
    std::vector<Sample> getSince(int64_t tsExclusive, size_t maxCount = 4096) const;

    // ¶Á£º°´Çø¼ä [from, to]£¨°üº¬±ß½ç£©
    std::vector<Sample> getRange(int64_t from_ts, int64_t to_ts, size_t maxCount = 4096) const;

    // ²éѯ / ά»¤
    size_t size() const;
    bool   empty() const;
    int64_t latestTs() const;
    void clear();

    // ÅäÖÃ
    void setPolicy(const RetentionPolicy& p);
    RetentionPolicy getPolicy() const;

    int64_t earliestTs() const;  // ÎÞÊý¾Ýʱ·µ»Ø 0

private:
    void pruneUnlocked(int64_t ref_now_ms);       // °´²ßÂÔÇåÀí
    size_t lowerBoundIndex(int64_t tsExclusive) const; // ¶þ·Ö£ºµÚÒ»¸ö > tsExclusive
    size_t lowerBoundInclusive(int64_t tsInclusive) const; // µÚÒ»¸ö >= tsInclusive
    size_t upperBoundInclusive(int64_t tsInclusive) const; // ×îºóÒ»¸ö <= tsInclusive µÄÏÂÒ»¸öλÖÃ

    mutable std::shared_mutex mtx_;
    std::deque<Sample> data_;
    RetentionPolicy policy_;
};