class_name LedgerEntry
extends RefCounted

## One immutable-in-practice double-entry ledger line.
##
## A debit increases the signed balance of debit_account and a credit decreases
## the signed balance of credit_account. EconomyService is the only component
## which may append entries or update its derived balance cache.

var transaction_id: StringName = &""
var absolute_minute := 0
var debit_account: StringName = &""
var credit_account: StringName = &""
var amount := 0
var category: StringName = &""
var source_entity_id: StringName = &""
var related_transaction_id: StringName = &""
var memo_key: StringName = &""


func configure(
	p_transaction_id: StringName,
	p_absolute_minute: int,
	p_debit_account: StringName,
	p_credit_account: StringName,
	p_amount: int,
	p_category: StringName,
	p_source_entity_id: StringName = &"",
	p_related_transaction_id: StringName = &"",
	p_memo_key: StringName = &""
) -> LedgerEntry:
	transaction_id = p_transaction_id
	absolute_minute = p_absolute_minute
	debit_account = p_debit_account
	credit_account = p_credit_account
	amount = p_amount
	category = p_category
	source_entity_id = p_source_entity_id
	related_transaction_id = p_related_transaction_id
	memo_key = p_memo_key
	return self


func validation_errors() -> Array[StringName]:
	var errors: Array[StringName] = []
	if transaction_id.is_empty():
		errors.append(&"EMPTY_TRANSACTION_ID")
	if absolute_minute < 0:
		errors.append(&"INVALID_ABSOLUTE_MINUTE")
	if debit_account.is_empty():
		errors.append(&"EMPTY_DEBIT_ACCOUNT")
	if credit_account.is_empty():
		errors.append(&"EMPTY_CREDIT_ACCOUNT")
	if not debit_account.is_empty() and debit_account == credit_account:
		errors.append(&"IDENTICAL_ACCOUNTS")
	if amount <= 0:
		errors.append(&"INVALID_AMOUNT")
	if category.is_empty():
		errors.append(&"EMPTY_CATEGORY")
	if not related_transaction_id.is_empty() and related_transaction_id == transaction_id:
		errors.append(&"SELF_RELATED_TRANSACTION")
	return errors


func is_valid() -> bool:
	return validation_errors().is_empty()


func reversed(
	p_transaction_id: StringName,
	p_absolute_minute: int,
	p_category: StringName = &"REVERSAL",
	p_source_entity_id: StringName = &"",
	p_memo_key: StringName = &""
) -> LedgerEntry:
	return LedgerEntry.new().configure(
		p_transaction_id,
		p_absolute_minute,
		credit_account,
		debit_account,
		amount,
		p_category,
		p_source_entity_id if not p_source_entity_id.is_empty() else source_entity_id,
		transaction_id,
		p_memo_key
	)


func copy() -> LedgerEntry:
	return LedgerEntry.new().configure(
		transaction_id,
		absolute_minute,
		debit_account,
		credit_account,
		amount,
		category,
		source_entity_id,
		related_transaction_id,
		memo_key
	)


func to_dictionary() -> Dictionary:
	return {
		&"transaction_id": String(transaction_id),
		&"absolute_minute": absolute_minute,
		&"debit_account": String(debit_account),
		&"credit_account": String(credit_account),
		&"amount": amount,
		&"category": String(category),
		&"source_entity_id": String(source_entity_id),
		&"related_transaction_id": String(related_transaction_id),
		&"memo_key": String(memo_key),
	}


static func from_dictionary(data: Dictionary) -> LedgerEntry:
	return LedgerEntry.new().configure(
		StringName(data.get(&"transaction_id", data.get("transaction_id", ""))),
		int(data.get(&"absolute_minute", data.get("absolute_minute", -1))),
		StringName(data.get(&"debit_account", data.get("debit_account", ""))),
		StringName(data.get(&"credit_account", data.get("credit_account", ""))),
		int(data.get(&"amount", data.get("amount", 0))),
		StringName(data.get(&"category", data.get("category", ""))),
		StringName(data.get(&"source_entity_id", data.get("source_entity_id", ""))),
		StringName(data.get(
			&"related_transaction_id",
			data.get("related_transaction_id", "")
		)),
		StringName(data.get(&"memo_key", data.get("memo_key", "")))
	)