"""DG430 串口协议二进制解析

解析测试工装上报的 B2 状态包（dat_type=8 对应的 raw_data 为 DG430 上报数据）。
"""

import logging
from dataclasses import dataclass

logger = logging.getLogger(__name__)

# ─── 协议常量 ───────────────────────────────────────────────────────

STX = 0x7F
PKT_MIN_LEN = 6  # STX + ADDR + LEN + CMD + XOR + SUM


@dataclass
class DG430Status:
    """解析后的 DG430 状态数据"""
    addr: int          # 地址
    dev_model: int     # 1 PD132, 2 DLD110
    test_mode: int     # 0 灵敏度, 1 模拟过车
    is_finished: bool  # 是否正常完成
    finish_code: int   # 0 正常, 1 未完成, 2 地感死机
    fault: int         # bitmask
    relay_out: int     # bitmask
    ppvalue: float     # 峰峰值 V
    idle_freq: float   # 开始工作频率 Hz
    enter_freq: float  # 进入工作频率 Hz
    exit_freq: float   # 离开工作频率 Hz
    enter_dist: int     # 进入高度 mm
    exit_dist: int      # 离开高度 mm
    enter_speed: int    # 进入速度 dm/s
    exit_speed: int     # 离开速度 dm/s


# ─── 工具函数 ───────────────────────────────────────────────────────

def _xor_checksum(data: bytes, start: int, end: int) -> int:
    """计算异或校验，区间 [start, end)"""
    result = 0
    for i in range(start, end):
        result ^= data[i]
    return result & 0xFF


def _sum_checksum(data: bytes, start: int, end: int) -> int:
    """计算和校验"""
    result = 0
    for i in range(start, end):
        result += data[i]
    return result & 0xFF


def _le16(data: bytes, offset: int) -> int:
    """小端 2 字节 → int"""
    return data[offset] | (data[offset + 1] << 8)


def _be16(data: bytes, offset: int) -> int:
    """大端 2 字节 → int"""
    return (data[offset] << 8) | data[offset + 1]


def verify_packet(data: bytes) -> bool:
    """校验数据包完整性"""
    if len(data) < PKT_MIN_LEN:
        return False
    if data[0] != STX:
        return False

    length = data[2]
    expected_len = 1 + 1 + 1 + length + 1 + 1  # STX + ADDR + LEN + DATA(LEN) + XOR + SUM
    if len(data) != expected_len:
        return False

    payload_end = 3 + length  # 校验范围 [ADDR .. DATA末尾]
    actual_xor = _xor_checksum(data, 1, payload_end)
    actual_sum = _sum_checksum(data, 1, payload_end)

    if data[payload_end] != actual_xor:
        return False
    if data[payload_end + 1] != actual_sum:
        return False

    return True


def hex_str_to_bytes(hex_str: str) -> bytes:
    """将十六进制字符串转为 bytes，如 '7F8118B2...' → bytes"""
    return bytes.fromhex(hex_str)


def split_packets(data: bytes) -> list[bytes]:
    """从拼接的字节流中拆分出各个 DG430 数据包

    每条记录可能包含多条串口指令拼在一起，如:
      B1 复位回复 + B2 状态上报 + ...
    根据 STX + LEN 字段确定包边界，逐个拆分。

    Returns:
        独立的数据包列表，每个元素为一个完整包 (含 STX .. SUM)
    """
    packets = []
    i = 0
    while i < len(data):
        # 找 STX
        stx_pos = data.find(STX, i)
        if stx_pos < 0:
            break

        # 需要至少读到 LEN 字段 (STX + ADDR + LEN = 3 bytes)
        if stx_pos + 3 > len(data):
            break

        pkt_len = 5 + data[stx_pos + 2]  # STX + ADDR + LEN + DATA(LEN) + XOR + SUM
        end = stx_pos + pkt_len

        if end > len(data):
            logger.warning(f"数据包不完整: stx_pos={stx_pos}, pkt_len={pkt_len}, data_len={len(data)}")
            break

        packets.append(data[stx_pos:end])
        i = end

    return packets


# ─── 解析指令 ───────────────────────────────────────────────────────

def parse_b2_status(data: bytes) -> DG430Status | None:
    """解析 0xB2 状态上报包

    格式: STX | ADDR | LEN | CMD | DATA(LEN-1 bytes) | XOR | SUM
    """
    if not verify_packet(data):
        logger.warning("DG430 数据包校验失败")
        return None

    addr = data[1] & 0x7F
    cmd = data[3]
    if cmd != 0xB2:
        logger.debug(f"非 B2 指令: 0x{cmd:02X}")
        return None

    payload = data[4:3 + data[2]]  # DATA = LEN - 1 bytes (CMD 占位置 3)
    if len(payload) < 20:
        logger.warning(f"B2 数据长度不足: {len(payload)} < 20")
        return None

    # 设备型号
    dev_model = payload[0]   # 1=PD132, 2=DLD110
    test_mode = payload[1]   # 0=灵敏度, 1=模拟过车
    finish_code = payload[2]  # 0=正常, 1=未完成, 2=死机
    fault = payload[3]       # bitmask
    relay_out = payload[4]   # bitmask

    # 峰峰值: 小端 2 字节，公式: (X * 3.3 / 4095) * 4
    pp_raw = _le16(payload, 5)
    ppvalue = (pp_raw * 3.3 / 4095) * 4

    # 频率: 小端 2 字节，公式: 10 * X
    idle_freq = _le16(payload, 7) * 10.0
    enter_freq = _le16(payload, 9) * 10.0
    exit_freq = _le16(payload, 11) * 10.0

    # 高度 mm
    enter_dist = _le16(payload, 13)
    exit_dist = _le16(payload, 15)

    # 速度 dm/s (V2.0.2 新增)
    enter_speed = _le16(payload, 17) if len(payload) >= 19 else 0
    exit_speed = _le16(payload, 19) if len(payload) >= 21 else 0

    return DG430Status(
        addr=addr,
        dev_model=dev_model,
        test_mode=test_mode,
        is_finished=(finish_code == 0),
        finish_code=finish_code,
        fault=fault,
        relay_out=relay_out,
        ppvalue=round(ppvalue, 4),
        idle_freq=round(idle_freq, 1),
        enter_freq=round(enter_freq, 1),
        exit_freq=round(exit_freq, 1),
        enter_dist=enter_dist,
        exit_dist=exit_dist,
        enter_speed=enter_speed,
        exit_speed=exit_speed,
    )


# ─── 故障解码 ───────────────────────────────────────────────────────

FAULT_BITS = {
    0: "工作频率不是最低频",
    1: "灵敏度不是最低灵敏度",
    2: "灵敏度提升拨码不在OFF",
    3: "脉冲输出不是离开脉冲",
}

RELAY_BITS = {
    0: "存在继电器信号有输出",
    1: "脉冲继电器信号有输出",
}


def decode_fault_info(fault: int) -> str:
    """解码故障 bitmask 为可读字符串"""
    items = []
    for bit, desc in FAULT_BITS.items():
        if fault & (1 << bit):
            items.append(desc)
    return "; ".join(items) if items else "无故障"


def decode_relay_info(relay: int) -> str:
    """解码继电器 bitmask"""
    items = []
    for bit, desc in RELAY_BITS.items():
        if relay & (1 << bit):
            items.append(desc)
    return "; ".join(items) if items else "无输出"


# ─── 0x4A 获取设备版本号响应 ──────────────────────────────────────

@dataclass
class DG430Version:
    addr: int
    hw_major: int
    hw_minor: int
    hw_patch: int
    sw_major: int
    sw_minor: int
    sw_patch: int


def parse_4a_version(data: bytes) -> DG430Version | None:
    """解析 0x4A 版本号响应

    格式: 7F | ADDR | 08 | 4A | 00 | HW(3B) | SW(3B) | XOR | SUM
    """
    if not verify_packet(data):
        return None
    cmd = data[3]
    if cmd != 0x4A:
        return None

    payload = data[4:3 + data[2]]
    if len(payload) < 7:
        return None

    addr = data[1] & 0x7F
    return DG430Version(
        addr=addr,
        hw_major=payload[1],
        hw_minor=payload[2],
        hw_patch=payload[3],
        sw_major=payload[4],
        sw_minor=payload[5],
        sw_patch=payload[6],
    )


# ─── 通用 Flag 响应 (0x4B/0x4D/0x4E) ─────────────────────────────

def parse_flag_response(data: bytes, expected_cmd: int) -> int | None:
    """解析 Flag 响应格式: STX | ADDR | 02 | CMD | Flag | XOR | SUM

    Returns:
        Flag 值 (0=正常, 1=故障), 或 None 表示解析失败
    """
    if not verify_packet(data):
        return None
    cmd = data[3]
    if cmd != expected_cmd:
        return None
    if data[2] < 2:
        return None
    return data[4]  # Flag


# ─── 0x4C 查询设备测试参数响应 ────────────────────────────────────

@dataclass
class DG430FixtureParams:
    addr: int
    flag: int           # 0=正常, 1=故障
    dev_addr: int       # 设备地址
    dev_type: int       # 设备型号
    test_mode: int      # 0 灵敏度, 1 模拟过车
    reset_dis: int      # 复位距离 cm
    minus_dis: int      # 皮距 cm
    sens_min: int       # 灵敏度最小值
    sens_max: int       # 灵敏度最大值
    fre_min: int        # 频率最小值 Hz
    fre_max: int        # 频率最大值 Hz
    peak_min: int       # 峰峰值最小值
    peak_max: int       # 峰峰值最大值


def parse_4c_params(data: bytes) -> DG430FixtureParams | None:
    """解析 0x4C 查询测试参数响应

    格式: 7F | ADDR | 13 | 4C | Flag | Addr | DevType | TestMode |
          ResetDis | MinusDis | SensMin(2) | SensMax(2) |
          FreMin(2) | FreMax(2) | PeakMin(2) | PeakMax(2) | XOR | SUM
    """
    if not verify_packet(data):
        return None
    cmd = data[3]
    if cmd != 0x4C:
        return None

    payload = data[4:3 + data[2]]
    if len(payload) < 18:
        return None

    addr = data[1] & 0x7F
    # 0x4B/0x4C 多字节字段为小端序
    return DG430FixtureParams(
        addr=addr,
        flag=payload[0],
        dev_addr=payload[1],
        dev_type=payload[2],
        test_mode=payload[3],
        reset_dis=payload[4],
        minus_dis=payload[5],
        sens_min=_le16(payload, 6),
        sens_max=_le16(payload, 8),
        fre_min=_le16(payload, 10),
        fre_max=_le16(payload, 12),
        peak_min=_le16(payload, 14),
        peak_max=_le16(payload, 16),
    )


# ─── 获取数据包 CMD（用于匹配）────────────────────────────────────

def get_packet_cmd(data: bytes) -> int | None:
    """从数据包中提取 CMD 字节"""
    if len(data) < 4:
        return None
    return data[3]