Files
bin/finance/app/engine/scenario.py

97 lines
3.2 KiB
Python

from dataclasses import dataclass
from datetime import date
from decimal import ROUND_HALF_UP, Decimal
from app.engine.loans import Installment
from app.engine.recurrence import occurrences
CENT = Decimal("0.01")
@dataclass(frozen=True)
class PlainRecurring:
id: int
name: str
amount: Decimal
rhythm: str
due_day: int
start_date: date | None
end_date: date | None
category_id: int | None
@dataclass(frozen=True)
class PlainPlanned:
name: str
amount: Decimal
due: date
category_id: int | None
@dataclass(frozen=True)
class PlainModifier:
target_type: str
target_id: int
kind: str
value: Decimal
end_date: date | None = None
def _modified(amount: Decimal, category_id: int | None, recurring_id: int | None,
modifiers: list[PlainModifier]) -> Decimal | None:
for m in modifiers:
hit = ((m.target_type == "category" and category_id == m.target_id)
or (m.target_type == "recurring" and recurring_id == m.target_id))
if not hit:
continue
if m.kind == "remove":
return None
if m.kind == "percent":
amount = (amount * (Decimal(100) - m.value) / Decimal(100)).quantize(CENT, ROUND_HALF_UP)
elif m.kind == "absolute":
if amount < 0:
amount = min(Decimal("0"), amount + m.value)
else:
amount = max(Decimal("0"), amount - m.value)
return amount
def _effective_end(r: PlainRecurring, modifiers: list[PlainModifier]) -> date | None:
"""Fruehestes Ende aus eigenem end_date und allen treffenden ende-Modifikatoren."""
end = r.end_date
for m in modifiers:
if m.kind != "ende" or m.end_date is None:
continue
hit = ((m.target_type == "category" and r.category_id == m.target_id)
or (m.target_type == "recurring" and r.id == m.target_id))
if hit:
end = m.end_date if end is None else min(end, m.end_date)
return end
def build_cashflows(recurring: list[PlainRecurring], planned: list[PlainPlanned],
loan_schedules: list[list[Installment]],
loan_payouts: list[tuple[date, Decimal]],
modifiers: list[PlainModifier],
window_start: date, window_end: date) -> list[tuple[date, Decimal]]:
flows: list[tuple[date, Decimal]] = []
for r in recurring:
amount = _modified(r.amount, r.category_id, r.id, modifiers)
if amount is None:
continue
for d in occurrences(r.rhythm, r.due_day, window_start, window_end,
r.start_date, _effective_end(r, modifiers)):
flows.append((d, amount))
for p in planned:
amount = _modified(p.amount, p.category_id, None, modifiers)
if amount is not None and window_start <= p.due <= window_end:
flows.append((p.due, amount))
for d, payout in loan_payouts:
if window_start <= d <= window_end:
flows.append((d, payout))
for sched in loan_schedules:
for inst in sched:
if window_start <= inst.due <= window_end:
flows.append((inst.due, inst.payment))
return sorted(flows)