rdmsandClaude Haiku 4.5
80b8b369c7
- Neuer schedule_for() in app/engine/loans.py: vereinheitlicht Tilgungsplan-Erstellung - Laufzeit-Validierung in LoanIn und LoanPatch: 1–1200 Monate - Aufrufstellen aktualisiert (routers/planning.py, services/breakdown.py, services/projection_service.py, services/planning_chart.py) - Keine direkten loan_schedule(Decimal(...)) Aufrufe außerhalb engine/loans.py mehr - Tests für schedule_for und Laufzeit-Grenzen (1, 1200, sowie 0/-5/1201 Ablehnung) Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
65 lines
2.6 KiB
Python
65 lines
2.6 KiB
Python
import calendar
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from dataclasses import dataclass
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from datetime import date
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from decimal import ROUND_HALF_UP, Decimal
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CENT = Decimal("0.01")
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@dataclass(frozen=True)
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class Installment:
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due: date
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payment: Decimal
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interest: Decimal
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principal: Decimal
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remaining: Decimal
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def add_months(d: date, months: int) -> date:
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y, m0 = divmod(d.year * 12 + d.month - 1 + months, 12)
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m = m0 + 1
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return date(y, m, min(d.day, calendar.monthrange(y, m)[1]))
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def annuity_payment(principal: Decimal, annual_rate_pct: Decimal, term_months: int) -> Decimal:
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i = annual_rate_pct / Decimal(100) / Decimal(12)
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if i == 0:
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return (principal / term_months).quantize(CENT, ROUND_HALF_UP)
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q = (Decimal(1) + i) ** term_months
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return (principal * i * q / (q - Decimal(1))).quantize(CENT, ROUND_HALF_UP)
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def loan_schedule(principal: Decimal, annual_rate_pct: Decimal, term_months: int,
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payout_date: date, repayment_type: str) -> list[Installment]:
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i = annual_rate_pct / Decimal(100) / Decimal(12)
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plan: list[Installment] = []
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remaining = principal
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if repayment_type == "bullet":
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for n in range(1, term_months + 1):
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interest = (remaining * i).quantize(CENT, ROUND_HALF_UP)
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principal_part = remaining if n == term_months else Decimal("0")
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remaining = remaining - principal_part
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plan.append(Installment(add_months(payout_date, n),
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-(interest + principal_part), interest,
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principal_part, remaining.quantize(CENT)))
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return plan
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rate = annuity_payment(principal, annual_rate_pct, term_months)
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for n in range(1, term_months + 1):
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interest = (remaining * i).quantize(CENT, ROUND_HALF_UP)
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principal_part = rate - interest
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if n == term_months or principal_part > remaining:
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principal_part = remaining
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remaining = remaining - principal_part
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plan.append(Installment(add_months(payout_date, n),
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-(interest + principal_part), interest,
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principal_part, remaining.quantize(CENT)))
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return plan
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def schedule_for(loan) -> list[Installment]:
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"""Tilgungsplan eines Kredit-Objekts (ORM-Loan oder gleichartig mit
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principal, annual_rate_pct, term_months, payout_date, repayment_type).
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Ersetzt die wiederholte Feld-für-Feld-Übergabe an loan_schedule (A14)."""
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return loan_schedule(Decimal(loan.principal), Decimal(loan.annual_rate_pct),
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loan.term_months, loan.payout_date, loan.repayment_type)
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