package meta

import (
	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
	"go.etcd.io/bbolt"
)

type bucketCache struct {
	locked    *bbolt.Bucket
	graveyard *bbolt.Bucket
	garbage   *bbolt.Bucket
	expired   map[cid.ID]*bbolt.Bucket
	primary   map[cid.ID]*bbolt.Bucket
}

func newBucketCache() *bucketCache {
	return &bucketCache{}
}

func getLockedBucket(bc *bucketCache, tx *bbolt.Tx) *bbolt.Bucket {
	if bc == nil {
		return tx.Bucket(bucketNameLocked)
	}
	return getBucket(&bc.locked, tx, bucketNameLocked)
}

func getGraveyardBucket(bc *bucketCache, tx *bbolt.Tx) *bbolt.Bucket {
	if bc == nil {
		return tx.Bucket(graveyardBucketName)
	}
	return getBucket(&bc.graveyard, tx, graveyardBucketName)
}

func getGarbageBucket(bc *bucketCache, tx *bbolt.Tx) *bbolt.Bucket {
	if bc == nil {
		return tx.Bucket(garbageBucketName)
	}
	return getBucket(&bc.garbage, tx, garbageBucketName)
}

func getBucket(cache **bbolt.Bucket, tx *bbolt.Tx, name []byte) *bbolt.Bucket {
	if *cache != nil {
		return *cache
	}

	*cache = tx.Bucket(name)
	return *cache
}

func getExpiredBucket(bc *bucketCache, tx *bbolt.Tx, cnr cid.ID) *bbolt.Bucket {
	if bc == nil {
		bucketName := make([]byte, bucketKeySize)
		bucketName = objectToExpirationEpochBucketName(cnr, bucketName)
		return tx.Bucket(bucketName)
	}
	return getMappedBucket(&bc.expired, tx, objectToExpirationEpochBucketName, cnr)
}

func getPrimaryBucket(bc *bucketCache, tx *bbolt.Tx, cnr cid.ID) *bbolt.Bucket {
	if bc == nil {
		bucketName := make([]byte, bucketKeySize)
		bucketName = primaryBucketName(cnr, bucketName)
		return tx.Bucket(bucketName)
	}
	return getMappedBucket(&bc.primary, tx, primaryBucketName, cnr)
}

func getMappedBucket(m *map[cid.ID]*bbolt.Bucket, tx *bbolt.Tx, nameFunc func(cid.ID, []byte) []byte, cnr cid.ID) *bbolt.Bucket {
	value, ok := (*m)[cnr]
	if ok {
		return value
	}

	if *m == nil {
		*m = make(map[cid.ID]*bbolt.Bucket, 1)
	}

	bucketName := make([]byte, bucketKeySize)
	bucketName = nameFunc(cnr, bucketName)
	(*m)[cnr] = getBucket(&value, tx, bucketName)
	return value
}