package service

import (
	"context"
	"errors"
	"time"

	"financeiro-carvalho/internal/model"
	"financeiro-carvalho/internal/repository"
)

var ErrPendingBillNotFound = errors.New("pending bill not found")

type PendingBillService struct {
	repo   repository.PendingBillRepository
	txRepo repository.TransactionRepository
}

func NewPendingBillService(repo repository.PendingBillRepository, txRepo repository.TransactionRepository) *PendingBillService {
	return &PendingBillService{repo: repo, txRepo: txRepo}
}

func (s *PendingBillService) List(ctx context.Context) ([]model.PendingBillImport, error) {
	items, err := s.repo.List(ctx)
	if items == nil {
		return []model.PendingBillImport{}, err
	}
	return items, err
}

// Save stores a credit-card import as pending when payment_date is in the future.
// Returns (true, pendingBill, nil) if saved as pending; (false, nil, nil) if not applicable.
func (s *PendingBillService) MaybeSaveAsPending(ctx context.Context, filename, paymentDate string, rows []model.ImportRow) (bool, *model.PendingBillImport, error) {
	if paymentDate == "" {
		return false, nil, nil
	}
	t, err := time.Parse("2006-01-02", paymentDate)
	if err != nil || !t.After(time.Now().Truncate(24*time.Hour)) {
		return false, nil, nil
	}

	var total float64
	newRows := make([]model.ImportRow, 0, len(rows))
	for _, r := range rows {
		if !r.IsDuplicate {
			total += r.Amount
			newRows = append(newRows, r)
		}
	}

	p, err := s.repo.Create(ctx, filename, paymentDate, total, newRows)
	if err != nil {
		return true, nil, err
	}
	return true, p, nil
}

// Confirm inserts the pending bill's rows as actual transactions and removes the pending record.
func (s *PendingBillService) Confirm(ctx context.Context, id int) error {
	p, err := s.repo.GetByID(ctx, id)
	if err != nil {
		return ErrPendingBillNotFound
	}
	if _, err := s.txRepo.BulkInsert(ctx, p.Rows); err != nil {
		return err
	}
	return s.repo.Delete(ctx, id)
}

// Discard removes a pending bill import without creating transactions.
func (s *PendingBillService) Discard(ctx context.Context, id int) error {
	return s.repo.Delete(ctx, id)
}