"""Send custom AMI 0x183 VCU display feedback; no vehicle actuation."""
import argparse
import math
import os
import time


def build_payload(task, locked, ebs_normal, valid=7, sequence=0):
    if task not in range(7) or locked not in (0, 1) or ebs_normal not in (0, 1):
        raise ValueError('task must be 0..6; locked and ebs-normal must be 0 or 1')
    if valid not in range(8) or sequence not in range(256):
        raise ValueError('valid must be 0..7 and sequence must be 0..255')
    return bytes([task, locked, ebs_normal, valid, sequence, 0, 0, 1])


def main():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument('--task', type=int, required=True, choices=range(7))
    parser.add_argument('--locked', type=int, required=True, choices=(0, 1))
    parser.add_argument('--ebs-normal', type=int, required=True, choices=(0, 1))
    parser.add_argument('--valid', type=int, default=7)
    parser.add_argument('--sequence', type=int, default=0)
    parser.add_argument('--interface', default='pcan')
    parser.add_argument('--channel', default='PCAN_USBBUS1')
    parser.add_argument('--bitrate', type=int, choices=(250000, 500000), default=500000)
    parser.add_argument('--period', type=float, default=.1)
    parser.add_argument('--duration', type=float, default=10)
    parser.add_argument('--dll-dir')
    parser.add_argument('--dry-run', action='store_true')
    args = parser.parse_args()
    try:
        payload = build_payload(args.task, args.locked, args.ebs_normal, args.valid, args.sequence)
    except ValueError as exc:
        parser.error(str(exc))
    if not (0 < args.period <= .5 and 0 < args.duration and math.isfinite(args.duration)):
        parser.error('period must be >0 and <=0.5 seconds; duration must be finite and positive')
    print(f'Standard ID 0x183, DLC 8, data {payload.hex(" ").upper()}, bitrate {args.bitrate}', flush=True)
    if args.dry_run:
        return
    dll_handle = None
    if args.dll_dir:
        directory = os.path.abspath(args.dll_dir)
        os.environ['PATH'] = directory + os.pathsep + os.environ['PATH']
        dll_handle = os.add_dll_directory(directory)
    import can
    count = 0
    try:
        with can.Bus(interface=args.interface, channel=args.channel, bitrate=args.bitrate) as bus:
            started = time.monotonic()
            deadline = started
            while time.monotonic() < started + args.duration:
                payload = build_payload(args.task, args.locked, args.ebs_normal,
                                        args.valid, (args.sequence + count) & 255)
                bus.send(can.Message(arbitration_id=0x183, is_extended_id=False, data=payload), timeout=.2)
                count += 1
                deadline += args.period
                time.sleep(max(0, min(deadline, started + args.duration) - time.monotonic()))
    finally:
        if dll_handle is not None:
            dll_handle.close()
    print(f'Sent {count} frames. Display becomes unknown over 500 ms after feedback stops.')


if __name__ == '__main__':
    main()