"""
PlatformIO pre-build script: injects the short git commit hash into firmware
as GIT_HASH (a C string literal), and writes web/version.js so the web UI
can compare against it.

Usage: referenced from platformio.ini as:
    extra_scripts = pre:scripts/git_hash.py
"""
import subprocess, os, re

Import("env")  # noqa: F821 - PlatformIO injects this

def get_git_hash():
    try:
        h = subprocess.check_output(
            ["git", "rev-parse", "--short=7", "HEAD"],
            cwd=env.subst("$PROJECT_DIR"),    # noqa: F821
            stderr=subprocess.DEVNULL,
        ).decode().strip()
        # Verify it looks like a hex hash (safety check)
        if re.fullmatch(r"[0-9a-f]{4,12}", h):
            return h
    except Exception:
        pass
    return "unknown"

git_hash = get_git_hash()
print(f"[git_hash] short hash = {git_hash}")

#  Inject into firmware build 
env.Append(CPPDEFINES=[("GIT_HASH", f'\\"{git_hash}\\"')])  # noqa: F821

#  Write web/version.js 
web_dir  = os.path.join(env.subst("$PROJECT_DIR"), "web")  # noqa: F821
ver_file = os.path.join(web_dir, "version.js")
os.makedirs(web_dir, exist_ok=True)
with open(ver_file, "w") as f:
    f.write(f"// Auto-generated by scripts/git_hash.py - do not edit\n")
    f.write(f"const FIRMWARE_BUILD_HASH = '{git_hash}';\n")
print(f"[git_hash] wrote {ver_file}")