package storage
//bolt存储引擎实现  
import (
    "github.com/boltdb/bolt"
    "time"
)

var wukong_documents = []byte("wukong_documents")
//bolt结构体 实现  同时实现storage接口
type boltStorage struct {
    db *bolt.DB
}
//实现存储引擎map集合  实现value  对应的函数  
func openBoltStorage(path string) (Storage, error) {
    db, err := bolt.Open(path, 0600, &bolt.Options{Timeout: 3600 * time.Second})
    if err != nil {
        return nil, err
    }
    err = db.Update(func(tx *bolt.Tx) error {
        _, err := tx.CreateBucketIfNotExists(wukong_documents)
        return err
    })
    if err != nil {
        db.Close()
        return nil, err
    }
    return &boltStorage{db}, nil
}

func (s *boltStorage) WALName() string {
    return s.db.Path()
}

func (s *boltStorage) Set(k []byte, v []byte) error {
    return s.db.Update(func(tx *bolt.Tx) error {
        return tx.Bucket(wukong_documents).Put(k, v)
    })
}

func (s *boltStorage) Get(k []byte) (b []byte, err error) {
    err = s.db.View(func(tx *bolt.Tx) error {
        b = tx.Bucket(wukong_documents).Get(k)
        return nil
    })
    return
}

func (s *boltStorage) Delete(k []byte) error {
    return s.db.Update(func(tx *bolt.Tx) error {
        return tx.Bucket(wukong_documents).Delete(k)
    })
}

func (s *boltStorage) ForEach(fn func(k, v []byte) error) error {
    return s.db.View(func(tx *bolt.Tx) error {
        b := tx.Bucket(wukong_documents)
        c := b.Cursor()
        for k, v := c.First(); k != nil; k, v = c.Next() {
            if err := fn(k, v); err != nil {
                return err
            }
        }
        return nil
    })
}

func (s *boltStorage) Close() error {
    return s.db.Close()
}