import {
  add,
  decimalFromString,
  divide,
  formatDecimal,
  multiply,
} from '../../../../common/decimal';

import { MoneyDto } from '../../../../common/money.dto';
import {
  PortfolioDto,
  PortfolioPositionDto,
} from '../../portfolio/portfolio.api';
import { StockPositionDto } from '../stocks/presentation/stock.dto';

const PRICE_DECIMAL_PLACES = 9;
const RETURN_PERCENT_DECIMAL_PLACES = 6;

export function instrumentPosition(
  portfolio: PortfolioDto,
  uid: string,
  type: 'STOCK' | 'BOND',
): StockPositionDto {
  const positions = portfolio.positions.filter(
    (p) => p.type === type && p.instrumentUid === uid,
  );
  const zero = decimalFromString('0');
  const quantity = positions
    .map((p) => decimalFromString(p.quantity))
    .reduce(add, zero);
  const costs = positions.map(cost);
  const totalCost = sumComplete(costs);
  const currentValue = sumComplete(positions.map((p) => p.currentValue));
  const absoluteReturn = sumComplete(positions.map((p) => p.absoluteReturn));
  const positive =
    positions.length > 0 &&
    positions.every((p) => decimalFromString(p.quantity).value > 0n);
  return {
    quantity: formatDecimal(quantity),
    currentValue,
    absoluteReturn,
    averagePurchasePrice:
      positive && totalCost
        ? {
            currency: totalCost.currency,
            value: formatDecimal(
              divide(
                decimalFromString(totalCost.value),
                quantity,
                PRICE_DECIMAL_PLACES,
              ),
            ),
          }
        : null,
    returnPercent: positive ? percent(absoluteReturn, totalCost) : null,
    accounts: positions.map((p) => ({
      ...p,
      returnPercent:
        decimalFromString(p.quantity).value > 0n
          ? percent(p.absoluteReturn, cost(p))
          : null,
    })),
    isStale: portfolio.isStale,
    observedAt: portfolio.lastSuccessfulAt,
  };
}
function cost(position: PortfolioPositionDto): MoneyDto | null {
  const price = position.averagePurchasePrice;
  return price
    ? {
        currency: price.currency,
        value: formatDecimal(
          multiply(
            decimalFromString(price.value),
            decimalFromString(position.quantity),
          ),
        ),
      }
    : null;
}
function sumComplete(values: (MoneyDto | null)[]): MoneyDto | null {
  const currency = values[0]?.currency;
  if (
    !currency ||
    !values.every((v): v is MoneyDto => v !== null && v.currency === currency)
  )
    return null;
  return {
    currency,
    value: formatDecimal(
      values.reduce(
        (sum, value) => add(sum, decimalFromString(value.value)),
        decimalFromString('0'),
      ),
    ),
  };
}
function percent(
  result: MoneyDto | null,
  base: MoneyDto | null,
): string | null {
  if (
    !base ||
    !result ||
    base.currency !== result.currency ||
    decimalFromString(base.value).value <= 0n
  )
    return null;
  return formatDecimal(
    divide(
      multiply(decimalFromString(result.value), decimalFromString('100')),
      decimalFromString(base.value),
      RETURN_PERCENT_DECIMAL_PLACES,
    ),
  );
}