package session

import (
	"github.com/evcc-io/evcc/util"
	"gorm.io/gorm"
)

// DB is a SQL database storage service
type DB struct {
	log  *util.Logger
	db   *gorm.DB
	name string
}

type Database interface {
	New(startEnergy float64) *Session
	Persist(session interface{})
}

// NewStore creates a session store
func NewStore(name string, db *gorm.DB) (*DB, error) {
	err := db.AutoMigrate(new(Session))

	sessiondb := &DB{
		log:  util.NewLogger("db"),
		db:   db,
		name: name,
	}

	return sessiondb, err
}

// New creates a charging session
func (s *DB) New(meter float64) *Session {
	t := Session{
		Loadpoint: s.name,
	}

	if meter > 0 {
		t.MeterStart = &meter
	}

	return &t
}

// Persist creates or updates a transaction in the database
func (s *DB) Persist(session interface{}) {
	if err := s.db.Save(session).Error; err != nil {
		s.log.ERROR.Printf("persist: %v", err)
	}
}

// Return sessions
// TODO make this part of server/db
func (s *DB) Sessions() (Sessions, error) {
	var res Sessions
	tx := s.db.Find(&res)
	return res, tx.Error
}