package utilsleveldb

import (
	"gitee.com/prestonTao/utils"
	"github.com/syndtr/goleveldb/leveldb"
	"github.com/syndtr/goleveldb/leveldb/util"
)

/*
保存到List集合中
*/
func (this *LevelDB) SaveList(dbkey LeveldbKey, value []byte) (uint64, error) {
	var err error
	if err = checkValueSize(value); err != nil {
		return 0, err
	}
	tr, err := this.db.OpenTransaction()
	if err != nil {
		return 0, err
	}
	//查询这个dbkey的最大index是多少
	indexDBKEY := append(dbkey.key, DataType_Index...)
	indexBs, err := tr.Get(indexDBKEY, nil)
	if err != nil {
		if err.Error() == leveldb.ErrNotFound.Error() {
			indexBs = []byte{0, 0, 0, 0, 0, 0, 0, 0}
		} else {
			tr.Discard()
			return 0, err
		}
	}
	index := utils.BytesToUint64ByBigEndian(indexBs)
	index++
	indexBs = utils.Uint64ToBytesByBigEndian(index)
	//保存最新的index
	err = tr.Put(indexDBKEY, indexBs, nil)
	if err != nil {
		tr.Discard()
		return 0, err
	}
	//保存记录
	tempKey := append(dbkey.key, DataType_Data_List...)
	err = tr.Put(append(tempKey, indexBs...), value, nil)
	if err != nil {
		tr.Discard()
		return 0, err
	}
	err = tr.Commit()
	if err != nil {
		tr.Discard()
		return 0, err
	}
	return index, nil
}

/*
查询List集合中的所有项目
*/
func (this *LevelDB) FindList(dbkey LeveldbKey) ([]DBItem, error) {
	var err error
	lists := make([]DBItem, 0)
	tempKey := append(dbkey.key, DataType_Data_List...)
	dbkeyLen := len(tempKey)
	iter := this.db.NewIterator(util.BytesPrefix(tempKey), nil)
	for iter.Next() {
		indexBs := make([]byte, len(iter.Key())-(dbkeyLen+len(DataType_Data_List)))
		copy(indexBs, iter.Key()[dbkeyLen+len(DataType_Data_List):])
		value := make([]byte, len(iter.Value()))
		copy(value, iter.Value())
		lists = append(lists, DBItem{
			Index: indexBs,
			Value: value,
		})
	}
	iter.Release()
	err = iter.Error()
	return lists, err
}