use crate::fork_choice::SszForkChoice;
use crate::head_tracker::SszHeadTracker;
use crate::{BeaconChainTypes, CheckPoint};
use operation_pool::PersistedOperationPool;
use ssz::{Decode, Encode};
use ssz_derive::{Decode, Encode};
use store::{DBColumn, Error as StoreError, SimpleStoreItem, SszBlockRootTree};
use types::Hash256;

/// 32-byte key for accessing the `PersistedBeaconChain`.
pub const BEACON_CHAIN_DB_KEY: &str = "PERSISTEDBEACONCHAINPERSISTEDBEA";

#[derive(Clone, Encode, Decode)]
pub struct PersistedBeaconChain<T: BeaconChainTypes> {
    pub canonical_head: CheckPoint<T::EthSpec>,
    pub finalized_checkpoint: CheckPoint<T::EthSpec>,
    pub op_pool: PersistedOperationPool<T::EthSpec>,
    pub genesis_block_root: Hash256,
    pub ssz_head_tracker: SszHeadTracker,
    pub fork_choice: SszForkChoice,
    pub block_root_tree: SszBlockRootTree,
}

impl<T: BeaconChainTypes> SimpleStoreItem for PersistedBeaconChain<T> {
    fn db_column() -> DBColumn {
        DBColumn::BeaconChain
    }

    fn as_store_bytes(&self) -> Vec<u8> {
        self.as_ssz_bytes()
    }

    fn from_store_bytes(bytes: &[u8]) -> Result<Self, StoreError> {
        Self::from_ssz_bytes(bytes).map_err(Into::into)
    }
}