package models

import (
	"github.com/dgraph-io/badger/v3"
	"go.uber.org/zap"
)

type Persister struct {
	log *zap.SugaredLogger
	db  *badger.DB
}

type PersisterResult struct {
	Value []byte
	Key   []byte
}

func NewPersister(log *zap.SugaredLogger, db *badger.DB) *Persister {
	aso := &Persister{log: log, db: db}
	return aso
}

func (p *Persister) Store(model model) error {
	err := p.db.Update(model.Save)
	return err
}

func (p *Persister) Count(model model) (int, error) {
	opts := badger.DefaultIteratorOptions
	opts.PrefetchValues = false
	var count int
	err := p.db.View(func(txn *badger.Txn) error {
		it := txn.NewIterator(opts)
		defer it.Close()
		prefix := []byte(model.Keybase())
		for it.Seek(prefix); it.ValidForPrefix([]byte(prefix)); it.Next() {
			count++
		}
		return nil
	})
	return count, err
}

func (p *Persister) Collect(model model) ([][]byte, error) {
	var result [][]byte
	err := p.db.View(func(txn *badger.Txn) error {
		opts := badger.DefaultIteratorOptions
		opts.PrefetchValues = true
		it := txn.NewIterator(opts)
		defer it.Close()
		prefix := []byte(model.Keybase())
		for it.Seek(prefix); it.ValidForPrefix(prefix); it.Next() {
			item := it.Item()
			item.Value(func(v []byte) error {
				result = append(result, v)
				return nil
			})
		}
		return nil
	})
	return result, err
}