// Copyright 2019 TiKV Project Authors. Licensed under Apache-2.0.

use crate::*;

pub trait Peekable {
    type DBVector: DBVector;

    fn get_value_opt(&self, opts: &ReadOptions, key: &[u8]) -> Result<Option<Self::DBVector>>;
    fn get_value_cf_opt(
        &self,
        opts: &ReadOptions,
        cf: &str,
        key: &[u8],
    ) -> Result<Option<Self::DBVector>>;

    fn get_value(&self, key: &[u8]) -> Result<Option<Self::DBVector>> {
        self.get_value_opt(&ReadOptions::default(), key)
    }

    fn get_value_cf(&self, cf: &str, key: &[u8]) -> Result<Option<Self::DBVector>> {
        self.get_value_cf_opt(&ReadOptions::default(), cf, key)
    }

    fn get_msg<M: protobuf::Message + Default>(&self, key: &[u8]) -> Result<Option<M>> {
        let value = self.get_value(key)?;
        if value.is_none() {
            return Ok(None);
        }

        let mut m = M::default();
        m.merge_from_bytes(&value.unwrap())?;
        Ok(Some(m))
    }

    fn get_msg_cf<M: protobuf::Message + Default>(
        &self,
        cf: &str,
        key: &[u8],
    ) -> Result<Option<M>> {
        let value = self.get_value_cf(cf, key)?;
        if value.is_none() {
            return Ok(None);
        }

        let mut m = M::default();
        m.merge_from_bytes(&value.unwrap())?;
        Ok(Some(m))
    }
}