"""The frozen single-stream type contract: identity, clock, source_dt_s, events.

The contract is defined in ``orisys.stream_contract`` and documented in
``docs/stream-contract.zh.md``.  These tests pin the four acceptance rules of
T03: per-stream identity and clock, an optional-but-never-partial group
identity, distinguishability of frames that share a timestamp, and JSON
round-trips for ``source_dt_s`` and events.  They are pure type tests: nothing
here starts a sensor, a pipeline or a session.
"""

from __future__ import annotations

import json

import pytest

from orisys import (
    STREAM_CONTRACT_VERSION,
    SUPPORTED_CONTRACT_VERSIONS,
    FrameClock,
    FrameIdentity,
    FrameStamp,
    MeasurementFrame,
    StreamEvent,
)


def _round_trip(value):
    """JSON round-trip exactly as a recording would read the contract back."""
    payload = json.loads(json.dumps(value.to_dict()))
    return type(value).from_dict(payload)


def _stamp(**overrides) -> FrameStamp:
    fields = {
        "sensor_id": "FINGER-001",
        "session_id": "run-7",
        "frame_id": 12,
        "source_frame_id": 41,
        "capture_time_ns": 1_600_000_000_000_000_000,
        "clock_id": "host_monotonic",
        "capture_time_basis": "capture_monotonic",
    }
    fields.update(overrides)
    return FrameStamp(**fields)


def test_the_contract_version_is_exported_and_explicit() -> None:
    assert STREAM_CONTRACT_VERSION == "stream-contract/1"
    # Every frozen type and the version are importable from the package root,
    # which is the public boundary downstream repositories import.
    import orisys

    for name in (
        "FrameIdentity",
        "FrameClock",
        "FrameStamp",
        "MeasurementFrame",
        "StreamEvent",
        "TIME_BASES",
        "STREAM_CONTRACT_VERSION",
    ):
        assert hasattr(orisys, name), name


# --------------------------------------------------------------- identity
def test_identity_keeps_a_per_stream_output_number_and_the_source_number() -> None:
    identity = FrameIdentity(
        sensor_id="BOX-3",
        session_id="run-7",
        frame_id=12,
        source_frame_id=41,
    )
    assert (identity.sensor_id, identity.session_id) == ("BOX-3", "run-7")
    assert identity.frame_id == 12
    assert identity.source_frame_id == 41
    # A source without its own numbering may say so; the output number still exists.
    identity = FrameIdentity(
        sensor_id="BOX-3", session_id="run-7", frame_id=0, source_frame_id=None
    )
    assert identity.frame_id == 0 and identity.source_frame_id is None
    with pytest.raises(ValueError):
        FrameIdentity(
            sensor_id="", session_id="run-7", frame_id=0, source_frame_id=None
        )
    with pytest.raises(ValueError):
        FrameIdentity(
            sensor_id="BOX-3", session_id="run-7", frame_id=-1, source_frame_id=None
        )
    with pytest.raises(TypeError):
        FrameIdentity(
            sensor_id="BOX-3", session_id="run-7", frame_id=True, source_frame_id=None
        )


def test_group_identity_is_optional_but_never_partial() -> None:
    without_group = FrameIdentity(
        sensor_id="BOX-3", session_id="run-7", frame_id=0, source_frame_id=0
    )
    assert without_group.has_group is False
    assert without_group.group_identity is None
    assert without_group.to_dict()["acquisition_id"] is None
    assert without_group.to_dict()["sync_group_id"] is None

    grouped = FrameIdentity(
        sensor_id="BOX-3",
        session_id="run-7",
        frame_id=0,
        source_frame_id=0,
        acquisition_id="acq-1",
        sync_group_id="group-1",
    )
    assert grouped.has_group is True
    assert grouped.group_identity == ("acq-1", "group-1")
    assert _round_trip(grouped) == grouped

    # A half group would look like synchronization without an owner.
    with pytest.raises(ValueError, match="both acquisition_id and sync_group_id"):
        FrameIdentity(
            sensor_id="BOX-3",
            session_id="run-7",
            frame_id=0,
            source_frame_id=0,
            acquisition_id="acq-1",
        )
    with pytest.raises(ValueError, match="both acquisition_id and sync_group_id"):
        FrameIdentity(
            sensor_id="BOX-3",
            session_id="run-7",
            frame_id=0,
            source_frame_id=0,
            sync_group_id="group-1",
        )
    with pytest.raises(ValueError):
        FrameIdentity(
            sensor_id="BOX-3",
            session_id="run-7",
            frame_id=0,
            source_frame_id=0,
            acquisition_id="",
            sync_group_id="group-1",
        )


# ------------------------------------------------------------------ clock
def test_clock_keeps_the_time_domain_basis_and_the_raw_source_pts() -> None:
    clock = FrameClock(
        capture_time_ns=1_600_000_000_000_000_000,
        clock_id="video:recording-4",
        capture_time_basis="video_pts",
        source_pts=90000,
    )
    assert clock.capture_time_basis == "video_pts"
    assert clock.source_pts == 90000
    # A derived file timestamp is explicitly labelled as estimated.
    assert FrameClock(
        0, "source:frame-numbers", "estimated_source"
    ).capture_time_basis == ("estimated_source")
    with pytest.raises(ValueError):
        FrameClock(0, "host", "wall_clock")
    with pytest.raises(ValueError):
        FrameClock(-1, "host", "capture_monotonic")
    with pytest.raises(ValueError):
        FrameClock(0, "", "capture_monotonic")
    with pytest.raises(ValueError):
        FrameClock(0, "host", "capture_monotonic", source_pts=float("nan"))
    with pytest.raises(TypeError):
        FrameClock(0, "host", "capture_monotonic", source_pts=True)


# ------------------------------------------------------------------ stamp
def test_stamp_composes_identity_and_clock_and_round_trips() -> None:
    identity = FrameIdentity(
        sensor_id="FINGER-001",
        session_id="run-7",
        frame_id=12,
        source_frame_id=41,
        acquisition_id="acq-1",
        sync_group_id="group-1",
    )
    clock = FrameClock(
        capture_time_ns=1_600_000_000_000_000_000,
        clock_id="host_monotonic",
        capture_time_basis="capture_monotonic",
        source_pts=41.5,
    )
    stamp = FrameStamp.from_parts(identity, clock)
    assert stamp.identity == identity
    assert stamp.clock == clock

    payload = stamp.to_dict()
    assert payload["schema"] == STREAM_CONTRACT_VERSION
    assert payload["sensor_id"] == "FINGER-001"
    assert payload["source_frame_id"] == 41
    assert payload["capture_time_ns"] == clock.capture_time_ns
    assert _round_trip(stamp) == stamp

    # The flattened fields are the same objects the components report.
    assert stamp.sensor_id == identity.sensor_id
    assert stamp.session_id == identity.session_id
    assert stamp.frame_id == identity.frame_id
    assert stamp.source_frame_id == identity.source_frame_id
    assert stamp.capture_time_ns == clock.capture_time_ns
    assert stamp.clock_id == clock.clock_id
    assert stamp.capture_time_basis == clock.capture_time_basis
    assert stamp.source_pts == clock.source_pts
    assert (stamp.acquisition_id, stamp.sync_group_id) == ("acq-1", "group-1")


def test_frames_that_share_a_pts_are_still_distinct_frames() -> None:
    """Timestamps are not identity: a recording must keep both frames."""
    first = _stamp(source_frame_id=41, frame_id=10)
    second = _stamp(source_frame_id=42, frame_id=11)
    assert first.capture_time_ns == second.capture_time_ns
    assert first.source_pts == second.source_pts
    assert first != second
    assert first.to_dict() != second.to_dict()
    assert _round_trip(first) != _round_trip(second)

    # A source without its own numbering can still emit repeated timestamps;
    # the contiguous output number keeps the frames apart.
    first = _stamp(source_frame_id=None, frame_id=10)
    second = _stamp(source_frame_id=None, frame_id=11)
    assert first != second
    assert (first.capture_time_ns, first.source_pts) == (
        second.capture_time_ns,
        second.source_pts,
    )

    # Different sessions are different streams even with identical numbers.
    other_session = _stamp(session_id="run-8")
    assert other_session != first and other_session != second


# -------------------------------------------------------- measurement frame
def test_measurement_frame_carries_source_dt_s_and_round_trips() -> None:
    stamp = _stamp()
    first = MeasurementFrame(stamp=stamp, source_dt_s=None)
    assert first.source_dt_s is None
    assert first.reference_generation == 0
    assert _round_trip(first) == first

    following = MeasurementFrame(
        stamp=_stamp(frame_id=13, source_frame_id=42),
        source_dt_s=0.033,
        reference_generation=3,
    )
    payload = following.to_dict()
    assert payload["schema"] == STREAM_CONTRACT_VERSION
    assert payload["source_dt_s"] == pytest.approx(0.033)
    assert payload["reference_generation"] == 3
    assert _round_trip(following) == following

    # Equal source timestamps are valid data; they do not collapse frames and do
    # not produce a negative/None interval.
    same_time = MeasurementFrame(stamp=_stamp(), source_dt_s=0.0)
    assert same_time.source_dt_s == 0.0


def test_measurement_frame_rejects_invalid_source_dt_and_generation() -> None:
    stamp = _stamp()
    with pytest.raises(ValueError):
        MeasurementFrame(stamp=stamp, source_dt_s=-0.001)
    with pytest.raises(ValueError):
        MeasurementFrame(stamp=stamp, source_dt_s=float("nan"))
    with pytest.raises(ValueError):
        MeasurementFrame(stamp=stamp, source_dt_s=float("inf"))
    with pytest.raises(TypeError):
        MeasurementFrame(stamp=stamp, source_dt_s=True)
    with pytest.raises(ValueError):
        MeasurementFrame(stamp=stamp, source_dt_s=None, reference_generation=-1)
    with pytest.raises(TypeError):
        MeasurementFrame(stamp=stamp, source_dt_s=None, reference_generation=1.5)
    with pytest.raises(TypeError):
        MeasurementFrame(stamp={}, source_dt_s=None)


# ------------------------------------------------------------------ events
def test_events_round_trip_through_json_with_a_frozen_payload() -> None:
    stamp = _stamp()
    event = StreamEvent(
        kind="source_gap",
        stamp=stamp,
        payload={
            "dropped_frames": 3,
            "source_dt_s": 0.5,
            "proportion": 0.25,
            "flags": [True, False, None],
            "context": {"reason": "overload", "counts": [1, 2]},
        },
        event_version=1,
    )
    assert event.payload["dropped_frames"] == 3
    # The payload is read-only after construction.
    with pytest.raises(TypeError):
        event.payload["dropped_frames"] = 4  # type: ignore[index]

    payload = event.to_dict()
    assert payload["schema"] == STREAM_CONTRACT_VERSION
    assert payload["event_version"] == 1
    assert _round_trip(event) == event

    # A lifecycle event may have no frame, and unknown kinds stay additive.
    event = StreamEvent(kind="stream_started", payload={})
    assert event.stamp is None
    assert _round_trip(event) == event
    assert _round_trip(StreamEvent(kind="some_future_kind", payload={"x": 1})).kind == (
        "some_future_kind"
    )


def test_events_reject_payloads_that_cannot_round_trip() -> None:
    with pytest.raises(ValueError):
        StreamEvent(kind="bad", payload={"nan": float("nan")})
    with pytest.raises(ValueError):
        StreamEvent(kind="bad", payload={"inf": float("inf")})
    with pytest.raises(TypeError):
        StreamEvent(kind="bad", payload={1: "non-string key"})
    with pytest.raises(TypeError):
        StreamEvent(kind="bad", payload={"bytes": b"raw"})
    with pytest.raises(TypeError):
        StreamEvent(kind="bad", payload={"set": {1, 2}})
    with pytest.raises(ValueError):
        StreamEvent(kind="", payload={})
    with pytest.raises(ValueError):
        StreamEvent(kind="bad", payload={}, event_version=0)


# -------------------------------------------------------------- read-back
@pytest.mark.parametrize(
    "factory",
    [
        lambda: _stamp(),
        lambda: _stamp(acquisition_id="acq-1", sync_group_id="group-1"),
        lambda: MeasurementFrame(_stamp(), None),
        lambda: MeasurementFrame(_stamp(), 0.033, 2),
        lambda: StreamEvent("reference_reset", _stamp(), {"from": 1, "to": 2}),
    ],
)
def test_every_frozen_type_round_trips_through_its_dictionary(factory) -> None:
    value = factory()
    assert _round_trip(value) == value


def test_unknown_fields_and_wrong_schema_are_rejected() -> None:
    stamp_payload = _stamp().to_dict()
    # Policy A: no same-version field additions - an unknown field names the
    # versioning rule instead of being silently dropped.
    with pytest.raises(ValueError, match="new STREAM_CONTRACT_VERSION"):
        FrameStamp.from_dict({**stamp_payload, "unexpected": 1})
    with pytest.raises(ValueError, match="schema"):
        FrameStamp.from_dict({**stamp_payload, "schema": "stream-contract/2"})
    with pytest.raises(ValueError, match="missing field"):
        FrameStamp.from_dict(
            {key: value for key, value in stamp_payload.items() if key != "sensor_id"}
        )
    with pytest.raises(ValueError, match="unknown field"):
        StreamEvent.from_dict(
            {"schema": STREAM_CONTRACT_VERSION, "kind": "x", "extra": 1}
        )
    with pytest.raises(ValueError, match="unknown field"):
        # A nested frame header follows the same policy.
        MeasurementFrame.from_dict(
            {
                "schema": STREAM_CONTRACT_VERSION,
                "stamp": {**stamp_payload, "unexpected": 1},
                "source_dt_s": None,
            }
        )
    with pytest.raises(ValueError, match="schema"):
        MeasurementFrame.from_dict(
            {
                "schema": "stream-contract/0",
                "stamp": stamp_payload,
                "source_dt_s": None,
            }
        )


def test_the_reader_lists_the_versions_it_accepts() -> None:
    """Policy A: strict reading, and only explicitly listed versions are read."""
    assert SUPPORTED_CONTRACT_VERSIONS == (STREAM_CONTRACT_VERSION,)
    payload = _stamp().to_dict()
    # The listed version is the one this reader was built for and it reads.
    assert FrameStamp.from_dict(payload) == _stamp()

    # A different version is a different field contract: it is rejected rather
    # than guessed at.  Bumping STREAM_CONTRACT_VERSION and adding the new value
    # to SUPPORTED_CONTRACT_VERSIONS is what makes a new version readable.
    for schema in ("stream-contract/0", "stream-contract/2", "other/1"):
        with pytest.raises(ValueError, match="must be one of"):
            FrameStamp.from_dict({**payload, "schema": schema})
        with pytest.raises(ValueError, match="must be one of"):
            MeasurementFrame.from_dict(
                {"schema": schema, "stamp": payload, "source_dt_s": None}
            )
        with pytest.raises(ValueError, match="must be one of"):
            StreamEvent.from_dict({"schema": schema, "kind": "x"})


# --------------------------------------------------------------- event extras
def test_events_are_hashable_and_equal_events_share_a_hash() -> None:
    """The frozen event is usable as a dict/set key; equality and hash agree."""
    first = StreamEvent(
        kind="reference_reset", stamp=_stamp(), payload={"from": 1, "to": 2}
    )
    second = StreamEvent(
        kind="reference_reset",
        stamp=_stamp(),
        payload={"to": 2, "from": 1},
    )
    assert first == second
    assert hash(first) == hash(second)
    # A JSON read-back is still the same value, so it must hash the same too.
    assert _round_trip(first) == first
    assert hash(_round_trip(first)) == hash(first)
    # The frozen payload is excluded from the hash, so it cannot make hashing
    # fail; events differing only in payload may still share a hash bucket.
    assert hash(StreamEvent(kind="source_gap", stamp=_stamp())) == hash(
        StreamEvent(kind="source_gap", stamp=_stamp(), payload={"dropped": 1})
    )


@pytest.mark.parametrize(
    "kind",
    ["NotSnake", "bad kind", "1leading", "with-dash", "_leading", ""],
)
def test_event_kind_rejects_names_outside_lower_snake(kind) -> None:
    with pytest.raises(ValueError):
        StreamEvent(kind=kind)
    with pytest.raises(ValueError):
        StreamEvent.from_dict({"schema": STREAM_CONTRACT_VERSION, "kind": kind})


@pytest.mark.parametrize(
    "kind", ["a", "source_gap", "reference_reset", "zero2", "a_b_c_1"]
)
def test_event_kind_accepts_lower_snake_and_round_trips(kind) -> None:
    event = StreamEvent(kind=kind, payload={"x": 1})
    assert event.kind == kind
    assert _round_trip(event) == event