import struct

# 默认容量
DefaultCapacity = 128


class BxByteArray:
    def __init__(self, capacity):
        self.list = bytearray(capacity)
        self.next = 0

    def add(self, data):
        if self.next == len(self.list):
            # 扩展容量
            self.list.extend(bytearray(len(self.list) * 2))
        self.list[self.next] = data
        self.next += 1

    def addInt16(self, data, endian):
        # 确保容量足够
        if self.next + 1 >= len(self.list):
            self.list.extend(bytearray(len(self.list) * 2))
        
        # 打包为2字节
        if endian == 0:  # LITTLE
            packed = struct.pack('<h', data)
        else:  # BIG
            packed = struct.pack('>h', data)
        
        # 复制到列表
        self.list[self.next:self.next+2] = packed
        self.next += 2

    def addInt(self, data, endian):
        # 确保容量足够
        if self.next + 3 >= len(self.list):
            self.list.extend(bytearray(len(self.list) * 2))
        
        # 打包为4字节
        if endian == 0:  # LITTLE
            packed = struct.pack('<i', data)
        else:  # BIG
            packed = struct.pack('>i', data)
        
        # 复制到列表
        self.list[self.next:self.next+4] = packed
        self.next += 4

    def addBytes(self, src):
        if src:
            # 确保容量足够
            if self.next + len(src) - 1 >= len(self.list):
                self.list.extend(bytearray(len(self.list) + len(src)))
            
            # 复制数据
            self.list[self.next:self.next+len(src)] = src
            self.next += len(src)

    def addBytesOffsetLength(self, src, offset, length):
        if src:
            # 确保容量足够
            if self.next + length - 1 >= len(self.list):
                self.list.extend(bytearray(len(self.list) + length))
            
            # 复制数据
            self.list[self.next:self.next+length] = src[offset:offset+length]
            self.next += length

    def set(self, index, data):
        if index < len(self.list):
            self.list[index] = data

    def get(self, index):
        return self.list[index]

    def Build(self):
        return bytes(self.list[:self.next])

    def size(self):
        return self.next

    def clear(self):
        self.next = 0


# 创建BxByteArray实例的函数
def NewBxByteArray(capacity):
    return BxByteArray(capacity)


# 创建默认容量的BxByteArray实例的函数
def NewDefaultBxByteArray():
    return NewBxByteArray(DefaultCapacity)