class_name FinancePolicy
extends RefCounted

## Front (表金) and hidden (裏金) funds, the World Tree rank tax and dark bank interest.
## Values are the user-approved initial test values (decisions A09-A12, 2026-10-23).
## The front fund keeps the existing PLAYER_CASH account; saves made before the split
## carry no hidden fund account and are read with every Gold as front funds (A12).

const FRONT_CASH: StringName = &"PLAYER_CASH"
const BACK_CASH: StringName = &"BACK_CASH"
const RANK_TAX_EXPENSE: StringName = &"RANK_TAX_EXPENSE"
const RANK_TAX_PAYABLE: StringName = &"RANK_TAX_PAYABLE"
const LOAN_INTEREST_EXPENSE: StringName = &"LOAN_INTEREST_EXPENSE"
const LOAN_INTEREST_PAYABLE: StringName = &"LOAN_INTEREST_PAYABLE"
const LOAN_LIABILITY_PREFIX := "LOAN_LIABILITY:"

## A10: 10% of the closed day's sales (front + hidden), whole Gold rounded down.
const RANK_TAX_PERCENT := 10
## A11: 1% of the outstanding principal per day, whole Gold rounded down.
const LOAN_INTEREST_PERCENT_PER_DAY := 1

## Services of facilities with one of these tags earn hidden funds (原本: 成人施設、
## カジノ、脅迫金、ユニット売却は裏の収益). Every other service earns front funds.
const BACK_FUND_TAGS: Array[StringName] = [&"restricted_service", &"adult_only"]

## Ledger categories. Accruals are expenses of the closed day; payments, top-ups and
## the payable balances are not income or expense.
const TOP_UP_CATEGORY: StringName = &"BACK_FUND_TOP_UP"
const RANK_TAX_CATEGORY: StringName = &"RANK_TAX"
const RANK_TAX_PAYMENT_CATEGORY: StringName = &"RANK_TAX_PAYMENT"
const LOAN_INTEREST_CATEGORY: StringName = &"LOAN_INTEREST"
const LOAN_INTEREST_PAYMENT_CATEGORY: StringName = &"LOAN_INTEREST_PAYMENT"
const NON_PROFIT_CATEGORIES: Array[StringName] = [TOP_UP_CATEGORY, RANK_TAX_PAYMENT_CATEGORY, LOAN_INTEREST_PAYMENT_CATEGORY]


static func rank_tax(sales: int) -> int:
	return maxi(sales, 0) / 100 * RANK_TAX_PERCENT + maxi(sales, 0) % 100 * RANK_TAX_PERCENT / 100


static func loan_interest(outstanding_principal: int) -> int:
	return maxi(outstanding_principal, 0) / 100 * LOAN_INTEREST_PERCENT_PER_DAY \
		+ maxi(outstanding_principal, 0) % 100 * LOAN_INTEREST_PERCENT_PER_DAY / 100


static func is_back_fund_service(tags: Array) -> bool:
	for tag: StringName in BACK_FUND_TAGS:
		if tag in tags:
			return true
	return false


## Accounts of the split funds. A save without BACK_CASH predates the split and must
## not hold any of the other accounts either; they are then created empty (A12).
## Any other partial or incompatible set is rejected.
static func prepare_accounts(economy: EconomyService) -> bool:
	if economy == null or not economy.has_account(FRONT_CASH) or economy.account_allows_negative(FRONT_CASH):
		return false
	var expected := {
		BACK_CASH: false, RANK_TAX_EXPENSE: false, LOAN_INTEREST_EXPENSE: false,
		RANK_TAX_PAYABLE: true, LOAN_INTEREST_PAYABLE: true,
	}
	if not economy.has_account(BACK_CASH):
		for account_id: StringName in expected:
			if economy.has_account(account_id):
				return false
		for account_id: StringName in expected:
			if not economy.register_account(account_id, bool(expected[account_id])):
				return false
		return true
	for account_id: StringName in expected:
		if not economy.has_account(account_id) \
				or economy.account_allows_negative(account_id) != bool(expected[account_id]):
			return false
	return true


static func outstanding_principal(economy: EconomyService) -> int:
	var total := 0
	for account: Dictionary in economy.get_accounts():
		if String(account[&"account_id"]).begins_with(LOAN_LIABILITY_PREFIX):
			total += -int(account[&"balance"])
	return total


static func available_funds(economy: EconomyService) -> int:
	return economy.get_balance(FRONT_CASH) + economy.get_balance(BACK_CASH)