diff --git a/src/part4/cart.py b/src/part4/cart.py index aed9bb72..c2eabc7f 100644 --- a/src/part4/cart.py +++ b/src/part4/cart.py @@ -1,18 +1,4 @@ -"""Shopping-cart operations layered on top of the product store. - -The cart is a plain dictionary mapping each product identifier to the -number of units of that product in the cart. 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 .storage import Product - - -# TODO: при необходимости добавьте свои вспомогательные функции +from .storage import QUANTITY_KEY, Product def add_to_cart( @@ -22,32 +8,19 @@ def add_to_cart( product_id: str, quantity: int, ) -> int | 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 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 - gains ``quantity`` units of ``product_id`` -- the product is added when - the cart had none of it. - - Args: - storage: The product store to draw stock from; modified in place on - success. - product_names: The normalised names in ``storage``; a - quantity-only change never renames a product, so it is left - unchanged here. - 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 quantity of ``product_id`` in the cart after the addition, or - ``None`` when the product is unknown or the store cannot cover the - request. - """ - # TODO: реализуйте функцию - return 0 + if product_id not in storage: + print(f"no product with id {product_id}") + return None + if storage[product_id][QUANTITY_KEY] < quantity: + print( + f"not enough stock for product {product_id}: " + f"{storage[product_id][QUANTITY_KEY]} available, " + f"{quantity} requested" + ) + return None + storage[product_id][QUANTITY_KEY] -= quantity + cart[product_id] = cart.get(product_id, 0) + quantity + return cart[product_id] def remove_from_cart( @@ -57,31 +30,21 @@ def remove_from_cart( product_id: str, quantity: int, ) -> int | None: - """Move ``quantity`` units of ``product_id`` from ``cart`` back to the store. - - If the cart holds no units of ``product_id``, a message is printed and - nothing changes. If it holds fewer units than requested, an explanatory - message is printed and nothing changes. If the product is missing from - ``storage``, a message is printed and nothing changes. Otherwise the cart loses - ``quantity`` units of the product -- the product is dropped from the - cart when its quantity reaches zero -- and the store record gains - ``quantity`` units back. - - Args: - storage: The product store to return stock to; modified in place on - success. - product_names: The normalised names in ``storage``; a - quantity-only change never renames a product, so it is left - unchanged here. - 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 quantity of ``product_id`` left in the cart after the removal - (zero means the product was dropped from the cart), or ``None`` when - the cart does not hold the product or holds too few units. - """ - # TODO: реализуйте функцию - return 0 + if product_id not in cart: + print(f"product {product_id} is not in the cart") + return None + if cart[product_id] < quantity: + print( + f"cart holds only {cart[product_id]} unit(s) " + f"of product {product_id}, cannot remove {quantity}" + ) + return None + if product_id not in storage: + print(f"no product with id {product_id}") + return None + storage[product_id][QUANTITY_KEY] += quantity + cart[product_id] -= quantity + if not cart[product_id]: + del cart[product_id] + return 0 + return cart[product_id] diff --git a/src/part4/crud.py b/src/part4/crud.py index 471eff00..b1423a0a 100644 --- a/src/part4/crud.py +++ b/src/part4/crud.py @@ -1,48 +1,17 @@ -"""Create/read/update/delete operations over the in-memory product store. - -Every operation takes the store -- a dictionary mapping product id to its -:data:`~src.part4.storage.Product` record -- as its first argument and -works on it in place. ``create_product``, ``update_product`` and -``delete_product`` additionally take ``product_names``, the ``set[str]`` -of normalised names currently in ``storage`` (see -:mod:`src.part4.storage`), and keep it in sync with ``storage`` on -every successful call. The failure path never raises: the operation -prints an explanatory message to stdout and returns ``None``. - -The identifier of a new product is a freshly generated UUID string -(:func:`generate_product_id`), independent of insertion order or of any -identifier already in ``storage``. - -Every product name that reaches the store is passed through -:func:`~src.part4.utils.normalize_product_name` first. A name that -normalises to an empty string is rejected -- the operation prints a -message and changes nothing. Names are also kept unique -- -:func:`create_product` refuses a normalised name that is already taken, -and :func:`update_product` refuses one that is already taken by another -product -- via an O(1) membership test against ``product_names`` rather -than a scan over ``storage.values()``. -""" - -import uuid # noqa: F401 +import uuid from typing import Any -from .storage import ( # noqa: F401 +from .storage import ( NAME_KEY, PRICE_KEY, QUANTITY_KEY, Product, ) -from .utils import normalize_price, normalize_product_name # noqa: F401 +from .utils import normalize_price, normalize_product_name def generate_product_id() -> str: - """Generate an identifier for a new product. - - Returns: - A freshly generated UUID, stringified. - """ - # TODO: реализуйте функцию - return "" + return str(uuid.uuid4()) def create_product( @@ -50,46 +19,30 @@ def create_product( product_names: set[str], fields: dict[str, Any], ) -> str | None: - """Add a new product to ``storage`` and return its new identifier. - - Args: - storage: The product store to add to; modified in place on - success. - product_names: The normalised names already in ``storage``; the - new name is added to it in place on success. - fields: A dictionary with the ``name``, ``price`` and ``quantity`` - keys (see :data:`~src.part4.storage.NAME_KEY`, - :data:`~src.part4.storage.PRICE_KEY` and - :data:`~src.part4.storage.QUANTITY_KEY`) describing the - product. ``name`` is normalised (surrounding whitespace - stripped, lower-cased) before it is stored or compared. - ``price`` is a :class:`~decimal.Decimal` amount and is rounded - to the stored money precision before it is saved. - - Returns: - The identifier generated for the new product, or ``None`` when - ``name`` is blank once normalised or a product with the same - normalised name already exists. In the ``None`` case ``storage`` - and ``product_names`` are left unchanged and an explanatory - message is printed. - """ - # TODO: реализуйте функцию - return "" + price_product = normalize_price(fields[PRICE_KEY]) + quantity_product = fields[QUANTITY_KEY] + name_product = normalize_product_name(fields[NAME_KEY]) + if not name_product: + print("product name must not be blank") + return None + if name_product in product_names: + print(f"product name '{name_product}' is already taken") + return None + product_names.add(name_product) + new_id = generate_product_id() + storage[new_id] = { + NAME_KEY: name_product, + PRICE_KEY: price_product, + QUANTITY_KEY: quantity_product, + } + return new_id def read_product(storage: dict[str, Product], product_id: str) -> Product | None: - """Return the product stored under ``product_id``. - - Args: - storage: The product store to search. - product_id: The identifier to look up. - - Returns: - The matching product record, or ``None`` when no product carries - that identifier (a message is printed in that case). - """ - # TODO: реализуйте функцию - return {} + reading = storage.get(product_id) + if reading is None: + print(f"no product with id {product_id}") + return reading def update_product( @@ -98,39 +51,30 @@ def update_product( product_id: str, fields: dict[str, Any], ) -> Product | None: - """Overwrite the fields of the product stored under ``product_id``. - - The identifier itself is preserved. ``fields`` may carry any subset of - ``name``, ``price`` and ``quantity``; a key that is missing keeps the - value the product already has, so a caller can update a single field - without repeating the other two. - - Args: - storage: The product store to modify; the matching record is - updated in place on success. - product_names: The normalised names already in ``storage``; on a - successful rename the old name is removed from it and the new - one added. - product_id: The identifier of the product to change. - fields: A dictionary with any of the ``name``, ``price`` and - ``quantity`` keys (see :data:`~src.part4.storage.NAME_KEY`, - :data:`~src.part4.storage.PRICE_KEY` and - :data:`~src.part4.storage.QUANTITY_KEY`) holding the new - values. ``price`` is a :class:`~decimal.Decimal` amount and is - rounded to the stored money precision before it is saved. - Mutated in place: a ``name`` or ``price`` value present in - ``fields`` is overwritten with its normalised form. - - Returns: - The updated product record, or ``None`` when ``name`` is present - and blank once normalised, no product carries that identifier, or - the normalised name is already taken by another product. In every - ``None`` case ``storage`` and ``product_names`` are left unchanged - and an explanatory message is printed. Renaming a product to its - own current name is allowed. - """ - # TODO: реализуйте функцию - return {} + if product_id not in storage: + print(f"no product with id {product_id}") + return None + if fields.get(NAME_KEY) is not None: + fields[NAME_KEY] = normalize_product_name(fields[NAME_KEY]) + if not fields[NAME_KEY]: + print("product name must not be blank") + return None + if (fields[NAME_KEY] != storage[product_id][NAME_KEY]) and ( + fields[NAME_KEY] in product_names + ): + print(f"product name '{fields[NAME_KEY]}' is already taken") + return None + if fields.get(PRICE_KEY) is not None: + fields[PRICE_KEY] = normalize_price(fields[PRICE_KEY]) + if fields.get(NAME_KEY) is not None: + product_names.discard(storage[product_id][NAME_KEY]) + product_names.add(fields[NAME_KEY]) + storage[product_id][NAME_KEY] = fields[NAME_KEY] + if fields.get(PRICE_KEY) is not None: + storage[product_id][PRICE_KEY] = fields[PRICE_KEY] + if fields.get(QUANTITY_KEY) is not None: + storage[product_id][QUANTITY_KEY] = fields[QUANTITY_KEY] + return storage[product_id] def delete_product( @@ -138,20 +82,9 @@ def delete_product( product_names: set[str], product_id: str, ) -> str | None: - """Remove the product stored under ``product_id`` from ``storage``. - - Args: - storage: The product store to remove from; modified in place on - success. - product_names: The normalised names already in ``storage``; the - departing product's name is removed from it 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`` and ``product_names`` - are left unchanged and a message is printed). - """ - # TODO: реализуйте функцию - return "" + if product_id not in storage: + print(f"no product with id {product_id}") + return None + product_names.discard(storage[product_id][NAME_KEY]) + del storage[product_id] + return product_id diff --git a/src/part4/run_admin.py b/src/part4/run_admin.py index 2247b29b..0a9da822 100644 --- a/src/part4/run_admin.py +++ b/src/part4/run_admin.py @@ -28,71 +28,103 @@ is left untouched and the loop keeps running; only ``exit`` stops it. """ -from decimal import Decimal, InvalidOperation # noqa: F401 +from decimal import Decimal, InvalidOperation from typing import Final -from .crud import ( # noqa: F401 +from .crud import ( create_product, delete_product, read_product, update_product, ) -from .storage import NAME_KEY, PRICE_KEY, QUANTITY_KEY, Product # noqa: F401 -from .utils import get_storage_str_representation # noqa: F401 +from .storage import NAME_KEY, PRICE_KEY, QUANTITY_KEY, Product +from .utils import get_storage_str_representation -# TODO: задайте приглашение и текст справки (используйте своё решение части 3) -PROMPT: Final[str] = "" -HELP_TEXT: Final[str] = "" +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 the command reference to stdout. - The text is the module-level :data:`HELP_TEXT` constant, printed as - is: a heading, one line per command with a short description, and a - note on how multi-word names are parsed. - """ - # TODO: реализуйте функцию (используйте своё решение части 3) +def show_help() -> None: + print(HELP_TEXT) def print_result(result: object) -> None: - """Print a CRUD result to stdout unless it is ``None``. - - Args: - result: The value returned by a CRUD operation. ``None`` means the - operation already reported its own failure, so nothing is - printed in that case. - """ - # TODO: реализуйте функцию (используйте своё решение части 3) + if result is not None: + print(result) def run_command( storage: dict[str, Product], product_names: set[str], line: str ) -> bool: - """Parse one console line and carry out the command it names. - - Args: - storage: The product store shared across the session; mutated in - place by the ``create``, ``update`` and ``delete`` commands. - product_names: The normalised names already in ``storage``; kept - in sync by the ``create``, ``update`` and ``delete`` commands. - line: One line of console input, already stripped of surrounding - whitespace. - - Returns: - ``True`` to keep the read-eval-print loop running, or ``False`` - once the ``exit`` command has been seen. A line that is not a - known command prints a notice and still returns ``True``. - - Raises: - ValueError: If the quantity argument of a CRUD command does not - parse as a base-10 integer. - decimal.InvalidOperation: If the price argument of ``create`` or - ``update`` does not parse as a decimal number. - """ - # TODO: реализуйте функцию - return False + parts = line.split() + match parts: + case ["exit"]: + return False + + case ["help"]: + show_help() + return True + + case ["show"]: + print(get_storage_str_representation(storage)) + return True + + case ["create", *name_parts, price_str, quantity_str] if name_parts: + name = " ".join(name_parts) + price = Decimal(price_str) + quantity = int(quantity_str) + print_result( + create_product( + storage, + product_names, + {NAME_KEY: name, PRICE_KEY: price, QUANTITY_KEY: quantity}, + ) + ) + return True + + case ["read", product_id]: + print_result(read_product(storage, product_id)) + return True + + case [ + "update", + product_id, + *name_parts, + price_str, + quantity_str, + ] if name_parts: + name = " ".join(name_parts) + price = Decimal(price_str) + quantity = int(quantity_str) + print_result( + update_product( + storage, + product_names, + product_id, + {NAME_KEY: name, PRICE_KEY: price, QUANTITY_KEY: quantity}, + ) + ) + return True + + case ["delete", product_id]: + print_result(delete_product(storage, product_names, product_id)) + return True + + case _: + print(f"'{line}' is not a command") + return True def main() -> None: diff --git a/src/part4/storage.py b/src/part4/storage.py index 9acedf07..564aa4ac 100644 --- a/src/part4/storage.py +++ b/src/part4/storage.py @@ -1,45 +1,9 @@ -"""In-memory product store for the shop CRUD exercise. - -The store is deliberately primitive: a plain dictionary, with no -persistence and no schema enforcement. It maps a product's ``id`` -- a -UUID string assigned by the create operation in :mod:`src.part4.crud` --- to its :data:`Product` record -- a dictionary with the keys ``name``, -``price`` and ``quantity`` -- where: - -* the ``storage`` key itself -- unique string identifier, assigned by the - create operation in :mod:`src.part4.crud`; it is not duplicated - inside the record; -* ``name`` -- human-readable product name, unique across the store, held - in normalised form (see - :func:`src.part4.utils.normalize_product_name`); -* ``price`` -- price of a single unit, held as a :class:`~decimal.Decimal` - amount rounded to a fixed number of decimal places (see - :func:`src.part4.utils.normalize_price`) so that money is never - subject to binary floating-point error; -* ``quantity`` -- number of units currently in stock. - -Field names are exposed as ``*_KEY`` constants so callers never hard-code -the dictionary keys. - -Every caller that mutates the store also threads along a second -structure, a ``set[str]`` of the normalised names currently in use -- -see, for example, the ``product_names`` parameter of -:func:`src.part4.crud.create_product`. Keeping that name index as a -plain set passed next to ``storage``, rather than bundling the two into -an object, lets a name-uniqueness check become an O(1) membership test -against the set instead of a linear scan over ``storage.values()``. The -set must always mirror the normalised names present in ``storage``; the -functions in :mod:`src.part4.crud` keep the two in sync on every -successful create, update and delete. -""" - from typing import Any, Final type Product = dict[str, Any] # Name of each field inside a Product record. -# TODO: задайте имена полей записи -NAME_KEY: Final = "" -PRICE_KEY: Final = "" -QUANTITY_KEY: Final = "" +NAME_KEY: Final = "name" +PRICE_KEY: Final = "price" +QUANTITY_KEY: Final = "quantity" diff --git a/src/part4/utils.py b/src/part4/utils.py index d2a940ea..42fb8d23 100644 --- a/src/part4/utils.py +++ b/src/part4/utils.py @@ -1,100 +1,76 @@ -"""Standalone helpers shared by the part4 storage and CRUD modules. +from decimal import ROUND_HALF_UP, Decimal +from typing import Final -Normalisation: +from .storage import NAME_KEY, PRICE_KEY, QUANTITY_KEY, Product -* :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. -* :func:`normalize_product_name` strips surrounding whitespace from a - product name, collapses every internal run of whitespace to a single - space and lower-cases it, giving every stored name a single canonical - form. -Presentation: +PRICE_PRECISION: Final[int] = 2 +PRICE_STEP: Final = Decimal(1).scaleb(-PRICE_PRECISION) -* :func:`get_storage_str_representation` renders the whole store as a - text table meant to be printed to a terminal; each column is sized to - the longest value it holds in that particular call. -""" +TABLE_HEADERS: Final[tuple[str, ...]] = ("ID", "name", "price", "quantity") -from decimal import ROUND_HALF_UP, Decimal # noqa: F401 -from typing import Final +PRODUCT_FIELDS: Final[tuple[str, ...]] = (NAME_KEY, PRICE_KEY, QUANTITY_KEY) + + +def normalize_price(price: Decimal) -> Decimal: + return price.quantize(PRICE_STEP, rounding=ROUND_HALF_UP) -from .storage import ( # noqa: F401 - NAME_KEY, - PRICE_KEY, - QUANTITY_KEY, - Product, -) +def normalize_product_name(name: str) -> str: + return " ".join(name.lower().split()) -# Number of fractional digits every stored price is rounded to. -# Quantisation step derived from PRICE_PRECISION, e.g. Decimal("0.01"). -# TODO: задайте число знаков после запятой и шаг квантования (используйте своё -# решение части 3) -PRICE_PRECISION: Final[int] = 0 -PRICE_STEP: Final = Decimal(0) -# Column headers of the table produced by get_storage_str_representation, -# left to right. The width of each column is not fixed here -- it is -# measured per call from the data (see the function). -# TODO: задайте заголовки столбцов таблицы (используйте своё решение части 3) -TABLE_HEADERS: Final[tuple[str, ...]] = () +def len_first_column(storage: dict[str, Product]) -> int: + max_len = max((len(s) for s in storage), default=0) + return max(max_len, len(TABLE_HEADERS[0])) -def normalize_price(price: Decimal) -> Decimal: - """Round a price to the precision every stored record uses. +def len_other_column(storage: dict[str, Product], column_number: int) -> int: + field_key = PRODUCT_FIELDS[column_number - 1] + max_len = max( + (len(str(product[field_key])) for product in storage.values()), + default=0, + ) + return max(max_len, len(TABLE_HEADERS[column_number])) - Args: - price: The raw price amount. - Returns: - ``price`` quantised to :data:`PRICE_PRECISION` fractional digits, - with halves rounded up. - """ - # TODO: реализуйте функцию (используйте своё решение части 3) - return Decimal(0) +def line_string_headers(max_len_column: list[int]) -> str: + line = "|" + for column_number, header in enumerate(TABLE_HEADERS): + line += " " + header.ljust(max_len_column[column_number]) + " |" + return line -def normalize_product_name(name: str) -> str: - """Reduce a product name to the canonical form the store keeps. +def line_string(product_id: str, storage_i: Product, max_len_column: list[int]) -> str: + line = "|" + line += " " + product_id.ljust(max_len_column[0]) + " |" + for column_number, field_key in enumerate(PRODUCT_FIELDS, start=1): + line += ( + " " + str(storage_i[field_key]).ljust(max_len_column[column_number]) + " |" + ) + return line - Args: - name: The raw product name. - Returns: - ``name`` with every leading and trailing whitespace character - removed, every internal run of whitespace (spaces, tabs and the - like) collapsed to a single space, and the rest lower-cased. For - example ``"abc def\tghi\tjkl"`` becomes ``"abc def ghi jkl"``. - The result is an empty string when ``name`` holds nothing but - whitespace. - """ - # TODO: реализуйте функцию (используйте своё решение части 3) - return "" +def line_void(max_len_column: list[int]) -> str: + line = "|" + for column_len in max_len_column: + line += "-" + "-" * column_len + "-|" + return line -# TODO: при необходимости добавьте свои вспомогательные функции +def max_len(storage: dict[str, Product]) -> list[int]: + max_len_column = [len_first_column(storage)] + max_len_column.extend( + len_other_column(storage, i) for i in range(1, len(TABLE_HEADERS)) + ) + return max_len_column def get_storage_str_representation(storage: dict[str, Product]) -> str: - """Render the product store as a text table with data-sized columns. - - The table has the columns named by :data:`TABLE_HEADERS` -- id, name, - price and quantity. Each column is made exactly as wide as the longest - value it carries in this call (its header counted), so the columns - line up when the string is printed to a terminal and no value is ever - truncated. - - Args: - storage: The product store to render. - - Returns: - A multi-line string: a header row, a dashed separator row, then - one row per product in ``storage``, in insertion order. When - ``storage`` is empty only the header and separator rows are - returned, sized to the header labels. - """ - # TODO: реализуйте функцию (используйте своё решение части 3) - return "" + max_len_column = max_len(storage) + str_representation = "" + str_representation += line_string_headers(max_len_column) + "\n" + str_representation += line_void(max_len_column) + "\n" + for product_id, storage_i in storage.items(): + str_representation += line_string(product_id, storage_i, max_len_column) + "\n" + return str_representation.rstrip("\n")