"""`sim/orders.py` — the ticket rail: seeded spawning, the concurrency cap,
the full-rail retry, tick-precise deadlines, and the miss bookkeeping.

The spec the rail runs on is the level's `orders` copied as scalars in tick
units onto the state (phase 04 task 02); `build_state` does the copy, and
these tests pin both halves: the copy (from a real `Level`) and the stage
itself (hand-built states, so a rule is one knob at a time). The
reproducibility contract is a pair: the same seed replays the same order
sequence (spawn ticks, recipes, ids, the `rng_state` thread), and a
different seed diverges.
"""

from __future__ import annotations

from dataclasses import replace
from itertools import pairwise
from typing import Any

import pytest

from undercooked.sim.grid import Grid
from undercooked.sim.level import Level, LevelDef
from undercooked.sim.model import (
    Event,
    EventKind,
    KitchenState,
    Order,
    TileKind,
)
from undercooked.sim.orders import (
    FIRST_ORDER_DELAY_TICKS,
    MIN_RETRY_TICKS,
    TICK_SECONDS,
    order_summary,
    step_orders,
    to_ticks,
)
from undercooked.sim.recipe import RecipeBook
from undercooked.sim.rng import Rng
from undercooked.sim.state_build import SeatSpec, build_state
from undercooked.sim.step import STEP_DT, step

pytestmark = pytest.mark.unit

#: The recipe ids the tests draw from — none of them is a shipped recipe id.
RECIPE_IDS: tuple[str, ...] = ("dish_a", "dish_b", "dish_c", "dish_d")

#: `base_score` per recipe id: the value an order carries, checked by the tests.
BASE_SCORES: dict[str, int] = {"dish_a": 40, "dish_b": 30, "dish_c": 50, "dish_d": 70}

SEED = 0x204F_0002


def book() -> RecipeBook:
    return RecipeBook.model_validate(
        {
            "recipes": {
                recipe_id: {
                    "id": recipe_id,
                    "name": recipe_id.title(),
                    "base_score": BASE_SCORES[recipe_id],
                    "ingredients": [{"kind": "tomato", "form": "raw"}],
                    "steps": [{"kind": "serve", "station": "serve"}],
                }
                for recipe_id in RECIPE_IDS
            }
        }
    )


def make_state(
    *,
    pool: tuple[str, ...] = ("dish_a", "dish_b"),
    concurrent: int = 2,
    spawn_min: int = 40,
    spawn_max: int = 80,
    deadline: int = 120,
    penalty: int = 10,
    next_order_at: int = FIRST_ORDER_DELAY_TICKS,
    next_order_id: int = 1,
    seed: int = SEED,
    tick: int = 0,
    orders: tuple[Order, ...] = (),
    target_score: int = 100,
) -> KitchenState:
    """A hand-built round: a bare floor, the spec scalars, nothing else."""
    return KitchenState(
        level_id="04_orders",
        seed=seed,
        grid=Grid(width=8, height=8, tiles=(TileKind.FLOOR,) * 64),
        tick=tick,
        orders=orders,
        order_pool=pool,
        order_concurrent=concurrent,
        order_spawn_min=spawn_min,
        order_spawn_max=spawn_max,
        order_deadline=deadline,
        order_penalty=penalty,
        next_order_at=next_order_at,
        next_order_id=next_order_id,
        rng_state=seed,
        target_score=target_score,
        time_left=600.0,
    )


def run_ticks(
    state: KitchenState,
    ticks: int,
    value_book: RecipeBook | None = None,
) -> tuple[KitchenState, list[Event]]:
    """`ticks` substeps of the order stage, driven the way the kernel drives
    them: the stage runs on the pre-increment tick, then the tick advances.
    The events come back in substep order.
    """
    events: list[Event] = []
    current = state
    for _ in range(ticks):
        current, produced = step_orders(current, STEP_DT, value_book)
        current = replace(current, tick=current.tick + 1)
        events.extend(produced)
    return current, events


def spawn_log(
    state: KitchenState, ticks: int
) -> tuple[list[int], list[str], list[int]]:
    """Run the stage for `ticks` substeps; return the spawn (tick, recipe, id) log.

    A spawn is detected by `next_order_id` rising — that also covers the
    busy-rail case where a spawn lands on the same substep an order expires
    and the rail length does not change.
    """
    spawn_ticks_found: list[int] = []
    recipes: list[str] = []
    ids: list[int] = []
    current = state
    book_value = book()
    for _ in range(ticks):
        due = current.tick  # the pre-increment tick this substep runs on
        before_id = current.next_order_id
        current, _ = step_orders(current, STEP_DT, book_value)
        current = replace(current, tick=current.tick + 1)
        if current.next_order_id != before_id:
            spawned = next(o for o in current.orders if o.id == before_id)
            spawn_ticks_found.append(due)
            recipes.append(spawned.recipe_id)
            ids.append(spawned.id)
    return spawn_ticks_found, recipes, ids


def rng_after_draws(seed: int, draws: int) -> int:
    """The `Rng` counter after exactly `draws` `next_u64`s from `seed`."""
    rng = Rng(seed)
    for _ in range(draws):
        rng.next_u64()
    return rng.state


# --- the constants and the conversion ----------------------------------------


def test_the_first_order_delay_is_one_and_a_half_seconds() -> None:
    assert FIRST_ORDER_DELAY_TICKS == 30
    assert pytest.approx(1.5) == FIRST_ORDER_DELAY_TICKS * TICK_SECONDS


def test_the_full_rail_retry_gap_is_one_second() -> None:
    assert MIN_RETRY_TICKS == 20
    assert pytest.approx(1.0) == MIN_RETRY_TICKS * TICK_SECONDS


@pytest.mark.parametrize(
    ("seconds", "ticks"),
    [(4.0, 80), (6.0, 120), (30.0, 600), (16.0, 320), (0.04, 1), (0.0, 1)],
)
def test_to_ticks_converts_and_clamps_to_at_least_one(
    seconds: float, ticks: int
) -> None:
    assert to_ticks(seconds) == ticks


# --- the first-order delay ----------------------------------------------------


def test_nothing_spawns_before_the_first_order_delay() -> None:
    state = make_state()
    assert state.next_order_at == FIRST_ORDER_DELAY_TICKS
    for _ in range(FIRST_ORDER_DELAY_TICKS):
        state, events = step_orders(state, STEP_DT, book())
        state = replace(state, tick=state.tick + 1)
        assert events == ()
        assert state.orders == (), f"a spawn before tick {FIRST_ORDER_DELAY_TICKS}"
        assert state.next_order_at == FIRST_ORDER_DELAY_TICKS
        assert state.rng_state == SEED  # no draw before the first spawn


def test_the_first_order_spawns_at_the_delay_and_schedules_the_next() -> None:
    state = make_state(spawn_min=40, spawn_max=80, deadline=120)
    state, _ = run_ticks(state, FIRST_ORDER_DELAY_TICKS + 1, book())  # spawn on tick 30
    assert state.tick == FIRST_ORDER_DELAY_TICKS + 1
    assert len(state.orders) == 1
    order = state.orders[0]
    assert order.id == 1
    assert order.recipe_id in ("dish_a", "dish_b")
    assert order.value == BASE_SCORES[order.recipe_id]
    assert order.deadline == FIRST_ORDER_DELAY_TICKS + 120
    assert order.time_left == 120 * TICK_SECONDS
    assert state.next_order_id == 2
    assert FIRST_ORDER_DELAY_TICKS + 40 <= state.next_order_at <= FIRST_ORDER_DELAY_TICKS + 80
    # a spawn is exactly two draws: the choice, then the interval.
    assert state.rng_state == rng_after_draws(SEED, 2)


def test_a_single_recipe_pool_spawns_that_recipe() -> None:
    state = make_state(pool=("dish_c",))
    state, _ = run_ticks(state, FIRST_ORDER_DELAY_TICKS + 1, book())
    assert len(state.orders) == 1
    assert state.orders[0].recipe_id == "dish_c"
    assert state.orders[0].value == 50  # BASE_SCORES["dish_c"]


# --- the full-rail retry (its own test) --------------------------------------


def test_a_full_rail_retries_after_one_second_without_consuming_a_draw() -> None:
    """The rule, stated: a due tick the rail cannot serve retries `MIN_RETRY_TICKS`
    later and spends neither the recipe draw nor the interval draw — otherwise
    a full rail would silently warp the cadence."""
    state = make_state(concurrent=1, spawn_min=50, spawn_max=50, deadline=100)
    state, _ = run_ticks(state, FIRST_ORDER_DELAY_TICKS + 1, book())  # spawn on tick 30
    assert len(state.orders) == 1
    assert state.orders[0].deadline == FIRST_ORDER_DELAY_TICKS + 100
    after_first = state.rng_state

    # due at 80 (30 + 50): the order lives until 130, so the rail is full:
    # retry from 80 to 100.
    state, _ = run_ticks(state, 50, book())  # substeps on ticks 31..80
    assert state.tick == 81
    assert len(state.orders) == 1
    assert state.next_order_at == 80 + MIN_RETRY_TICKS
    assert state.rng_state == after_first, "a retry must not consume a draw"

    # due at 100 and 120: still full, still no draw.
    state, _ = run_ticks(state, 20, book())
    assert state.tick == 101
    assert state.next_order_at == 100 + MIN_RETRY_TICKS
    assert state.rng_state == after_first
    state, _ = run_ticks(state, 20, book())
    assert state.tick == 121
    assert state.next_order_at == 120 + MIN_RETRY_TICKS
    assert state.rng_state == after_first

    # the order expires on the tick it reaches 0 (30 + 100 = 130) — a miss.
    state, events = run_ticks(state, 10, book())  # substeps on ticks 121..130
    assert state.tick == 131
    assert state.orders == ()
    assert state.counters["missed"] == 1
    assert len(events) == 1 and events[0].kind is EventKind.ORDER_MISSED

    # due at 140: the rail is free — the *first* draw after the first spawn
    # is this spawn's, and the interval draw it consumed was the retry's, not
    # one of the blocked due ticks'.
    state, _ = run_ticks(state, 10, book())  # substeps on ticks 131..140
    assert state.tick == 141
    assert len(state.orders) == 1
    assert state.orders[0].id == 2
    assert state.rng_state == rng_after_draws(SEED, 4)


def test_an_empty_pool_never_spawns_and_never_retries() -> None:
    state = make_state(pool=(), next_order_at=FIRST_ORDER_DELAY_TICKS)
    for _ in range(100):
        state, events = step_orders(state, STEP_DT, None)  # no book needed
        state = replace(state, tick=state.tick + 1)
        assert events == ()
        assert state.orders == ()
        assert state.next_order_id == 1
        assert state.rng_state == SEED


def test_never_two_spawns_on_the_same_tick_even_with_a_zero_tick_span() -> None:
    """A `spawn_min` of 0 ticks (a hand-built state the schema would refuse)
    still schedules at least one tick ahead: the clamp is the guard."""
    state = make_state(spawn_min=0, spawn_max=0, deadline=1000)
    state, _ = run_ticks(state, FIRST_ORDER_DELAY_TICKS + 1, book())  # spawn on tick 30
    assert len(state.orders) == 1
    assert state.next_order_at == FIRST_ORDER_DELAY_TICKS + 1  # clamped, one ahead
    state, _ = run_ticks(state, 1, book())  # the substep on tick 31
    assert len(state.orders) == 2  # the clamp bought exactly the *next* tick


# --- deadline expiry, to the tick ---------------------------------------------


def test_an_order_lives_exactly_its_deadline_substeps() -> None:
    deadline_ticks = 10
    state = make_state(deadline=deadline_ticks, spawn_min=1000, spawn_max=1000)
    state, _ = run_ticks(state, FIRST_ORDER_DELAY_TICKS + 1, book())  # spawn on tick 30
    assert len(state.orders) == 1
    spawn_tick = state.tick - 1
    assert state.orders[0].deadline == spawn_tick + deadline_ticks

    # the second substep of life: one tick has gone, 0.05 s of clock remains
    # per remaining tick.
    for expected_remaining in range(deadline_ticks - 1, 0, -1):
        state, events = step_orders(state, STEP_DT, book())
        state = replace(state, tick=state.tick + 1)
        assert events == ()
        assert len(state.orders) == 1
        assert state.orders[0].time_left == pytest.approx(
            expected_remaining * TICK_SECONDS, abs=1e-9
        )

    # on the tick that reaches 0 the order is gone, missed, and named.
    expire_tick = spawn_tick + deadline_ticks
    state, events = step_orders(state, STEP_DT, book())
    state = replace(state, tick=state.tick + 1)
    assert state.tick == expire_tick + 1
    assert state.orders == ()
    assert state.counters["missed"] == 1
    assert len(events) == 1
    assert events[0].kind is EventKind.ORDER_MISSED


def test_the_order_missed_event_names_the_order_and_the_tick() -> None:
    state = make_state(deadline=10, spawn_min=1000, spawn_max=1000)
    state, _ = run_ticks(state, FIRST_ORDER_DELAY_TICKS + 1, book())  # spawn on tick 30
    order = state.orders[0]
    _state, events = run_ticks(state, 10, book())  # substeps on ticks 31..40: expiry at 40
    event = events[0]
    assert event.kind is EventKind.ORDER_MISSED
    assert event.x == 0.0 and event.y == 0.0  # the rail is HUD, not floor
    assert dict(event.payload) == {
        "id": order.id,
        "r": order.recipe_id,
        "tick": order.deadline,
    }


def test_a_miss_is_counted_per_order_and_the_penalty_is_on_the_state() -> None:
    state = make_state(concurrent=2, deadline=10, spawn_min=1000, spawn_max=1000)
    state, _ = run_ticks(state, FIRST_ORDER_DELAY_TICKS + 1, book())  # spawn on tick 30
    assert len(state.orders) == 1
    # a second order cannot spawn (the interval is 1000 ticks away), so fill
    # the rail by hand: a pre-placed order that expires on the next substep.
    other = Order(
        id=99,
        recipe_id="dish_b",
        time_left=0.05,
        deadline=float(state.tick),  # due this substep: it is the miss
        value=30,
    )
    state = replace(state, orders=(*state.orders, other))
    state, events = step_orders(state, STEP_DT, book())
    assert state.counters["missed"] == 1
    assert len(events) == 1
    assert state.order_penalty == 10  # task 03's scoring spends it, not this stage


# --- 200 seconds: cadence bounds, the cap, and unbounded growth ---------------


def test_spawn_gaps_stay_in_the_interval_bounds_over_200_seconds() -> None:
    """A rail that is always free when a spawn is due (the orders outlive no
    interval): every gap is a plain interval draw, so all of them are in
    `[min, max]` — and the cap, the ids and the first delay hold for the whole
    200 simulated seconds."""
    min_ticks, max_ticks, deadline = 40, 120, 30
    state = make_state(
        pool=RECIPE_IDS,
        concurrent=4,
        spawn_min=min_ticks,
        spawn_max=max_ticks,
        deadline=deadline,
        seed=0x204F_0003,
    )
    total_ticks = 200 * round(1.0 / TICK_SECONDS)  # 200 s of substeps
    spawns: list[int] = []
    seen_ids: list[int] = []
    max_rail = 0
    for _ in range(total_ticks):
        before = state
        state, _ = step_orders(state, STEP_DT, book())
        state = replace(state, tick=state.tick + 1)
        assert len(state.orders) <= 4, "the rail exceeded its cap"
        max_rail = max(max_rail, len(state.orders))
        if state.next_order_id != before.next_order_id:
            spawns.append(before.tick)  # the pre-increment tick the spawn ran on
            seen_ids.append(before.next_order_id)
    assert spawns, "200 seconds with a live pool must spawn orders"
    assert spawns[0] == FIRST_ORDER_DELAY_TICKS
    gaps = [b - a for a, b in pairwise(spawns)]
    assert all(min_ticks <= gap <= max_ticks for gap in gaps), gaps
    assert seen_ids == list(range(1, len(seen_ids) + 1)), "ids are monotonic, unique"
    assert max_rail >= 1
    # the cap actually bound somewhere is proven by the busy-rail test; here
    # the orders outlive no interval, so the rail never fills.
    assert state.counters.get("missed", 0) >= 0


def test_the_rail_never_exceeds_the_cap_under_a_busy_rail_over_200_seconds() -> None:
    """A rail that is often full: the cap holds on every tick, spawns only
    ever land on due ticks, the full-rail retry path is actually exercised,
    and the id sequence stays a contiguous run."""
    state = make_state(
        pool=RECIPE_IDS,
        concurrent=2,
        spawn_min=20,
        spawn_max=40,
        deadline=400,  # the orders outlive the interval: the rail stays busy
        seed=0x204F_0004,
    )
    total_ticks = 200 * round(1.0 / TICK_SECONDS)
    seen_ids: list[int] = []
    retries = 0
    for _ in range(total_ticks):
        before = state
        state, _ = step_orders(state, STEP_DT, book())
        state = replace(state, tick=state.tick + 1)
        assert len(state.orders) <= 2, "the rail exceeded its cap"
        if state.next_order_id != before.next_order_id:
            assert before.tick >= before.next_order_at, "a spawn off a non-due tick"
            seen_ids.append(before.next_order_id)
        elif before.tick >= before.next_order_at and before.order_pool:
            # a due tick the full rail could not serve: the documented retry.
            assert state.next_order_at == before.tick + MIN_RETRY_TICKS
            retries += 1
    assert seen_ids, "a busy 200 s must spawn orders"
    assert seen_ids == list(range(1, len(seen_ids) + 1)), "ids are monotonic, unique"
    assert retries >= 1, "a busy rail must exercise the full-rail retry path"


# --- reproducibility ----------------------------------------------------------


def test_the_same_seed_replays_the_identical_order_sequence() -> None:
    def run(seed: int) -> tuple[list[int], list[str], list[int], int]:
        state = make_state(
            pool=RECIPE_IDS,
            concurrent=3,
            spawn_min=30,
            spawn_max=90,
            deadline=120,
            seed=seed,
        )
        ticks, recipes, ids = spawn_log(state, 6000)  # 300 s
        return ticks, recipes, ids, state.rng_state

    first = run(SEED)
    second = run(SEED)
    assert first == second
    assert len(first[0]) >= 2, "300 s must spawn more than one order"
    assert len(set(first[1])) >= 2, "a four-recipe pool must show at least two dishes"
    # counters agree too: rebuild one side and compare the miss count.
    state = make_state(
        pool=RECIPE_IDS, concurrent=3, spawn_min=30, spawn_max=90, deadline=120, seed=SEED
    )
    state, _ = run_ticks(state, 6000, book())
    assert state.counters.get("missed", 0) >= 1


def test_a_different_seed_diverges() -> None:
    def run(seed: int) -> tuple[list[int], list[str], list[int]]:
        state = make_state(
            pool=RECIPE_IDS,
            concurrent=3,
            spawn_min=30,
            spawn_max=90,
            deadline=120,
            seed=seed,
        )
        return spawn_log(state, 6000)

    one = run(0x204F_0005)
    two = run(0x204F_0006)
    assert one[1] != two[1] or one[0] != two[0], "different seeds must diverge"


# --- order_summary ------------------------------------------------------------


def test_order_summary_is_the_compact_rail() -> None:
    state = make_state(
        pool=("dish_a",), next_order_at=5, deadline=20, spawn_min=100, spawn_max=100
    )
    state, _ = run_ticks(state, 6, book())  # the spawn lands on pre-increment tick 5
    assert state.tick == 6
    assert len(state.orders) == 1
    summary = order_summary(state)
    assert len(summary) == 1
    assert dict(summary[0]) == {
        "id": 1,
        "r": "dish_a",
        "l": 0.95,  # (20 - 1) / 20, two decimals: one substep of life has gone
        "pts": 40,
    }


def test_order_summary_of_an_empty_rail_is_empty() -> None:
    assert order_summary(make_state()) == ()


def test_order_summary_clamps_the_fraction_to_the_unit_interval() -> None:
    state = make_state(deadline=20)
    # a hand-placed order whose deadline already passed: the fraction is 0, not negative
    overdue = Order(id=7, recipe_id="dish_b", time_left=0.0, deadline=10.0, value=30)
    state = replace(state, tick=11, orders=(overdue,))
    summary = order_summary(state)
    assert dict(summary[0]) == {"id": 7, "r": "dish_b", "l": 0.0, "pts": 30}


# --- build_state: the spec copy -----------------------------------------------


TILES: dict[str, dict[str, str]] = {
    ".": {"kind": "floor"},
    "#": {"kind": "wall"},
    "S": {"kind": "floor", "station": "spawn_shelf", "item": "tomato"},
    "V": {"kind": "floor", "station": "serve"},
}

GRID = [
    "#####",
    "#S.V#",
    "#...#",
    "#####",
]


def make_level(**overrides: Any) -> Level:
    data: dict[str, Any] = {
        "id": "04_orders_build",
        "name": "Orders Kitchen",
        "order": 1,
        "time_limit": 120,
        "target_score": 40,
        "difficulty": 1,
        "grid": list(GRID),
        "tiles": {key: dict(value) for key, value in TILES.items()},
        "spawns": [[2, 1]],
        "orders": {
            "pool": ["dish_a", "dish_b"],
            "concurrent": 3,
            "spawn_interval": [4.0, 6.0],
            "deadline": 30.0,
            "penalty": 15,
        },
    }
    data.update(overrides)
    return Level.build(LevelDef.model_validate(data))


def test_build_state_copies_the_orders_spec_as_scalars() -> None:
    state = build_state(make_level(), (SeatSpec("p0", 0, "A"),), 7, book())
    assert state.order_pool == ("dish_a", "dish_b")
    assert state.order_concurrent == 3
    assert state.order_spawn_min == 80  # 4 s / TICK_SECONDS
    assert state.order_spawn_max == 120  # 6 s / TICK_SECONDS
    assert state.order_deadline == 600  # 30 s / TICK_SECONDS
    assert state.order_penalty == 15
    assert state.next_order_at == FIRST_ORDER_DELAY_TICKS
    assert state.next_order_id == 1
    assert state.orders == ()


def test_a_round_built_from_a_level_spawns_through_the_kernel() -> None:
    state = build_state(make_level(), (SeatSpec("p0", 0, "A"),), 7, book())
    for _ in range(FIRST_ORDER_DELAY_TICKS + 1):  # the spawn is on tick 30
        state, _ = step(state, STEP_DT, book=book())
    assert len(state.orders) == 1
    order = state.orders[0]
    assert order.value in (BASE_SCORES["dish_a"], BASE_SCORES["dish_b"])
    assert order.deadline == FIRST_ORDER_DELAY_TICKS + 600


def test_the_kernel_is_loud_when_a_spawning_round_has_no_book() -> None:
    state = build_state(make_level(), (SeatSpec("p0", 0, "A"),), 7, book())
    for _ in range(FIRST_ORDER_DELAY_TICKS):
        state, _ = step(state, STEP_DT)  # the 29 ticks before the delay are book-free
    with pytest.raises(ValueError, match="recipe book"):
        step(state, STEP_DT)  # tick 30 would spawn: a `None` book names itself


def test_a_never_spawning_round_runs_book_free() -> None:
    state = make_state(pool=())
    for _ in range(60):
        state, events = step(state, STEP_DT)  # no book: the pool is empty
        assert events == ()
        assert state.orders == ()
    assert state.state_hash()  # still a perfectly hashable round