#!/usr/bin/env python3
"""Send one Sony RCP-TX7 candidate serial frame.

Use carefully. This is for controlled experiments on the host-to-RCP line
through an RS-232 adapter. It can either send a complete hex frame or build the
observed 6-byte frame shape and checksum from fields.
"""

from __future__ import annotations

import argparse
import sys
import time

try:
    import serial
except ImportError:
    print(
        "Missing dependency: pyserial\n"
        "Install it with: python -m pip install pyserial",
        file=sys.stderr,
    )
    raise SystemExit(2)


def parse_hex_bytes(text: str) -> bytes:
    normalized = text.replace(",", " ").replace("0x", "").replace("0X", "")
    parts = normalized.split()
    try:
        data = bytes(int(part, 16) for part in parts)
    except ValueError as exc:
        raise argparse.ArgumentTypeError(f"invalid hex byte list: {text}") from exc
    if not data:
        raise argparse.ArgumentTypeError("hex frame cannot be empty")
    if any(part and int(part, 16) > 0xFF for part in parts):
        raise argparse.ArgumentTypeError("hex values must be bytes")
    return data


def build_frame(prefix1: int, prefix2: int, command: int, state: int, value: int) -> bytes:
    body = bytes([prefix1, prefix2, command, state, value])
    checksum = 0x5A
    for byte in body:
        checksum ^= byte
    return body + bytes([checksum])


def hex_preview(data: bytes) -> str:
    return " ".join(f"{byte:02X}" for byte in data)


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(
        description="Send an explicit or checksum-built 6-byte RCP-TX7 frame."
    )
    parser.add_argument("--port", required=True, help="serial port, for example COM3")
    parser.add_argument("--baud", type=int, default=38400)
    parser.add_argument(
        "--frame",
        type=parse_hex_bytes,
        help="complete hex frame, for example \"00 00 00 00 80 DA\"",
    )
    parser.add_argument("--prefix1", type=lambda s: int(s, 0), default=0)
    parser.add_argument("--prefix2", type=lambda s: int(s, 0), default=0)
    parser.add_argument("--command", type=lambda s: int(s, 0), default=0)
    parser.add_argument("--state", type=lambda s: int(s, 0), default=0)
    parser.add_argument("--value", type=lambda s: int(s, 0), default=0x80)
    parser.add_argument("--repeat", type=int, default=1)
    parser.add_argument("--interval", type=float, default=0.2)
    parser.add_argument(
        "--dry-run",
        action="store_true",
        help="print the frame but do not open the serial port",
    )
    return parser.parse_args()


def validate_byte(name: str, value: int) -> None:
    if not 0 <= value <= 0xFF:
        raise SystemExit(f"{name} must be a byte, got {value!r}")


def main() -> int:
    args = parse_args()
    if args.frame:
        frame = args.frame
    else:
        for name in ("prefix1", "prefix2", "command", "state", "value"):
            validate_byte(name, getattr(args, name))
        frame = build_frame(args.prefix1, args.prefix2, args.command, args.state, args.value)

    print(f"Frame: {hex_preview(frame)}")
    if args.dry_run:
        return 0

    with serial.Serial(
        port=args.port,
        baudrate=args.baud,
        bytesize=serial.EIGHTBITS,
        parity=serial.PARITY_NONE,
        stopbits=serial.STOPBITS_ONE,
        timeout=0.2,
        write_timeout=1.0,
        rtscts=False,
        dsrdtr=False,
        xonxoff=False,
    ) as ser:
        for index in range(args.repeat):
            ser.write(frame)
            ser.flush()
            print(f"Sent {index + 1}/{args.repeat}")
            if index + 1 < args.repeat:
                time.sleep(args.interval)
    return 0


if __name__ == "__main__":
    raise SystemExit(main())