function roundCurrency(value) {
  const amount = Number(value ?? 0);
  if (!Number.isFinite(amount)) {
    return 0;
  }

  return Number(amount.toFixed(2));
}

function normalizeAmount(value) {
  const amount = Number(value);
  if (!Number.isFinite(amount)) {
    return null;
  }

  return roundCurrency(amount);
}

function normalizeUserKey(name) {
  return String(name ?? '').replace(/\s+/g, '');
}

function createUserNameResolver(users = []) {
  const exactNames = new Set();
  const normalizedNameMap = new Map();

  for (const user of users) {
    const userName = String(user?.name ?? '').trim();
    if (!userName) {
      continue;
    }

    exactNames.add(userName);

    const userKey = normalizeUserKey(userName);
    if (!normalizedNameMap.has(userKey)) {
      normalizedNameMap.set(userKey, new Set());
    }
    normalizedNameMap.get(userKey).add(userName);
  }

  return (inputName, fallbackName = '') => {
    const rawName = String(inputName ?? '').trim();

    if (!rawName) {
      return fallbackName;
    }

    if (exactNames.has(rawName)) {
      return rawName;
    }

    const matches = [...(normalizedNameMap.get(normalizeUserKey(rawName)) || [])];
    if (matches.length === 1) {
      return matches[0];
    }

    return rawName;
  };
}

module.exports = {
  createUserNameResolver,
  normalizeAmount,
  normalizeUserKey,
  roundCurrency,
};