use util::*;
use rocksdb::{DB};
use blockchain::{BlockChain, BlockProvider};
use views::BlockView;
use error::*;
use header::BlockNumber;
use spec::Spec;
use engine::Engine;
use queue::BlockQueue;
use sync::NetSyncMessage;
use env_info::LastHashes;
use verification::*;
use block::*;

/// General block status
pub enum BlockStatus {
	/// Part of the blockchain.
	InChain,
	/// Queued for import.
	Queued,
	/// Known as bad.
	Bad,
	/// Unknown.
	Unknown,
}

/// Information about the blockchain gthered together.
pub struct BlockChainInfo {
	/// Blockchain difficulty.
	pub total_difficulty: U256,
	/// Block queue difficulty.
	pub pending_total_difficulty: U256,
	/// Genesis block hash.
	pub genesis_hash: H256,
	/// Best blockchain block hash.
	pub best_block_hash: H256,
	/// Best blockchain block number.
	pub best_block_number: BlockNumber
}

/// Block queue status
pub struct BlockQueueStatus {
	pub full: bool,
}

pub type TreeRoute = ::blockchain::TreeRoute;

/// Blockchain database client. Owns and manages a blockchain and a block queue.
pub trait BlockChainClient : Sync + Send {
	/// Get raw block header data by block header hash.
	fn block_header(&self, hash: &H256) -> Option<Bytes>;

	/// Get raw block body data by block header hash.
	/// Block body is an RLP list of two items: uncles and transactions.
	fn block_body(&self, hash: &H256) -> Option<Bytes>;

	/// Get raw block data by block header hash.
	fn block(&self, hash: &H256) -> Option<Bytes>;

	/// Get block status by block header hash.
	fn block_status(&self, hash: &H256) -> BlockStatus;

	/// Get raw block header data by block number.
	fn block_header_at(&self, n: BlockNumber) -> Option<Bytes>;

	/// Get raw block body data by block number.
	/// Block body is an RLP list of two items: uncles and transactions.
	fn block_body_at(&self, n: BlockNumber) -> Option<Bytes>;

	/// Get raw block data by block number.
	fn block_at(&self, n: BlockNumber) -> Option<Bytes>;

	/// Get block status by block number.
	fn block_status_at(&self, n: BlockNumber) -> BlockStatus;

	/// Get a tree route between `from` and `to`.
	/// See `BlockChain::tree_route`.
	fn tree_route(&self, from: &H256, to: &H256) -> Option<TreeRoute>;

	/// Get latest state node
	fn state_data(&self, hash: &H256) -> Option<Bytes>;

	/// Get raw block receipts data by block header hash.
	fn block_receipts(&self, hash: &H256) -> Option<Bytes>;

	/// Import a block into the blockchain.
	fn import_block(&mut self, byte: &[u8]) -> ImportResult;

	/// Get block queue information.
	fn queue_status(&self) -> BlockQueueStatus;

	/// Clear block queue and abort all import activity.
	fn clear_queue(&mut self);

	/// Get blockchain information.
	fn chain_info(&self) -> BlockChainInfo;
}

/// Blockchain database client backed by a persistent database. Owns and manages a blockchain and a block queue.
pub struct Client {
	chain: Arc<RwLock<BlockChain>>,
	engine: Arc<Box<Engine>>,
	state_db: OverlayDB,
	queue: BlockQueue,
}

impl Client {
	/// Create a new client with given spec and DB path.
	pub fn new(spec: Spec, path: &Path, message_channel: IoChannel<NetSyncMessage> ) -> Result<Client, Error> {
		let chain = Arc::new(RwLock::new(BlockChain::new(&spec.genesis_block(), path)));
		let engine = Arc::new(try!(spec.to_engine()));
		let mut state_path = path.to_path_buf();
		state_path.push("state");
		let db = DB::open_default(state_path.to_str().unwrap()).unwrap();
		let mut state_db = OverlayDB::new(db);
		engine.spec().ensure_db_good(&mut state_db);
		state_db.commit().expect("Error commiting genesis state to state DB");

		Ok(Client {
			chain: chain.clone(),
			engine: engine.clone(),
			state_db: state_db,
			queue: BlockQueue::new(engine.clone(), message_channel),
		})
	}

	/// This is triggered by a message coming from a block queue when the block is ready for insertion
	pub fn import_verified_block(&mut self, bytes: Bytes) {
		let block = BlockView::new(&bytes);
		let header = block.header();
		if let Err(e) = verify_block_family(&bytes, self.engine.deref().deref(), self.chain.read().unwrap().deref()) {
			warn!(target: "client", "Stage 3 block verification failed for #{} ({})\nError: {:?}", header.number(), header.hash(), e);
			// TODO: mark as bad
			return;
		};
		let parent = match self.chain.read().unwrap().block_header(&header.parent_hash) {
			Some(p) => p,
			None => {
				warn!(target: "client", "Block import failed for #{} ({}): Parent not found ({}) ", header.number(), header.hash(), header.parent_hash);
				return;
			},
		};
		// build last hashes
		let mut last = self.chain.read().unwrap().best_block_hash();
		let mut last_hashes = LastHashes::new();
		last_hashes.resize(256, H256::new());
		for i in 0..255 {
			match self.chain.read().unwrap().block_details(&last) {
				Some(details) => {
					last_hashes[i + 1] = details.parent.clone();
					last = details.parent.clone();
				},
				None => break,
			}
		}

		let result = match enact(&bytes, self.engine.deref().deref(), self.state_db.clone(), &parent, &last_hashes) {
			Ok(b) => b,
			Err(e) => {
				warn!(target: "client", "Block import failed for #{} ({})\nError: {:?}", header.number(), header.hash(), e);
				return;
			}
		};
		if let Err(e) = verify_block_final(&header, result.block().header()) {
			warn!(target: "client", "Stage 4 block verification failed for #{} ({})\nError: {:?}", header.number(), header.hash(), e);
			return;
		}

		self.chain.write().unwrap().insert_block(&bytes); //TODO: err here?
		match result.drain().commit() {
			Ok(_) => (),
			Err(e) => {
				warn!(target: "client", "State DB commit failed: {:?}", e);
				return;
			}
		}
		info!(target: "client", "Imported #{} ({})", header.number(), header.hash());
	}
}

impl BlockChainClient for Client {
	fn block_header(&self, hash: &H256) -> Option<Bytes> {
		self.chain.read().unwrap().block(hash).map(|bytes| BlockView::new(&bytes).rlp().at(0).as_raw().to_vec())
	}

	fn block_body(&self, hash: &H256) -> Option<Bytes> {
		self.chain.read().unwrap().block(hash).map(|bytes| {
			let rlp = Rlp::new(&bytes);
			let mut body = RlpStream::new();
			body.append_raw(rlp.at(1).as_raw(), 1);
			body.append_raw(rlp.at(2).as_raw(), 1);
			body.out()
		})
	}

	fn block(&self, hash: &H256) -> Option<Bytes> {
		self.chain.read().unwrap().block(hash)
	}

	fn block_status(&self, hash: &H256) -> BlockStatus {
		if self.chain.read().unwrap().is_known(&hash) { BlockStatus::InChain } else { BlockStatus::Unknown }
	}

	fn block_header_at(&self, n: BlockNumber) -> Option<Bytes> {
		self.chain.read().unwrap().block_hash(n).and_then(|h| self.block_header(&h))
	}

	fn block_body_at(&self, n: BlockNumber) -> Option<Bytes> {
		self.chain.read().unwrap().block_hash(n).and_then(|h| self.block_body(&h))
	}

	fn block_at(&self, n: BlockNumber) -> Option<Bytes> {
		self.chain.read().unwrap().block_hash(n).and_then(|h| self.block(&h))
	}

	fn block_status_at(&self, n: BlockNumber) -> BlockStatus {
		match self.chain.read().unwrap().block_hash(n) {
			Some(h) => self.block_status(&h),
			None => BlockStatus::Unknown
		}
	}

	fn tree_route(&self, from: &H256, to: &H256) -> Option<TreeRoute> {
		self.chain.read().unwrap().tree_route(from.clone(), to.clone())
	}

	fn state_data(&self, _hash: &H256) -> Option<Bytes> {
		unimplemented!();
	}

	fn block_receipts(&self, _hash: &H256) -> Option<Bytes> {
		unimplemented!();
	}

	fn import_block(&mut self, bytes: &[u8]) -> ImportResult {
		let header = BlockView::new(bytes).header();
		if self.chain.read().unwrap().is_known(&header.hash()) {
			return Err(ImportError::AlreadyInChain);
		}
		self.queue.import_block(bytes)
	}

	fn queue_status(&self) -> BlockQueueStatus {
		BlockQueueStatus {
			full: false
		}
	}

	fn clear_queue(&mut self) {
	}

	fn chain_info(&self) -> BlockChainInfo {
		let chain = self.chain.read().unwrap();
		BlockChainInfo {
			total_difficulty: chain.best_block_total_difficulty(),
			pending_total_difficulty: chain.best_block_total_difficulty(),
			genesis_hash: chain.genesis_hash(),
			best_block_hash: chain.best_block_hash(),
			best_block_number: From::from(chain.best_block_number())
		}
	}
}