"""
Tests for shaliach + tevilah — property 4 (role-separated operator)
of azazel_engineering_reading.md §14.

The disposal handler (IshItti, "designated man") is the ONLY role
authorized to invoke disposal-channel functions. The handler
accumulates state during a disposal (payload references, intermediate
tags) that MUST be cleared by tevilah before the handler can be
re-used or before the same process touches non-azazel code.

The CI invariant — test_tevilah_clears_all_non_immutable_state —
catches future contributors who add state-bearing attributes to
IshItti without extending tevilah() to clear them. Without that
invariant, the property would silently degrade as the codebase
evolves.
"""

import pytest

from azazel_processor.shaliach import (
    IshItti,
    ShaliachError,
    assert_shaliach_active,
)


# ============================================================
# Construction
# ============================================================


def test_handler_requires_named_identifier():
    h = IshItti("aharon")
    assert h.identifier == "aharon"


def test_handler_refuses_empty_identifier():
    with pytest.raises(ShaliachError):
        IshItti("")


def test_handler_refuses_whitespace_identifier():
    with pytest.raises(ShaliachError):
        IshItti("   ")


def test_handler_refuses_non_string_identifier():
    with pytest.raises(ShaliachError):
        IshItti(None)  # type: ignore[arg-type]
    with pytest.raises(ShaliachError):
        IshItti(123)  # type: ignore[arg-type]


def test_identifier_is_immutable():
    """The identifier is set at construction and propagates onto
    AzazelRecords for shaliach attribution. It must not be
    re-assignable, and it must survive tevilah."""
    h = IshItti("aharon")
    h.activate()
    h.tevilah()
    assert h.identifier == "aharon"


# ============================================================
# Activation lifecycle
# ============================================================


def test_handler_starts_inactive():
    h = IshItti("aharon")
    assert h.is_active() is False


def test_activate_marks_handler_active():
    h = IshItti("aharon")
    h.activate()
    assert h.is_active() is True


def test_activate_when_already_active_raises():
    """Re-activation without tevilah would mix two disposals' state.
    Refuse — the handler must wash before rejoining (Vayikra 16:26)."""
    h = IshItti("aharon")
    h.activate()
    with pytest.raises(ShaliachError) as exc:
        h.activate()
    assert "tevilah" in str(exc.value).lower()


def test_tevilah_then_reactivate_succeeds():
    """The handler can perform many disposals across its lifetime,
    one at a time, with mandatory tevilah between."""
    h = IshItti("aharon")
    h.activate()
    h.tevilah()
    assert h.is_active() is False
    h.activate()
    assert h.is_active() is True


# ============================================================
# Hold payload + tag — only when active
# ============================================================


def test_hold_payload_requires_active():
    h = IshItti("aharon")
    with pytest.raises(ShaliachError):
        h.hold_payload({"data": "x"})


def test_hold_payload_tracks_references():
    h = IshItti("aharon")
    h.activate()
    h.hold_payload({"data": "first"})
    h.hold_payload({"data": "second"})
    assert h.held_payload_count() == 2


def test_tag_requires_active():
    h = IshItti("aharon")
    with pytest.raises(ShaliachError):
        h.tag("checkpoint", "STAGED")


def test_tag_round_trip():
    h = IshItti("aharon")
    h.activate()
    h.tag("checkpoint", "STAGED")
    assert h.get_tag("checkpoint") == "STAGED"
    assert h.get_tag("missing") is None
    assert h.get_tag("missing", "default") == "default"


# ============================================================
# Tevilah — the load-bearing reset
# ============================================================


def test_tevilah_clears_payload_refs():
    h = IshItti("aharon")
    h.activate()
    h.hold_payload({"data": "x"})
    assert h.held_payload_count() == 1

    h.tevilah()
    assert h.held_payload_count() == 0


def test_tevilah_clears_intermediate_tags():
    h = IshItti("aharon")
    h.activate()
    h.tag("checkpoint", "STAGED")
    h.tag("vidui_id", "abc")

    h.tevilah()
    h.activate()  # re-activate to allow get_tag (which doesn't actually require active, but for clarity)
    assert h.get_tag("checkpoint") is None
    assert h.get_tag("vidui_id") is None


def test_tevilah_returns_handler_to_inactive():
    h = IshItti("aharon")
    h.activate()
    h.tevilah()
    assert h.is_active() is False


def test_tevilah_preserves_immutable_identifier():
    h = IshItti("aharon")
    h.activate()
    h.tevilah()
    assert h.identifier == "aharon"


# ============================================================
# THE LOAD-BEARING CI INVARIANT
# ============================================================


def test_tevilah_clears_all_non_immutable_state():
    """Property 4's structural defense: ANY attribute on IshItti
    that does not start with `_immutable_` MUST be reset to a fresh
    value (or removed entirely) by tevilah().

    A future contributor who adds `self._cache = {}` (or any other
    state attribute) to IshItti without extending tevilah() to
    clear it breaks the property — and this test fires before the
    regression ships.

    The discovery is dynamic: we walk the handler's `vars()` after
    pre-tevilah state has been seeded, then verify each non-immutable
    attribute is in a 'fresh' state post-tevilah.
    """
    h = IshItti("aharon")
    h.activate()

    # Seed every state-bearing attribute we know about.
    h.hold_payload({"data": "first"})
    h.hold_payload({"data": "second"})
    h.tag("checkpoint", "STAGED")
    h.tag("disposal_id", "abc-123")

    # Snapshot the pre-tevilah attribute set.
    pre_tevilah = dict(vars(h))
    # Sanity: at least one non-immutable attribute should be non-fresh.
    non_immutable = {
        k: v for k, v in pre_tevilah.items() if not k.startswith("_immutable_")
    }
    assert any(_is_non_fresh(v) for v in non_immutable.values()), (
        "Test setup error: no non-fresh state to clear"
    )

    h.tevilah()

    # Post-tevilah: every non-immutable attribute must be 'fresh'.
    for attr_name, value in vars(h).items():
        if attr_name.startswith("_immutable_"):
            continue
        assert _is_fresh(value), (
            f"tevilah() did not reset {attr_name}: value is {value!r}. "
            f"If this attribute was added without extending tevilah, "
            f"that is the property-4 regression. Either prefix the "
            f"name with `_immutable_` (if it is set once at "
            f"construction) or extend tevilah() to clear it."
        )

    # All immutable attributes must STILL be present.
    for attr_name in pre_tevilah:
        if attr_name.startswith("_immutable_"):
            assert attr_name in vars(h), (
                f"tevilah() incorrectly removed immutable attribute {attr_name!r}."
            )


def _is_fresh(value) -> bool:
    """A value is 'fresh' if it is the canonical empty value for its
    type — empty container, False, None, 0."""
    if value is None or value is False:
        return True
    if value == 0:
        return True
    if isinstance(value, (list, tuple, set, dict, str, bytes)) and len(value) == 0:
        return True
    return False


def _is_non_fresh(value) -> bool:
    return not _is_fresh(value)


# ============================================================
# assert_shaliach_active — the role gate
# ============================================================


def test_assert_shaliach_active_passes_for_active_ish_itti():
    h = IshItti("aharon")
    h.activate()
    # Should not raise
    assert_shaliach_active(h)


def test_assert_shaliach_active_refuses_inactive_handler():
    h = IshItti("aharon")
    with pytest.raises(ShaliachError) as exc:
        assert_shaliach_active(h)
    assert "not active" in str(exc.value).lower()


def test_assert_shaliach_active_refuses_non_ish_itti():
    """A kohen-shaped or owner-shaped value passed where a shaliach
    is expected — refuse. Property 4: cross-role invocation is
    forbidden."""
    not_a_shaliach = "string-not-an-IshItti"
    with pytest.raises(ShaliachError) as exc:
        assert_shaliach_active(not_a_shaliach)  # type: ignore[arg-type]
    assert "ishitti" in str(exc.value).lower() or "shaliach" in str(exc.value).lower()


def test_assert_shaliach_active_refuses_object_impersonating_handler():
    """A duck-typed object with the same method names is NOT an
    IshItti. The role gate is identity, not interface."""

    class DuckIshItti:
        identifier = "fake"

        def is_active(self):
            return True

    with pytest.raises(ShaliachError):
        assert_shaliach_active(DuckIshItti())  # type: ignore[arg-type]


# ============================================================
# Stale-state-across-disposals detection
# ============================================================


def test_stale_state_across_disposals_is_prevented():
    """The integration property: state from disposal-N must not
    leak into disposal-N+1. tevilah is the gate; this test verifies
    it works end-to-end."""
    h = IshItti("aharon")

    # Disposal 1
    h.activate()
    h.hold_payload({"id": 1, "data": "first"})
    h.tag("disposal_id", "first")
    h.tevilah()

    # Disposal 2 — must start fresh
    h.activate()
    assert h.held_payload_count() == 0
    assert h.get_tag("disposal_id") is None
    h.hold_payload({"id": 2, "data": "second"})
    h.tag("disposal_id", "second")
    assert h.held_payload_count() == 1
    assert h.get_tag("disposal_id") == "second"