"""Build payroll formula settings from company deduction catalog.""" from __future__ import annotations import json from decimal import Decimal from human_resource.models import Deduction, HrPayrollSettings from system_administration.models import CompanyProfile DEFAULT_PAYE_CONFIG = { "personal_relief": "2400", "insurance_relief_rate": "0.15", "insurance_relief_cap": "5000", "housing_levy_rate": "0.015", "include_housing_levy_in_paye": True, "paye_band1_limit": "24000", "paye_band1_rate": "0.10", "paye_band2_limit": "8333", "paye_band2_rate": "0.25", "paye_band3_limit": "467667", "paye_band3_rate": "0.30", "paye_band4_limit": "300000", "paye_band4_rate": "0.325", "paye_band5_threshold": "800000", "paye_band5_rate": "0.35", } DEFAULT_NSSF_CONFIG = { "rate": "0.06", "tier1_limit": "8000", "tier2_limit": "72000", } def _decimal(value) -> Decimal: return Decimal(str(value or 0).replace(",", "")) def _parse_config(raw) -> dict: if not raw: return {} if isinstance(raw, dict): return raw try: parsed = json.loads(str(raw)) return parsed if isinstance(parsed, dict) else {} except (TypeError, ValueError, json.JSONDecodeError): return {} def _infer_statutory_formula(deduction: Deduction) -> str: if deduction.statutory_formula: return str(deduction.statutory_formula) title = str(deduction.deduction_title or "").strip().upper() if title == "NSSF": return "nssf_tiered" if title in ("SHA", "SHIF"): return "sha_percentage" if title == "PAYE": return "paye_progressive" if "HOUSING" in title and "LEVY" in title: return "housing_levy" return "" def default_payroll_settings_map() -> dict: return payroll_settings_to_map(HrPayrollSettings(company_profile_id=0)) def get_or_create_payroll_settings(company_profile: CompanyProfile) -> HrPayrollSettings: settings_obj, _created = HrPayrollSettings.objects.get_or_create( company_profile=company_profile, ) return settings_obj def payroll_settings_to_map(settings_obj: HrPayrollSettings) -> dict: """Legacy shape used by payroll_calculations — values come from deductions now.""" return { "nssf_contribution_rate": str(settings_obj.nssf_contribution_rate), "nssf_tier1_limit": str(settings_obj.nssf_tier1_limit), "nssf_tier2_limit": str(settings_obj.nssf_tier2_limit), "shif_contribution_rate": str(settings_obj.shif_contribution_rate), "normalize_shif_to_sha": "true", "housing_levy_rate": str(settings_obj.housing_levy_rate), "include_housing_levy_in_paye": "true" if settings_obj.include_housing_levy_in_paye else "false", "paye_personal_relief": str(settings_obj.paye_personal_relief), "paye_insurance_relief_rate": str(settings_obj.paye_insurance_relief_rate), "paye_insurance_relief_cap": str(settings_obj.paye_insurance_relief_cap), "paye_band1_limit": str(settings_obj.paye_band1_limit), "paye_band1_rate": str(settings_obj.paye_band1_rate), "paye_band2_limit": str(settings_obj.paye_band2_limit), "paye_band2_rate": str(settings_obj.paye_band2_rate), "paye_band3_limit": str(settings_obj.paye_band3_limit), "paye_band3_rate": str(settings_obj.paye_band3_rate), "paye_band4_limit": str(settings_obj.paye_band4_limit), "paye_band4_rate": str(settings_obj.paye_band4_rate), "paye_band5_threshold": str(settings_obj.paye_band5_threshold), "paye_band5_rate": str(settings_obj.paye_band5_rate), } def build_settings_from_deductions(deductions) -> dict: settings = default_payroll_settings_map() housing_from_catalog = False for deduction in deductions or []: formula = _infer_statutory_formula(deduction) cfg = _parse_config(deduction.formula_config) title = str(deduction.deduction_title or "").strip().upper() if formula == "nssf_tiered" or title == "NSSF": merged = {**DEFAULT_NSSF_CONFIG, **cfg} settings["nssf_contribution_rate"] = str(merged.get("rate", "0.06")) settings["nssf_tier1_limit"] = str(merged.get("tier1_limit", "8000")) settings["nssf_tier2_limit"] = str(merged.get("tier2_limit", "72000")) continue if formula == "sha_percentage" or title in ("SHA", "SHIF"): if str(deduction.deduction_module) == "percentage": settings["shif_contribution_rate"] = str(_decimal(deduction.deduction_value) / Decimal("100")) elif cfg.get("rate") is not None: settings["shif_contribution_rate"] = str(cfg.get("rate")) continue if formula == "housing_levy" or ("HOUSING" in title and "LEVY" in title): if str(deduction.deduction_module) == "percentage": settings["housing_levy_rate"] = str(_decimal(deduction.deduction_value) / Decimal("100")) elif cfg.get("rate") is not None: settings["housing_levy_rate"] = str(cfg.get("rate")) settings["include_housing_levy_in_paye"] = "true" if cfg.get("include_in_paye", True) else "false" housing_from_catalog = True continue if formula == "paye_progressive" or title == "PAYE": merged = {**DEFAULT_PAYE_CONFIG, **cfg} settings["paye_personal_relief"] = str(merged.get("personal_relief", "2400")) settings["paye_insurance_relief_rate"] = str(merged.get("insurance_relief_rate", "0.15")) settings["paye_insurance_relief_cap"] = str(merged.get("insurance_relief_cap", "5000")) if not housing_from_catalog: settings["housing_levy_rate"] = str(merged.get("housing_levy_rate", "0.015")) settings["include_housing_levy_in_paye"] = ( "true" if merged.get("include_housing_levy_in_paye", True) else "false" ) for key in ( "paye_band1_limit", "paye_band1_rate", "paye_band2_limit", "paye_band2_rate", "paye_band3_limit", "paye_band3_rate", "paye_band4_limit", "paye_band4_rate", "paye_band5_threshold", "paye_band5_rate", ): if key in merged: settings[key] = str(merged[key]) return settings def resolve_payroll_settings(company_profile: CompanyProfile | None = None) -> dict: if company_profile is None: return default_payroll_settings_map() deductions = company_profile.company_deductions.filter(recycle_bin=False).order_by("-id") return build_settings_from_deductions(deductions) def deduction_row_map(deduction: Deduction) -> dict: return { "deduction_id": str(deduction.id), "deduction_title": deduction.deduction_title, "deduction_description": deduction.deduction_description, "deduction_type": deduction.deduction_type, "deduction_module": deduction.deduction_module, "deduction_value": deduction.deduction_value, "statutory_formula": deduction.statutory_formula or "", "formula_config": deduction.formula_config or "", "date_effective_from": deduction.date_effective_from, "date_effective_to": deduction.date_effective_to, }