# -*- coding: utf-8 -*-
'''
 * @Author       : zoufuzhou
 * @Date         : 2024-09-02 16:34:37
 * @Description  : Fixed element pointer position. 
                   The current pointer points to the latest element
 * @LastEditTime : 2024-09-05 16:34:37
'''

from shm.Head import Head
from shm.GlobMem import GlobMem
import logging as d


class MemFix:
 
    __head = Head(0, 0, 0)
    __ptr = None
    __getnext = None
    __mem = None
    __pos = None
    __step = None

    def __init(self, memname: str, step: int):
        gmem = GlobMem()
        self.__mem = gmem.GetMem(memname)
        if (self.__mem is None):
            d.error("MemFix init failed")
            return
        self.__pos = self.__mem.tell()

        self.__readHead()
        d.debug(f"Head: {self.__head}")
        self.__ptr = self.__pos + self.__head.length()
        self.__step = step

    def __readHead(self):

        self.__head.unpack(
            self.__mem[self.__pos: self.__pos + self.__head.length()])
        # d.debug(f"Head: {self.__head}")

    def __writeHead(self):
        packed_data = self.__head.pack()
        self.__mem[self.__pos: self.__pos + self.__head.length()] = packed_data

    def __init__(self, memname: str, step: int, cache_size=0):
        if (cache_size <= 0):
            self.__init(memname, step)
            self.__getnext = self.__head.next
            return

        self.__init(memname, step)
        self.__head.maxsize = cache_size
        if (self.__head.size > self.__head.maxsize):
            self.__head.size = self.__head.maxsize

        if (self.__head.next > self.__head.maxsize):
            self.__head.next = self.__head.maxsize

        self.__head.next = self.__head.next % self.__head.maxsize
        self.__getnext = self.__head.next
        self.__writeHead()

    def getNext(self) -> bytes:
        if (self.__ptr is None):
            return None
        self.__readHead()
        if (self.__getnext == self.__head.next):
            return None
        else:
            tmpnext = self.__getnext
            self.__getnext = (self.__getnext + 1) % self.__head.maxsize
            self.__mem.seek(self.__ptr + tmpnext * self.__step)
            return self.__mem.read(self.__step)

    def read(self, index: int) -> bytes:
        if (self.__ptr is None):
            return None
        self.__readHead()
        if (index > self.__head.maxsize):
            return None
        self.__mem.seek(self.__ptr + index * self.__step)
        return self.__mem.read(self.__step)

    def getCur(self) -> bytes:
        if (self.__ptr is None):
            return None
        self.__readHead()
        self.__mem.seek(self.__ptr + self.index_cur() * self.__step)
        return self.__mem.read(self.__step)

    def index_cur(self) -> int:
        if (self.__ptr is None):
            return 0
        self.__readHead()
        if (self.__head.next <= 0):
            return self.__head.maxsize - 1
        else:
            return (self.__head.next-1) % self.__head.maxsize

    def max_size(self) -> int:
        if (self.__ptr is None):
            return 0
        self.__readHead()
        return self.__head.maxsize

    def size(self) -> int:
        if (self.__ptr is None):
            return 0
        self.__readHead()
        return self.__head.size

    def push(self, struct_data: bytes):
        if (self.__ptr is None):
            return None
        self.__readHead()
        if (self.__head.size < self.__head.maxsize):
            self.__head.size += 1

        # d.debug(f"next:{self.__head.next} {self.__ptr + self.__head.next * self.__step}: {self.__ptr + (self.__head.next + 1) * self.__step}")

        self.__mem.seek(self.__ptr + self.__head.next * self.__step)
        self.__mem.write(struct_data[: self.__step])

        self.__head.next = (self.__head.next + 1) % self.__head.maxsize
        self.__writeHead()

    def clear(self):
        if (self.__ptr is None):
            return None
        self.__head.size = 0
        self.__head.next = 0
        self.__getnext = self.__head.next
        self.__writeHead()
        d.info(f"init Head: {self.__head}")


# 测试代码
from log.LogUtil import LogUtil
import struct
if __name__ == '__main__':
    LogUtil.init("app")
    mm = MemFix('TRKCOIL', 50, 100)  # 初始化
    # mm.clear() # 清空内存
    for i in range(51):

        # 打包数据
        packed_data = b''  # 初始化空字节串

        for data in range(1, 26):
            # 使用 struct.pack() 打包每个数据项
            packed_data += struct.pack('h', data)
        mm.push(packed_data)  # 写入数据

    packed_data = mm.getCur()
    d.debug(f"packed_data: {struct.unpack('25h', packed_data)}")

    for i in range(25):
        unpacked_data = struct.unpack_from('h', packed_data, i*2)
        d.debug(f"unpacked_data: {unpacked_data[0]}")