modules/purchase_trade/fee.py

@@ -334,7 +334,7 @@ class Fee(ModelSQL,ModelView):
                 if self.sale_line:
                     if self.sale_line.sale.payment_term:
                         beg_date = self.fee_date if self.fee_date else Date.today()
-                        est_date = self.sale_line.sale.payment_term.get_date(beg_date)
+                        est_date = self.sale_line.sale.payment_term[0].get_date(beg_date)
                         if est_date and beg_date:
                             factor = InterestCalculator.calculate(
                                 start_date=beg_date,

modules/purchase_trade/financing_tools.py

@@ -0,0 +1,259 @@
+from decimal import Decimal, getcontext
+from datetime import datetime, date
+from calendar import isleap
+from typing import Callable, Dict
+import uuid
+
+getcontext().prec = 28
+
+# {
+#   "computation_type": "INTEREST_ACCRUAL",
+#   "input": {
+#     "start_date": "2026-01-01",
+#     "end_date": "2026-06-30",
+#     "notional": "1000000",
+#     "rate": {
+#       "value": "0.08",
+#       "type": "ANNUAL"
+#     },
+#     "day_count_convention": "ACT/360",
+#     "compounding_method": "SIMPLE"
+#   }
+# }
+
+# result = FinancialComputationService.execute(payload)
+# interest = Decimal(result["result"]["interest_amount"])
+# interest = currency.round(interest)
+
+# ============================================================
+# VERSIONING
+# ============================================================
+
+ENGINE_VERSION = "1.0.0"
+
+
+# ============================================================
+# REGISTRY (PLUGIN SYSTEM)
+# ============================================================
+
+DAY_COUNT_REGISTRY: Dict[str, Callable] = {}
+COMPOUNDING_REGISTRY: Dict[str, Callable] = {}
+
+
+def register_day_count(name: str):
+    def decorator(func):
+        DAY_COUNT_REGISTRY[name] = func
+        return func
+    return decorator
+
+
+def register_compounding(name: str):
+    def decorator(func):
+        COMPOUNDING_REGISTRY[name] = func
+        return func
+    return decorator
+
+
+# ============================================================
+# DOMAIN – DAY COUNT CONVENTIONS
+# ============================================================
+
+@register_day_count("ACT/360")
+def act_360(start: date, end: date) -> Decimal:
+    return Decimal((end - start).days) / Decimal(360)
+
+
+@register_day_count("ACT/365F")
+def act_365f(start: date, end: date) -> Decimal:
+    return Decimal((end - start).days) / Decimal(365)
+
+
+@register_day_count("ACT/ACT_ISDA")
+def act_act_isda(start: date, end: date) -> Decimal:
+    total = Decimal("0")
+    current = start
+
+    while current < end:
+        year_end = date(current.year, 12, 31)
+        next_year = date(current.year + 1, 1, 1)
+        period_end = min(next_year, end)
+
+        days = (period_end - current).days
+        year_days = 366 if isleap(current.year) else 365
+
+        total += Decimal(days) / Decimal(year_days)
+        current = period_end
+
+    return total
+
+
+@register_day_count("30E/360")
+def thirty_e_360(start: date, end: date) -> Decimal:
+    d1 = min(start.day, 30)
+    d2 = min(end.day, 30)
+
+    days = (
+        (end.year - start.year) * 360 +
+        (end.month - start.month) * 30 +
+        (d2 - d1)
+    )
+
+    return Decimal(days) / Decimal(360)
+
+
+# ============================================================
+# DOMAIN – COMPOUNDING STRATEGIES
+# ============================================================
+
+@register_compounding("SIMPLE")
+def simple(rate: Decimal, yf: Decimal) -> Decimal:
+    return rate * yf
+
+
+@register_compounding("ANNUAL")
+def annual(rate: Decimal, yf: Decimal) -> Decimal:
+    return (Decimal(1) + rate) ** yf - Decimal(1)
+
+
+@register_compounding("MONTHLY")
+def monthly(rate: Decimal, yf: Decimal) -> Decimal:
+    monthly_rate = rate / Decimal(12)
+    months = yf * Decimal(12)
+    return (Decimal(1) + monthly_rate) ** months - Decimal(1)
+
+
+@register_compounding("CONTINUOUS")
+def continuous(rate: Decimal, yf: Decimal) -> Decimal:
+    from math import exp
+    return Decimal(exp(float(rate * yf))) - Decimal(1)
+
+
+# ============================================================
+# DOMAIN – INTEREST COMPUTATION OBJECT
+# ============================================================
+
+class InterestComputation:
+
+    def __init__(
+        self,
+        start_date: date,
+        end_date: date,
+        notional: Decimal,
+        rate_value: Decimal,
+        rate_type: str,
+        day_count: str,
+        compounding: str,
+    ):
+        self.start_date = start_date
+        self.end_date = end_date
+        self.notional = notional
+        self.rate_value = rate_value
+        self.rate_type = rate_type
+        self.day_count = day_count
+        self.compounding = compounding
+
+    def compute(self):
+
+        if self.end_date <= self.start_date:
+            raise ValueError("end_date must be after start_date")
+
+        if self.day_count not in DAY_COUNT_REGISTRY:
+            raise ValueError("Unsupported day count convention")
+
+        if self.compounding not in COMPOUNDING_REGISTRY:
+            raise ValueError("Unsupported compounding method")
+
+        yf = DAY_COUNT_REGISTRY[self.day_count](
+            self.start_date,
+            self.end_date
+        )
+
+        # Normalize rate to annual
+        if self.rate_type == "MONTHLY":
+            annual_rate = self.rate_value * Decimal(12)
+        else:
+            annual_rate = self.rate_value
+
+        factor = COMPOUNDING_REGISTRY[self.compounding](
+            annual_rate,
+            yf
+        )
+
+        interest_amount = self.notional * factor
+
+        return {
+            "year_fraction": yf,
+            "interest_factor": factor,
+            "interest_amount": interest_amount,
+        }
+
+
+# ============================================================
+# APPLICATION LAYER – JSON SERVICE (Camunda Ready)
+# ============================================================
+
+class FinancialComputationService:
+
+    @staticmethod
+    def execute(payload: dict) -> dict:
+        """
+        Stateless JSON entrypoint.
+        Compatible Camunda / REST / Tryton bridge.
+        """
+
+        try:
+            request_id = str(uuid.uuid4())
+
+            input_data = payload["input"]
+
+            start_date = datetime.strptime(
+                input_data["start_date"], "%Y-%m-%d"
+            ).date()
+
+            end_date = datetime.strptime(
+                input_data["end_date"], "%Y-%m-%d"
+            ).date()
+
+            notional = Decimal(input_data["notional"])
+            rate_value = Decimal(input_data["rate"]["value"])
+            rate_type = input_data["rate"]["type"].upper()
+            day_count = input_data["day_count_convention"]
+            compounding = input_data["compounding_method"]
+
+            computation = InterestComputation(
+                start_date=start_date,
+                end_date=end_date,
+                notional=notional,
+                rate_value=rate_value,
+                rate_type=rate_type,
+                day_count=day_count,
+                compounding=compounding,
+            )
+
+            result = computation.compute()
+
+            return {
+                "metadata": {
+                    "engine_version": ENGINE_VERSION,
+                    "request_id": request_id,
+                    "timestamp": datetime.utcnow().isoformat() + "Z"
+                },
+                "result": {
+                    "year_fraction": str(result["year_fraction"]),
+                    "interest_factor": str(result["interest_factor"]),
+                    "interest_amount": str(result["interest_amount"]),
+                },
+                "explainability": {
+                    "formula": "Interest = Notional × Factor",
+                    "factor_definition": f"{compounding} compounding applied to annualized rate",
+                    "day_count_used": day_count
+                },
+                "status": "SUCCESS"
+            }
+
+        except Exception as e:
+            return {
+                "status": "ERROR",
+                "message": str(e),
+                "engine_version": ENGINE_VERSION
+            }