#!/usr/bin/env python3

import os
import shutil
import subprocess
import sys
import tempfile

from posix_parity import fail


def has_tool(name):
    return shutil.which(name) is not None


def main():
    if len(sys.argv) != 2:
        print("usage: TEST_mount_lifecycle <mountpoint>", file=sys.stderr)
        return 1

    # This is a soft integration harness check for init/destroy wiring.
    # Skip when environment is not prepared for nested mount tests.
    if os.geteuid() != 0:
        return 0
    if not has_tool("mergerfs"):
        return 0
    if not has_tool("fusermount") and not has_tool("fusermount3"):
        return 0

    with tempfile.TemporaryDirectory() as td:
        b1 = os.path.join(td, "b1")
        b2 = os.path.join(td, "b2")
        mp = os.path.join(td, "mp")
        os.makedirs(b1, exist_ok=True)
        os.makedirs(b2, exist_ok=True)
        os.makedirs(mp, exist_ok=True)

        cmd = [
            "mergerfs",
            f"{b1}:{b2}",
            mp,
            "-o",
            "defaults,allow_other,use_ino,category.create=mfs",
        ]

        p = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        if p.returncode != 0:
            return 0

        try:
            with open(os.path.join(mp, "lifecycle-file"), "wb") as fp:
                fp.write(b"ok")
            if not os.path.exists(os.path.join(mp, "lifecycle-file")):
                return fail("mount lifecycle: expected created file to exist")
        finally:
            um = shutil.which("fusermount3") or shutil.which("fusermount")
            u = subprocess.run([um, "-u", mp], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
            if u.returncode != 0:
                return fail("mount lifecycle: failed to unmount test mount")

        return 0


if __name__ == "__main__":
    raise SystemExit(main())