"""CAN485 DevBoard_V1 USB command and frame helpers (no GUI/serial dependency)."""

from __future__ import annotations

import re
from dataclasses import dataclass


FRAME_RE = re.compile(
    r"^\[\s*(\d+)\.(\d{3})\]\s+(?:(RS485)\s+)?"
    r"(EXT|STD)\s+0x([0-9A-Fa-f]+)\s+"
    r"(RTR\s+)?DLC=(\d)(?:\s+DATA=([0-9A-Fa-f ]*))?"
)


@dataclass(frozen=True, slots=True)
class BoardFrame:
    timestamp: float
    extended: bool
    can_id: int
    data: bytes
    rtr: bool = False
    source: str = "CAN"


def parse_frame_line(line: str) -> BoardFrame | None:
    match = FRAME_RE.match(line.strip())
    if match is None:
        return None
    seconds, millis, source, frame_type, raw_id, raw_rtr, raw_dlc, raw_data = match.groups()
    dlc = int(raw_dlc)
    data = bytes.fromhex(raw_data or "")
    rtr = bool(raw_rtr)
    if (not rtr and len(data) != dlc) or (rtr and data):
        return None
    extended = frame_type == "EXT"
    can_id = int(raw_id, 16)
    if can_id > (0x1FFFFFFF if extended else 0x7FF):
        return None
    return BoardFrame(int(seconds) + int(millis) / 1000.0, extended, can_id,
                      data, rtr, source or "CAN")


def command_transmit(frame: BoardFrame) -> bytes:
    if len(frame.data) > 8:
        raise ValueError("DLC cannot exceed 8")
    kind = "E" if frame.extended else "S"
    return f"T,{kind},{frame.can_id:X},{len(frame.data)},{frame.data.hex().upper()}\n".encode("ascii")


def command_setup(*, can_bitrate: int = 500, rs485_baud: int = 512000,
                  route: int = 3) -> tuple[bytes, ...]:
    if can_bitrate not in (25, 50, 100, 125, 250, 500, 800, 1000):
        raise ValueError("unsupported CAN bitrate")
    if not 1200 <= rs485_baud <= 4_000_000:
        raise ValueError("unsupported RS485 baud")
    if route not in range(4):
        raise ValueError("route must be 0..3")
    return (f"S{can_bitrate}\n".encode("ascii"), b"M0\n",
            f"B{rs485_baud}\n".encode("ascii"), f"Q{route}\n".encode("ascii"))