"""配电系统 UDP 协议封装（声明式消息定义）。

字段顺序、大小与 C++ 侧 pmSysvariable.h / ccuUdpMsg.h 严格对齐。

帧格式（配电消息，单字节校验）:
  start1(0x40) start2(0x40) | id(uint16 LE) | length(uint16 LE) | body | checkCode(和校验 &0xFF)

说明:
  - 字段表(FIELDS)是唯一数据源，length、pack/unpack 均由此推导，
    避免手工维护长度字段与 C++ 结构体大小不一致。
  - unpack 采用固定偏移解析 + 起始字节/最小长度/校验和校验。
"""

import struct

DIS_START1 = 0x40
DIS_START2 = 0x40

# 断路器状态定义（与 C++ 一致）
BREAKER_ON = 0x55      # 合
BREAKER_OFF = 0xAA     # 分
BREAKER_FAULT = 0x5A   # 故障


class Field:
    """协议字段定义。fmt 支持 'B'(uchar) / 'H'(ushort LE)。"""

    __slots__ = ("name", "fmt", "size")

    def __init__(self, name, fmt):
        self.name = name
        self.fmt = fmt
        self.size = struct.calcsize(fmt)


class Message:
    """声明式消息基类：由 FIELDS 自动生成 pack/unpack 与长度。"""

    MSG_ID = 0x0000
    CN = "未知消息"
    FIELDS = ()  # tuple[Field]

    def __init__(self):
        self.start1 = DIS_START1
        self.start2 = DIS_START2
        self.msg_id = self.MSG_ID
        self.length = self.body_size()
        self.checkCode = 0
        for f in self.FIELDS:
            setattr(self, f.name, 0)

    # ---- 派生属性 -------------------------------------------------
    @classmethod
    def body_size(cls):
        return sum(f.size for f in cls.FIELDS)

    @classmethod
    def field_names(cls):
        return [f.name for f in cls.FIELDS]

    def to_dict(self):
        return {f.name: getattr(self, f.name) for f in self.FIELDS}

    def __repr__(self):
        parts = [f"{self.__class__.__name__}(id=0x{self.MSG_ID:04X}, len={self.length}"]
        for f in self.FIELDS:
            parts.append(f"{f.name}={getattr(self, f.name)}")
        return ", ".join(parts) + ")"

    # ---- 打包/解包 ------------------------------------------------
    def pack(self):
        body = b""
        for f in self.FIELDS:
            body += struct.pack("<" + f.fmt, getattr(self, f.name))
        self.length = self.body_size()
        header = struct.pack("<BBHH", DIS_START1, DIS_START2, self.MSG_ID, self.length)
        data = header + body
        self.checkCode = sum(data) & 0xFF
        return data + struct.pack("<B", self.checkCode)

    def unpack(self, data):
        if len(data) < 7:
            return False
        if data[0] != DIS_START1 or data[1] != DIS_START2:
            return False
        if struct.unpack_from("<H", data, 2)[0] != self.MSG_ID:
            return False
        expected = 6 + self.body_size() + 1
        if len(data) < expected:
            return False

        self.start1, self.start2 = data[0], data[1]
        self.msg_id = struct.unpack_from("<H", data, 2)[0]
        self.length = struct.unpack_from("<H", data, 4)[0]

        offset = 6
        for f in self.FIELDS:
            if f.size == 1:
                setattr(self, f.name, data[offset])
                offset += 1
            else:
                setattr(self, f.name, struct.unpack_from("<H", data, offset)[0])
                offset += 2
        self.checkCode = data[-1]

        checksum = sum(data[:-1]) & 0xFF
        return checksum == data[-1]


# ---------------------------------------------------------------
# 高压母线反馈  0x0005   body=53
# ---------------------------------------------------------------
class MsgDisHighVolBusFb(Message):
    MSG_ID = 0x0005
    CN = "动力母线反馈"
    FIELDS = (
        Field("fuelCellCircuitBreaker", "B"),
        Field("powerLithiumBatteryCircuitBreaker", "B"),
        Field("propulsionMotorCircuitBreaker", "B"),
        Field("lithiumBatteryGroupInstrumentCircuitBreaker", "B"),
        Field("dcDc5ModuleCircuitBreaker", "B"),
        Field("bowHighVoltageDistributionBoxCircuitBreaker", "B"),
        Field("sternFTDevice45CircuitBreaker", "B"),
        Field("fbReservedCircuitBreaker", "B"),
        Field("sternRudderSwitch1CircuitBreaker", "B"),
        Field("sternRudderSwitch2CircuitBreaker", "B"),
        Field("tyzReservedCircuitBreaker", "B"),
        Field("reservedCircuitBreaker", "B"),
        Field("dcDcFaultWord1", "B"),
        Field("dcDcFaultWord2", "B"),
        Field("powerBusInsulationStatus", "B"),
        Field("aBusInsulationStatus", "B"),
        Field("meterPowerLossSignal", "B"),
        Field("emergencyPowerLossSignal", "B"),
        Field("dcdcTemperature", "B"),
        Field("powerBusVoltage", "H"),
        Field("dcDc5ModuleCurrent", "H"),
        Field("powerBusCurrent", "H"),
        Field("busbarAVoltage", "H"),
        Field("propulsionMotorControlBoxCurrent", "H"),
        Field("busbarACurrent", "H"),
        Field("lithiumBatteryGroupMeterCurrent", "H"),
        Field("bowHighVoltageDistributionBoxCurrent", "H"),
        Field("sternFTDevice45Current", "H"),
        Field("tyzReservedSwitchCurrent", "H"),
        Field("sternRudderSwitch1Current", "H"),
        Field("reservedCurrent1", "H"),
        Field("sternRudderSwitch2Current", "H"),
        Field("reservedCurrent2", "H"),
        Field("fbReservedSwitchCurrent", "H"),
        Field("reservedCurrent3", "H"),
        Field("coolWaterPressure", "H"),
    )


# ---------------------------------------------------------------
# 高压A母线反馈  0x0006   body=25
# ---------------------------------------------------------------
class MsgDisHighAVolBusFb(Message):
    MSG_ID = 0x0006
    CN = "艏部高压反馈"
    FIELDS = (
        Field("bowFTDevice123CircuitBreaker", "B"),
        Field("actuatorCircuitBreaker", "B"),
        Field("mastSteeringGearControlBoxCircuitBreaker", "B"),
        Field("xczCircuitBreaker", "B"),
        Field("bowRudderControlBoxCircuitBreaker", "B"),
        Field("openWaterCoverStartCylinderCircuitBreaker", "B"),
        Field("instrumentPowerFailureSignal", "B"),
        Field("emergencyPowerFailureSignal", "B"),
        Field("waterIngressionAlarm", "B"),
        Field("busbarBVoltage", "H"),
        Field("busbarBCurrent", "H"),
        Field("bowFTDevice123Current", "H"),
        Field("actuatorCurrent", "H"),
        Field("mastSteeringGearControlBoxCurrent", "H"),
        Field("xczCurrent", "H"),
        Field("bowRudderControlBoxCurrent", "H"),
        Field("openWaterCoverStartCylinderCurrent", "H"),
    )


# ---------------------------------------------------------------
# 仪表主母线反馈  0x0007   body=34
# ---------------------------------------------------------------
class MsgDisLowMainBusFb(Message):
    MSG_ID = 0x0007
    CN = "仪表主母线反馈"
    FIELDS = (
        Field("lithiumBatteryGroupInstrumentCircuitBreaker", "B"),
        Field("bowLowVoltageDistributionBoxCircuitBreaker", "B"),
        Field("unit4InstrumentDC48VCircuitBreaker", "B"),
        Field("dcC1DCDistributionPanelCircuitBreaker", "B"),
        Field("reservedCircuitBreaker1", "B"),
        Field("reservedCircuitBreaker2", "B"),
        Field("emergencyLithiumBatteryGroup2CircuitBreaker", "B"),
        Field("instrumentPowerFailureSignal", "B"),
        Field("emergencyPowerFailureSignal", "B"),
        Field("instrumentBusbarInsulationLow", "B"),
        Field("instrumentBusbarVoltage", "H"),
        Field("bowLowVoltageDistributionBoxCurrent", "H"),
        Field("dcC1InstrumentDC48VCurrent", "H"),
        Field("reservedCurrent1", "H"),
        Field("emergencyLithiumBatteryGroup2Current", "H"),
        Field("lithiumBatteryGroupInstrumentCurrent", "H"),
        Field("unit4InstrumentDC48VCurrent", "H"),
        Field("reservedCurrent2", "H"),
        Field("emergency2BusbarVoltage", "H"),
        Field("compositeEnergyManagementSystemEmergencyDC48VCurrent", "H"),
        Field("fuelCellSecuritySystemEmergencyDC48VCurrent", "H"),
        Field("plcControlPowerCurrent", "H"),
    )


# ---------------------------------------------------------------
# 仪表汇流排反馈  0x0008   body=29
# ---------------------------------------------------------------
class MsgDisLowBusFb(Message):
    MSG_ID = 0x0008
    CN = "艏部低压反馈"
    FIELDS = (
        Field("unit1CircuitBreaker", "B"),
        Field("unit2CircuitBreaker", "B"),
        Field("unit3CircuitBreaker", "B"),
        Field("unit5CircuitBreaker", "B"),
        Field("bowPZDeviceCircuitBreaker", "B"),
        Field("reservedCircuitBreaker1", "B"),
        Field("reservedCircuitBreaker2", "B"),
        Field("emergencyLithiumBatteryGroup1CircuitBreaker", "B"),
        Field("instrumentPowerFailureSignal", "B"),
        Field("emergencyPowerFailureSignal", "B"),
        Field("waterIngressionAlarm", "B"),
        Field("instrumentBusbarVoltage", "H"),
        Field("instrumentBusbarCurrent", "H"),
        Field("unit1Current", "H"),
        Field("unit2Current", "H"),
        Field("unit3Current", "H"),
        Field("unit5Current", "H"),
        Field("bowPZDeviceCurrent", "H"),
        Field("emergencyLithiumBatteryGroup1Current", "H"),
        Field("emergency1BusbarVoltage", "H"),
    )


# ---------------------------------------------------------------
# 动力母线配电指令  0x0001   body=14
# ---------------------------------------------------------------
class MsgDisHVBCmd(Message):
    MSG_ID = 0x0001
    CN = "动力母线配电指令"
    FIELDS = (
        Field("fuelCellCircuitBreaker", "B"),
        Field("powerLithiumBatteryCircuitBreaker", "B"),
        Field("propulsionMotorCircuitBreaker", "B"),
        Field("lithiumBatteryGroupInstrumentCircuitBreaker", "B"),
        Field("dcDc5ModuleCircuitBreaker", "B"),
        Field("bowHighVoltageDistributionBoxCircuitBreaker", "B"),
        Field("sternFTDevice45CircuitBreaker", "B"),
        Field("fbReservedCircuitBreaker", "B"),
        Field("sternRudderSwitch1CircuitBreaker", "B"),
        Field("sternRudderSwitch2CircuitBreaker", "B"),
        Field("tyzReservedCircuitBreaker", "B"),
        Field("reservedCircuitBreaker", "B"),
        Field("dcdc5Module", "B"),
        Field("coolingSystem", "B"),
    )


# ---------------------------------------------------------------
# 动力汇流排A配电指令  0x0002   body=6
# ---------------------------------------------------------------
class MsgDisHVBACmd(Message):
    MSG_ID = 0x0002
    CN = "艏部高压配电指令"
    FIELDS = (
        Field("bowFTDevice123CircuitBreaker", "B"),
        Field("actuatorCircuitBreaker", "B"),
        Field("mastSteeringGearControlBoxCircuitBreaker", "B"),
        Field("xczCircuitBreaker", "B"),
        Field("bowRudderControlBoxCircuitBreaker", "B"),
        Field("openWaterCoverStartCylinderCircuitBreaker", "B"),
    )


# ---------------------------------------------------------------
# 仪表主母线配电指令  0x0003   body=7
# ---------------------------------------------------------------
class MsgDisLVMBCmd(Message):
    MSG_ID = 0x0003
    CN = "仪表主母线配电指令"
    FIELDS = (
        Field("lithiumBatteryGroupInstrumentCircuitBreaker", "B"),
        Field("bowLowVoltageDistributionBoxCircuitBreaker", "B"),
        Field("unit4InstrumentDC48VCircuitBreaker", "B"),
        Field("dcC1DCDistributionPanelCircuitBreaker", "B"),
        Field("reservedCircuitBreaker1", "B"),
        Field("reservedCircuitBreaker2", "B"),
        Field("emergencyLithiumBatteryGroup2CircuitBreaker", "B"),
    )


# ---------------------------------------------------------------
# 仪表汇流排配电指令  0x0004   body=8
# ---------------------------------------------------------------
class MsgDisLVBCmd(Message):
    MSG_ID = 0x0004
    CN = "艏部低压配电指令"
    FIELDS = (
        Field("unit1CircuitBreaker", "B"),
        Field("unit2CircuitBreaker", "B"),
        Field("unit3CircuitBreaker", "B"),
        Field("unit5CircuitBreaker", "B"),
        Field("bowPZDeviceCircuitBreaker", "B"),
        Field("reservedCircuitBreaker1", "B"),
        Field("reservedCircuitBreaker2", "B"),
        Field("emergencyLithiumBatteryGroup1CircuitBreaker", "B"),
    )


# ---------------------------------------------------------------
# 消息注册表
# ---------------------------------------------------------------
FB_MESSAGES = {c.MSG_ID: c for c in (MsgDisHighVolBusFb, MsgDisHighAVolBusFb,
                                     MsgDisLowMainBusFb, MsgDisLowBusFb)}
CMD_MESSAGES = {c.MSG_ID: c for c in (MsgDisHVBCmd, MsgDisHVBACmd,
                                      MsgDisLVMBCmd, MsgDisLVBCmd)}
ALL_MESSAGES = {**FB_MESSAGES, **CMD_MESSAGES}


def msg_id_of(data):
    """从原始帧提取消息 ID。数据不合法时返回 None。"""
    if len(data) < 6:
        return None
    if data[0] != DIS_START1 or data[1] != DIS_START2:
        return None
    return struct.unpack_from("<H", data, 2)[0]


def make_message(msg_id):
    cls = ALL_MESSAGES.get(msg_id)
    return cls() if cls else None


def self_test():
    """pack/unpack 往返 + 长度断言。返回 (ok, 报告)。"""
    lines = []
    ok = True
    for cls in (MsgDisHighVolBusFb, MsgDisHighAVolBusFb, MsgDisLowMainBusFb,
                MsgDisLowBusFb, MsgDisHVBCmd, MsgDisHVBACmd, MsgDisLVMBCmd,
                MsgDisLVBCmd):
        m = cls()
        data = m.pack()
        expected = 6 + cls.body_size() + 1
        frame_ok = len(data) == expected
        len_ok = m.length == cls.body_size()
        m2 = cls()
        round_ok = m2.unpack(data)
        # 翻转一个字节应导致校验失败
        bad = bytearray(data)
        bad[6] ^= 0xFF
        neg_ok = not m2.unpack(bytes(bad))
        status = "OK" if (frame_ok and len_ok and round_ok and neg_ok) else "FAIL"
        if status == "FAIL":
            ok = False
        lines.append(f"  [{status}] {cls.__name__}: id=0x{cls.MSG_ID:04X} "
                     f"body={cls.body_size()}B frame={len(data)}B "
                     f"length_field={m.length} roundtrip={round_ok} neg={neg_ok}")
    return ok, "\n".join(lines)


if __name__ == "__main__":
    ok, report = self_test()
    print(report)
    print("PROTOCOL SELF-TEST:", "PASS" if ok else "FAIL")