package writecachebadger

import (
	"fmt"
	"math"
	"sync/atomic"

	"github.com/dgraph-io/badger/v4"
)

func (c *cache) estimateCacheSize() uint64 {
	onDiskSize, _ := c.db.EstimateSize(nil)
	c.metrics.SetEstimateSize(onDiskSize, 0)
	return onDiskSize
}

func (c *cache) incSizeDB(sz uint64) uint64 {
	return sz + c.maxObjectSize
}

type counters struct {
	cDB atomic.Uint64
}

func (x *counters) IncDB() {
	x.cDB.Add(1)
}

func (x *counters) DecDB() {
	x.cDB.Add(math.MaxUint64)
}

func (x *counters) DB() uint64 {
	return x.cDB.Load()
}

func (c *cache) initCounters() error {
	var inDB uint64
	err := c.db.View(func(tx *badger.Txn) error {
		opts := badger.DefaultIteratorOptions
		opts.PrefetchValues = false
		it := tx.NewIterator(opts)
		defer it.Close()
		for it.Rewind(); it.Valid(); it.Next() {
			inDB++
		}
		return nil
	})
	if err != nil {
		return fmt.Errorf("could not read write-cache DB counter: %w", err)
	}

	c.objCounters.cDB.Store(inDB)
	c.metrics.SetActualCounters(inDB, 0)

	return nil
}

func (c *cache) incDB() {
	c.objCounters.IncDB()
	c.metrics.SetActualCounters(c.objCounters.DB(), 0)
}

func (c *cache) decDB() {
	c.objCounters.DecDB()
	c.metrics.SetActualCounters(c.objCounters.DB(), 0)
}