"""Free-space accounting across the filesystems a pull can fill.

docker 29 keeps image layers in containerd's store, which is frequently on a different
filesystem than DockerRootDir. env-dev-08 (2026-09-09) had 93 GiB free on the data-root and
2.8 GiB on the filesystem containerd was writing to; the pull died with "no space left on
device" after the pre-flight had reported plenty of room.
"""

from __future__ import annotations

import monky_deployd.compose as compose_mod
from monky_deployd.compose import Docker


class _FixedDocker(Docker):
    def __init__(self, root: str):
        super().__init__()
        self._root = root

    def data_root(self) -> str:
        return self._root


def test_storage_paths_include_containerd_root_when_present(tmp_path, monkeypatch):
    root = tmp_path / "docker"
    containerd = tmp_path / "containerd"
    root.mkdir()
    containerd.mkdir()
    monkeypatch.setattr(compose_mod, "CONTAINERD_ROOTS", (str(containerd),))
    assert _FixedDocker(str(root)).storage_paths() == [str(root), str(containerd)]


def test_storage_paths_skip_a_containerd_root_that_does_not_exist(tmp_path, monkeypatch):
    root = tmp_path / "docker"
    root.mkdir()
    monkeypatch.setattr(compose_mod, "CONTAINERD_ROOTS", (str(tmp_path / "absent"),))
    assert _FixedDocker(str(root)).storage_paths() == [str(root)]


def test_free_bytes_reports_the_tightest_filesystem(tmp_path, monkeypatch):
    root = tmp_path / "docker"
    containerd = tmp_path / "containerd"
    root.mkdir()
    containerd.mkdir()
    monkeypatch.setattr(compose_mod, "CONTAINERD_ROOTS", (str(containerd),))
    d = _FixedDocker(str(root))
    monkeypatch.setattr(d, "_free_at", lambda p: 900 if p == str(root) else 5)
    assert d.free_bytes() == 5
    # an explicit path is still measured on its own
    assert d.free_bytes(str(root)) == 900


def test_free_bytes_is_none_when_nothing_can_be_measured(tmp_path, monkeypatch):
    root = tmp_path / "docker"
    root.mkdir()
    monkeypatch.setattr(compose_mod, "CONTAINERD_ROOTS", ())
    d = _FixedDocker(str(root))
    monkeypatch.setattr(d, "_free_at", lambda p: None)
    assert d.free_bytes() is None