dashcam-transfer/docs/superpowers/plans/2026-05-29-dashcam-transfer-implementation.md

Dashcam Transfer Implementation Plan

For agentic workers: REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (- [ ]) syntax for tracking.

Goal: Automatic transfer of dashcam MP4 files from SD card to USB-SSD.

Architecture: Single Python script (dashcam-transfer.py) using stdlib only, triggered by udev rule via systemd oneshot service.

Tech Stack: Python 3 (stdlib), systemd, udev

---

Task 1: Write dashcam-transfer.py

Files:

• Create: dashcam-transfer.py (local repo)
• Deploy to: /usr/local/bin/dashcam-transfer on nextcloud

The script must:

1. Parse all .MP4 files from /mnt/sdcard/Novatek/Movie/
2. Extract date (first 8 chars of filename) → YYYYMMDD/ dir
3. Extract camera suffix (last char before .MP4):
   • F → front/
   • B → back/
4. Create target dirs: /mnt/ultratouch/dashcam/YYYYMMDD/{front,back}/
5. Calculate total space needed, check available space
6. If insufficient: sort date dirs on ultratouch by name, delete oldest dirs until enough space
7. mv each file (not copy)
8. Log every action to /var/log/dashcam-transfer.log
9. Use flock lockfile to prevent concurrent runs
10. Error handling: skip unreadable files, abort if SD not mounted

• Write dashcam-transfer.py

#!/usr/bin/env python3
"""Transfer dashcam MP4 files from SD card to USB-SSD with date/camera structure."""

import fcntl
import logging
import os
import re
import shutil
import sys

# Config
SD_CARD = "/mnt/sdcard"
SOURCE_DIR = os.path.join(SD_CARD, "Novatek", "Movie")
SSD = "/mnt/ultratouch"
TARGET_BASE = os.path.join(SSD, "dashcam")
LOG_FILE = "/var/log/dashcam-transfer.log"
LOCK_FILE = "/var/run/dashcam-transfer.lock"

CAMERA_MAP = {"F": "front", "B": "back"}
FILE_PATTERN = re.compile(r"^(\d{8})\d{6}_\d+([FB])\.MP4$")

logging.basicConfig(
    filename=LOG_FILE,
    level=logging.INFO,
    format="[%(asctime)s] %(levelname)s %(message)s",
    datefmt="%Y-%m-%d %H:%M:%S",
)


def acquire_lock():
    lock_fd = open(LOCK_FILE, "w")
    try:
        fcntl.flock(lock_fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
    except IOError:
        logging.warning("Lockfile actief — script al bezig")
        sys.exit(1)
    return lock_fd


def check_mount(path, name):
    if not os.path.ismount(path):
        logging.error("%s niet gemount: %s", name, path)
        sys.exit(1)


def get_mp4_files(src_dir):
    if not os.path.isdir(src_dir):
        logging.info("Geen bronmap: %s", src_dir)
        return []
    files = []
    for fname in os.listdir(src_dir):
        match = FILE_PATTERN.match(fname)
        if match:
            files.append((fname, match.group(1), match.group(2).upper()))
    return files


def ensure_free_space(needed_bytes, target_base):
    stat = os.statvfs(target_base)
    free = stat.f_frsize * stat.f_bavail
    if free >= needed_bytes:
        return

    logging.info("Onvoldoende ruimte: %d nodig, %d vrij", needed_bytes, free)
    date_dirs = sorted(
        d for d in os.listdir(target_base)
        if re.match(r"^\d{8}$", d) and os.path.isdir(os.path.join(target_base, d))
    )

    freed = 0
    removed = []
    for d in date_dirs:
        if free + freed >= needed_bytes:
            break
        dir_path = os.path.join(target_base, d)
        dir_size = sum(
            os.path.getsize(os.path.join(dirpath, f))
            for dirpath, _, filenames in os.walk(dir_path)
            for f in filenames
        )
        shutil.rmtree(dir_path)
        freed += dir_size
        removed.append(d)
        logging.info("Verwijderd (ruimte gebrek): %s (%d bytes)", d, dir_size)

    if free + freed < needed_bytes:
        logging.error(
            "Nog steeds onvoldoende ruimte na verwijderen %d mappen", len(removed)
        )
        sys.exit(1)

    logging.info("Ruimte vrijgemaakt: %d bytes door %d mappen", freed, len(removed))


def main():
    lock_fd = acquire_lock()

    check_mount(SD_CARD, "SD-kaart")
    check_mount(SSD, "Ultratouch SSD")

    files = get_mp4_files(SOURCE_DIR)
    if not files:
        logging.info("Geen MP4 bestanden gevonden in %s", SOURCE_DIR)
        return

    total_size = sum(
        os.path.getsize(os.path.join(SOURCE_DIR, fname)) for fname, _, _ in files
    )
    logging.info(
        "Start transfer: %d bestanden, %d bytes", len(files), total_size
    )

    ensure_free_space(total_size, TARGET_BASE)

    ok = 0
    errors = 0
    for fname, date_str, cam in files:
        target_dir = os.path.join(TARGET_BASE, date_str, CAMERA_MAP[cam])
        os.makedirs(target_dir, exist_ok=True)
        src = os.path.join(SOURCE_DIR, fname)
        dst = os.path.join(target_dir, fname)
        try:
            shutil.move(src, dst)
            logging.info("Verplaatst: %s → %s/%s/", fname, date_str, CAMERA_MAP[cam])
            ok += 1
        except OSError as e:
            logging.error("Fout bij %s: %s", fname, e)
            errors += 1

    logging.info(
        "Transfer voltooid: %d ok, %d fouten, %d bytes", ok, errors, total_size
    )


if __name__ == "__main__":
    main()

• Commit to repo

git add dashcam-transfer.py
git commit -m "feat: dashcam-transfer.py script"
git push

---

Task 2: Deploy and test on nextcloud

Files:

• Modify: /usr/local/bin/dashcam-transfer on nextcloud

• Copy script to nextcloud

scp dashcam-transfer.py aiaiaiaiagent@nextcloud:/tmp/
ssh aiaiaiaiagent@nextcloud 'sudo -A install -m 755 /tmp/dashcam-transfer.py /usr/local/bin/dashcam-transfer'

• Dry-run test (check detection, no transfer yet)

ssh aiaiaiaiagent@nextcloud '/usr/local/bin/dashcam-transfer'

Expected: Script should find 338 MP4 files, log the start, and proceed with transfer.

---

Task 3: Add udev rule + systemd service (if needed)

Files:

• Create: /etc/udev/rules.d/99-dashcam-sdcard.rules on nextcloud

• Create: /etc/systemd/system/dashcam-transfer.service on nextcloud

• Create: dashcam-transfer-trigger script on nextcloud

• Create trigger script

ssh aiaiaiaiagent@nextcloud 'sudo tee /usr/local/bin/dashcam-transfer-trigger << "TRIGGER"
#!/bin/bash
sleep 5
/usr/local/bin/dashcam-transfer
TRIGGER'
ssh aiaiaiaiagent@nextcloud 'sudo -A chmod +x /usr/local/bin/dashcam-transfer-trigger'

• Create systemd service

[Unit]
Description=Dashcam SD card transfer
After=mnt-sdcard.mount

[Service]
Type=oneshot
ExecStart=/usr/local/bin/dashcam-transfer

• Create udev rule

ACTION=="add", KERNEL=="sdd1", RUN+="/usr/local/bin/dashcam-transfer-trigger"