use crate::Config;
use crate::{
    block_cache::BlockCache,
    deposit_cache::{DepositCache, SszDepositCache},
};
use parking_lot::RwLock;
use ssz::{Decode, Encode};
use ssz_derive::{Decode, Encode};

#[derive(Default)]
pub struct DepositUpdater {
    pub cache: DepositCache,
    pub last_processed_block: Option<u64>,
}

impl DepositUpdater {
    pub fn new(deposit_contract_deploy_block: u64) -> Self {
        let cache = DepositCache::new(deposit_contract_deploy_block);
        DepositUpdater {
            cache,
            last_processed_block: None,
        }
    }
}

#[derive(Default)]
pub struct Inner {
    pub block_cache: RwLock<BlockCache>,
    pub deposit_cache: RwLock<DepositUpdater>,
    pub config: RwLock<Config>,
}

impl Inner {
    /// Prunes the block cache to `self.target_block_cache_len`.
    ///
    /// Is a no-op if `self.target_block_cache_len` is `None`.
    pub fn prune_blocks(&self) {
        if let Some(block_cache_truncation) = self.config.read().block_cache_truncation {
            self.block_cache.write().truncate(block_cache_truncation);
        }
    }

    /// Encode the eth1 block and deposit cache as bytes.
    pub fn as_bytes(&self) -> Vec<u8> {
        let ssz_eth1_cache = SszEth1Cache::from_inner(&self);
        ssz_eth1_cache.as_ssz_bytes()
    }

    /// Recover `Inner` given byte representation of eth1 deposit and block caches.
    pub fn from_bytes(bytes: &[u8], config: Config) -> Result<Self, String> {
        let ssz_cache = SszEth1Cache::from_ssz_bytes(bytes)
            .map_err(|e| format!("Ssz decoding error: {:?}", e))?;
        Ok(ssz_cache.to_inner(config)?)
    }
}

#[derive(Encode, Decode, Clone)]
pub struct SszEth1Cache {
    block_cache: BlockCache,
    deposit_cache: SszDepositCache,
    last_processed_block: Option<u64>,
}

impl SszEth1Cache {
    pub fn from_inner(inner: &Inner) -> Self {
        let deposit_updater = inner.deposit_cache.read();
        let block_cache = inner.block_cache.read();
        Self {
            block_cache: (*block_cache).clone(),
            deposit_cache: SszDepositCache::from_deposit_cache(&deposit_updater.cache),
            last_processed_block: deposit_updater.last_processed_block,
        }
    }

    pub fn to_inner(&self, config: Config) -> Result<Inner, String> {
        Ok(Inner {
            block_cache: RwLock::new(self.block_cache.clone()),
            deposit_cache: RwLock::new(DepositUpdater {
                cache: self.deposit_cache.to_deposit_cache()?,
                last_processed_block: self.last_processed_block,
            }),
            config: RwLock::new(config),
        })
    }
}
