diff --git a/src/part1/constants.py b/src/part1/constants.py index 9abfbba2..36c12506 100644 --- a/src/part1/constants.py +++ b/src/part1/constants.py @@ -1,38 +1,23 @@ -"""Bit layout and default epoch for the Twitter Snowflake ID generator. - -A Snowflake identifier is a 63-bit positive integer packed as follows, from -the most significant bit downwards: - - 1 bit unused sign bit, always zero - 41 bits milliseconds elapsed since a custom epoch - 10 bits node identifier - 12 bits per-millisecond sequence counter - -The shift and mask constants should be derived from the bit widths so that -changing a width keeps everything else consistent. -""" - from typing import Final -# TODO: замените заглушки (0) на корректные значения, см. TASK.md. -# Все константы, зависящие от ёмкостей *_BITS, должны вычисляться из них. +def bits_value_max(n: int) -> int: + return 2**n - 1 + -# Twitter's original Snowflake epoch: 2010-11-04 01:42:54.657 UTC. -EPOCH_MS_DEFAULT: Final[int] = 0 +EPOCH_MS_DEFAULT: Final[int] = 1219190400 # Node identifier used when the caller does not supply one. -NODE_ID_DEFAULT: Final[int] = 0 +NODE_ID_DEFAULT: Final[int] = 1 # Width of each field, in bits. -TIMESTAMP_BITS: Final[int] = 0 -NODE_ID_BITS: Final[int] = 0 -SEQUENCE_ID_BITS: Final[int] = 0 +TIMESTAMP_BITS: Final[int] = 41 +NODE_ID_BITS: Final[int] = 10 +SEQUENCE_ID_BITS: Final[int] = 12 + -# Largest value each field can hold. -TIMESTAMP_MS_MAX: Final[int] = 0 -NODE_ID_MAX: Final[int] = 0 -SEQUENCE_ID_MAX: Final[int] = 0 +TIMESTAMP_MS_MAX: Final[int] = bits_value_max(TIMESTAMP_BITS) +NODE_ID_MAX: Final[int] = bits_value_max(NODE_ID_BITS) +SEQUENCE_ID_MAX: Final[int] = bits_value_max(SEQUENCE_ID_BITS) -# Здесь можно добавить собственные вспомогательные константы -# (например, сдвиги полей при сборке идентификатора). +TIMESTAMP_MOVE: Final[int] = NODE_ID_BITS + SEQUENCE_ID_BITS diff --git a/src/part1/snowflake.py b/src/part1/snowflake.py index d3abf050..5292efee 100644 --- a/src/part1/snowflake.py +++ b/src/part1/snowflake.py @@ -13,102 +13,69 @@ :func:`decode_node_id` and :func:`decode_sequence_id`. """ -import time # noqa: F401 +import time -from .constants import ( # noqa: F401 - EPOCH_MS_DEFAULT, - NODE_ID_DEFAULT, - NODE_ID_MAX, - SEQUENCE_ID_MAX, - TIMESTAMP_MS_MAX, -) +from .constants import * def read_current_millis(epoch_ms: int) -> int: - """Read the number of milliseconds elapsed since the custom epoch. + call_time = ( + time.time_ns() // 1_000_000 # наносекунды в милисекунды(time.time() - float) + ) + return call_time - epoch_ms + # """Read the number of milliseconds elapsed since the custom epoch. - Args: - epoch_ms: The custom epoch expressed as Unix milliseconds. + # Args: + # epoch_ms: The custom epoch expressed as Unix milliseconds. - Returns: - The count of whole milliseconds between ``epoch_ms`` and now. May be - negative if ``epoch_ms`` lies in the future. - """ - # TODO: реализуйте функцию - return 0 + # Returns: + # The count of whole milliseconds between ``epoch_ms`` and now. May be + # negative if ``epoch_ms`` lies in the future. + # """ def decode_timestamp_ms(snowflake_id: int, epoch_ms: int = EPOCH_MS_DEFAULT) -> int: - """Read the timestamp field out of a Snowflake identifier. + return (snowflake_id >> TIMESTAMP_MOVE) + epoch_ms - Args: - snowflake_id: An identifier produced against the same epoch. - epoch_ms: The epoch the identifier was generated against. Defaults to - the original Twitter epoch (2010-11-04 01:42:54.657 UTC). + # """Read the timestamp field out of a Snowflake identifier. - Returns: - The absolute Unix time in milliseconds at which the identifier was - generated. - """ - # TODO: реализуйте функцию - return 0 + # Args: + # snowflake_id: An identifier produced against the same epoch. + # epoch_ms: The epoch the identifier was generated against. Defaults to + # the original Twitter epoch (2010-11-04 01:42:54.657 UTC). + + # Returns: + # The absolute Unix time in milliseconds at which the identifier was + # generated. + # """ def decode_node_id(snowflake_id: int) -> int: - """Read the node identifier field out of a Snowflake identifier. + return (snowflake_id >> SEQUENCE_ID_BITS) & NODE_ID_BITS - Args: - snowflake_id: An identifier produced by :func:`generate_snowflake_id`. - Returns: - The node identifier packed into ``snowflake_id``, in the range - ``[0, NODE_ID_MAX]``. - """ - # TODO: реализуйте функцию - return 0 +def decode_sequence_id(snowflake_id: int) -> int: + return snowflake_id & SEQUENCE_ID_MAX -def decode_sequence_id(snowflake_id: int) -> int: - """Read the sequence counter field out of a Snowflake identifier. +def generate_snowflake_id( + sequence_id: int, node_id: int = NODE_ID_DEFAULT, epoch_ms: int = EPOCH_MS_DEFAULT +) -> int | None: + time_call_gen = read_current_millis(epoch_ms) - Args: - snowflake_id: An identifier produced by :func:`generate_snowflake_id`. + if node_id < 0 or node_id > NODE_ID_MAX: + print("node_id must be in [0,", NODE_ID_MAX, "]") + return None - Returns: - The per-millisecond sequence counter packed into ``snowflake_id``, in - the range ``[0, SEQUENCE_ID_MAX]``. - """ - # TODO: реализуйте функцию - return 0 + if sequence_id < 0 or sequence_id > SEQUENCE_ID_MAX: + print("sequence_id must be in [0,", SEQUENCE_ID_MAX, "]") + return None + if time_call_gen > TIMESTAMP_MS_MAX: + print("overflows time stamp") + return None -def generate_snowflake_id( - sequence_id: int, - node_id: int = NODE_ID_DEFAULT, - epoch_ms: int = EPOCH_MS_DEFAULT, -) -> int | None: - """Build and return a Snowflake identifier for the current millisecond. - - The function is stateless: the caller passes the per-millisecond sequence - counter explicitly. It is the caller's responsibility to increment - ``sequence_id`` for identifiers minted within the same millisecond and to - reset it once the clock advances. - - Args: - sequence_id: The per-millisecond sequence counter, in the range - ``[0, SEQUENCE_ID_MAX]``. - node_id: The identifier of this node, in the range ``[0, NODE_ID_MAX]``. - Optional; defaults to ``NODE_ID_DEFAULT``. - epoch_ms: The start of the epoch as Unix milliseconds. Optional; - defaults to the original Twitter epoch (2010-11-04 01:42:54.657 - UTC). - - Returns: - The Snowflake identifier as a positive 63-bit integer, or ``None`` if - ``node_id`` is outside ``[0, NODE_ID_MAX]``, ``sequence_id`` is outside - ``[0, SEQUENCE_ID_MAX]``, or the elapsed time no longer fits in the - timestamp field (roughly 69 years after ``epoch_ms``). In each of those - cases an explanatory message is printed to stdout first. - """ - # TODO: реализуйте функцию - return 0 + snowflake_id = ( + (time_call_gen << TIMESTAMP_MOVE) | (node_id << sequence_id) | sequence_id + ) + return snowflake_id diff --git a/src/part2/cart.py b/src/part2/cart.py index 063f9aea..aa495e89 100644 --- a/src/part2/cart.py +++ b/src/part2/cart.py @@ -11,8 +11,8 @@ from typing import Final -from .crud import read_product, update_product # noqa: F401 -from .storage import ( # noqa: F401 +from .crud import read_product, update_product +from .storage import ( NAME_INDEX, PRICE_INDEX, QUANTITY_INDEX, @@ -24,7 +24,7 @@ # TODO: задайте позиции полей внутри кортежа CartLine LINE_PRODUCT_ID_INDEX: Final = 0 -LINE_QUANTITY_INDEX: Final = 0 +LINE_QUANTITY_INDEX: Final = 1 def add_to_cart( @@ -53,9 +53,30 @@ def add_to_cart( The cart line for ``product_id`` after the addition, or ``None`` when the product is unknown or the store cannot cover the request. """ - # TODO: реализуйте функцию - return (0, 0) - + prod = read_product(storage, product_id) + if prod is None: + return None + + if prod[QUANTITY_INDEX] < quantity: + print(f"not enough stock for product {product_id}") + return None + + new_stock_qty = prod[QUANTITY_INDEX] - quantity + update_product( + storage, + product_id, + (prod[NAME_INDEX], prod[PRICE_INDEX], new_stock_qty), + ) + + for i, line in enumerate(cart): + if line[LINE_PRODUCT_ID_INDEX] == product_id: + new_cart_qty = line[LINE_QUANTITY_INDEX] + quantity + cart[i] = (product_id, new_cart_qty) + return (product_id, new_cart_qty) + + new_line = (product_id, quantity) + cart.append(new_line) + return new_line def remove_from_cart( storage: list[Product], @@ -85,5 +106,36 @@ def remove_from_cart( zero means the line was dropped), or ``None`` when the cart has no line for the product or holds too few units. """ - # TODO: реализуйте функцию - return (0, 0) + found_index = -1 + for i, line in enumerate(cart): + if line[LINE_PRODUCT_ID_INDEX] == product_id: + found_index = i + break + + if found_index == -1: + print(f"product {product_id} is not in the cart") + return None + + line = cart[found_index] + if line[LINE_QUANTITY_INDEX] < quantity: + print(f"not enough quantity in cart for product {product_id}") + return None + + new_cart_qty = line[LINE_QUANTITY_INDEX] - quantity + if new_cart_qty == 0: + cart.pop(found_index) + res_line = (product_id, 0) + else: + cart[found_index] = (product_id, new_cart_qty) + res_line = (product_id, new_cart_qty) + + product = read_product(storage, product_id) + if product is not None: + new_stock_qty = product[QUANTITY_INDEX] + quantity + update_product( + storage, + product_id, + (product[NAME_INDEX], product[PRICE_INDEX], new_stock_qty), + ) + + return res_line diff --git a/src/part2/crud.py b/src/part2/crud.py index d026cbcb..692f091b 100644 --- a/src/part2/crud.py +++ b/src/part2/crud.py @@ -14,13 +14,13 @@ from decimal import Decimal -from .storage import ( # noqa: F401 +from .storage import ( NAME_INDEX, PRODUCT_ID_INDEX, PRODUCT_ID_MIN, Product, ) -from .utils import normalize_price # noqa: F401 +from .utils import normalize_price def generate_product_id(storage: list[Product]) -> int: @@ -34,9 +34,11 @@ def generate_product_id(storage: list[Product]) -> int: :data:`~src.part2.storage.PRODUCT_ID_MIN` when ``storage`` is empty. """ - # TODO: реализуйте функцию - return 0 - + if len(storage) == 0: + return PRODUCT_ID_MIN + + max_id = max(product[PRODUCT_ID_INDEX] for product in storage) + return max_id + 1 def create_product( storage: list[Product], fields: tuple[str, Decimal, int] @@ -56,9 +58,17 @@ def create_product( ``storage`` is left unchanged and a message naming the clashing name is printed. """ - # TODO: реализуйте функцию - return 0 - + name, price, quantity = fields[0], fields[1], fields[2] + for product in storage: + if product[NAME_INDEX] == name: + print(f"product name '{name}' is already taken") + return None + + new_id = generate_product_id(storage) + normalized_price = normalize_price(price) + + new_product: Product = (new_id, name, normalized_price, quantity) + storage.append(new_product) def read_product(storage: list[Product], product_id: int) -> Product | None: """Return the product stored under ``product_id``. @@ -72,9 +82,12 @@ def read_product(storage: list[Product], product_id: int) -> Product | None: ``None`` when no product carries that identifier (a message is printed in that case). """ - # TODO: реализуйте функцию - return (0, "", Decimal(0), 0) + for product in storage: + if product[PRODUCT_ID_INDEX] == product_id: + return product + print(f"product with id {product_id} not found") + return None def update_product( storage: list[Product], @@ -99,9 +112,18 @@ def update_product( ``None`` when no product carries that identifier (``storage`` is left unchanged and a message is printed). """ - # TODO: реализуйте функцию - return (0, "", Decimal(0), 0) + name, price, quantity = fields[0], fields[1], fields[2] + + for i, product in enumerate(storage): + if product[PRODUCT_ID_INDEX] == product_id: + norm_price = normalize_price(price) + upd_product: Product = (product_id, name, norm_price, quantity) + storage[i] = upd_product + return upd_product + + print(f"product with id {product_id} not found") + return None def delete_product(storage: list[Product], product_id: int) -> int | None: """Remove the product stored under ``product_id`` from ``storage``. @@ -116,5 +138,10 @@ def delete_product(storage: list[Product], product_id: int) -> int | None: product carried that identifier (``storage`` is left unchanged and a message is printed). """ - # TODO: реализуйте функцию - return 0 + for i, product in enumerate(storage): + if product[PRODUCT_ID_INDEX] == product_id: + storage.pop(i) + return product_id + + print(f"product with id {product_id} not found") + return None diff --git a/src/part2/storage.py b/src/part2/storage.py index b63d5fc7..35821c5f 100644 --- a/src/part2/storage.py +++ b/src/part2/storage.py @@ -26,9 +26,9 @@ # TODO: задайте позиции полей внутри кортежа Product PRODUCT_ID_INDEX: Final = 0 -NAME_INDEX: Final = 0 -PRICE_INDEX: Final = 0 -QUANTITY_INDEX: Final = 0 +NAME_INDEX: Final = 1 +PRICE_INDEX: Final = 2 +QUANTITY_INDEX: Final = 3 # TODO: задайте идентификатор первого товара в пустом хранилище -PRODUCT_ID_MIN: Final[int] = 0 +PRODUCT_ID_MIN: Final[int] = 1 diff --git a/src/part2/utils.py b/src/part2/utils.py index 11bd7a76..2fe6df39 100644 --- a/src/part2/utils.py +++ b/src/part2/utils.py @@ -6,13 +6,13 @@ currency values free of binary floating-point error. """ -from decimal import ROUND_HALF_UP, Decimal # noqa: F401 +from decimal import ROUND_HALF_UP, Decimal from typing import Final # TODO: задайте число знаков после запятой и шаг квантования -PRICE_PRECISION: Final[int] = 0 -PRICE_STEP: Final = Decimal(0) +PRICE_PRECISION: Final[int] = 2 +PRICE_STEP: Final = Decimal(1).scaleb(-PRICE_PRECISION) def normalize_price(price: Decimal) -> Decimal: @@ -25,5 +25,4 @@ def normalize_price(price: Decimal) -> Decimal: ``price`` quantised to :data:`PRICE_PRECISION` fractional digits, with halves rounded up. """ - # TODO: реализуйте функцию - return Decimal(0) + return price.quantize(PRICE_STEP, rounding=ROUND_HALF_UP)