import { CURRENCY_CATALOG } from '@mento/shared';
import { Prisma } from '@prisma/client';
import { PrismaService } from '../prisma/prisma.service';

export type RateMap = {
  baseCurrency: string;
  /** currency code → how many base units for 1 unit of that currency */
  rates: Map<string, number>;
};

export function isKnownCurrency(code: string): boolean {
  return CURRENCY_CATALOG.some((c) => c.code === code);
}

export async function loadOrgRates(
  prisma: PrismaService,
  organizationId: string,
): Promise<RateMap> {
  const org = await prisma.organization.findUnique({
    where: { id: organizationId },
    select: {
      baseCurrency: true,
      exchangeRates: { select: { currency: true, rateToBase: true } },
    },
  });
  const baseCurrency = org?.baseCurrency || 'IRR';
  const rates = new Map<string, number>();
  rates.set(baseCurrency, 1);
  for (const row of org?.exchangeRates ?? []) {
    rates.set(row.currency, Number(row.rateToBase));
  }
  return { baseCurrency, rates };
}

export function toBaseAmount(
  amount: number | null | undefined,
  currency: string | null | undefined,
  map: RateMap,
): number {
  if (amount == null || Number.isNaN(amount)) return 0;
  const code = (currency || map.baseCurrency).trim() || map.baseCurrency;
  if (code === map.baseCurrency) return amount;
  const rate = map.rates.get(code);
  if (rate == null || rate <= 0) return amount;
  return amount * rate;
}

export function decimalToBase(
  amount: Prisma.Decimal | null | undefined,
  currency: string | null | undefined,
  map: RateMap,
): number {
  return toBaseAmount(amount == null ? 0 : Number(amount), currency, map);
}