use scale::{Encode, Decode};

pub use serai_db::*;

use serai_client::{
  primitives::NetworkId,
  validator_sets::primitives::{Session, KeyPair},
};

#[derive(Debug)]
pub struct SubstrateDb<D: Db>(pub D);
impl<D: Db> SubstrateDb<D> {
  pub fn new(db: D) -> Self {
    Self(db)
  }

  fn substrate_key(dst: &'static [u8], key: impl AsRef<[u8]>) -> Vec<u8> {
    D::key(b"coordinator_substrate", dst, key)
  }

  fn block_key() -> Vec<u8> {
    Self::substrate_key(b"block", [])
  }
  pub fn set_next_block(&mut self, block: u64) {
    let mut txn = self.0.txn();
    txn.put(Self::block_key(), block.to_le_bytes());
    txn.commit();
  }
  pub fn next_block(&self) -> u64 {
    u64::from_le_bytes(self.0.get(Self::block_key()).unwrap_or(vec![0; 8]).try_into().unwrap())
  }

  fn event_key(id: &[u8], index: u32) -> Vec<u8> {
    Self::substrate_key(b"event", [id, index.to_le_bytes().as_ref()].concat())
  }
  pub fn handled_event<G: Get>(getter: &G, id: [u8; 32], index: u32) -> bool {
    getter.get(Self::event_key(&id, index)).is_some()
  }
  pub fn handle_event(txn: &mut D::Transaction<'_>, id: [u8; 32], index: u32) {
    assert!(!Self::handled_event(txn, id, index));
    txn.put(Self::event_key(&id, index), []);
  }

  fn session_key(key: &[u8]) -> Vec<u8> {
    Self::substrate_key(b"session", key)
  }
  pub fn session_for_key<G: Get>(getter: &G, key: &[u8]) -> Option<Session> {
    getter.get(Self::session_key(key)).map(|bytes| Session::decode(&mut bytes.as_ref()).unwrap())
  }
  pub fn save_session_for_keys(txn: &mut D::Transaction<'_>, key_pair: &KeyPair, session: Session) {
    let session = session.encode();
    let key_0 = Self::session_key(&key_pair.0);
    let existing = txn.get(&key_0);
    // This may trigger if 100% of a DKG are malicious, and they create a key equivalent to a prior
    // key. Since it requires 100% maliciousness, not just 67% maliciousness, this will only assert
    // in a modified-to-be-malicious stack, making it safe
    assert!(existing.is_none() || (existing.as_ref() == Some(&session)));
    txn.put(key_0, session.clone());
    txn.put(Self::session_key(&key_pair.1), session);
  }

  fn batch_instructions_key(network: NetworkId, id: u32) -> Vec<u8> {
    Self::substrate_key(b"batch", (network, id).encode())
  }
  pub fn batch_instructions_hash<G: Get>(
    getter: &G,
    network: NetworkId,
    id: u32,
  ) -> Option<[u8; 32]> {
    getter.get(Self::batch_instructions_key(network, id)).map(|bytes| bytes.try_into().unwrap())
  }
  pub fn save_batch_instructions_hash(
    txn: &mut D::Transaction<'_>,
    network: NetworkId,
    id: u32,
    hash: [u8; 32],
  ) {
    txn.put(Self::batch_instructions_key(network, id), hash);
  }
}