1. Дябденко Богдан Константинович. 613

src/part1/constants.py

@@ -16,23 +16,22 @@
 
 
 # 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
+EPOCH_MS_DEFAULT: Final[int] = 1288834974657
 
 # 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] = 2**TIMESTAMP_BITS - 1
+NODE_ID_MAX: Final[int] = 2**NODE_ID_BITS - 1
+SEQUENCE_ID_MAX: Final[int] = 2**SEQUENCE_ID_BITS - 1
 
 # Здесь можно добавить собственные вспомогательные константы
 # (например, сдвиги полей при сборке идентификатора).

src/part1/snowflake.py

@@ -13,45 +13,35 @@
 :func:`decode_node_id` and :func:`decode_sequence_id`.
 """
 
-import time  # noqa: F401
+import time
 
-from .constants import (  # noqa: F401
+from .constants import (
     EPOCH_MS_DEFAULT,
+    NODE_ID_BITS,
     NODE_ID_DEFAULT,
     NODE_ID_MAX,
+    SEQUENCE_ID_BITS,
     SEQUENCE_ID_MAX,
     TIMESTAMP_MS_MAX,
 )
 
 
 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.
+    user_time = int(time.time() * 1000)
 
-    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
+    differnse_time = user_time - epoch_ms
+
+    return differnse_time
 
 
 def decode_timestamp_ms(snowflake_id: int, epoch_ms: int = EPOCH_MS_DEFAULT) -> int:
-    """Read the timestamp field out of a Snowflake identifier.
 
-    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).
+    user_mc = snowflake_id >> (NODE_ID_BITS + SEQUENCE_ID_BITS)
 
-    Returns:
-        The absolute Unix time in milliseconds at which the identifier was
-        generated.
-    """
-    # TODO: реализуйте функцию
-    return 0
+    absolut_time = user_mc + epoch_ms
+
+    return absolut_time
 
 
 def decode_node_id(snowflake_id: int) -> int:
@@ -64,8 +54,8 @@ def decode_node_id(snowflake_id: int) -> int:
         The node identifier packed into ``snowflake_id``, in the range
         ``[0, NODE_ID_MAX]``.
     """
-    # TODO: реализуйте функцию
-    return 0
+    identifier_id = (snowflake_id >> SEQUENCE_ID_BITS) & NODE_ID_MAX
+    return identifier_id
 
 
 def decode_sequence_id(snowflake_id: int) -> int:
@@ -78,8 +68,8 @@ def decode_sequence_id(snowflake_id: int) -> int:
         The per-millisecond sequence counter packed into ``snowflake_id``, in
         the range ``[0, SEQUENCE_ID_MAX]``.
     """
-    # TODO: реализуйте функцию
-    return 0
+    sequence_id = snowflake_id & SEQUENCE_ID_MAX
+    return sequence_id
 
 
 def generate_snowflake_id(
@@ -110,5 +100,19 @@ def generate_snowflake_id(
         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
+    if node_id < 0 or node_id > NODE_ID_MAX:
+        print(f"node_id must be in [0, {NODE_ID_MAX}], got {node_id}")
+        return None
+    if sequence_id < 0 or sequence_id > SEQUENCE_ID_MAX:
+        print(f"sequence_id must be in [0, {SEQUENCE_ID_MAX}], got {sequence_id}")
+        return None
+    elapsed_ms = read_current_millis(epoch_ms)
+    if elapsed_ms > TIMESTAMP_MS_MAX:
+        print(f"timestamp overflows: {elapsed_ms} > {TIMESTAMP_MS_MAX}")
+        return None
+    snowflake_id = (
+        (elapsed_ms << (NODE_ID_BITS + SEQUENCE_ID_BITS))
+        | (node_id << SEQUENCE_ID_BITS)
+        | sequence_id
+    )
+    return snowflake_id

src/part2/cart.py

@@ -11,10 +11,11 @@
 
 from typing import Final
 
-from .crud import read_product, update_product  # noqa: F401
-from .storage import (  # noqa: F401
+from .crud import read_product
+from .storage import (
     NAME_INDEX,
     PRICE_INDEX,
+    PRODUCT_ID_INDEX,
     QUANTITY_INDEX,
     Product,
 )
@@ -24,7 +25,25 @@
 
 # TODO: задайте позиции полей внутри кортежа CartLine
 LINE_PRODUCT_ID_INDEX: Final = 0
-LINE_QUANTITY_INDEX: Final = 0
+LINE_QUANTITY_INDEX: Final = 1
+
+
+def find_cart_line(cart: list[CartLine], product_id: int) -> CartLine | None:
+    """Return the cart line stored under ``product_id``.
+
+    Args:
+        cart: The store of cart line.
+        product_id: The identifier to look up.
+
+    Returns:
+        The matching ``(product_id, line_quantity)`` record,
+        ``None`` when no cart line carries that identifier (a message is
+        printed in that case).
+    """
+    for cart_line in cart:
+        if cart_line[LINE_PRODUCT_ID_INDEX] == product_id:
+            return cart_line
+    return None
 
 
 def add_to_cart(
@@ -53,8 +72,40 @@ 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)
+    product = read_product(storage, product_id)
+    if product is None:
+        return None
+    if product[QUANTITY_INDEX] < quantity:
+        print(
+            f"not enough stock for product {product_id}: "
+            f"{product[QUANTITY_INDEX]} available, {quantity} requested"
+        )
+        return None
+
+    for index_product, cell in enumerate(storage):
+        if cell[PRODUCT_ID_INDEX] == product_id:
+            storage[index_product] = (
+                cell[PRODUCT_ID_INDEX],
+                cell[NAME_INDEX],
+                cell[PRICE_INDEX],
+                cell[QUANTITY_INDEX] - quantity,
+            )
+            break
+    else:
+        return None
+
+    for index_line, purchase in enumerate(cart):
+        if purchase[LINE_PRODUCT_ID_INDEX] == product_id:
+            new_line: CartLine = (
+                purchase[LINE_PRODUCT_ID_INDEX],
+                purchase[LINE_QUANTITY_INDEX] + quantity,
+            )
+            cart[index_line] = new_line
+            return new_line
+
+    new_line = (product_id, quantity)
+    cart.append(new_line)
+    return new_line
 
 
 def remove_from_cart(
@@ -85,5 +136,41 @@ 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)
+    our_line = find_cart_line(cart, product_id)
+    if our_line is None:
+        print(f"product {product_id} is not in the cart")
+        return None
+    if our_line[LINE_QUANTITY_INDEX] < quantity:
+        print(
+            f"cart holds only {our_line[LINE_QUANTITY_INDEX]} unit(s) "
+            f"of product {product_id}, cannot remove {quantity}"
+        )
+        return None
+
+    product = read_product(storage, product_id)
+    if product is None:
+        return None
+
+    for index_product, stored_product in enumerate(storage):
+        if stored_product[PRODUCT_ID_INDEX] == product_id:
+            storage[index_product] = (
+                stored_product[PRODUCT_ID_INDEX],
+                stored_product[NAME_INDEX],
+                stored_product[PRICE_INDEX],
+                stored_product[QUANTITY_INDEX] + quantity,
+            )
+            break
+    else:
+        return None
+
+    for index_cart_line, cart_line in enumerate(cart):
+        if cart_line[LINE_PRODUCT_ID_INDEX] == product_id:
+            new_quantity = cart_line[LINE_QUANTITY_INDEX] - quantity
+            if new_quantity == 0:
+                del cart[index_cart_line]
+                return (product_id, 0)
+            updated_line: CartLine = (product_id, new_quantity)
+            cart[index_cart_line] = updated_line
+            return updated_line
+
+    return None

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:
@@ -34,8 +34,10 @@ 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 not storage:
+        return PRODUCT_ID_MIN
+    product_id = max(product[PRODUCT_ID_INDEX] for product in storage) + 1
+    return product_id
 
 
 def create_product(
@@ -56,8 +58,15 @@ def create_product(
         ``storage`` is left unchanged and a message naming the clashing
         name is printed.
     """
-    # TODO: реализуйте функцию
-    return 0
+
+    for product in storage:
+        if product[NAME_INDEX] == fields[0]:
+            print(f"product name {product[NAME_INDEX]} is already taken")
+            return None
+    new_product_id = generate_product_id(storage)
+    new_product = (new_product_id, fields[0], normalize_price(fields[1]), fields[2])
+    storage.append(new_product)
+    return new_product_id
 
 
 def read_product(storage: list[Product], product_id: int) -> Product | None:
@@ -72,8 +81,11 @@ 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"no product with id {product_id}")
+    return None
 
 
 def update_product(
@@ -99,8 +111,19 @@ 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)
+    norm_price = normalize_price(fields[1])
+    for index_old_product, old_product in enumerate(storage):
+        if old_product[PRODUCT_ID_INDEX] == product_id:
+            updation_product: Product = (
+                old_product[PRODUCT_ID_INDEX],
+                fields[0],
+                norm_price,
+                fields[2],
+            )
+            storage[index_old_product] = updation_product
+            return updation_product
+    print(f"no product with id {product_id}")
+    return None
 
 
 def delete_product(storage: list[Product], product_id: int) -> int | None:
@@ -116,5 +139,10 @@ 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 product in storage:
+        if product[PRODUCT_ID_INDEX] == product_id:
+            storage.remove(product)
+            return product_id
+
+    print(f"no product with id {product_id}")
+    return None

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

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 +25,7 @@ def normalize_price(price: Decimal) -> Decimal:
         ``price`` quantised to :data:`PRICE_PRECISION` fractional digits,
         with halves rounded up.
     """
-    # TODO: реализуйте функцию
-    return Decimal(0)
+    ratio = price / PRICE_STEP
+    steps = ratio.quantize(Decimal("1."), rounding=ROUND_HALF_UP)
+    real_price = steps * PRICE_STEP
+    return real_price