package kvdb

import (
	"github.com/go-redis/redis"
	"strings"
)

type (
	RedisDb struct {
		addr     string
		db       int
		password string
		engine   *redis.Client
	}

	redisIterator struct {
		pos    int      //当前位置
		cursor uint64   //游标位置
		key    string   //当前获取的key
		keys   []string //存储的keys数组
		prefix string   //搜索的前缀
		flag   int32    //是否结束搜索
		client *redis.Client
	}
)

func (i *redisIterator) Next() bool {
	if (i.keys == nil || i.pos >= len(i.keys)) && i.flag != 1 {
		ret := i.client.Scan(i.cursor, i.prefix, 100)
		if ret.Err() != nil {
			return false
		}
		i.keys, i.cursor = ret.Val()
		if i.cursor == 0 {
			i.flag = 1
		}
		i.pos = 0
	}
	if i.pos < len(i.keys) {
		i.key = i.keys[i.pos]
		i.pos++
		return true
	}
	return false
}

func (i *redisIterator) Key() string {
	return strings.TrimPrefix(i.key,"kv:db$:")
}

func (i *redisIterator) Value() []byte {
	cmd := i.client.Get(i.key)
	if cmd.Err() == nil {
		return []byte(cmd.Val())
	} else {
		return nil
	}
}

func (i *redisIterator) Close() error {
	i.pos = 0
	return nil
}

func newRedisIterator(c *redis.Client, prefix string) *redisIterator {
	if !strings.HasSuffix(prefix, "*") {
		prefix = prefix + "*"
	}
	return &redisIterator{client: c, prefix: prefix}
}

func (db *RedisDb) Open() error {
	db.engine = redis.NewClient(&redis.Options{
		Addr:     db.addr,
		Password: db.password,
		DB:       db.db,
	})
	return db.engine.Ping().Err()
}

func (db *RedisDb) generateKey(s string) string {
	return "kv:db$:" + s
}

func (db *RedisDb) Put(s string, bytes []byte) error {
	return db.engine.Set(db.generateKey(s), string(bytes), 0).Err()
}

func (db *RedisDb) Get(s string) ([]byte, error) {
	cmd := db.engine.Get(db.generateKey(s))
	if cmd.Err() == nil {
		return []byte(cmd.Val()), nil
	} else {
		return nil, cmd.Err()
	}
}

func (db *RedisDb) Delete(s string) error {
	return db.engine.Del(db.generateKey(s)).Err()
}

func (db *RedisDb) Iterator(s string) (Iterator, error) {
	return newRedisIterator(db.engine, db.generateKey(s)), nil
}

func (db *RedisDb) Close() error {
	return db.engine.Close()
}

func NewRedis(addr, password string, db int) *RedisDb {
	return &RedisDb{
		addr:     addr,
		password: password,
		db:       db,
	}
}