"""`sim/carry.py` + the action gate's carry verbs — the hands, pinned.

PLAN §5 gives the cook one button and a pair of hands; this file pins what the
hands do:

* **one item per hand** — a second pick while carrying is `HANDS_FULL`, and a press
  at open floor with a full hand is the ladder's named `NOTHING_HERE` (v1 has no
  floor drops);
* **the set-down** — `RELEASE` / `PLACE_ON_STATION` / `PLATE_DISH` put the item on
  the fixture, stamp it with a mark, and leave it grabbable the moment it is set
  down (while an unmarked pipeline input stays the work press's); a pick-and-place
  round trip preserves the `Item`'s identity and clears the fixture's cell;
* **the hand-off** — a pick of a set-down placed by another cook within
  `HANDOFF_WINDOW_TICKS` (inclusive) is a `HANDED_OFF` with both ids; a self-pick,
  or a third party's pick outside the window, is a plain `PICKED`;
* **the trash** — a long press over the trash can destroys the carried item on the
  8th substep of the hold and not the 7th; a short press and a walk-away do
  nothing; a threshold met with an empty hand is `TRASHED_ALREADY_EMPTY`, never a
  silent no-op; the raw score delta rides the event payload;
* **the contested pick** — one winner, one `CONTESTED_LOST` loser, the item count
  conserved;
* **the conservation law** — a 100-tick fuzz of random simultaneous presses from a
  fixed seed re-checks `hands + stations + trashed == initial` after *every* tick,
  and runs bit-identical twice.

The two-player pass-and-contest script with its committed golden hash is
`test_replay_carry.py`.
"""

from __future__ import annotations

from dataclasses import replace
from typing import Any

import pytest

from undercooked.sim.carry import (
    HANDOFF_WINDOW_TICKS,
    TRASH_HOLD_TICKS,
    TRASH_SCORE_DELTA,
    first_loose_entry,
    pick_item,
    place_item,
    trash_effect,
)
from undercooked.sim.grid import Grid
from undercooked.sim.interact import (
    ItemTarget,
    StationTarget,
    action_gate,
    resolve_action,
    select_target,
)
from undercooked.sim.model import (
    Event,
    EventKind,
    Facing,
    Item,
    ItemForm,
    ItemKind,
    KitchenState,
    Player,
    PlayerState,
    Station,
    StationKind,
    StationState,
    TileKind,
    Vec2,
)
from undercooked.sim.rng import Rng
from undercooked.sim.step import STEP_DT, PlayerInput, step

pytestmark = pytest.mark.unit

WIDTH, HEIGHT = 13, 9
DEFAULT_POS = Vec2(5.5, 5.5)  # module-level so a default argument may use it (B008)


# --- fixtures ---------------------------------------------------------------------------


def make_state(
    stations: tuple[Station, ...] = (),
    players: tuple[Player, ...] = (),
    tick: int = 0,
) -> KitchenState:
    return KitchenState(
        level_id="03_carry",
        seed=7,
        grid=Grid(width=WIDTH, height=HEIGHT, tiles=(TileKind.FLOOR,) * (WIDTH * HEIGHT)),
        tick=tick,
        stations=stations,
        players=players,
        target_score=40,
        time_left=90.0,
    )


def cook(
    player_id: str = "p0",
    *,
    pos: Vec2 = DEFAULT_POS,
    facing: Facing = Facing.UP,
    carrying: Item | None = None,
    state: PlayerState = PlayerState.IDLE,
    seat: int = 0,
) -> Player:
    return Player(
        id=player_id,
        pos=pos,
        facing=facing,
        carrying=carrying,
        state=state,
        seat=seat,
    )


def fixture(
    kind: StationKind = StationKind.STOVE,
    *,
    x: int = 5,
    y: int = 4,
    state: StationState = StationState.IDLE,
    contents: tuple[Item, ...] = (),
    dirty: bool = False,
) -> Station:
    return Station(
        id=f"{kind.value}-{x}-{y}",
        kind=kind,
        x=x,
        y=y,
        state=state,
        contents=contents,
        dirty=dirty,
    )


def tomato(form: ItemForm = ItemForm.RAW) -> Item:
    return Item(kind=ItemKind.TOMATO, form=form)


def lettuce() -> Item:
    return Item(kind=ItemKind.LETTUCE, form=ItemForm.RAW)


def rice() -> Item:
    return Item(kind=ItemKind.RICE, form=ItemForm.RAW)


def frame(player_id: str, seq: int, action: bool, tick: int) -> PlayerInput:
    return PlayerInput(player_id=player_id, seq=seq, action=action, received_at_tick=tick)


def kinds(events: tuple[Event, ...]) -> list[EventKind]:
    return [EventKind(event.kind) for event in events]


def payload(event: Event) -> dict[str, Any]:
    return dict(event.payload)


def total_items(state: KitchenState) -> int:
    """The conservation quantity: hands + station contents + trashed."""
    in_hands = sum(1 for player in state.players if player.carrying is not None)
    on_stations = sum(len(station.contents) for station in state.stations)
    trashed = state.counters.get("trashed", 0)
    return in_hands + on_stations + trashed


# --- grabbability: a set-down is an object, a pipeline input is work ---------------------


def test_a_set_down_item_is_targeted_by_a_free_hand_on_an_idle_surface() -> None:
    """The whole of the hand-off: a placed item on a counter is grabbable at once."""
    prep = fixture(kind=StationKind.PREP, contents=(lettuce(),))
    state = make_state(stations=(prep,), players=(cook("p0"),))
    state = replace(state, item_marks={prep.id: (("placerr", 3),)})
    target = select_target(state, state.players[0])
    assert isinstance(target, ItemTarget)
    assert target.item == lettuce()


def test_an_unmarked_loaded_surface_holds_its_item_for_the_work_press() -> None:
    """An onion on an idle board is *to be chopped*: no mark, not `READY`, not a shelf."""
    board = fixture(kind=StationKind.CHOP_BOARD, contents=(tomato(),))
    state = make_state(stations=(board,), players=(cook("p0"),))
    target = select_target(state, state.players[0])
    assert isinstance(target, StationTarget)
    assert first_loose_entry(state, board) is None


def test_a_ready_unmarked_fixture_hands_its_output_to_a_free_hand() -> None:
    ready = fixture(
        kind=StationKind.CHOP_BOARD,
        state=StationState.READY,
        contents=(tomato(ItemForm.CHOPPED),),
    )
    state = make_state(stations=(ready,), players=(cook("p0"),))
    target = select_target(state, state.players[0])
    assert isinstance(target, ItemTarget)
    assert target.item.form is ItemForm.CHOPPED


def test_the_shelf_hands_its_entries_whether_marked_or_stock() -> None:
    """Shelf entries are all grabbable: stock (unmarked) first, then set-downs."""
    shelf = fixture(kind=StationKind.SPAWN_SHELF, contents=(tomato(), lettuce()))
    state = make_state(stations=(shelf,), players=(cook("p0"),))
    entry = first_loose_entry(state, shelf)
    assert entry is not None and entry[0] == tomato()  # the unmarked stock entry is first
    target = select_target(state, state.players[0])
    assert isinstance(target, ItemTarget)
    assert target.item == tomato()


def test_a_marked_set_down_stays_grabbable_after_the_placer_moves_away() -> None:
    """The mark outlives the press: the object is on the counter, not in a hand."""
    station = fixture(kind=StationKind.PREP, contents=(lettuce(),))
    state = make_state(stations=(station,), players=(cook("p0"),))
    state = replace(state, item_marks={station.id: (("other", 5),)})
    target = select_target(state, state.players[0])
    assert isinstance(target, ItemTarget)
    assert target.item == lettuce()


# --- one item per hand -----------------------------------------------------------------


def test_a_full_hand_refuses_a_second_pick_with_one_named_denial() -> None:
    ready = fixture(state=StationState.READY, contents=(tomato(),))
    state = make_state(stations=(ready,), players=(cook("p0", carrying=lettuce()),))
    frames = {"p0": frame("p0", 0, True, 0)}
    _new_state, events = action_gate(state, frames, STEP_DT)
    denied = [event for event in events if event.kind is EventKind.DENIED]
    assert len(denied) == 1  # one refusal per press, never per tick
    assert payload(denied[0])["reason"] == "hands_full"


def test_a_press_at_open_floor_with_a_full_hand_is_a_named_nothing_here() -> None:
    """v1 has no floor drops: a `RELEASE` at a FLOOR cell is `NOTHING_HERE`, not a drop."""
    state = make_state(players=(cook("p0", carrying=lettuce()),))  # no stations at all
    new_state, events = resolve_action(state, state.players[0])
    assert new_state is state
    assert len(events) == 1
    assert payload(events[0])["reason"] == "nothing_here"


# --- pick/place round trip --------------------------------------------------------------


def test_pick_and_place_preserve_the_item_and_clear_the_station_cell() -> None:
    """The identity fields survive the whole round trip; the cell is cleared on the pick."""
    item = Item(kind=ItemKind.TOMATO, form=ItemForm.CHOPPED, quality=0.42, ttl=3.5)
    ready = fixture(state=StationState.READY, contents=(item,))
    shelf = fixture(kind=StationKind.SPAWN_SHELF, x=8)
    state = make_state(stations=(ready, shelf), players=(cook("p0"),))
    new_state, events = resolve_action(state, state.players[0])
    assert len(events) == 1 and events[0].kind is EventKind.PICKED
    carried = new_state.players[0].carrying
    assert carried is item  # value identity: the very object left the fixture
    assert new_state.stations[0].contents == ()  # the cell is cleared
    # the set-down: move the cook to the shelf, press again
    cook_at_shelf = replace(new_state.players[0], pos=Vec2(8.5, 5.5))
    new_state2, events2 = resolve_action(new_state, cook_at_shelf)
    assert len(events2) == 1 and events2[0].kind is EventKind.DROPPED
    assert new_state2.players[0].carrying is None
    assert new_state2.stations[1].contents == (item,)  # the same object, back on a fixture
    assert item.quality == 0.42 and item.ttl == 3.5  # the fields never move


@pytest.mark.parametrize(
    "kind",
    [StationKind.CHOP_BOARD, StationKind.PREP, StationKind.SPAWN_SHELF],
    ids=["place_on_station", "plate_dish", "release"],
)
def test_place_verbs_put_the_item_on_the_counter_and_stamp_the_mark(
    kind: StationKind,
) -> None:
    """`PLACE_ON_STATION` (board), `PLATE_DISH` (the counter) and `RELEASE` (the shelf)."""
    held = lettuce()
    station = fixture(kind=kind)
    state = make_state(stations=(station,), players=(cook("p0", carrying=held),))
    new_state, events = resolve_action(state, state.players[0])
    assert len(events) == 1 and events[0].kind is EventKind.DROPPED
    assert new_state.players[0].carrying is None
    assert new_state.stations[0].contents == (held,)
    # the mark: who put it down, at which tick — the hand-off's whole memory
    assert new_state.item_marks[station.id] == (("p0", 0),)


# --- the hand-off -----------------------------------------------------------------------


def _pass_kitchen() -> KitchenState:
    """A at the prep, B at its left diagonal, both facing the counter; A holds an item."""
    prep = fixture(kind=StationKind.PREP, x=9, y=4)
    a = cook("cook-a", pos=Vec2(9.5, 5.5), carrying=lettuce(), seat=0)
    b = cook("cook-b", pos=Vec2(8.5, 5.5), seat=1)
    return make_state(stations=(prep,), players=(a, b))


def test_a_pass_is_a_handed_off_with_both_ids() -> None:
    state = _pass_kitchen()
    # t0: A sets the item down (the marked place)
    state, events = step(state, STEP_DT, (frame("cook-a", 0, True, 0),))
    assert kinds(events) == [EventKind.DROPPED]
    assert payload(events[0])["player_id"] == "cook-a"
    # t1: A releases; B picks it up -> the sanctioned pass
    state, events = step(
        state,
        STEP_DT,
        (frame("cook-a", 1, False, 1), frame("cook-b", 1, True, 1)),
    )
    handed = [event for event in events if event.kind is EventKind.HANDED_OFF]
    assert len(handed) == 1
    assert payload(handed[0]) == {
        "from": "cook-a",
        "to": "cook-b",
        "item": "lettuce",
        "form": "raw",
    }
    assert state.players[1].carrying is not None
    assert state.players[0].carrying is None
    assert state.stations[0].contents == ()


def test_the_hand_off_window_is_inclusive_at_the_twentieth_tick() -> None:
    station = fixture(kind=StationKind.PREP)
    a = cook("cook-a", carrying=lettuce())
    b = cook("cook-b", seat=1)
    state = make_state(stations=(station,), players=(a, b))
    held = a.carrying
    assert held is not None
    placed, _events = place_item(state, a, station, held)
    at_boundary = placed.with_tick(HANDOFF_WINDOW_TICKS)
    _new_state, events = pick_item(at_boundary, b, station, lettuce())
    assert kinds(events) == [EventKind.HANDED_OFF]
    assert payload(events[0]) == {
        "from": "cook-a",
        "to": "cook-b",
        "item": "lettuce",
        "form": "raw",
    }
    just_after = placed.with_tick(HANDOFF_WINDOW_TICKS + 1)
    _new_state, events = pick_item(just_after, b, station, lettuce())
    assert kinds(events) == [EventKind.PICKED]


def test_the_placer_picking_their_own_item_is_a_plain_pick() -> None:
    station = fixture(kind=StationKind.PREP)
    a = cook("cook-a", carrying=lettuce())
    state = make_state(stations=(station,), players=(a,))
    held = a.carrying
    assert held is not None
    placed, _events = place_item(state, a, station, held)
    new_state, events = pick_item(placed.with_tick(1), a, station, lettuce())
    assert kinds(events) == [EventKind.PICKED]
    assert new_state.players[0].carrying is not None


def test_a_third_party_pick_outside_the_window_is_a_plain_pick() -> None:
    """A's set-down, C's pick one tick past the window: a pick, never a pass."""
    station = fixture(kind=StationKind.PREP)
    a = cook("cook-a", carrying=lettuce())
    c = cook("cook-c", seat=2)
    state = make_state(stations=(station,), players=(a, c))
    held = a.carrying
    assert held is not None
    placed, _events = place_item(state, a, station, held)
    late = placed.with_tick(HANDOFF_WINDOW_TICKS + 1)
    new_state, events = pick_item(late, c, station, lettuce())
    assert kinds(events) == [EventKind.PICKED]
    assert payload(events[0])["player_id"] == "cook-c"
    assert new_state.players[1].carrying is not None
    assert EventKind.HANDED_OFF not in kinds(events)


def test_a_same_tick_pass_is_inside_the_window() -> None:
    """Place and pick in the same substep (seat order): the pass, at zero ticks old."""
    station = fixture(kind=StationKind.PREP)
    a = cook("cook-a", carrying=lettuce(), seat=0)
    b = cook("cook-b", seat=1)
    state = make_state(stations=(station,), players=(a, b))
    frames = {"cook-a": frame("cook-a", 0, True, 0), "cook-b": frame("cook-b", 0, True, 0)}
    new_state, events = action_gate(state, frames, STEP_DT)
    assert kinds(events) == [EventKind.DROPPED, EventKind.HANDED_OFF]
    assert payload(events[1]) == {
        "from": "cook-a",
        "to": "cook-b",
        "item": "lettuce",
        "form": "raw",
    }
    assert new_state.players[1].carrying is not None
    assert new_state.players[0].carrying is None
    assert new_state.stations[0].contents == ()


# --- the trash ---------------------------------------------------------------------------


def _trash_kitchen() -> KitchenState:
    trash = fixture(kind=StationKind.TRASH)
    return make_state(stations=(trash,), players=(cook("p0", carrying=lettuce()),))


def test_a_trash_long_press_destroys_on_the_eighth_substep_not_the_seventh() -> None:
    state = _trash_kitchen()
    for substep in range(TRASH_HOLD_TICKS - 1):  # substeps 1..7: the hold builds
        state, events = step(state, STEP_DT, (frame("p0", substep, True, state.tick),))
        assert state.players[0].carrying is not None
        assert EventKind.TRASHED not in kinds(events)
    # the 8th substep of the hold: the item goes
    state, events = step(
        state, STEP_DT, (frame("p0", TRASH_HOLD_TICKS - 1, True, state.tick),)
    )
    trashed = [event for event in events if event.kind is EventKind.TRASHED]
    assert len(trashed) == 1
    assert payload(trashed[0]) == {
        "player_id": "p0",
        "item": "lettuce",
        "form": "raw",
        "score_delta": TRASH_SCORE_DELTA,
    }
    assert state.players[0].carrying is None
    assert state.counters["trashed"] == 1
    assert state.score == 0  # the raw delta is phase 04's to spend (clamped at 0)


def test_a_short_press_does_not_trash() -> None:
    state = _trash_kitchen()
    for substep in range(3):
        state, _events = step(state, STEP_DT, (frame("p0", substep, True, state.tick),))
    state, _events = step(state, STEP_DT, (frame("p0", 3, False, state.tick),))
    assert state.players[0].carrying is not None
    assert "trashed" not in state.counters


def test_releasing_before_the_threshold_starts_a_fresh_hold() -> None:
    state = _trash_kitchen()
    plan = (True, True, True, True, True, False) + (True,) * TRASH_HOLD_TICKS
    for substep, action in enumerate(plan):
        state, events = step(state, STEP_DT, (frame("p0", substep, action, state.tick),))
        if substep < len(plan) - 1:
            assert state.players[0].carrying is not None
            assert EventKind.TRASHED not in kinds(events)
    assert state.players[0].carrying is None  # the 8th substep of the *second* hold
    assert state.counters["trashed"] == 1


def test_walking_away_from_the_trash_voids_the_hold() -> None:
    """The gate re-derives the hold: off the can, the button is no longer `TRASH`."""
    state = _trash_kitchen()
    for substep in range(TRASH_HOLD_TICKS):  # the hold's 8 substeps, walking right
        walking = PlayerInput(
            player_id="p0",
            seq=substep,
            action=True,
            move=Vec2(1.0, 0.0),
            received_at_tick=state.tick,
        )
        state, events = step(state, STEP_DT, (walking,))
        assert EventKind.TRASHED not in kinds(events)
    for substep in range(TRASH_HOLD_TICKS, TRASH_HOLD_TICKS + 6):
        state, events = step(state, STEP_DT, (frame("p0", substep, True, state.tick),))
        assert EventKind.TRASHED not in kinds(events)
    assert state.players[0].carrying is not None  # the hold was voided, nothing trashed
    assert "trashed" not in state.counters


def test_a_trash_threshold_with_an_empty_hand_is_named_not_silent() -> None:
    """Defensive path: the threshold met with an empty hand is an event, not a no-op."""
    trash = fixture(kind=StationKind.TRASH)
    state = make_state(stations=(trash,), players=(cook("p0"),))  # nothing carried
    before = state.state_hash()
    new_state, events = trash_effect(state, state.players[0])
    assert kinds(events) == [EventKind.TRASHED_ALREADY_EMPTY]
    assert payload(events[0]) == {"player_id": "p0"}
    assert new_state is state  # nothing moved
    assert state.state_hash() == before


# --- contested picks (the new paths, conserved) ------------------------------------------


def _contested_kitchen() -> tuple[KitchenState, dict[str, PlayerInput]]:
    """Two cooks on one ready item: seat 0 in front, seat 1 on the left diagonal."""
    ready = fixture(state=StationState.READY, contents=(tomato(),))
    state = make_state(
        stations=(ready,),
        players=(
            cook("cook-a", seat=0),  # (5, 5) facing UP: front cell (5, 4)
            cook("cook-b", pos=Vec2(6.5, 5.5), facing=Facing.LEFT, seat=1),
        ),
    )
    frames = {
        "cook-a": frame("cook-a", 0, True, 0),
        "cook-b": frame("cook-b", 0, True, 0),
    }
    return state, frames


def test_a_contested_pick_has_exactly_one_winner_and_conserves_items() -> None:
    state, frames = _contested_kitchen()
    initial = total_items(state)
    new_state, events = action_gate(state, frames, STEP_DT)
    picked = [event for event in events if event.kind is EventKind.PICKED]
    denied = [event for event in events if event.kind is EventKind.DENIED]
    assert len(picked) == 1 and len(denied) == 1
    assert payload(picked[0])["player_id"] == "cook-a"  # the full tie goes to the seat
    assert payload(denied[0]) == {
        "player_id": "cook-b",
        "reason": "contested_lost",
        "verb": "none",
    }
    assert new_state.players[0].carrying is not None
    assert new_state.players[1].carrying is None
    assert new_state.stations[0].contents == ()
    assert total_items(new_state) == initial  # the item is in exactly one place


def test_the_earlier_received_frame_wins_regardless_of_seat() -> None:
    state, frames = _contested_kitchen()
    frames["cook-a"] = frame("cook-a", 0, True, 1)  # seat 0 arrives one tick later
    new_state, _events = action_gate(state, frames, STEP_DT)
    assert new_state.players[1].carrying is not None  # the earlier frame wins
    assert new_state.players[0].carrying is None


def test_a_contested_start_work_claims_the_worker_slot() -> None:
    """A loaded unmarked board: the single worker slot is the claim, not an item."""
    board = fixture(kind=StationKind.CHOP_BOARD, contents=(tomato(),))
    a = cook("cook-a", seat=0)
    b = cook("cook-b", pos=Vec2(6.5, 5.5), facing=Facing.LEFT, seat=1)
    state = make_state(stations=(board,), players=(a, b))
    frames = {"cook-a": frame("cook-a", 0, True, 0), "cook-b": frame("cook-b", 0, True, 0)}
    new_state, events = action_gate(state, frames, STEP_DT)
    denied = [event for event in events if event.kind is EventKind.DENIED]
    assert len(denied) == 1
    assert payload(denied[0]) == {
        "player_id": "cook-b",
        "reason": "contested_lost",
        "verb": "none",
    }
    assert new_state.stations[0].contents == (tomato(),)  # the input stays for the work


# --- the conservation law: 100-tick fuzz -------------------------------------------------


DIRECTIONS: tuple[Vec2, ...] = (
    Vec2(0.0, 0.0),
    Vec2(1.0, 0.0),
    Vec2(-1.0, 0.0),
    Vec2(0.0, 1.0),
    Vec2(0.0, -1.0),
    Vec2(1.0, 1.0),
    Vec2(1.0, -1.0),
    Vec2(-1.0, 1.0),
    Vec2(-1.0, -1.0),
)


def _fuzz_kitchen() -> KitchenState:
    """Three cooks, one carried item each, at a shelf / prep / trash in a row."""
    shelf = fixture(kind=StationKind.SPAWN_SHELF, x=5)
    prep = fixture(kind=StationKind.PREP, x=7)
    trash = fixture(kind=StationKind.TRASH, x=9)
    state = make_state(
        stations=(shelf, prep, trash),
        players=(
            cook("p0", pos=Vec2(5.5, 5.5), carrying=tomato(), seat=0),
            cook("p1", pos=Vec2(7.5, 5.5), carrying=lettuce(), seat=1),
            cook("p2", pos=Vec2(9.5, 5.5), carrying=rice(), seat=2),
        ),
    )
    assert total_items(state) == 3
    return state


def _fuzz_run(seed: int, ticks: int = 100) -> tuple[KitchenState, list[str]]:
    """One fuzz run: random move + random press per cook per tick, from `seed`."""
    rng = Rng(seed)
    state = _fuzz_kitchen()
    hashes: list[str] = []
    for tick in range(ticks):
        frames = tuple(
            PlayerInput(
                player_id=player.id,
                seq=tick,
                move=rng.choice(DIRECTIONS),
                action=rng.next_float() < 0.35,
                received_at_tick=state.tick,
            )
            for player in state.players
        )
        state, _events = step(state, STEP_DT, frames)
        assert total_items(state) == 3, f"item count lost at tick {state.tick}"
        hashes.append(state.state_hash())
    return state, hashes


def test_the_item_count_is_conserved_over_a_hundred_tick_fuzz() -> None:
    """The per-tick assert is the point: a leak mid-run would surface immediately."""
    state, _hashes = _fuzz_run(0xC0FFEE)
    assert total_items(state) == 3  # and at the end, as the task requires


def test_the_fuzz_is_bit_identical_across_two_runs() -> None:
    first, first_hashes = _fuzz_run(0xC0FFEE)
    second, second_hashes = _fuzz_run(0xC0FFEE)
    assert first_hashes == second_hashes  # the whole history, tick for tick
    assert first.state_hash() == second.state_hash()