"""Step 5 tests — local-folder retriever core (exact locators + EscapeRoute path-security).

Citations are exact by construction (locator slices the snippet byte-for-byte) and
deterministic; the path-security checks are behavioural (traversal / symlink-escape /
prefix-collision sibling all fail-closed). Pattern: tests/test_reference_domain.py +
tests/test_backends.py (raises).
"""

import os

import pytest

from portfolio_optimiser.retrieval import (
    PathSecurityError,
    is_within_dir,
    retrieve,
    safe_resolve,
)


@pytest.fixture()
def docs(tmp_path):
    d = tmp_path / "docs"
    d.mkdir()
    (d / "asphalt.txt").write_text(
        "Asphalt Ab11 unit rate renegotiation reduced the paving cost on the school stretch.",
        encoding="utf-8",
    )
    (d / "drainage.txt").write_text(
        "Drainage length was reduced after a survey on the low-traffic section.",
        encoding="utf-8",
    )
    return d


def test_locator_exactly_slices_snippet(docs) -> None:
    hits = retrieve("asphalt paving cost", str(docs), top_k=5)
    assert hits
    for h in hits:
        text = (docs / h.file).read_text(encoding="utf-8")
        assert text[h.locator.start_index : h.locator.end_index] == h.snippet


def test_retrieve_is_deterministic(docs) -> None:
    a = retrieve("drainage survey", str(docs), top_k=3)
    b = retrieve("drainage survey", str(docs), top_k=3)
    assert [(h.file, h.locator) for h in a] == [(h.file, h.locator) for h in b]


def test_top_k_respected(docs) -> None:
    assert len(retrieve("the", str(docs), top_k=1)) <= 1


def test_non_positive_top_k_rejected(docs) -> None:
    with pytest.raises(ValueError):
        retrieve("x", str(docs), top_k=0)


def test_parent_traversal_rejected(docs) -> None:
    # A `..` traversal escaping the docs folder is rejected fail-closed.
    with pytest.raises(PathSecurityError):
        safe_resolve(str(docs), "../outside.txt")


def test_symlink_escape_is_not_read(tmp_path, docs) -> None:
    # A symlink INSIDE docs_dir pointing OUTSIDE must never be read (fail-closed).
    secret = tmp_path / "secret.txt"
    secret.write_text("TOPSECRET asphalt asphalt asphalt exfiltrated", encoding="utf-8")
    os.symlink(str(secret), str(docs / "link.txt"))
    # safe_resolve refuses the escaping symlink...
    with pytest.raises(PathSecurityError):
        safe_resolve(str(docs), "link.txt")
    # ...and retrieve never surfaces the outside content even on a matching query.
    hits = retrieve("asphalt", str(docs), top_k=10)
    assert all("TOPSECRET" not in h.snippet for h in hits)


def test_prefix_collision_sibling_rejected(tmp_path) -> None:
    # A sibling dir sharing a name prefix (docs vs docs-evil) is NOT inside docs.
    root = tmp_path / "docs"
    root.mkdir()
    sibling = tmp_path / "docs-evil"
    sibling.mkdir()
    intruder = sibling / "secret.txt"
    intruder.write_text("x", encoding="utf-8")
    assert is_within_dir(str(intruder), str(root)) is False