use util::hash::*;
use util::bytes::*;
use util::uint::*;
use util::rlp::*;
use util::sha3;

/// view onto block header rlp
pub struct BlockView<'a> {
	rlp: Rlp<'a>
}

impl<'a> BlockView<'a> {
	pub fn new(bytes: &'a [u8]) -> BlockView<'a> {
		BlockView {
			rlp: Rlp::new(bytes)
		}
	}

	pub fn new_from_rlp(rlp: Rlp<'a>) -> BlockView<'a> {
		BlockView {
			rlp: rlp
		}
	}

	pub fn parent_hash(&self) -> H256 { self.rlp.val_at(0) }
	pub fn uncles_hash(&self) -> H256 { self.rlp.val_at(1) }
	pub fn coinbase(&self) -> Address { self.rlp.val_at(2) }
	pub fn state_root(&self) -> H256 { self.rlp.val_at(3) }
	pub fn transactions_root(&self) -> H256 { self.rlp.val_at(4) }
	pub fn receipts_root(&self) -> H256 { self.rlp.val_at(5) }
	pub fn log_bloom(&self) -> H2048 { self.rlp.val_at(6) }
	pub fn difficulty(&self) -> U256 { self.rlp.val_at(7) }
	pub fn number(&self) -> U256 { self.rlp.val_at(8) }
	pub fn gas_limit(&self) -> U256 { self.rlp.val_at(9) }
	pub fn gas_usd(&self) -> U256 { self.rlp.val_at(10) }
	pub fn timestamp(&self) -> U256 { self.rlp.val_at(11) }
	pub fn mix_hash(&self) -> H256 { self.rlp.val_at(12) }
	pub fn nonce(&self) -> H64 { self.rlp.val_at(13) }
}

impl<'a> sha3::Hashable for BlockView<'a> {
	fn sha3(&self) -> H256 {
		self.rlp.raw().sha3()
	}
}

pub static ZERO_ADDRESS: Address = Address([0x00; 20]);
pub static ZERO_H256: H256 = H256([0x00; 32]);
pub static ZERO_LOGBLOOM: LogBloom = H2048([0x00; 256]);

pub type LogBloom = H2048;

#[derive(Debug)]
pub struct Header {
	parent_hash: H256,
	timestamp: U256,
	number: U256,
	author: Address,

	transactions_root: H256,
	uncles_hash: H256,
	extra_data: Bytes,

	state_root: H256,
	receipts_root: H256,
	log_bloom: LogBloom,
	gas_used: U256,
	gas_limit: U256,

	difficulty: U256,
	seal: Vec<Bytes>,
}

impl Header {
	pub fn new() -> Header {
		Header {
			parent_hash: ZERO_H256.clone(),
			timestamp: BAD_U256.clone(),
			number: ZERO_U256.clone(),
			author: ZERO_ADDRESS.clone(),

			transactions_root: ZERO_H256.clone(),
			uncles_hash: ZERO_H256.clone(),
			extra_data: vec![],

			state_root: ZERO_H256.clone(),
			receipts_root: ZERO_H256.clone(),
			log_bloom: ZERO_LOGBLOOM.clone(),
			gas_used: ZERO_U256.clone(),
			gas_limit: ZERO_U256.clone(),

			difficulty: ZERO_U256.clone(),
			seal: vec![],
		}
	}
}

impl Decodable for Header {
	fn decode<D>(decoder: &D) -> Result<Self, DecoderError> where D: Decoder {
		decoder.read_list(| d | {
			let blockheader = Header {
				parent_hash: try!(Decodable::decode(&d[0])),
				uncles_hash: try!(Decodable::decode(&d[1])),
				author: try!(Decodable::decode(&d[2])),
				state_root: try!(Decodable::decode(&d[3])),
				transactions_root: try!(Decodable::decode(&d[4])),
				receipts_root: try!(Decodable::decode(&d[5])),
				log_bloom: try!(Decodable::decode(&d[6])),
				difficulty: try!(Decodable::decode(&d[7])),
				number: try!(Decodable::decode(&d[8])),
				gas_limit: try!(Decodable::decode(&d[9])),
				gas_used: try!(Decodable::decode(&d[10])),
				timestamp: try!(Decodable::decode(&d[11])),
				extra_data: try!(Decodable::decode(&d[12])),
				seal: vec![],
			};
			// TODO: fill blockheader.seal with (raw) list items index 12..)
			Ok(blockheader)
		})
	}
}

impl Encodable for Header {
	fn encode<E>(&self, encoder: &mut E) where E: Encoder {
		encoder.emit_list(| e | {
			self.parent_hash.encode(e);
			self.uncles_hash.encode(e);
			self.author.encode(e);
			self.state_root.encode(e);
			self.transactions_root.encode(e);
			self.receipts_root.encode(e);
			self.log_bloom.encode(e);
			self.difficulty.encode(e);
			self.number.encode(e);
			self.gas_limit.encode(e);
			self.gas_used.encode(e);
			self.timestamp.encode(e);
			self.extra_data.encode(e);
			// TODO: emit raw seal items.
		})
	}
}

#[cfg(test)]
mod tests {
	fn encoding_and_decoding() {
	}
}