"""The two ACL predicates behind list queries.

`get_note_permission` answers "may I read THIS note?" one row at a time, which a
list query can't use. These express the same resolution as set membership. They
are pure SQL builders — group membership is a subquery rather than a fetched
list, so they need no session and callers' unit tests need not know they exist.

Two scopes, deliberately different (decision note 2094):
  readable_*  — everything the ACL permits, for explicit acts (a typed search, a
                fetch by id).
  browsable_* — owner + project access only, for passive surfaces (browse lists,
                facet counts, the process→skill manifest).

Assertions compile each clause to SQL and inspect its shape.
"""
import pytest

from scribe.services.access import (
    browsable_notes_clause,
    notes_visibility_clause,
    readable_notes_clause,
)


def _sql(clause) -> str:
    return str(clause.compile(compile_kwargs={"literal_binds": True}))


def _read(user_id: int = 7) -> str:
    return _sql(readable_notes_clause(user_id))


def _browse(user_id: int = 7) -> str:
    return _sql(browsable_notes_clause(user_id))


# --- read scope --------------------------------------------------------------

def test_read_scope_covers_ownership_and_every_share_path():
    sql = _read()
    assert "notes.user_id = 7" in sql          # 1. ownership
    assert "note_shares" in sql                # 2/3. direct or group note share
    assert "notes.project_id IN" in sql        # 4. inherited from a shared project
    assert "project_shares" in sql


def test_read_scope_resolves_group_membership_in_sql():
    """Group ids are a subquery, not a pre-fetched list — that's what keeps this
    a pure function with no session of its own."""
    sql = _read()
    assert "group_memberships.user_id = 7" in sql
    # Both the note-level and project-level share lookups consult it. Count FROM
    # clauses rather than bare occurrences — each rendered subquery names the
    # table in SELECT, FROM and WHERE — and compare loosely, since the assertion
    # is about the arms existing, not about SQLAlchemy's formatting.
    assert sql.count("FROM group_memberships") >= 2
    assert _browse().count("FROM group_memberships") >= 1


def test_read_scope_is_never_the_whole_table():
    """Guard against the predicate degrading to always-true, which would expose
    every user's notes to every other user."""
    sql = _read().lower()
    assert " true" not in sql
    assert "1 = 1" not in sql


# --- browse scope: the trust boundary ---------------------------------------

def test_browse_scope_excludes_direct_note_shares():
    """The whole point of the narrower scope. If `note_shares` leaks in here, a
    record someone shared one-to-one with the operator lands in their own browse
    list, facet counts and skill manifest as though they had recorded it."""
    assert "note_shares" not in _browse()


def test_browse_scope_keeps_ownership_and_project_access():
    sql = _browse()
    assert "notes.user_id = 7" in sql   # your own records
    assert "project_shares" in sql      # a project shared with you
    assert "projects" in sql            # a project you own


def test_browse_scope_is_strictly_narrower_than_read_scope():
    """Browse must never surface something read scope wouldn't also allow, or a
    list could show a record the caller cannot then open."""
    browse, read = _browse(), _read()
    assert "note_shares" in read and "note_shares" not in browse
    for arm in ("notes.user_id = 7", "project_shares"):
        assert arm in browse and arm in read


def test_browse_scope_is_never_the_whole_table():
    sql = _browse().lower()
    assert " true" not in sql
    assert "1 = 1" not in sql


# --- the scope resolver ------------------------------------------------------

def test_own_scope_is_ownership_alone():
    """The near-duplicate gate depends on this: its verdict must not turn on
    another person's records, or it would refuse a write and point the caller at
    something they may not be able to edit."""
    sql = _sql(notes_visibility_clause(7, "own"))
    assert sql == "notes.user_id = 7"


def test_scope_resolver_maps_to_the_right_clauses():
    assert _sql(notes_visibility_clause(7, "browse")) == _browse()
    assert _sql(notes_visibility_clause(7, "read")) == _read()


def test_scope_defaults_to_the_narrowest():
    """A caller that forgets to choose must be wrong in the safe direction."""
    assert _sql(notes_visibility_clause(7)) == _sql(notes_visibility_clause(7, "own"))


def test_unknown_scope_is_rejected_loudly():
    """Silently falling back would turn a typo into a data-exposure bug."""
    with pytest.raises(ValueError):
        notes_visibility_clause(7, "everything")


@pytest.mark.parametrize("clause_fn", [readable_notes_clause, browsable_notes_clause])
def test_clauses_are_pure_builders(clause_fn):
    """Synchronous and side-effect free — no coroutine, no session of their own.

    This is the property that keeps them usable: when they opened their own
    session, every unrelated service test had to know they existed and stub them,
    and four test modules broke the moment a service started calling one."""
    import inspect
    assert not inspect.iscoroutinefunction(clause_fn)
    assert _sql(clause_fn(7))  # builds without touching a database