Fix spin-offs calculations (#524)

* Fix spin-offs calculations

* Fix linter errors.

* Address review feedback.

* * Add spin-offs caching in the filesystem
* Fix calculations for case where there were multiple buy and sell transactions before spin-off - make spin-off a CalculationEntry
* Adjust pdf formating
* Add test for spin-offs.

* Add missing file.

* Fix typing in spin_off_handler.py.

.gitignore

@@ -8,3 +8,4 @@ env
 dist
 calculations.pdf
 exchange_rates.csv
+spin_offs.csv

cgt_calc/args_parser.py

@@ -3,7 +3,11 @@
 import argparse
 import datetime
 
-from .const import DEFAULT_EXCHANGE_RATES_FILE, DEFAULT_REPORT_PATH
+from .const import (
+    DEFAULT_EXCHANGE_RATES_FILE,
+    DEFAULT_REPORT_PATH,
+    DEFAULT_SPIN_OFF_FILE,
+)
 
 
 def get_last_elapsed_tax_year() -> int:
@@ -78,6 +82,13 @@ def create_parser() -> argparse.ArgumentParser:
         nargs="?",
         help="output file for monthly exchange rates from HMRC",
     )
+    parser.add_argument(
+        "--spin-offs-file",
+        type=str,
+        default=DEFAULT_SPIN_OFF_FILE,
+        nargs="?",
+        help="output file for spin offs data",
+    )
     parser.add_argument(
         "--initial-prices",
         type=str,

cgt_calc/const.py

@@ -35,6 +35,8 @@
 # Initial vesting and spin-off prices
 DEFAULT_INITIAL_PRICES_FILE: Final = "initial_prices.csv"
 
+DEFAULT_SPIN_OFF_FILE: Final = "spin_offs.csv"
+
 # Latex template for calculations report
 TEMPLATE_NAME: Final = "template.tex.j2"
 

cgt_calc/current_price_fetcher.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+from contextlib import suppress
 import datetime
 from decimal import Decimal
 
@@ -17,9 +18,11 @@ def __init__(
         self,
         converter: CurrencyConverter,
         current_prices_data: dict[str, Decimal | None] | None = None,
+        historical_prices_data: dict[str, dict[datetime.date, Decimal]] | None = None,
     ):
         """Load data from exchange_rates_file and optionally from initial_data."""
         self.current_prices_data = current_prices_data
+        self.historical_prices_data = historical_prices_data or {}
         self.converter = converter
 
     def get_current_market_price(self, symbol: str) -> Decimal | None:
@@ -35,3 +38,20 @@ def get_current_market_price(self, symbol: str) -> Decimal | None:
         return self.converter.to_gbp(
             market_price_usd, "USD", datetime.datetime.now().date()
         )
+
+    def get_closing_price(self, symbol: str, date: datetime.date) -> Decimal:
+        """Get the price of the share on closing time."""
+        with suppress(KeyError):
+            return self.historical_prices_data[symbol][date]
+
+        prices = yf.Ticker(symbol).history(
+            period="1d",
+            interval="1d",
+            start=date.strftime("%Y-%m-%d"),
+            end=(date + datetime.timedelta(days=1)).strftime("%Y-%m-%d"),
+        )
+        closing_price = prices.iloc[0]["Close"]
+        market_price_usd = Decimal(format(closing_price, ".15g"))
+        return self.converter.to_gbp(
+            market_price_usd, "USD", datetime.datetime.now().date()
+        )