diff --git a/Solve Task 2/cart.py b/Solve Task 2/cart.py new file mode 100644 index 00000000..61036def --- /dev/null +++ b/Solve Task 2/cart.py @@ -0,0 +1,99 @@ +from typing import Final +from crud import ( + read_product, + update_product, +) +from storage import ( + QUANTITY_INDEX, + NAME_INDEX, + PRICE_INDEX, + Product) + +CartLine = tuple[int, int] +LINE_PRODUCT_ID_INDEX: Final = 0 +LINE_QUANTITY_INDEX: Final = 1 + + +def find_cart_line(cart: list[CartLine], + product_id: int,) -> CartLine | None: + for line in cart: + if line[LINE_PRODUCT_ID_INDEX] == product_id: + return line + print(f"Product {product_id} is not in the cart/") + return None + + +def add_to_cart(storage: list[Product], + cart: list[CartLine], + product_id: int, + quantity: int) -> CartLine | None: + product = read_product(storage, product_id) + if product is None: + return product + storage_quantity = product[QUANTITY_INDEX] + if storage_quantity < quantity: + print(f"Not enough stock for product {product_id}: " + f"{storage_quantity} available, " + f"{quantity} requested.") + return None + + new_field = ( + product[NAME_INDEX], + product[PRICE_INDEX], + storage_quantity - quantity + ) + update_product(storage, product_id, new_field) + + for index, line in enumerate(cart): + if line[LINE_PRODUCT_ID_INDEX] == product_id: + new_line: CartLine = ( + product_id, + line[LINE_QUANTITY_INDEX] + quantity + ) + cart[index] = new_line + return new_line + new_line: CartLine = (product_id, quantity) + cart.append(new_line) + return new_line + + +def remove_from_cart(storage: list[Product], + cart: list[CartLine], + product_id: int, + quantity: int) -> CartLine | None: + cart_line = find_cart_line(cart, product_id) + product = read_product(storage, product_id) + if cart_line is None: + return cart_line + if cart_line[LINE_QUANTITY_INDEX] < quantity: + print(f"Cart holds only {cart_line[LINE_QUANTITY_INDEX]} " + f"unit(s) of product {product_id}, cannot remove {quantity}.") + return None + if product is None: + return None + new_quantity = product[QUANTITY_INDEX] + quantity + new_fields = ( + product[NAME_INDEX], + product[PRICE_INDEX], + new_quantity, + ) + update_product( + storage, + product_id, + new_fields, + ) + new_line: CartLine = ( + product_id, + cart_line[LINE_QUANTITY_INDEX] - quantity, + ) + new_line: CartLine = ( + product_id, + cart_line[LINE_QUANTITY_INDEX]-quantity + ) + if new_line[LINE_QUANTITY_INDEX] == 0: + cart.remove(cart_line) + return new_line + for index, line in enumerate(cart): + if line == cart_line: + cart[index] = new_line + return new_line diff --git a/Solve Task 2/crud.py b/Solve Task 2/crud.py new file mode 100644 index 00000000..6202f484 --- /dev/null +++ b/Solve Task 2/crud.py @@ -0,0 +1,65 @@ +from decimal import Decimal +from storage import ( + PRODUCT_ID_MIN, + PRODUCT_ID_INDEX, + NAME_INDEX, + Product, +) +from utils import normalize_price + + +def create_product(storage: list[Product], + fields: tuple[str, Decimal, int]) -> int | None: + product_name, product_price, product_quantity = fields + for product in storage: + if product_name == product[NAME_INDEX]: + print(f"Product name {product_name} is already taken.") + return None + product_id = generate_product_id(storage) + storage.append(( + product_id, + product_name, + normalize_price(product_price), + product_quantity + )) + return product_id + + +def generate_product_id(storage: list[Product]) -> int: + if not storage: + return PRODUCT_ID_MIN + MAX_INDEX = max(product[PRODUCT_ID_INDEX] for product in storage) + return MAX_INDEX + 1 + + +def read_product(storage: list[Product], product_id: int) -> Product | None: + for product in storage: + if product[PRODUCT_ID_INDEX] == product_id: + return product + print(f"No product with id {product_id}") + return None + + +def update_product( + storage: list[Product], + product_id: int, + fields: tuple[str, Decimal, int], +) -> Product | None: + for index, product in enumerate(storage): + if product[PRODUCT_ID_INDEX] == product_id: + new_name, new_price, new_quantity = fields + norm_price = normalize_price(new_price) + NEW_PRODUCT = (product_id, new_name, norm_price, new_quantity) + storage[index] = NEW_PRODUCT + return NEW_PRODUCT + print(f"No product with id {product_id}") + return None + + +def delete_product(storage: list[Product], product_id: int) -> int | None: + for index, product in enumerate(storage): + if product[PRODUCT_ID_INDEX] == product_id: + storage.pop(index) + return product_id + print(f"No product with id {product_id}.") + return None diff --git a/Solve Task 2/storage.py b/Solve Task 2/storage.py new file mode 100644 index 00000000..cdd56923 --- /dev/null +++ b/Solve Task 2/storage.py @@ -0,0 +1,11 @@ +from decimal import Decimal +from typing import Final + +Product = tuple[int, str, Decimal, int] + +PRODUCT_ID_INDEX: Final[int] = 0 +NAME_INDEX: Final[int] = 1 +PRICE_INDEX: Final[int] = 2 +QUANTITY_INDEX: Final[int] = 3 + +PRODUCT_ID_MIN: Final[int] = 1 diff --git a/Solve Task 2/utils.py b/Solve Task 2/utils.py new file mode 100644 index 00000000..7d9077bb --- /dev/null +++ b/Solve Task 2/utils.py @@ -0,0 +1,9 @@ +from typing import Final +from decimal import Decimal, ROUND_HALF_UP + +PRICE_PRECISION: Final[int] = 2 +PRICE_STEP: Final = Decimal(1).scaleb(-PRICE_PRECISION) + + +def normalize_price(price: Decimal) -> Decimal: + return price.quantize(PRICE_STEP, rounding=ROUND_HALF_UP) diff --git a/src/part1/constants.py b/src/part1/constants.py index 9abfbba2..0d968954 100644 --- a/src/part1/constants.py +++ b/src/part1/constants.py @@ -1,38 +1,12 @@ -"""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. - -# Twitter's original Snowflake epoch: 2010-11-04 01:42:54.657 UTC. -EPOCH_MS_DEFAULT: Final[int] = 0 - -# Node identifier used when the caller does not supply one. -NODE_ID_DEFAULT: Final[int] = 0 - -# Width of each field, in bits. -TIMESTAMP_BITS: Final[int] = 0 -NODE_ID_BITS: Final[int] = 0 -SEQUENCE_ID_BITS: Final[int] = 0 - -# Largest value each field can hold. -TIMESTAMP_MS_MAX: Final[int] = 0 -NODE_ID_MAX: Final[int] = 0 -SEQUENCE_ID_MAX: Final[int] = 0 - -# Здесь можно добавить собственные вспомогательные константы -# (например, сдвиги полей при сборке идентификатора). +from time import time + + +CURRENT_EPOCH_MS: int = int(time() * 1000) +EPOCH_MS_DEFAULT: int = 1288834974657 +NODE_ID_DEFAULT: int = 1 +TIMESTAMP_BITS: int = 41 +NODE_ID_BITS: int = 10 +SEQUENCE_ID_BITS: int = 12 +TIMESTAMP_MS_MAX: int = 2**TIMESTAMP_BITS - 1 +NODE_ID_MAX: int = 2**NODE_ID_BITS - 1 +SEQUENCE_ID_MAX: int = 2**SEQUENCE_ID_BITS - 1 diff --git a/src/part1/snowflake.py b/src/part1/snowflake.py index d3abf050..9d99c64c 100644 --- a/src/part1/snowflake.py +++ b/src/part1/snowflake.py @@ -1,114 +1,44 @@ -"""Twitter Snowflake identifier generator. - -Snowflake produces roughly time-ordered 64-bit integer identifiers without -coordination between nodes. Each identifier packs the milliseconds elapsed -since a custom epoch, a node identifier and a per-millisecond sequence counter -into a single 63-bit positive integer (see ``constants`` for the layout). - -The public entry point is :func:`generate_snowflake_id`. It is stateless: the -caller passes the sequence counter on every call and is responsible for -advancing it within a millisecond and resetting it when the clock ticks over. - -Each packed field can be read back on its own with :func:`decode_timestamp_ms`, -:func:`decode_node_id` and :func:`decode_sequence_id`. -""" - -import time # noqa: F401 - -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. - - 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 - - -def decode_timestamp_ms(snowflake_id: int, epoch_ms: int = EPOCH_MS_DEFAULT) -> int: - """Read the timestamp field out of a Snowflake identifier. + return CURRENT_EPOCH_MS - 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). - Returns: - The absolute Unix time in milliseconds at which the identifier was - generated. - """ - # TODO: реализуйте функцию - return 0 +def generate_snowflake_id( + sequence_id: int, node_id: int = NODE_ID_DEFAULT, epoch_ms: int = EPOCH_MS_DEFAULT +) -> int | None: + if not (0 <= node_id <= NODE_ID_MAX): + print(f"node_id must be in [0 ; {NODE_ID_MAX}]") + return None + if not (0 <= sequence_id <= SEQUENCE_ID_MAX): + print(f"sequence_id must be in [0 ; {SEQUENCE_ID_MAX}]") + return None -def decode_node_id(snowflake_id: int) -> int: - """Read the node identifier field out of a Snowflake identifier. + timestamp_ms = read_current_millis(epoch_ms) - Args: - snowflake_id: An identifier produced by :func:`generate_snowflake_id`. + if timestamp_ms > TIMESTAMP_MS_MAX: + print("Timestamp overflows") + return None - Returns: - The node identifier packed into ``snowflake_id``, in the range - ``[0, NODE_ID_MAX]``. - """ - # TODO: реализуйте функцию - return 0 + snowflake_id: int = ( + (timestamp_ms << (NODE_ID_BITS + SEQUENCE_ID_BITS)) + | (node_id << SEQUENCE_ID_BITS) + | sequence_id + ) + return snowflake_id def decode_sequence_id(snowflake_id: int) -> int: - """Read the sequence counter field out of a Snowflake identifier. - - Args: - snowflake_id: An identifier produced by :func:`generate_snowflake_id`. - - Returns: - The per-millisecond sequence counter packed into ``snowflake_id``, in - the range ``[0, SEQUENCE_ID_MAX]``. - """ - # TODO: реализуйте функцию - return 0 + return snowflake_id & SEQUENCE_ID_MAX -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. +def decode_node_id(snowflake_id: int) -> int: + return (snowflake_id >> SEQUENCE_ID_BITS) & NODE_ID_MAX - 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 +def decode_timestamp_ms(snowflake_id: int, epoch_ms: int = EPOCH_MS_DEFAULT) -> int: + return ( + (snowflake_id >> NODE_ID_BITS + SEQUENCE_ID_BITS) & TIMESTAMP_MS_MAX + ) + epoch_ms diff --git a/src/part2/cart.py b/src/part2/cart.py index 063f9aea..cbdaa539 100644 --- a/src/part2/cart.py +++ b/src/part2/cart.py @@ -1,18 +1,7 @@ -"""Shopping-cart operations layered on top of the product store. - -The cart is a plain list of tuples, one :data:`CartLine` -- -``(product_id, quantity)`` -- per distinct product. Moving units between the -store and the cart keeps the two sides in balance: :func:`add_to_cart` takes -units out of stock, :func:`remove_from_cart` puts them back. - -Like the CRUD layer, the failure path never raises -- the operation prints -an explanatory message to stdout and returns ``None``. -""" - 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, @@ -20,11 +9,22 @@ ) -type CartLine = tuple[int, int] +CartLine = tuple[int, int] + +LINE_PRODUCT_ID_INDEX: Final[int] = 0 +LINE_QUANTITY_INDEX: Final[int] = 1 + -# TODO: задайте позиции полей внутри кортежа CartLine -LINE_PRODUCT_ID_INDEX: Final = 0 -LINE_QUANTITY_INDEX: Final = 0 +def find_cart_line( + cart: list[CartLine], + product_id: int, +) -> CartLine | None: + for line in cart: + if line[LINE_PRODUCT_ID_INDEX] == product_id: + return line + + print(f"Product {product_id} is not in the cart") + return None def add_to_cart( @@ -33,28 +33,45 @@ def add_to_cart( product_id: int, quantity: int, ) -> CartLine | None: - """Move ``quantity`` units of ``product_id`` from the store into ``cart``. - - The product is looked up in ``storage``. If it is missing, a message is - printed (by :func:`~src.part2.crud.read_product`) and nothing - changes. If the store holds fewer units than requested, an explanatory - message is printed and nothing changes. Otherwise the store record is - decremented by ``quantity`` and the cart line for ``product_id`` gains - ``quantity`` units -- a new line is created when the cart had none. - - Args: - storage: The product store to draw stock from; modified in place on - success. - cart: The cart to add the units to; modified in place on success. - product_id: The identifier of the product to add. - quantity: Number of units to move into the cart. - - Returns: - 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) + product = read_product(storage, product_id) + + if product is None: + return None + + storage_quantity = product[QUANTITY_INDEX] + + if storage_quantity < quantity: + print( + f"Not enough stock for product {product_id}: " + f"{storage_quantity} available, " + f"{quantity} requested." + ) + return None + + new_fields = ( + product[NAME_INDEX], + product[PRICE_INDEX], + storage_quantity - quantity, + ) + + update_product( + storage, + product_id, + new_fields, + ) + + for index, line in enumerate(cart): + if line[LINE_PRODUCT_ID_INDEX] == product_id: + new_line = ( + product_id, + line[LINE_QUANTITY_INDEX] + quantity, + ) + cart[index] = new_line + return new_line + + new_line = (product_id, quantity) + cart.append(new_line) + return new_line def remove_from_cart( @@ -63,27 +80,50 @@ def remove_from_cart( product_id: int, quantity: int, ) -> CartLine | None: - """Move ``quantity`` units of ``product_id`` from ``cart`` back to the store. - - The cart line for ``product_id`` is looked up. If there is none, a - message is printed and nothing changes. If the line holds fewer units - than requested, an explanatory message is printed and nothing changes. - Otherwise the cart line loses ``quantity`` units -- the line is dropped - when it reaches zero -- and the store record gains ``quantity`` units - back. - - Args: - storage: The product store to return stock to; modified in place on - success. - cart: The cart to take the units from; modified in place on - success. - product_id: The identifier of the product to remove. - quantity: Number of units to move back into the store. - - Returns: - The cart line for ``product_id`` after the removal (a quantity of - 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) + cart_line = find_cart_line(cart, product_id) + + if cart_line is None: + return None + + if cart_line[LINE_QUANTITY_INDEX] < quantity: + print( + f"Cart holds only {cart_line[LINE_QUANTITY_INDEX]} " + f"unit(s) of product {product_id}, " + f"cannot remove {quantity}." + ) + return None + + product = read_product(storage, product_id) + + if product is None: + return None + + new_quantity = product[QUANTITY_INDEX] + quantity + + new_fields = ( + product[NAME_INDEX], + product[PRICE_INDEX], + new_quantity, + ) + + update_product( + storage, + product_id, + new_fields, + ) + + new_line: CartLine = ( + product_id, + cart_line[LINE_QUANTITY_INDEX] - quantity, + ) + + if new_line[LINE_QUANTITY_INDEX] == 0: + cart.remove(cart_line) + return new_line + + for index, line in enumerate(cart): + if line == cart_line: + cart[index] = new_line + return new_line + + return None diff --git a/src/part2/crud.py b/src/part2/crud.py index d026cbcb..a37746cc 100644 --- a/src/part2/crud.py +++ b/src/part2/crud.py @@ -1,79 +1,58 @@ -"""Create/read/update/delete operations over the in-memory product store. - -Every operation takes the store -- a list of -:data:`~src.part2.storage.Product` tuples -- as its first argument and -works on it in place. The failure path never raises: the operation prints -an explanatory message to stdout and returns ``None``. - -The identifier of a new product is derived from the store itself -(:func:`generate_product_id`): one past the greatest identifier in use, or -:data:`~src.part2.storage.PRODUCT_ID_MIN` when the store is empty. -Product names are kept unique -- :func:`create_product` refuses a name that -is already taken. -""" - 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: - """Choose the identifier for the next product added to ``storage``. +def create_product( + storage: list[Product], + fields: tuple[str, Decimal, int], +) -> int | None: + product_name, product_price, product_quantity = fields - Args: - storage: The product store to inspect. + for product in storage: + if product_name == product[NAME_INDEX]: + print(f"Product name {product_name} is already taken.") + return None - Returns: - One past the greatest identifier currently held in ``storage``, or - :data:`~src.part2.storage.PRODUCT_ID_MIN` when ``storage`` is - empty. - """ - # TODO: реализуйте функцию - return 0 + product_id = generate_product_id(storage) + storage.append( + ( + product_id, + product_name, + normalize_price(product_price), + product_quantity, + ) + ) + + return product_id -def create_product( - storage: list[Product], fields: tuple[str, Decimal, int] -) -> int | None: - """Append a new product to ``storage`` and return its new identifier. - Args: - storage: The product store to append to; modified in place on - success. - fields: A ``(name, price, quantity)`` tuple describing the product. - ``price`` is a :class:`~decimal.Decimal` amount and is rounded - to the stored money precision before it is saved. +def generate_product_id(storage: list[Product]) -> int: + if not storage: + return PRODUCT_ID_MIN - Returns: - The identifier generated for the new product, or ``None`` when a - product with the same name already exists. In the ``None`` case - ``storage`` is left unchanged and a message naming the clashing - name is printed. - """ - # TODO: реализуйте функцию - return 0 + max_id = max(product[PRODUCT_ID_INDEX] for product in storage) + return max_id + 1 -def read_product(storage: list[Product], product_id: int) -> Product | None: - """Return the product stored under ``product_id``. - Args: - storage: The product store to search. - product_id: The identifier to look up. +def read_product( + storage: list[Product], + product_id: int, +) -> Product | None: + for product in storage: + if product[PRODUCT_ID_INDEX] == product_id: + return product - Returns: - The matching ``(product_id, name, price, quantity)`` record, or - ``None`` when no product carries that identifier (a message is - printed in that case). - """ - # TODO: реализуйте функцию - return (0, "", Decimal(0), 0) + print(f"No product with id {product_id}") + return None def update_product( @@ -81,40 +60,32 @@ def update_product( product_id: int, fields: tuple[str, Decimal, int], ) -> Product | None: - """Overwrite the fields of the product stored under ``product_id``. - - The identifier itself is preserved; only ``name``, ``price`` and - ``quantity`` are replaced. - - Args: - storage: The product store to modify; the matching record is - replaced in place on success. - product_id: The identifier of the product to change. - fields: A ``(name, price, quantity)`` tuple with the new values. - ``price`` is a :class:`~decimal.Decimal` amount and is rounded - to the stored money precision before it is saved. - - Returns: - The updated ``(product_id, name, price, quantity)`` record, or - ``None`` when no product carries that identifier (``storage`` is - left unchanged and a message is printed). - """ - # TODO: реализуйте функцию - return (0, "", Decimal(0), 0) - - -def delete_product(storage: list[Product], product_id: int) -> int | None: - """Remove the product stored under ``product_id`` from ``storage``. - - Args: - storage: The product store to remove from; modified in place on - success. - product_id: The identifier of the product to remove. - - Returns: - ``product_id`` when a product was removed, or ``None`` when no - product carried that identifier (``storage`` is left unchanged and - a message is printed). - """ - # TODO: реализуйте функцию - return 0 + for index, product in enumerate(storage): + if product[PRODUCT_ID_INDEX] == product_id: + new_name, new_price, new_quantity = fields + + new_product: Product = ( + product_id, + new_name, + normalize_price(new_price), + new_quantity, + ) + + storage[index] = new_product + return new_product + + print(f"No product with id {product_id}") + return None + + +def delete_product( + storage: list[Product], + product_id: int, +) -> int | None: + for index, product in enumerate(storage): + if product[PRODUCT_ID_INDEX] == product_id: + storage.pop(index) + return product_id + + print(f"No product with id {product_id}.") + return None diff --git a/src/part2/storage.py b/src/part2/storage.py index b63d5fc7..726ab823 100644 --- a/src/part2/storage.py +++ b/src/part2/storage.py @@ -1,34 +1,12 @@ -"""In-memory product store for the shop CRUD exercise. - -The store is deliberately primitive: a plain list of tuples, with no -persistence, no indexing and no schema enforcement. Each element is a -:data:`Product` record -- a ``(product_id, name, price, quantity)`` tuple -where: - -* ``product_id`` -- unique positive integer key, assigned by the create - operation in :mod:`src.part2.crud`; -* ``name`` -- human-readable product name, unique across the store; -* ``price`` -- price of a single unit, held as a :class:`~decimal.Decimal` - amount rounded to a fixed number of decimal places (see - :func:`src.part2.utils.normalize_price`) so that money is never - subject to binary floating-point error; -* ``quantity`` -- number of units currently in stock. - -Field positions are exposed as ``*_INDEX`` constants so callers never -hard-code tuple offsets. -""" - from decimal import Decimal from typing import Final -type Product = tuple[int, str, Decimal, int] +Product = tuple[int, str, Decimal, int] -# 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 ec0348d3..28fe897f 100644 --- a/src/part2/utils.py +++ b/src/part2/utils.py @@ -1,29 +1,10 @@ -"""Standalone helpers shared by the hw4 storage and CRUD modules. - -For now this is limited to money handling: :func:`normalize_price` rounds a -raw :class:`~decimal.Decimal` amount to the fixed number of fractional -digits (:data:`PRICE_PRECISION`) that every stored price uses, keeping -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] = Decimal(1).scaleb(-PRICE_PRECISION) def normalize_price(price: Decimal) -> Decimal: - """Round a price to the precision every stored record uses. - - Args: - price: The raw price amount. - - Returns: - ``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) diff --git a/src/part3/__init__.py b/src/part3/__init__.py new file mode 100644 index 00000000..e69de29b diff --git a/src/part3/crud.py b/src/part3/crud.py new file mode 100644 index 00000000..2774f58c --- /dev/null +++ b/src/part3/crud.py @@ -0,0 +1,116 @@ +from decimal import Decimal + +from .storage import ( + NAME_INDEX, + PRODUCT_ID_INDEX, + PRODUCT_ID_MIN, + Product, +) +from .utils import normalize_price, normalize_product_name + + +def check_product(storage: list[Product], product_name: str) -> bool | None: + if not (product_name): + print("product name must not be blank") + return None + + for product in storage: + if product_name == product[NAME_INDEX]: + print(f"product name '{product_name}' is already taken") + return None + return True + + +def generate_product_id(storage: list[Product]) -> int: + if not storage: + 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], +) -> int | None: + product_name, product_price, product_quantity = fields + + normalized_name = normalize_product_name(product_name) + if (status := check_product(storage, normalized_name)) is None: + return status + + product_id = generate_product_id(storage) + normalized_price = normalize_price(product_price) + + storage.append( + ( + product_id, + normalized_name, + normalized_price, + product_quantity, + ) + ) + + return product_id + + +def read_product(storage: list[Product], product_id: int) -> Product | None: + for product in storage: + if product[PRODUCT_ID_INDEX] == product_id: + return product + + print(f"no product with id {product_id}") + return None + + +def update_product( + storage: list[Product], + product_id: int, + fields: tuple[str, Decimal, int], +) -> Product | None: + product_name, product_price, product_quantity = fields + normalized_name = normalize_product_name(product_name) + + if not normalized_name: + print("product name must not be blank") + return None + + product_index = None + + for index, product in enumerate(storage): + if product[PRODUCT_ID_INDEX] == product_id: + product_index = index + break + + if product_index is None: + print(f"no product with id {product_id}") + return None + + for product in storage: + if ( + product[PRODUCT_ID_INDEX] != product_id + and product[NAME_INDEX] == normalized_name + ): + print(f"product name '{normalized_name}' is already taken") + return None + + new_product: Product = ( + product_id, + normalized_name, + normalize_price(product_price), + product_quantity, + ) + + storage[product_index] = new_product + return new_product + + +def delete_product(storage: list[Product], product_id: int) -> int | None: + for index, product in enumerate(storage): + if product[PRODUCT_ID_INDEX] == product_id: + storage.pop(index) + return product_id + + print(f"no product with id {product_id}") + return None diff --git a/src/part3/run_admin.py b/src/part3/run_admin.py new file mode 100644 index 00000000..53847ec6 --- /dev/null +++ b/src/part3/run_admin.py @@ -0,0 +1,96 @@ +from decimal import Decimal, InvalidOperation +from typing import Final + +from .crud import ( + create_product, + delete_product, + read_product, + update_product, +) +from .storage import Product +from .utils import get_storage_str_representation + + +PROMPT: Final[str] = "admin> " + +HELP_TEXT: Final[str] = """Available commands: + help show this message + exit leave the console + show print the whole store as a table + create add a product, print its new id + read print the product with that id + update overwrite that product's fields + delete remove the product with that id + +For create and update the price and quantity are the last two words of the +line; everything before them is the product name, so it may contain spaces +(for example "Gibson SG Junior") and needs no quoting.""" + + +def show_help() -> None: + print(HELP_TEXT) + + +def print_result(result: object) -> None: + if result is not None: + print(result) + + +def run_command(storage: list[Product], line: str) -> bool: + parts = line.split() + + match parts: + case ["help"]: + show_help() + + case ["exit"]: + return False + + case ["show"]: + print(get_storage_str_representation(storage)) + + case ["create", *args] if len(args) >= 3: + name = " ".join(args[:-2]) + price = Decimal(args[-2]) + quantity = int(args[-1]) + print_result(create_product(storage, (name, price, quantity))) + + case ["read", product_id]: + print_result(read_product(storage, int(product_id))) + + case ["update", product_id, *args] if len(args) >= 3: + name = " ".join(args[:-2]) + price = Decimal(args[-2]) + quantity = int(args[-1]) + result = update_product( + storage, + int(product_id), + (name, price, quantity), + ) + print_result(result) + + case ["delete", product_id]: + print_result(delete_product(storage, int(product_id))) + + case _: + print(f"'{line}' is not a command") + + return True + + +def main() -> None: + storage: list[Product] = [] + running = True + + while running: + line = input(PROMPT).strip() + + try: + running = run_command(storage, line) + + except (ValueError, InvalidOperation): + print(f"{line!r} names a command but its arguments are invalid") + + +if __name__ == "__main__": + main() diff --git a/src/part3/storage.py b/src/part3/storage.py new file mode 100644 index 00000000..726ab823 --- /dev/null +++ b/src/part3/storage.py @@ -0,0 +1,12 @@ +from decimal import Decimal +from typing import Final + + +Product = tuple[int, str, Decimal, int] + +PRODUCT_ID_INDEX: Final = 0 +NAME_INDEX: Final = 1 +PRICE_INDEX: Final = 2 +QUANTITY_INDEX: Final = 3 + +PRODUCT_ID_MIN: Final[int] = 1 diff --git a/src/part3/utils.py b/src/part3/utils.py new file mode 100644 index 00000000..f5cc90b5 --- /dev/null +++ b/src/part3/utils.py @@ -0,0 +1,53 @@ +from decimal import ROUND_HALF_UP, Decimal +from typing import Final + +from .storage import Product + + +PRICE_PRECISION: Final[int] = 2 +PRICE_STEP: Final[Decimal] = Decimal(1).scaleb(-PRICE_PRECISION) + +TABLE_HEADERS: Final[tuple[str, str, str, str]] = ( + "ID", + "name", + "price", + "quantity", +) + + +def normalize_price(price: Decimal) -> Decimal: + return price.quantize(PRICE_STEP, rounding=ROUND_HALF_UP) + + +def normalize_product_name(name: str) -> str: + return " ".join(name.split()).lower() + + +def get_storage_str_representation(storage: list[Product]) -> str: + rows: list[list[str]] = [list(TABLE_HEADERS)] + + for p in storage: + rows.append( + [ + str(p[0]), + str(p[1]), + str(p[2]), + str(p[3]), + ] + ) + + col_widths = [max(len(row[i]) for row in rows) for i in range(len(TABLE_HEADERS))] + + formatted_rows = [] + for row in rows: + padded_cells = [ + f" {row[i].ljust(col_widths[i])} " for i in range(len(TABLE_HEADERS)) + ] + formatted_rows.append(f"|{'|'.join(padded_cells)}|") + + dash_cells = ["-" * (w + 2) for w in col_widths] + separator_line = f"|{'|'.join(dash_cells)}|" + + formatted_rows.insert(1, separator_line) + + return "\n".join(formatted_rows)