package internal

import (
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"strings"
	"time"
)

type HashService struct {
	lastRecord *LastRecord
}

type LastRecord struct {
	EmisorNIF string
	NumSerie  string
	Fecha     time.Time
	Huella    string
	FechaGen  time.Time
}

func NewHashService() *HashService {
	return &HashService{}
}

func (s *HashService) SetLastRecord(r *LastRecord) {
	s.lastRecord = r
}

func (s *HashService) GetLastRecord() *LastRecord {
	return s.lastRecord
}

func (s *HashService) CalculateHash(data *InvoiceData, previousHash string) string {
	fechaGen := data.FechaGen.Format(time.RFC3339)

	fields := fmt.Sprintf("%s|%s|%s|%s|%.2f|%.2f|%s|%s",
		data.EmisorNIF,
		data.NumSerie,
		data.Fecha.Format("02-01-2006"),
		data.TipoFactura,
		data.CuotaTotal,
		data.ImporteTotal,
		previousHash,
		fechaGen,
	)

	hash := sha256.Sum256([]byte(fields))
	return strings.ToUpper(hex.EncodeToString(hash[:]))
}

func (s *HashService) IsFirstRecord() bool {
	return s.lastRecord == nil
}

func (s *HashService) GetPreviousHash() string {
	if s.lastRecord == nil {
		return ""
	}
	return s.lastRecord.Huella
}

type LastRecordStorage interface {
	GetLastRecord(emisorNIF string) (*LastRecord, error)
	SaveLastRecord(r *LastRecord) error
}