"""
gen_littlefs.py — PlatformIO pre-build script placeholder.

This script is referenced in platformio.ini under extra_scripts.
It is a no-op here because PlatformIO's built-in 'uploadfs' target
(pio run -t uploadfs) already handles LittleFS image creation from
the /data directory.

If you need to auto-generate files into /data before every build,
add your logic inside the pre_build() function below.
"""

import os

Import("env")  # noqa: F821 — provided by PlatformIO's SCons environment


def pre_build(source, target, env):
    """Called before every firmware build."""
    data_dir = os.path.join(env.subst("$PROJECT_DIR"), "data")
    os.makedirs(data_dir, exist_ok=True)
    # Example: auto-generate a version file in the filesystem
    version = env.GetProjectOption("build_flags", "")
    version_file = os.path.join(data_dir, "version.txt")
    with open(version_file, "w") as f:
        import datetime
        f.write(f"Built: {datetime.datetime.utcnow().isoformat()}Z\n")


env.AddPreAction("buildprog", pre_build)