"""The filesystem allowlist: which server-side paths a source may ever read.

Rejecting traversal, symlinks and relative paths only proves a path is well
formed. These tests are about the separate question the allowlist answers --
whether a well-formed path is one an operator ever intended RAGcore to read.
"""

from __future__ import annotations

from pathlib import Path

import pytest

from ragcore.domain.sources import (
    SourceRootError,
    assert_within_allowed_roots,
    normalize_allowed_roots,
    resolve_within_allowed_roots,
)

pytestmark = pytest.mark.security

_ROOTS = (Path("/mnt/rag-sources"), Path("/srv/corpora"))


def test_no_configured_roots_allows_nothing() -> None:
    """Fail closed. An empty allowlist is a real answer -- "this deployment
    reads no server-side paths" -- not a missing one to be defaulted away."""

    with pytest.raises(SourceRootError, match="no allowed source roots"):
        assert_within_allowed_roots("/mnt/rag-sources/runbooks", ())


@pytest.mark.parametrize(
    "requested",
    [
        "/mnt/rag-sources",
        "/mnt/rag-sources/runbooks",
        "/mnt/rag-sources/runbooks/fleet",
        "/srv/corpora/handbook",
    ],
)
def test_a_root_and_anything_below_it_is_allowed(requested: str) -> None:
    assert assert_within_allowed_roots(requested, _ROOTS) == Path(requested)


@pytest.mark.parametrize(
    "requested",
    [
        "/etc",
        "/etc/shadow",
        "/app/src/ragcore/config.py",
        "/var/lib/postgresql/data",
        "/mnt",
        "/",
    ],
)
def test_a_path_outside_every_root_is_refused(requested: str) -> None:
    with pytest.raises(SourceRootError, match="outside every allowed source root"):
        assert_within_allowed_roots(requested, _ROOTS)


@pytest.mark.parametrize(
    "requested",
    [
        "/mnt/rag-sources-secret",
        "/mnt/rag-sources-secret/keys",
        "/srv/corpora-backup",
    ],
)
def test_a_sibling_sharing_a_string_prefix_is_not_contained(requested: str) -> None:
    """Containment is decided on path *components*, never on string prefixes.
    ``/mnt/rag-sources`` does not contain ``/mnt/rag-sources-secret``, however
    much the two look alike to ``startswith``."""

    with pytest.raises(SourceRootError, match="outside every allowed source root"):
        assert_within_allowed_roots(requested, _ROOTS)


@pytest.mark.parametrize(
    "requested",
    ["relative/path", "", "rag-sources", "C:x"],
)
def test_a_path_that_is_not_absolute_is_refused(requested: str) -> None:
    with pytest.raises(SourceRootError):
        assert_within_allowed_roots(requested, _ROOTS)


def test_traversal_is_refused_before_containment_is_even_considered() -> None:
    """``/mnt/rag-sources/../../etc`` normalises to ``/etc``, so a check that
    normalised first and compared second would be fine either way -- but the
    path is rejected outright, so a root that happens to be near the top of
    the tree cannot be walked out of."""

    with pytest.raises(SourceRootError, match="must not traverse"):
        assert_within_allowed_roots("/mnt/rag-sources/../../etc", _ROOTS)


def test_a_nul_byte_is_refused() -> None:
    with pytest.raises(SourceRootError, match="NUL-free"):
        assert_within_allowed_roots("/mnt/rag-sources/x\x00.txt", _ROOTS)


def test_the_stored_spelling_survives_validation() -> None:
    """The API host validating a POSIX deployment path must hand back exactly
    what the operator wrote: a Windows-side ``normpath`` would rewrite it into
    something the Linux worker could never open."""

    assert str(assert_within_allowed_roots("/mnt/rag-sources/docs", _ROOTS)).replace(
        "\\", "/"
    ) == "/mnt/rag-sources/docs"


# -- operator-configured roots ----------------------------------------------


def test_a_filesystem_root_may_not_be_an_allowed_root() -> None:
    """Allowing ``/`` would make the allowlist meaningless."""

    with pytest.raises(SourceRootError, match="must not be a filesystem root"):
        normalize_allowed_roots(["/"])


def test_a_relative_or_traversing_root_is_refused_at_startup() -> None:
    with pytest.raises(SourceRootError, match="absolute"):
        normalize_allowed_roots(["mnt/rag-sources"])
    with pytest.raises(SourceRootError, match="traverse"):
        normalize_allowed_roots(["/mnt/rag-sources/../.."])


def test_duplicate_roots_collapse() -> None:
    assert normalize_allowed_roots(["/mnt/rag", "/mnt/rag"]) == (Path("/mnt/rag"),)


# -- filesystem truth --------------------------------------------------------


def test_resolution_rejects_a_path_that_does_not_exist(tmp_path: Path) -> None:
    """The worker's check is about the filesystem as it is: a lexically fine
    path that cannot be resolved is not a path it may read."""

    with pytest.raises(SourceRootError, match="cannot be resolved"):
        resolve_within_allowed_roots(tmp_path / "absent", (tmp_path,))


def test_resolution_accepts_a_real_directory_inside_an_allowed_root(tmp_path: Path) -> None:
    allowed = tmp_path / "corpora"
    inside = allowed / "runbooks"
    inside.mkdir(parents=True)

    assert resolve_within_allowed_roots(inside, (allowed,)) == inside.resolve(strict=True)


def test_resolution_refuses_a_real_directory_outside_every_allowed_root(tmp_path: Path) -> None:
    allowed = tmp_path / "corpora"
    allowed.mkdir()
    elsewhere = tmp_path / "secrets"
    elsewhere.mkdir()

    with pytest.raises(SourceRootError, match="outside every allowed source root"):
        resolve_within_allowed_roots(elsewhere, (allowed,))


def test_an_unmounted_root_contains_nothing_but_does_not_break_the_others(
    tmp_path: Path,
) -> None:
    """A deployment may configure roots that only some containers mount. One
    that is absent here simply cannot contain anything; the roots that are
    present still get their chance."""

    allowed = tmp_path / "corpora"
    allowed.mkdir()

    assert resolve_within_allowed_roots(
        allowed, (tmp_path / "never-mounted", allowed)
    ) == allowed.resolve(strict=True)