// Copyright 2015-2019 Parity Technologies (UK) Ltd.
// This file is part of Parity Ethereum.

// Parity Ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Parity Ethereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Parity Ethereum.  If not, see <http://www.gnu.org/licenses/>.

//! Account system expressed in Plain Old Data.
use log::warn;
use std::collections::BTreeMap;
use itertools::Itertools;
use keccak_hash::keccak;
use ethereum_types::{H256, U256, BigEndianHash};
use hash_db::HashDB;
use kvdb::DBValue;
use keccak_hasher::KeccakHasher;
use triehash::sec_trie_root;
use parity_bytes::Bytes;
use trie_db::TrieFactory;
use ethtrie::Layout;
use ethjson;
use common_types::account_diff::*;
use rlp::{self, RlpStream};
use serde::{Serializer, Serialize};
use rustc_hex::ToHex;

#[derive(Debug, Clone, PartialEq, Eq, Serialize)]
/// An account, expressed as Plain-Old-Data (hence the name).
/// Does not have a DB overlay cache, code hash or anything like that.
pub struct PodAccount {
	/// The balance of the account.
	pub balance: U256,
	/// The nonce of the account.
	pub nonce: U256,
	#[serde(serialize_with="opt_bytes_to_hex")]
	/// The code of the account or `None` in the special case that it is unknown.
	pub code: Option<Bytes>,
	/// The storage of the account.
	pub storage: BTreeMap<H256, H256>,
	/// The version of the account.
	#[serde(default)]
	pub version: U256,
}

fn opt_bytes_to_hex<S>(opt_bytes: &Option<Bytes>, serializer: S) -> Result<S::Ok, S::Error>
	where S: Serializer
{
	let readable = opt_bytes.as_ref().map(|b| b.to_hex()).unwrap_or_default();
	serializer.collect_str(&format_args!("0x{}", readable))
}

impl PodAccount {
	/// Returns the RLP for this account.
	pub fn rlp(&self) -> Bytes {
		let mut stream = RlpStream::new_list(4);
		stream.append(&self.nonce);
		stream.append(&self.balance);
		stream.append(&sec_trie_root(self.storage.iter().map(|(k, v)| (k, rlp::encode(&v.into_uint())))));
		stream.append(&keccak(&self.code.as_ref().unwrap_or(&vec![])));
		stream.out()
	}

	/// Place additional data into given hash DB.
	pub fn insert_additional(&self, db: &mut dyn HashDB<KeccakHasher, DBValue>, factory: &TrieFactory<Layout>) {
		match self.code {
			Some(ref c) if !c.is_empty() => { db.insert(hash_db::EMPTY_PREFIX, c); }
			_ => {}
		}
		let mut r = H256::zero();
		let mut t = factory.create(db, &mut r);
		for (k, v) in &self.storage {
			if let Err(e) = t.insert(k.as_bytes(), &rlp::encode(&v.into_uint())) {
				warn!("Encountered potential DB corruption: {}", e);
			}
		}
	}
}

impl From<ethjson::blockchain::Account> for PodAccount {
	fn from(a: ethjson::blockchain::Account) -> Self {
		PodAccount {
			balance: a.balance.into(),
			nonce: a.nonce.into(),
			code: Some(a.code.into()),
			storage: a.storage.into_iter().map(|(key, value)| {
				let key: U256 = key.into();
				let value: U256 = value.into();
				(BigEndianHash::from_uint(&key), BigEndianHash::from_uint(&value))
			}).collect(),
			version: a.version.into(),
		}
	}
}

impl From<ethjson::spec::Account> for PodAccount {
	fn from(a: ethjson::spec::Account) -> Self {
		PodAccount {
			balance: a.balance.map_or_else(U256::zero, Into::into),
			nonce: a.nonce.map_or_else(U256::zero, Into::into),
			code: Some(a.code.map_or_else(Vec::new, Into::into)),
			storage: a.storage.map_or_else(BTreeMap::new, |s| s.into_iter().map(|(key, value)| {
				let key: U256 = key.into();
				let value: U256 = value.into();
				(BigEndianHash::from_uint(&key), BigEndianHash::from_uint(&value))
			}).collect()),
			version: a.version.map_or_else(U256::zero, Into::into),
		}
	}
}

/// Determine difference between two optionally existant `Account`s. Returns None
/// if they are the same.
pub fn diff_pod(pre: Option<&PodAccount>, post: Option<&PodAccount>) -> Option<AccountDiff> {
	match (pre, post) {
		(None, Some(x)) => Some(AccountDiff {
			balance: Diff::Born(x.balance),
			nonce: Diff::Born(x.nonce),
			code: Diff::Born(x.code.as_ref().expect("account is newly created; newly created accounts must be given code; all caches should remain in place; qed").clone()),
			storage: x.storage.iter().map(|(k, v)| (k.clone(), Diff::Born(v.clone()))).collect(),
		}),
		(Some(x), None) => Some(AccountDiff {
			balance: Diff::Died(x.balance),
			nonce: Diff::Died(x.nonce),
			code: Diff::Died(x.code.as_ref().expect("account is deleted; only way to delete account is running SUICIDE; account must have had own code cached to make operation; all caches should remain in place; qed").clone()),
			storage: x.storage.iter().map(|(k, v)| (k.clone(), Diff::Died(v.clone()))).collect(),
		}),
		(Some(pre), Some(post)) => {
			let storage: Vec<_> = pre.storage.keys().merge(post.storage.keys())
				.filter(|k| pre.storage.get(k).unwrap_or(&H256::zero()) != post.storage.get(k).unwrap_or(&H256::zero()))
				.collect();
			let r = AccountDiff {
				balance: Diff::new(pre.balance, post.balance),
				nonce: Diff::new(pre.nonce, post.nonce),
				code: match (pre.code.clone(), post.code.clone()) {
					(Some(pre_code), Some(post_code)) => Diff::new(pre_code, post_code),
					_ => Diff::Same,
				},
				storage: storage.into_iter().map(|k|
					(k.clone(), Diff::new(
						pre.storage.get(k).cloned().unwrap_or_else(H256::zero),
						post.storage.get(k).cloned().unwrap_or_else(H256::zero)
					))).collect(),
			};
			if r.balance.is_same() && r.nonce.is_same() && r.code.is_same() && r.storage.is_empty() {
				None
			} else {
				Some(r)
			}
		},
		_ => None,
	}
}

#[cfg(test)]
mod test {
	use std::collections::BTreeMap;
	use common_types::account_diff::*;
	use super::{PodAccount, diff_pod};
	use ethereum_types::H256;
	use macros::map;

	#[test]
	fn existence() {
		let a = PodAccount {
			balance: 69.into(), nonce: 0.into(), code: Some(vec![]), storage: map![], version: 0.into(),
		};
		assert_eq!(diff_pod(Some(&a), Some(&a)), None);
		assert_eq!(diff_pod(None, Some(&a)), Some(AccountDiff{
			balance: Diff::Born(69.into()),
			nonce: Diff::Born(0.into()),
			code: Diff::Born(vec![]),
			storage: map![],
		}));
	}

	#[test]
	fn basic() {
		let a = PodAccount {
			balance: 69.into(), nonce: 0.into(), code: Some(vec![]), storage: map![], version: 0.into(),
		};
		let b = PodAccount {
			balance: 42.into(), nonce: 1.into(), code: Some(vec![]), storage: map![], version: 0.into(),
		};
		assert_eq!(diff_pod(Some(&a), Some(&b)), Some(AccountDiff {
			balance: Diff::Changed(69.into(), 42.into()),
			nonce: Diff::Changed(0.into(), 1.into()),
			code: Diff::Same,
			storage: map![],
		}));
	}

	#[test]
	fn code() {
		let a = PodAccount {
			balance: 0.into(), nonce: 0.into(), code: Some(vec![]), storage: map![], version: 0.into(),
		};
		let b = PodAccount {
			balance: 0.into(), nonce: 1.into(), code: Some(vec![0]), storage: map![], version: 0.into(),
		};
		assert_eq!(diff_pod(Some(&a), Some(&b)), Some(AccountDiff {
			balance: Diff::Same,
			nonce: Diff::Changed(0.into(), 1.into()),
			code: Diff::Changed(vec![], vec![0]),
			storage: map![],
		}));
	}

	#[test]
	fn storage() {
		let a = PodAccount {
			balance: 0.into(),
			nonce: 0.into(),
			code: Some(vec![]),
			storage: map![
				H256::from_low_u64_be(1) => H256::from_low_u64_be(1),
				H256::from_low_u64_be(2) => H256::from_low_u64_be(2),
				H256::from_low_u64_be(3) => H256::from_low_u64_be(3),
				H256::from_low_u64_be(4) => H256::from_low_u64_be(4),
				H256::from_low_u64_be(5) => H256::from_low_u64_be(0),
				H256::from_low_u64_be(6) => H256::from_low_u64_be(0),
				H256::from_low_u64_be(7) => H256::from_low_u64_be(0)
			],
			version: 0.into(),
		};
		let b = PodAccount {
			balance: 0.into(),
			nonce: 0.into(),
			code: Some(vec![]),
			storage: map![
				H256::from_low_u64_be(1) => H256::from_low_u64_be(1),
				H256::from_low_u64_be(2) => H256::from_low_u64_be(3),
				H256::from_low_u64_be(3) => H256::from_low_u64_be(0),
				H256::from_low_u64_be(5) => H256::from_low_u64_be(0),
				H256::from_low_u64_be(7) => H256::from_low_u64_be(7),
				H256::from_low_u64_be(8) => H256::from_low_u64_be(0),
				H256::from_low_u64_be(9) => H256::from_low_u64_be(9)
			],
			version: 0.into(),
		};
		assert_eq!(diff_pod(Some(&a), Some(&b)), Some(AccountDiff {
			balance: Diff::Same,
			nonce: Diff::Same,
			code: Diff::Same,
			storage: map![
				H256::from_low_u64_be(2) => Diff::new(H256::from_low_u64_be(2), H256::from_low_u64_be(3)),
				H256::from_low_u64_be(3) => Diff::new(H256::from_low_u64_be(3), H256::from_low_u64_be(0)),
				H256::from_low_u64_be(4) => Diff::new(H256::from_low_u64_be(4), H256::from_low_u64_be(0)),
				H256::from_low_u64_be(7) => Diff::new(H256::from_low_u64_be(0), H256::from_low_u64_be(7)),
				H256::from_low_u64_be(9) => Diff::new(H256::from_low_u64_be(0), H256::from_low_u64_be(9))
			],
		}));
	}
}