from engine.inventory import Inventory
from engine.item import ItemDef, ItemInstance

STAFF = ItemDef(id="staff_oak", name="Oak Staff", width=1, height=5)
SANDWICH = ItemDef(id="sandwich", name="Sandwich", width=2, height=2, stackable=True, max_stack=4)


def test_place_non_overlapping_items_succeeds():
    inv = Inventory(6, 5)
    staff = ItemInstance("item-1", "staff_oak")
    sandwich = ItemInstance("item-2", "sandwich")

    assert inv.place(staff, STAFF, 0, 0) is True
    assert inv.place(sandwich, SANDWICH, 1, 0) is True
    assert {p.item.item_id for p in inv.items()} == {"item-1", "item-2"}


def test_overlapping_placement_rejected():
    inv = Inventory(6, 5)
    staff = ItemInstance("item-1", "staff_oak")
    other = ItemInstance("item-2", "sandwich")

    assert inv.place(staff, STAFF, 0, 0) is True
    assert inv.can_place(SANDWICH, 0, 2) is False  # overlaps rows 2-3 of the staff at x=0
    assert inv.place(other, SANDWICH, 0, 2) is False


def test_out_of_bounds_placement_rejected():
    inv = Inventory(6, 4)
    assert inv.can_place(STAFF, 0, 0) is False  # height 5 doesn't fit in a 4-tall grid at all


def test_remove_frees_footprint_for_reuse():
    inv = Inventory(6, 5)
    staff = ItemInstance("item-1", "staff_oak")
    inv.place(staff, STAFF, 0, 0)

    removed = inv.remove("item-1", STAFF)
    assert removed is staff
    assert inv.can_place(STAFF, 0, 0) is True
    assert inv.place(staff, STAFF, 0, 0) is True


def test_find_first_fit_returns_leftmost_topmost_slot():
    inv = Inventory(6, 5)
    inv.place(ItemInstance("item-1", "staff_oak"), STAFF, 0, 0)

    slot = inv.find_first_fit(SANDWICH)
    assert slot == (1, 0)


def test_item_at_finds_item_from_its_top_left_corner():
    inv = Inventory(6, 5)
    staff = ItemInstance("item-1", "staff_oak")
    inv.place(staff, STAFF, 0, 0)
    placed = inv.item_at(0, 0)
    assert placed is not None
    assert placed.item is staff


def test_item_at_finds_item_from_anywhere_in_its_footprint():
    inv = Inventory(6, 5)
    sandwich = ItemInstance("item-2", "sandwich")
    inv.place(sandwich, SANDWICH, 1, 0)  # occupies (1,0),(2,0),(1,1),(2,1)
    for cx, cy in [(1, 0), (2, 0), (1, 1), (2, 1)]:
        placed = inv.item_at(cx, cy)
        assert placed is not None
        assert placed.item is sandwich


def test_item_at_returns_none_for_an_empty_cell():
    inv = Inventory(6, 5)
    inv.place(ItemInstance("item-1", "staff_oak"), STAFF, 0, 0)
    assert inv.item_at(5, 4) is None


def test_item_at_returns_none_out_of_bounds():
    inv = Inventory(6, 5)
    assert inv.item_at(-1, 0) is None
    assert inv.item_at(6, 0) is None
    assert inv.item_at(0, 5) is None