"""
slow_sweep_v2.py — Drive turntable through a slow sweep via L298N stepper.

Usage:
  python3 slow_sweep_v2.py [--degrees 360] [--rpm 0.5] [--shots 36]

  --degrees   Total rotation (default 360)
  --rpm       Rotation speed in RPM (default 0.5 = 1 rev per 2 minutes)
  --shots     If set, pause every (degrees/shots) degrees and print "CAPTURE <n>"
              so an external trigger script or you manually fire the camera.
  --reverse   Step in reverse direction

7200 steps = 1 full revolution = 0.05 deg/step = 20 steps/deg
"""

import serial, time, sys, argparse

PORT             = '/dev/ttyACM0'
BAUD             = 115200
STEPS_PER_REV    = 14400  # half-step mode
DEGREES_PER_STEP = 360.0 / STEPS_PER_REV   # 0.025
STEPS_PER_DEGREE = STEPS_PER_REV / 360.0   # 40.0

def connect():
    s = serial.Serial(PORT, BAUD, timeout=2)
    s.setDTR(False); s.setRTS(False)
    time.sleep(1)
    s.reset_input_buffer()
    return s

def send_step(s, n, delay_ms):
    s.write(f'STEP {n} {delay_ms}\n'.encode())
    deadline = time.time() + abs(n) * delay_ms / 1000.0 + 5
    while time.time() < deadline:
        line = s.readline().decode(errors='replace').strip()
        if '[STEP]' in line:
            return line
    return None

def read_enc(s):
    s.write(b'ENC\n')
    deadline = time.time() + 3
    while time.time() < deadline:
        line = s.readline().decode(errors='replace').strip()
        if '[ENC]' in line:
            return line
    return '[ENC] timeout'

def main():
    ap = argparse.ArgumentParser()
    ap.add_argument('--degrees', type=float, default=360.0,
                    help='Total rotation in degrees (default 360)')
    ap.add_argument('--rpm',     type=float, default=0.5,
                    help='Speed in RPM (default 0.5)')
    ap.add_argument('--shots',   type=int,   default=0,
                    help='Number of capture pauses evenly spaced across sweep')
    ap.add_argument('--reverse', action='store_true',
                    help='Rotate in reverse direction')
    args = ap.parse_args()

    total_steps = round(args.degrees * STEPS_PER_DEGREE)
    # delay_ms per step from RPM: RPM * STEPS_PER_REV steps/min => steps/sec => ms/step
    steps_per_sec = args.rpm * STEPS_PER_REV / 60.0
    delay_ms      = max(1, round(1000.0 / steps_per_sec))
    direction     = -1 if args.reverse else 1

    eta_sec = total_steps * delay_ms / 1000.0

    print(f"{'='*52}")
    print(f"  PROJECT SLOW-SWEEP v2")
    print(f"{'='*52}")
    print(f"  Degrees   : {args.degrees}°")
    print(f"  Steps     : {total_steps}")
    print(f"  Speed     : {args.rpm} RPM  ({delay_ms} ms/step)")
    print(f"  Direction : {'reverse (CCW)' if args.reverse else 'forward (CW)'}")
    print(f"  ETA       : {eta_sec:.0f}s  ({eta_sec/60:.1f} min)")
    if args.shots:
        interval_deg = args.degrees / args.shots
        print(f"  Shots     : {args.shots}  (every {interval_deg:.1f}°)")
    print(f"{'='*52}")

    s = connect()
    s.write(b'ZERO\n')
    time.sleep(0.3)

    batch = 50          # steps per serial command
    sent  = 0
    shot_num = 0
    next_shot_step = round((args.degrees / args.shots) * STEPS_PER_DEGREE) if args.shots else None
    start = time.time()

    try:
        while sent < total_steps:
            # Check if next shot pause is due
            if args.shots and sent >= next_shot_step * (shot_num + 1):
                shot_num += 1
                elapsed = time.time() - start
                deg_done = sent * DEGREES_PER_STEP
                print(f"\n  [SHOT {shot_num}/{args.shots}] at {deg_done:.1f}°  t={elapsed:.1f}s")
                input("  >> Press Enter to continue...")

            this_batch = min(batch, total_steps - sent)
            step_cmd   = this_batch * direction
            send_step(s, step_cmd, delay_ms)
            sent += this_batch

            elapsed = time.time() - start
            pct     = sent / total_steps * 100
            deg     = sent * DEGREES_PER_STEP
            remain  = (total_steps - sent) * delay_ms / 1000.0
            sys.stdout.write(
                f'\r  {deg:6.1f}° / {args.degrees}°  ({pct:5.1f}%)  '
                f'elapsed={elapsed:.0f}s  remain~{remain:.0f}s   '
            )
            sys.stdout.flush()

    except KeyboardInterrupt:
        print('\n  [INTERRUPTED]')

    print()
    enc_line = read_enc(s)
    elapsed  = time.time() - start
    print(f"\n  Encoder final : {enc_line}")
    print(f"  Time elapsed  : {elapsed:.1f}s  ({elapsed/60:.1f} min)")

    s.write(b'RELEASE\n')
    time.sleep(0.3)
    s.close()
    print("  Coils released. Done.")

if __name__ == '__main__':
    main()