import struct
import math

def encode_ais_fields():
    """编码AIS消息字段并打印解码结果"""
    # 初始化二进制位列表
    bits = []
    
    # 示例数据
    message_id = 1              # 消息ID (6 bits)
    repeat_indicator = 0         # 转发指示符 (2 bits)
    user_id = 123456789          # 用户ID/MMSI (30 bits)
    navigation_status = 8        # 导航状态 (4 bits) - 航行中
    rot = -128                   # 旋转速率 (8 bits) - 无信息
    sog = 102                    # 地面航速 (10 bits) - 10.2节
    position_accuracy = 1        # 位置准确度 (1 bit) - 高
    longitude = 120.5            # 经度 (28 bits) - 东经120.5°
    latitude = 30.5              # 纬度 (27 bits) - 北纬30.5°
    cog = 900                    # 地面航线 (12 bits) - 90.0°
    true_heading = 90            # 实际航向 (9 bits) - 90°
    timestamp = 30               # 时戳 (6 bits) - UTC秒
    special_maneuver = 0         # 特定操纵指示符 (2 bits)
    spare = 0                    # 备用 (3 bits)
    raim_flag = 0                # RAIM标志 (1 bit)
    comm_state = 0               # 通信状态 (19 bits)
    
    # 添加各个字段（按照协议顺序）
    bits.append(format(message_id, '06b'))              # 消息ID
    bits.append(format(repeat_indicator, '02b'))        # 转发指示符
    bits.append(format(user_id, '030b'))                # 用户ID
    bits.append(format(navigation_status, '04b'))       # 导航状态
    
    # 旋转速率 (8位有符号整数)
    rot_bits = rot & 0xFF
    bits.append(format(rot_bits, '08b'))
    
    # 地面航速 (10位)
    bits.append(format(min(sog, 1023), '010b'))
    
    # 位置准确度 (1位)
    bits.append(str(position_accuracy))
    
    # 经度 (28位)
    # 转换为1/10,000分钟单位
    longitude_min = int(longitude * 60 * 10000)
    bits.append(format(longitude_min & 0x0FFFFFFF, '028b'))
    
    # 纬度 (27位)
    latitude_min = int(latitude * 60 * 10000)
    bits.append(format(latitude_min & 0x07FFFFFF, '027b'))
    
    # 地面航线 (12位)
    bits.append(format(min(cog, 3600), '012b'))
    
    # 实际航向 (9位)
    bits.append(format(min(true_heading, 511), '09b'))
    
    # 时戳 (6位)
    bits.append(format(min(timestamp, 63), '06b'))
    
    # 特定操纵指示符 (2位)
    bits.append(format(special_maneuver, '02b'))
    
    # 备用 (3位)
    bits.append(format(spare, '03b'))
    
    # RAIM标志 (1位)
    bits.append(str(raim_flag))
    
    # 通信状态 (19位)
    bits.append(format(comm_state, '019b'))
    
    # 合并所有位
    bit_string = ''.join(bits)
    
    # 验证总位数
    total_bits = len(bit_string)
    if total_bits != 168:
        print(f"警告: 总位数应为168，实际为{total_bits}")
    
    # 将位字符串转换为字节
    byte_count = total_bits // 8
    ais_data = bytearray()
    for i in range(byte_count):
        byte_str = bit_string[i*8:(i+1)*8]
        ais_data.append(int(byte_str, 2))
    
    # 解码过程
    decoded = {}
    pos = 0
    
    # 消息ID (6 bits)
    decoded['消息ID'] = int(bit_string[pos:pos+6], 2)
    pos += 6
    
    # 转发指示符 (2 bits)
    decoded['转发指示符'] = int(bit_string[pos:pos+2], 2)
    pos += 2
    
    # 用户ID (30 bits)
    decoded['用户ID'] = int(bit_string[pos:pos+30], 2)
    pos += 30
    
    # 导航状态 (4 bits)
    decoded['导航状态'] = int(bit_string[pos:pos+4], 2)
    pos += 4
    
    # 旋转速率 (8 bits)
    rot_value = int(bit_string[pos:pos+8], 2)
    # 转换为有符号整数
    if rot_value > 127:
        rot_value -= 256
    decoded['旋转速率'] = rot_value
    pos += 8
    
    # SOG (10 bits)
    decoded['SOG'] = int(bit_string[pos:pos+10], 2)
    pos += 10
    
    # 位置准确度 (1 bit)
    decoded['位置准确度'] = int(bit_string[pos], 2)
    pos += 1
    
    # 经度 (28 bits)
    longitude_value = int(bit_string[pos:pos+28], 2)
    # 转换为度
    longitude_deg = longitude_value / (60 * 10000)
    decoded['经度'] = longitude_deg
    pos += 28
    
    # 纬度 (27 bits)
    latitude_value = int(bit_string[pos:pos+27], 2)
    # 转换为度
    latitude_deg = latitude_value / (60 * 10000)
    decoded['纬度'] = latitude_deg
    pos += 27
    
    # COG (12 bits)
    decoded['COG'] = int(bit_string[pos:pos+12], 2)
    pos += 12
    
    # 实际航向 (9 bits)
    decoded['实际航向'] = int(bit_string[pos:pos+9], 2)
    pos += 9
    
    # 时戳 (6 bits)
    decoded['时戳'] = int(bit_string[pos:pos+6], 2)
    pos += 6
    
    # 特定操纵指示符 (2 bits)
    decoded['特定操纵指示符'] = int(bit_string[pos:pos+2], 2)
    pos += 2
    
    # 备用 (3 bits)
    decoded['备用'] = int(bit_string[pos:pos+3], 2)
    pos += 3
    
    # RAIM标志 (1 bit)
    decoded['RAIM标志'] = int(bit_string[pos], 2)
    pos += 1
    
    # 通信状态 (19 bits)
    decoded['通信状态'] = int(bit_string[pos:pos+19], 2)
    
    # 打印结果
    print("\n编码字段的二进制表示:")
    print(bit_string[:6] + " " + bit_string[6:8] + " " + bit_string[8:38] + " " + 
          bit_string[38:42] + " " + bit_string[42:50] + " " + bit_string[50:60] + " " +
          bit_string[60:61] + " " + bit_string[61:89] + " " + bit_string[89:116] + " " +
          bit_string[116:128] + " " + bit_string[128:137] + " " + bit_string[137:143] + " " +
          bit_string[143:145] + " " + bit_string[145:148] + " " + bit_string[148:149] + " " +
          bit_string[149:])
    
    print("\n解码结果:")
    print(f"消息ID: {decoded['消息ID']} (1=AIS消息1)")
    print(f"转发指示符: {decoded['转发指示符']} (0=默认)")
    print(f"用户ID (MMSI): {decoded['用户ID']}")
    
    # 导航状态描述
    nav_status_desc = {
        0: "发动机使用中", 1: "锚泊", 2: "未操纵", 3: "有限适航性",
        4: "受船舶吃水限制", 5: "系泊", 6: "搁浅", 7: "从事捕捞",
        8: "航行中", 15: "未规定(默认)"
    }
    status = decoded['导航状态']
    print(f"导航状态: {status} ({nav_status_desc.get(status, '未知状态')})")
    
    # 旋转速率描述
    rot = decoded['旋转速率']
    if rot == -128:
        rot_desc = "无可用旋转信息(默认)"
    elif rot == 127:
        rot_desc = "右旋超过5º/30s"
    elif rot == -127:
        rot_desc = "左旋超过5º/30s"
    else:
        # 计算实际旋转速度
        rot_speed = (rot/4.733)**2 if rot != 0 else 0
        direction = "右旋" if rot > 0 else "左旋"
        rot_desc = f"{direction} {abs(rot_speed):.1f} 度/分钟"
    print(f"旋转速率: {rot} ({rot_desc})")
    
    # SOG描述
    sog_val = decoded['SOG']
    if sog_val == 1023:
        sog_desc = "不可用"
    elif sog_val == 1022:
        sog_desc = "102.2节或更快"
    else:
        sog_desc = f"{sog_val/10:.1f} 节"
    print(f"SOG: {sog_val} ({sog_desc})")
    
    print(f"位置准确度: {decoded['位置准确度']} ({'高(>10m)' if decoded['位置准确度'] else '低(<10m)'})")
    print(f"经度: {decoded['经度']:.5f}° ({'东经' if decoded['经度'] >= 0 else '西经'})")
    print(f"纬度: {decoded['纬度']:.5f}° ({'北纬' if decoded['纬度'] >= 0 else '南纬'})")
    
    # COG描述
    cog_val = decoded['COG']
    if cog_val == 3600:
        cog_desc = "不可用(默认)"
    else:
        cog_desc = f"{cog_val/10:.1f}°"
    print(f"COG: {cog_val} ({cog_desc})")
    
    # 实际航向描述
    heading = decoded['实际航向']
    heading_desc = "不可用(默认)" if heading == 511 else f"{heading}°"
    print(f"实际航向: {heading} ({heading_desc})")
    
    # 时戳描述
    ts = decoded['时戳']
    ts_desc = {
        60: "时戳不可用",
        61: "人工输入模式",
        62: "航迹推算模式",
        63: "定位系统不起作用"
    }.get(ts, f"{ts}秒")
    print(f"时戳: {ts} ({ts_desc})")
    
    # 特定操纵指示符描述
    maneuver = decoded['特定操纵指示符']
    maneuver_desc = {
        0: "不可用(默认)",
        1: "未进行特定操纵",
        2: "进行特定操纵"
    }.get(maneuver, "未知")
    print(f"特定操纵指示符: {maneuver} ({maneuver_desc})")
    
    print(f"备用: {decoded['备用']} (未使用)")
    print(f"RAIM标志: {decoded['RAIM标志']} ({'RAIM正在使用' if decoded['RAIM标志'] else 'RAIM未使用(默认)'})")
    print(f"通信状态: {decoded['通信状态']} (见表49)")
    
    # 打印二进制字节
    print("\n二进制字节表示 (168 bits = 21 bytes):")
    hex_str = ' '.join(f'{b:02x}' for b in ais_data)
    print(hex_str)
    
    return ais_data

# 执行编码和解码
ais_binary = encode_ais_fields()




binary_str = "000001000001110101101111001101000101011000100000000001100110101000100111100110101111000000010001011100111100011000000011100001000010110100111100000000000000000000000000"
binary_int = int(binary_str, 2)  # 将二进制字符串转换为整数
byte_length = (len(binary_str) + 7) // 8  # 计算需要的字节数
binary_data = binary_int.to_bytes(byte_length, 'big')  # 转换为字节

print(binary_data)  # 输出二进制数据