import Foundation

enum CurrencyFormatter {
    static func currentCurrencyCode() -> String {
        let context = CoreDataStack.shared.viewContext
        return AppSettings.getOrCreate(in: context).currency
    }

    static func locale(for currencyCode: String?) -> Locale {
        guard let currencyCode, !currencyCode.isEmpty else { return Locale.current }
        if let match = Locale.availableIdentifiers.first(where: {
            Locale(identifier: $0).currency?.identifier == currencyCode
        }) {
            return Locale(identifier: match)
        }
        return Locale.current
    }

    static func format(_ decimal: Decimal, style: NumberFormatter.Style = .currency, maximumFractionDigits: Int = 2) -> String {
        let formatter = NumberFormatter()
        formatter.numberStyle = style
        formatter.currencyCode = currentCurrencyCode()
        formatter.maximumFractionDigits = maximumFractionDigits
        return formatter.string(from: decimal as NSDecimalNumber) ?? "\(decimal)"
    }

    static func format(
        _ decimal: Decimal,
        currencyCode: String?,
        style: NumberFormatter.Style = .currency,
        maximumFractionDigits: Int = 2,
        preferredLocale: Locale? = nil
    ) -> String {
        let formatter = NumberFormatter()
        formatter.numberStyle = style
        formatter.currencyCode = currencyCode ?? currentCurrencyCode()
        formatter.maximumFractionDigits = maximumFractionDigits
        formatter.locale = preferredLocale ?? locale(for: currencyCode)
        return formatter.string(from: decimal as NSDecimalNumber) ?? "\(decimal)"
    }

    static func symbol(for code: String) -> String {
        let formatter = NumberFormatter()
        formatter.numberStyle = .currency
        formatter.currencyCode = code
        return formatter.currencySymbol ?? code
    }
}