package ledger

type Files []string

func NewFiles(p string, q ...string) (Files, error) {
	f := Files(append([]string{p}, q...))
	_, err := f.Deltas()
	return f, err
}

func (files Files) Deltas(like ...Like) (Deltas, error) {
	transactions, err := files.transactions()
	if err != nil {
		return nil, err
	}
	result := make(Deltas, 0, len(transactions)*2)
	for _, transaction := range transactions {
		sums := map[string]float64{}
		for _, recipient := range transaction.recipients {
			sums[recipient.currency] += recipient.value
			delta := newDelta(
				transaction.date,
				transaction.description,
				recipient.name,
				recipient.value,
				recipient.currency,
			)
			result = append(result, delta)
		}
		for currency, value := range sums {
			if value == 0 {
				continue
			}
			if transaction.payee == "" {
				//return nil, fmt.Errorf("didnt find net zero and no dumping ground payee set: %+v", transaction)
			} else {
				delta := newDelta(
					transaction.date,
					transaction.description,
					transaction.payee,
					-1.0*value,
					currency,
				)
				result = append(result, delta)
			}
		}
	}
	return result.Like(like...), nil
}