2. Пенская Алина Павловна. 613

src/part1/constants.py

@@ -19,20 +19,23 @@
 # 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] = (1 << TIMESTAMP_BITS) - 1
+NODE_ID_MAX: Final[int] = (1 << NODE_ID_BITS) - 1
+SEQUENCE_ID_MAX: Final[int] = (1 << SEQUENCE_ID_BITS) - 1
 
 # Здесь можно добавить собственные вспомогательные константы
 # (например, сдвиги полей при сборке идентификатора).
+SEQUENCE_ID_SHIFT: Final[int] = 0  # справа(младшие разряды)
+NODE_ID_SHIFT: Final[int] = SEQUENCE_ID_BITS
+TIMESTAMP_SHIFT: Final[int] = SEQUENCE_ID_BITS + NODE_ID_BITS

src/part1/snowflake.py

@@ -13,14 +13,17 @@
 :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_DEFAULT,
     NODE_ID_MAX,
+    NODE_ID_SHIFT,
+    SEQUENCE_ID_BITS,
     SEQUENCE_ID_MAX,
     TIMESTAMP_MS_MAX,
+    TIMESTAMP_SHIFT,
 )
 
 
@@ -34,8 +37,7 @@ def read_current_millis(epoch_ms: int) -> int:
         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
+    return int(time.time() * 1000) - epoch_ms
 
 
 def decode_timestamp_ms(snowflake_id: int, epoch_ms: int = EPOCH_MS_DEFAULT) -> int:
@@ -51,7 +53,8 @@ def decode_timestamp_ms(snowflake_id: int, epoch_ms: int = EPOCH_MS_DEFAULT) ->
         generated.
     """
     # TODO: реализуйте функцию
-    return 0
+    time_res = snowflake_id >> TIMESTAMP_SHIFT
+    return time_res + epoch_ms
 
 
 def decode_node_id(snowflake_id: int) -> int:
@@ -65,7 +68,8 @@ def decode_node_id(snowflake_id: int) -> int:
         ``[0, NODE_ID_MAX]``.
     """
     # TODO: реализуйте функцию
-    return 0
+    node_id = (snowflake_id >> SEQUENCE_ID_BITS) & NODE_ID_MAX
+    return node_id
 
 
 def decode_sequence_id(snowflake_id: int) -> int:
@@ -79,7 +83,8 @@ def decode_sequence_id(snowflake_id: int) -> int:
         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(
@@ -111,4 +116,19 @@ def generate_snowflake_id(
         cases an explanatory message is printed to stdout first.
     """
     # TODO: реализуйте функцию
-    return 0
+    if not (0 <= node_id <= NODE_ID_MAX):
+        print(f"node_id must be in [0, {NODE_ID_MAX}], but you wrote {node_id}")
+        return None
+    if not (0 <= sequence_id <= SEQUENCE_ID_MAX):
+        print(
+            f"sequence_id must be in [0, {SEQUENCE_ID_MAX}], but you wrote {sequence_id}"
+        )
+        return None
+    timestamp = read_current_millis(epoch_ms)
+    if not (0 <= timestamp <= TIMESTAMP_MS_MAX):
+        print("overflows")
+        return None
+    node_res = node_id << NODE_ID_SHIFT
+    timestamp_res = timestamp << TIMESTAMP_SHIFT
+    result = timestamp_res | node_res | sequence_id
+    return result

src/part2/cart.py

@@ -9,10 +9,10 @@
 an explanatory message to stdout and returns ``None``.
 """
 
-from typing import Final
+from typing import Final, cast
 
-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 +24,21 @@
 
 # TODO: задайте позиции полей внутри кортежа CartLine
 LINE_PRODUCT_ID_INDEX: Final = 0
-LINE_QUANTITY_INDEX: Final = 0
+LINE_QUANTITY_INDEX: Final = 1
+
+
+def make_cart(product_id: int, quantity: int) -> CartLine:  # переставлять
+    fields: list[int] = [0] * 2
+    fields[LINE_PRODUCT_ID_INDEX] = product_id
+    fields[LINE_QUANTITY_INDEX] = quantity
+    return cast(CartLine, tuple(fields))
+
+
+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
+    return None
 
 
 def add_to_cart(
@@ -54,7 +68,31 @@ def add_to_cart(
         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:
+        if product[QUANTITY_INDEX] < quantity:
+            print(
+                f"not enough stock for product {product_id}: {product[QUANTITY_INDEX]} available, {quantity} requested"
+            )
+            return None
+        product = update_product(
+            storage,
+            product_id,
+            (
+                product[NAME_INDEX],
+                product[PRICE_INDEX],
+                product[QUANTITY_INDEX] - quantity,
+            ),
+        )
+        for line in cart:
+            if line[LINE_PRODUCT_ID_INDEX] == product_id:
+                new_line = make_cart(product_id, line[LINE_QUANTITY_INDEX] + quantity)
+                cart[cart.index(line)] = new_line
+                return new_line
+        new_line = make_cart(product_id, quantity)
+        cart.append(new_line)
+        return new_line
+    return None
 
 
 def remove_from_cart(
@@ -86,4 +124,32 @@ def remove_from_cart(
         line for the product or holds too few units.
     """
     # TODO: реализуйте функцию
-    return (0, 0)
+    line = find_cart_line(cart, product_id)
+    if line is None:
+        print(f"product {product_id} is not in the cart")
+        return None
+    if line[LINE_QUANTITY_INDEX] < quantity:
+        print(
+            f"cart holds only {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
+    update_product(
+        storage,
+        product_id,
+        (
+            product[NAME_INDEX],
+            product[PRICE_INDEX],
+            product[QUANTITY_INDEX] + quantity,
+        ),
+    )
+    new_quantity = line[LINE_QUANTITY_INDEX] - quantity
+    if new_quantity == 0:
+        cart.remove(line)
+        return make_cart(product_id, 0)
+    new_line = make_cart(product_id, new_quantity)
+    cart[cart.index(line)] = new_line
+    return new_line

src/part2/crud.py

@@ -13,14 +13,31 @@
 """
 
 from decimal import Decimal
+from typing import cast
 
-from .storage import (  # noqa: F401
+from .storage import (
     NAME_INDEX,
+    PRICE_INDEX,
     PRODUCT_ID_INDEX,
     PRODUCT_ID_MIN,
+    QUANTITY_INDEX,
     Product,
 )
-from .utils import normalize_price  # noqa: F401
+from .utils import normalize_price
+
+
+def make(  # чтобы можно было переставлять
+    product_id: int,
+    name: str,
+    price: Decimal,
+    quantity: int,
+) -> Product:
+    fields: list[int | str | Decimal] = [0] * 4
+    fields[PRODUCT_ID_INDEX] = product_id
+    fields[NAME_INDEX] = name
+    fields[PRICE_INDEX] = price
+    fields[QUANTITY_INDEX] = quantity
+    return cast(Product, tuple(fields))
 
 
 def generate_product_id(storage: list[Product]) -> int:
@@ -35,7 +52,12 @@ def generate_product_id(storage: list[Product]) -> int:
         empty.
     """
     # TODO: реализуйте функцию
-    return 0
+    if not storage:
+        return PRODUCT_ID_MIN
+    max_id = 0
+    for product in storage:
+        max_id = max(max_id, product[PRODUCT_ID_INDEX])
+    return max_id + 1
 
 
 def create_product(
@@ -57,7 +79,15 @@ def create_product(
         name is printed.
     """
     # TODO: реализуйте функцию
-    return 0
+    name, price, quantity = fields
+    for product in storage:
+        if product[NAME_INDEX] == name:
+            print(f"product name '{name}' is already taken")
+            return None
+    product_id = generate_product_id(storage)
+    normalized_price = normalize_price(price)
+    storage.append(make(product_id, name, normalized_price, quantity))
+    return product_id
 
 
 def read_product(storage: list[Product], product_id: int) -> Product | None:
@@ -73,7 +103,11 @@ def read_product(storage: list[Product], product_id: int) -> Product | None:
         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(
@@ -100,7 +134,16 @@ def update_product(
         left unchanged and a message is printed).
     """
     # TODO: реализуйте функцию
-    return (0, "", Decimal(0), 0)
+    name, price, quantity = fields
+    price = normalize_price(price)
+    for i in range(len(storage)):
+        product = storage[i]
+        if product[PRODUCT_ID_INDEX] == product_id:
+            updated_product = make(product_id, name, price, quantity)
+            storage[i] = updated_product
+            return updated_product
+    print(f"no product with id {product_id}")
+    return None
 
 
 def delete_product(storage: list[Product], product_id: int) -> int | None:
@@ -117,4 +160,9 @@ def delete_product(storage: list[Product], product_id: int) -> int | None:
         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:
@@ -26,4 +26,4 @@ def normalize_price(price: Decimal) -> Decimal:
         with halves rounded up.
     """
     # TODO: реализуйте функцию
-    return Decimal(0)
+    return price.quantize(PRICE_STEP, rounding=ROUND_HALF_UP)