#pragma once
#include <mutex>
#include "ecsmemorypool_global.h"

class MemoryPage;

/// <summary>
/// 内存页访问控制块
/// </summary>
struct PageControlBlock {
	uint16_t active_elements_count = 0;		// 活跃element数量，决定是否需要卸载
	uint16_t byte_count_per_element = 32;	// 单个element大小，16的倍数，带ElementControlBlock
	uint32_t total_buffer_size = 0;			// 可用数据缓冲区大小

	uint64_t typecode_of_element = 0;		// 元素类型标识码

	uint64_t curr_access_usec = 0;			// 最近访问时间点，lsb：us

	uint32_t acc_count_per_cycle = 0;		// 单周期内累积访问次数
	uint32_t backup = 0;

	std::mutex access_protected;			// 内存数据访问保护锁
};

/// <summary>
/// 元素访问控制块
/// </summary>
struct ElementControlBlock {
	uint32_t	refer_count = 0;			// 外部元素的引用数量，活跃标志
	uint16_t	element_index = 0;			// 本元素在Page中的索引
	uint16_t	backup_1 = 0;

	MemoryPage* page_refer = nullptr;		// 页面关联指针
	void* extend_bind = nullptr;		// 绑定控制块内存指针
};



/// <summary>
/// 内存页面16K大小
/// </summary>
class ECSMEMORYPOOL_EXPORT MemoryPage {
private:
	PageControlBlock pcb;
	unsigned char data_buffer[16 * 1024 - (sizeof(PageControlBlock) / 8 + 1) * 8] = {};

public:
	/// <summary>
	/// 构建内存页
	/// </summary>
	/// <param name="raw_esize_16B">原始element尺寸</param>
	explicit MemoryPage(uint16_t raw_esize_16B, uint64_t typecode);

	/// <summary>
	/// 内存存储的数据元素的尺寸
	/// </summary>
	/// <returns></returns>
	uint16_t chunkSize() const;

	/// <summary>
	/// 获取当前活跃元素数量
	/// </summary>
	/// <param name="inc">变化值</param>
	/// <returns>当前元素数量</returns>
	uint16_t getActiveCount(uint16_t inc = 0) const;

	/// <summary>
	/// 记录单次访问时间
	/// </summary>
	/// <param name="timepoint_usec"></param>
	void accessRecord(uint64_t timepoint_usec);
	/// <summary>
	/// 清除访问次数记录
	/// </summary>
	/// <returns>上一周期累积次数</returns>
	uint32_t timesClear();
	/// <summary>
	/// 获取访问记录
	/// </summary>
	/// <returns>{最近访问时间,累积次数}</returns>
	std::pair<uint64_t, uint32_t> getRecords() const;

	/// <summary>
	/// 加锁，在release之前不能访问本类型任何接口，否则会造成死锁
	/// </summary>
	void lock();
	/// <summary>
	/// 解锁
	/// </summary>
	void release();

	/// <summary>
	/// 获取element元素数据访问指针
	/// </summary>
	/// <param name="index">元素索引</param>
	/// <param name="active_set">是否设置</param>
	/// <returns>数据指针</returns>
	ElementControlBlock* getChunkPtr(int index);
	/// <summary>
	/// 元素类型码
	/// </summary>
	/// <returns></returns>
	uint64_t elementTypeCode() const;
	/// <summary>
	/// 获取单个元素尺寸
	/// </summary>
	/// <returns>字节数量</returns>
	uint16_t chunkRawSize() const;
	/// <summary>
	/// 获取元素数量
	/// </summary>
	/// <returns></returns>
	uint16_t maxChunkCapacity() const;
};

/// <summary>
/// 内存元素访问接口
/// </summary>
class ECSMEMORYPOOL_EXPORT MemoryElement {
protected:
	ElementControlBlock* const data_ptr;

public:
	static const uint32_t data_buffer_offset;
	static uint32_t validOffset();
	static uint32_t rawSize(uint32_t data_type_size);
	/// <summary>
	/// 数据活跃状态
	/// </summary>
	/// <returns></returns>
	static bool isActived(ElementControlBlock* refer);

	/// <summary>
	/// 构建内存元素访问接口
	/// </summary>
	/// <param name="access_bind"></param>
	MemoryElement(ElementControlBlock* access_bind);

	/// <summary>
	/// 提取关联元素尺寸
	/// </summary>
	/// <returns></returns>
	uint16_t typeSize() const;

	/// <summary>
	/// 更新最终访问时间
	/// </summary>
	/// <param name="time_usec"></param>
	void accessUpdate(uint64_t time_usec);

	/// <summary>
	/// 设置数据活跃状态
	/// </summary>
	/// <param name="ste"></param>
	void referAdd();
	/// <summary>
	/// 设置数据活跃状态
	/// </summary>
	/// <param name="ste"></param>
	void referSub();

	/// <summary>
	/// 锁定数据，返回数据存储内存指针
	/// </summary>
	/// <returns></returns>
	unsigned char* dataLock();
	/// <summary>
	/// 解锁数据
	/// </summary>
	void release();
};