import ctypes
from pymsc.lib1553.datatypes.navigation import Semicircle


class MsgA8Payload(ctypes.Structure):
    """Message A8: Data Link Targets (Message#2) - partial typed mapping.

    This message is provisionally defined in the ICD. We map the common
    header/validity word and provide semicircle-typed placeholders for the
    first few coordinate fields.
    """
    _pack_ = 1
    _fields_ = [
        ("dl2_validity", ctypes.c_uint16),
        ("t1_pos_x", Semicircle),
        ("t1_pos_y", Semicircle),
        ("t1_track", Semicircle),
    ] + [(f"word_{i:02d}", ctypes.c_uint16) for i in range(5, 33)]

    def __init__(self):
        super().__init__()