import struct
import socket
import time
from fuadmin import settings

class VdesMessagePackaged:
    """VDES消息打包工具类"""
    def __init__(self, Message, MMSI):
        self.message = Message
        self.MMSI = int(MMSI)
        self.chunk_size = 32755
        self.host = getattr(settings, 'VDES_MONITOR_HOST', 'localhost')
        self.port = getattr(settings, 'VDES_MONITOR_PORT', 8083)
        self.buffer_size = getattr(settings, 'VDES_BUFFER_SIZE', 4096)


    def create_tcp_packet(self, packet_type, content):
        """创建符合VDES TCP协议的报文"""
        # 报文帧头 (4字节)
        header = b'####'
        
        # 报文类型 (4字节，大端)
        type_field = struct.pack('>I', packet_type)
        
        # 报文长度 (4字节，大端，内容长度)
        length = len(content)
        length_field = struct.pack('>I', length)
        
        # 构建完整报文
        packet = header + type_field + length_field + content
        return packet
    
    #长消息起始片段
    def long_message_start_frame(self, target_mmsi, send_priority):
        data_type = 0                #数据类型
        target_MMSI = target_mmsi    #目标MMSI
        priority = send_priority     #优先级
        # 打包为二进制 (大端字节序)
        content = struct.pack('>BIB', data_type, target_MMSI, priority)
        return content
    
    #长消息延续片段
    def long_message_middle_frame(self, valid_binary_data):
        data_type = 1         #数据类型
        data = valid_binary_data     #有效数据
        # 打包为二进制 (大端字节序)
        content = struct.pack('>B', data_type) + data
        return content
    
    #长消息结束片段
    def long_message_end_frame(self):
        data_type = 2         #数据类型
        # 打包为二进制 (大端字节序)
        content = struct.pack('>B', data_type)
        return content

    def create_message_packet(self, message, target_mmsi, send_priority):
        binary_data = message.encode('utf-8')
        message_frames = []
        if len(binary_data) < 4:
            print("使用短消息，编码后的字节数小于4字节")
            return message_frames
        else:
            print(f"使用长消息编码后的字节数为{len(binary_data)}字节")
            
            chunks = [binary_data[i:i+self.chunk_size] 
                for i in range(0, len(binary_data), self.chunk_size)]
            # 3. 检查总长度限制
            
            if len(binary_data) > 256 * 1024:
                raise ValueError("总数据长度超过256KB限制") 
            start_frame = self.long_message_start_frame(target_mmsi, send_priority)
            message_frames.append(self.create_tcp_packet(10, start_frame))
            for chunk in chunks:
                middle_frame = self.long_message_middle_frame(chunk)
                message_frames.append(self.create_tcp_packet(10, middle_frame))
            end_frame = self.long_message_end_frame()
            message_frames.append(self.create_tcp_packet(10, end_frame))
            return message_frames

    def send_message(self):
        """启动Socket服务端"""  
        Target_MMSI = self.MMSI  # 示例目标MMSI
        Send_Priority = 1  # 示例发送优先级 
        message = self.message
        message_frames = self.create_message_packet(message, Target_MMSI, Send_Priority)
        with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
            try:
                sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
                sock.connect((self.host, self.port))
                print(f"Socket服务端已启动，监听 {self.host}:{self.port}")
                try:
                    for message_frame in message_frames:
                        print(f"发送报文: {message_frame.hex()}")
                        sock.sendall(message_frame)
                        # print("二进制表示:", ' '.join(format(byte, '08b') for byte in message_frame))
                        time.sleep(0.5)
                    # time.sleep(3)

                    sock.shutdown(socket.SHUT_WR)
                    sock.close()
                
                except (ConnectionResetError, BrokenPipeError):
                    print("客户端断开连接")
                        
            except KeyboardInterrupt:
                print("\n服务端已停止")

            except Exception as e:
                print(f"服务端错误: {e}")



# if __name__ == "__main__":
#     send_message()