Add trading journal and portfolio tracking

app/trading_models.py

@@ -0,0 +1,73 @@
+"""Exact trading values, vocabulary and validation (no binary floats)."""
+import re
+from decimal import Decimal, localcontext, ROUND_HALF_UP
+from models import valid_date
+
+TYPES = {'buy': 'Kauf', 'sell': 'Verkauf'}
+SOURCES = {'manual': 'Manuell', 'savings_plan': 'Sparplan', 'roundup': 'Round-up', 'cashback': 'Cashback', 'rebalancing': 'Rebalancing', 'other': 'Sonstiges'}
+STRATEGIES = {'core': 'Core', 'income': 'Income', 'conviction': 'Conviction', 'dip_buy': 'Dip Buy', 'speculation': 'Spekulation', 'rebalancing': 'Rebalancing', 'other': 'Sonstiges'}
+CENT = Decimal('0.01')
+ZERO = Decimal(0)
+
+
+class TradingValidationError(ValueError):
+    """Safe, user-facing domain error, never contains database internals."""
+
+
+def decimal_value(value, label, places=12, positive=False):
+    if not isinstance(value, (str, Decimal)):
+        raise TradingValidationError(f'{label} als Dezimalstring eingeben.')
+    text = str(value).strip().replace(',', '.')
+    if not re.fullmatch(r'\d{1,12}(?:\.\d{1,' + str(places) + r'})?', text):
+        raise TradingValidationError(f'{label}: maximal 12 Vorkomma- und {places} Nachkommastellen, ohne Tausendertrennzeichen.')
+    number = Decimal(text)
+    if positive and number <= 0:
+        raise TradingValidationError(f'{label} muss größer als 0 sein.')
+    return number
+
+
+def currency_code(value):
+    code = str(value).strip().upper()
+    if not re.fullmatch('[A-Z]{3}', code):
+        raise TradingValidationError('Währung als dreistelligen Code eingeben, z. B. EUR.')
+    return code
+
+
+def fixed(value, places=2):
+    with localcontext() as ctx:
+        ctx.prec = 60
+        return format(Decimal(value).quantize(Decimal(1).scaleb(-places), rounding=ROUND_HALF_UP), f'.{places}f')
+
+
+def exact(value):
+    return format(Decimal(value), 'f')
+
+
+def display_decimal(value, places=2):
+    return fixed(value, places).replace('.', ',')
+
+
+def validate_trade(data):
+    try:
+        day = valid_date(data.get('date', ''))
+    except ValueError as error:
+        raise TradingValidationError(str(error)) from None
+    try:
+        asset_id = int(data.get('asset_id', ''))
+        if isinstance(data.get('asset_id'), bool) or not 1 <= asset_id <= 9223372036854775807:
+            raise ValueError
+    except (ValueError, TypeError):
+        raise TradingValidationError('Bitte eine gültige Position auswählen.') from None
+    kind, source = data.get('transaction_type', 'buy'), data.get('source', 'manual')
+    strategy = data.get('strategy_tag') or None
+    if kind not in TYPES or source not in SOURCES or (strategy is not None and strategy not in STRATEGIES):
+        raise TradingValidationError('Ungültiger Typ, Source oder Strategie-Tag.')
+    quantity = decimal_value(data.get('quantity', ''), 'Stückzahl', positive=True)
+    price = decimal_value(data.get('price_per_unit', ''), 'Kurs')
+    fees = decimal_value(data.get('fees', '0'), 'Gebühren', places=2)
+    note = (data.get('note') or '').strip()
+    if len(note) > 2000:
+        raise TradingValidationError('Notiz darf maximal 2000 Zeichen enthalten.')
+    return dict(date=day, asset_id=asset_id, transaction_type=kind, quantity=exact(quantity),
+                price_per_unit=exact(price), currency=currency_code(data.get('currency', 'EUR')),
+                fees=fixed(fees), source=source, strategy_tag=strategy, note=note or None)