refactor(chart): Added docstring in each file and function. Fixed long lines

chart/function/create_chart.py

@@ -1,3 +1,8 @@
+"""
+This module provides functionality to generate currency rate charts
+based on historical data retrieved from the database.
+"""
+
 from datetime import datetime
 
 from matplotlib import pyplot as plt
@@ -5,7 +10,29 @@ from matplotlib import pyplot as plt
 from chart.function.gen_unique_name import generate_unique_name
 from ..database.server import create_pool
 
-async def create_chart(from_currency: str, conv_currency: str, start_date: str, end_date: str) -> (str, None):
+async def create_chart(
+        from_currency: str,
+        conv_currency: str,
+        start_date: str,
+        end_date: str
+) -> (str, None):
+    """
+    Generates a line chart of currency rates for a given date range.
+
+    The chart shows the exchange rate trend between `from_currency` and
+    `conv_currency` within the specified `start_date` and `end_date` range.
+    The generated chart is saved as a PNG file, and the function returns the
+    file name. If data is invalid or insufficient, the function returns `None`.
+
+    Args:
+        from_currency (str): The base currency (e.g., "USD").
+        conv_currency (str): The target currency (e.g., "EUR").
+        start_date (str): The start date in the format 'YYYY-MM-DD'.
+        end_date (str): The end date in the format 'YYYY-MM-DD'.
+
+    Returns:
+        str | None: The name of the saved chart file, or `None` if the operation fails.
+    """
     pool = await create_pool()
 
     if not validate_date(start_date) or not validate_date(end_date):
@@ -58,6 +85,15 @@ async def create_chart(from_currency: str, conv_currency: str, start_date: str,
 
 
 def validate_date(date_str: str) -> bool:
+    """
+    Validates whether the provided string is a valid date in the format 'YYYY-MM-DD'.
+
+    Args:
+        date_str (str): The date string to validate.
+
+    Returns:
+        bool: `True` if the string is a valid date, `False` otherwise.
+    """
     try:
         datetime.strptime(date_str, '%Y-%m-%d')
         return True

chart/function/gen_unique_name.py

@@ -1,9 +1,23 @@
+"""
+This module provides a function to generate a unique name for chart files.
+"""
 import datetime
 import random
 import string
 
 
 async def generate_unique_name(currency_pair: str, date: datetime) -> str:
+    """
+    Generates a unique name for a chart file based on the currency pair,
+    current date, and a random suffix.
+
+    Args:
+        currency_pair (str): A string representing the currency pair (e.g., "USD_EUR").
+        date (datetime.datetime): The current datetime object.
+
+    Returns:
+        str: A unique name in the format "CURRENCYPAIR_YYYYMMDD_RANDOMSUFFIX".
+    """
     date_str = date.strftime("%Y%m%d")
     random_suffix = ''.join(random.choices(string.ascii_uppercase + string.digits, k=6))
     unique_name = f"{currency_pair}_{date_str}_{random_suffix}"