/*
	This file is part of cpp-ethereum.

	cpp-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.

	cpp-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 cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
/** @file State.h
 * @author Gav Wood <i@gavwood.com>
 * @date 2014
 */

#pragma once

#include <array>
#include <map>
#include <unordered_map>
#include "Common.h"
#include "RLP.h"
#include "TransactionQueue.h"
#include "Exceptions.h"
#include "BlockInfo.h"
#include "AddressState.h"
#include "Transaction.h"
#include "TrieDB.h"
#include "FeeStructure.h"
#include "Dagger.h"
#include "ExtVMFace.h"

namespace eth
{

class BlockChain;

extern u256 c_genesisDifficulty;
std::map<Address, AddressState> const& genesisState();

static const std::map<u256, u256> EmptyMapU256U256;

static const bytes EmptyBytes;

struct StateChat: public LogChannel { static const char* name() { return "=S="; } static const int verbosity = 4; };

class VM;
class ExtVM;
class State;

class Executive
{
public:
	Executive(State& _s): m_s(_s) {}
	~Executive();

	void setup(bytesConstRef _transaction);
	void create(Address _txSender, u256 _endowment, u256 _gasPrice, u256 _gas, bytesConstRef _code, bytesConstRef _init, Address _originAddress);
	void call(Address _myAddress, Address _txSender, u256 _txValue, u256 _gasPrice, bytesConstRef _txData, u256 _gas, Address _originAddress);
	bool go(uint64_t _steps = (unsigned)-1);
	void finalize();

	u256 gas() const;

	bytesConstRef out() const { return m_out; }
	h160 newAddress() const { return m_newAddress; }

	VM const& vm() const { return *m_vm; }
	State const& state() const { return m_s; }
	ExtVM const& ext() const { return *m_ext; }

private:
	State& m_s;
	ExtVM* m_ext = nullptr;	// TODO: make safe.
	VM* m_vm = nullptr;
	bytesConstRef m_out;
	Address m_newAddress;

	Transaction m_t;

	u256 m_startGas;
	u256 m_endGas;
};

/**
 * @brief Model of the current state of the ledger.
 * Maintains current ledger (m_current) as a fast hash-map. This is hashed only when required (i.e. to create or verify a block).
 * Should maintain ledger as of last N blocks, also, in case we end up on the wrong branch.
 */
class State
{
	template <unsigned T> friend class UnitTest;
	friend class ExtVM;
	friend class Executive;

public:
	/// Construct state object.
	State(Address _coinbaseAddress = Address(), Overlay const& _db = Overlay());

	/// Copy state object.
	State(State const& _s);

	/// Copy state object.
	State& operator=(State const& _s);

	/// Set the coinbase address for any transactions we do.
	/// This causes a complete reset of current block.
	void setAddress(Address _coinbaseAddress) { m_ourAddress = _coinbaseAddress; resetCurrent(); }
	Address address() const { return m_ourAddress; }

	/// Open a DB - useful for passing into the constructor & keeping for other states that are necessary.
    static Overlay openDB(std::string _path, bool _killExisting = false);
	static Overlay openDB(bool _killExisting = false) { return openDB(std::string(), _killExisting); }

	/// @returns the set containing all addresses currently in use in Ethereum.
	std::map<Address, u256> addresses() const;

	/// Cancels transactions and rolls back the state to the end of the previous block.
	/// @warning This will only work for on any transactions after you called the last commitToMine().
	/// It's one or the other.
	void rollback() { m_cache.clear(); }

	/// Prepares the current state for mining.
	/// Commits all transactions into the trie, compiles uncles and transactions list, applies all
	/// rewards and populates the current block header with the appropriate hashes.
	/// The only thing left to do after this is to actually mine().
	///
	/// This may be called multiple times and without issue, however, until the current state is cleared,
	/// calls after the first are ignored.
	void commitToMine(BlockChain const& _bc);

	/// Attempt to find valid nonce for block that this state represents.
	/// @param _msTimeout Timeout before return in milliseconds.
	/// @returns a non-empty byte array containing the block if it got lucky. In this case, call blockData()
	/// to get the block if you need it later.
	MineInfo mine(uint _msTimeout = 1000);

	/// Get the complete current block, including valid nonce.
	/// Only valid after mine() returns true.
	bytes const& blockData() const { return m_currentBytes; }

	/// Sync our state with the block chain.
	/// This basically involves wiping ourselves if we've been superceded and rebuilding from the transaction queue.
	bool sync(BlockChain const& _bc);

	/// Sync with the block chain, but rather than synching to the latest block, instead sync to the given block.
	bool sync(BlockChain const& _bc, h256 _blockHash);

	/// Sync our transactions, killing those from the queue that we have and assimilating those that we don't.
	bool sync(TransactionQueue& _tq);
	/// Like sync but only operate on _tq, killing the invalid/old ones.
	bool cull(TransactionQueue& _tq) const;

	/// Execute a given transaction.
	/// This will append @a _t to the transaction list and change the state accordingly.
	void execute(bytes const& _rlp) { return execute(&_rlp); }
	void execute(bytesConstRef _rlp);

	/// Check if the address is a valid normal (non-contract) account address.
	bool isNormalAddress(Address _address) const;

	/// Check if the address is a valid contract's address.
	bool isContractAddress(Address _address) const;

	/// Get an account's balance.
	/// @returns 0 if the address has never been used.
	u256 balance(Address _id) const;

	/// Add some amount to balance.
	/// Will initialise the address if it has never been used.
	void addBalance(Address _id, u256 _amount);

	/** Subtract some amount from balance.
	 * @throws NotEnoughCash if balance of @a _id is less than @a _value (or has never been used).
	 * @note We use bigint here as we don't want any accidental problems with negative numbers.
	 */
	void subBalance(Address _id, bigint _value);

	/// Get the value of a memory position of a contract.
	/// @returns 0 if no contract exists at that address.
	u256 contractStorage(Address _contract, u256 _memory) const;

	/// Get the memory of a contract.
	/// @returns std::map<u256, u256> if no contract exists at that address.
	std::map<u256, u256> const& contractStorage(Address _contract) const;

	/// Get the code of a contract.
	/// @returns bytes() if no contract exists at that address.
	bytes const& contractCode(Address _contract) const;

	/// Note that the given address is sending a transaction and thus increment the associated ticker.
	void noteSending(Address _id);

	/// Get the number of transactions a particular address has sent (used for the transaction nonce).
	/// @returns 0 if the address has never been used.
	u256 transactionsFrom(Address _address) const;

	/// The hash of the root of our state tree.
	h256 rootHash() const { return m_state.root(); }

	/// Get the list of pending transactions.
	Transactions const& pending() const { return m_transactions; }

	/// Execute all transactions within a given block.
	/// @returns the additional total difficulty.
	/// If the _grandParent is passed, it will check the validity of each of the uncles.
	/// This might throw.
	u256 playback(bytesConstRef _block, BlockInfo const& _bi, BlockInfo const& _parent, BlockInfo const& _grandParent, bool _fullCommit);

	/// Get the fee associated for a contract created with the given data.
	u256 createGas(uint _dataCount, u256 _gas = 0) const { return c_txDataGas * _dataCount + c_createGas + _gas; }

	/// Get the fee associated for a normal transaction.
	u256 callGas(uint _dataCount, u256 _gas = 0) const { return c_txDataGas * _dataCount + c_callGas + _gas; }

private:
	/// Retrieve all information about a given address into the cache.
	/// If _requireMemory is true, grab the full memory should it be a contract item.
	/// If _forceCreate is true, then insert a default item into the cache, in the case it doesn't
	/// exist in the DB.
	void ensureCached(Address _a, bool _requireMemory, bool _forceCreate) const;

	/// Retrieve all information about a given address into a cache.
	void ensureCached(std::map<Address, AddressState>& _cache, Address _a, bool _requireMemory, bool _forceCreate) const;

	/// Commit all changes waiting in the address cache to the DB.
	void commit();

	/// Execute the given block on our previous block. This will set up m_currentBlock first, then call the other playback().
	/// Any failure will be critical.
	u256 playback(bytesConstRef _block, bool _fullCommit);

	/// Execute the given block, assuming it corresponds to m_currentBlock. If _grandParent is passed, it will be used to check the uncles.
	/// Throws on failure.
	u256 playback(bytesConstRef _block, BlockInfo const& _grandParent, bool _fullCommit);

	// Two priviledged entry points for transaction processing used by the VM (these don't get added to the Transaction lists):
	// We assume all instrinsic fees are paid up before this point.

	/// Execute a contract-creation transaction.
	h160 create(Address _txSender, u256 _endowment, u256 _gasPrice, u256* _gas, bytesConstRef _code, bytesConstRef _init, Address _originAddress = Address());

	/// Execute a call.
	/// @a _gas points to the amount of gas to use for the call, and will lower it accordingly.
	/// @returns false if the call ran out of gas before completion. true otherwise.
	bool call(Address _myAddress, Address _txSender, u256 _txValue, u256 _gasPrice, bytesConstRef _txData, u256* _gas, bytesRef _out, Address _originAddress = Address());

	/// Sets m_currentBlock to a clean state, (i.e. no change from m_previousBlock).
	void resetCurrent();

	/// Finalise the block, applying the earned rewards.
	void applyRewards(Addresses const& _uncleAddresses);

	/// Unfinalise the block, unapplying the earned rewards.
	void unapplyRewards(Addresses const& _uncleAddresses);

	Overlay m_db;								///< Our overlay for the state tree.
	TrieDB<Address, Overlay> m_state;			///< Our state tree, as an Overlay DB.
	Transactions m_transactions;				///< The current list of transactions that we've included in the state.
	std::set<h256> m_transactionSet;			///< The set of transaction hashes that we've included in the state.

	mutable std::map<Address, AddressState> m_cache;	///< Our address cache. This stores the states of each address that has (or at least might have) been changed.

	BlockInfo m_previousBlock;					///< The previous block's information.
	BlockInfo m_currentBlock;					///< The current block's information.
	bytes m_currentBytes;						///< The current block.
	uint m_currentNumber;

	bytes m_currentTxs;
	bytes m_currentUncles;

	Address m_ourAddress;						///< Our address (i.e. the address to which fees go).

	Dagger m_dagger;

	u256 m_blockReward;

	static std::string c_defaultPath;

	friend std::ostream& operator<<(std::ostream& _out, State const& _s);
};

class ExtVM: public ExtVMFace
{
public:
	ExtVM(State& _s, Address _myAddress, Address _caller, Address _origin, u256 _value, u256 _gasPrice, bytesConstRef _data, bytesConstRef _code):
		ExtVMFace(_myAddress, _caller, _origin, _value, _gasPrice, _data, _code, _s.m_previousBlock, _s.m_currentBlock, _s.m_currentNumber), m_s(_s), m_origCache(_s.m_cache)
	{
		m_s.ensureCached(_myAddress, true, true);
		m_store = &(m_s.m_cache[_myAddress].memory());
	}

	u256 store(u256 _n)
	{
		auto i = m_store->find(_n);
		return i == m_store->end() ? 0 : i->second;
	}
	void setStore(u256 _n, u256 _v)
	{
		if (_v)
			(*m_store)[_n] = _v;
		else
			m_store->erase(_n);
	}

	h160 create(u256 _endowment, u256* _gas, bytesConstRef _code, bytesConstRef _init)
	{
		// Increment associated nonce for sender.
		m_s.noteSending(myAddress);

		return m_s.create(myAddress, _endowment, gasPrice, _gas, _code, _init, origin);
	}

	bool call(Address _receiveAddress, u256 _txValue, bytesConstRef _txData, u256* _gas, bytesRef _out)
	{
		return m_s.call(_receiveAddress, myAddress, _txValue, gasPrice, _txData, _gas, _out, origin);
	}

	u256 balance(Address _a) { return m_s.balance(_a); }
	void subBalance(u256 _a) { m_s.subBalance(myAddress, _a); }
	u256 txCount(Address _a) { return m_s.transactionsFrom(_a); }
	void suicide(Address _a)
	{
		m_s.addBalance(_a, m_s.balance(myAddress));
		m_s.m_cache[myAddress].kill();
	}

	void revert()
	{
		m_s.m_cache = m_origCache;
	}

private:
	State& m_s;
	std::map<Address, AddressState> m_origCache;
	std::map<u256, u256>* m_store;
};

inline std::ostream& operator<<(std::ostream& _out, State const& _s)
{
	_out << "--- " << _s.rootHash() << std::endl;
	std::set<Address> d;
	for (auto const& i: TrieDB<Address, Overlay>(const_cast<Overlay*>(&_s.m_db), _s.rootHash()))
	{
		auto it = _s.m_cache.find(i.first);
		if (it == _s.m_cache.end())
		{
			RLP r(i.second);
			_out << "[    " << (r.itemCount() == 3 ? "CONTRACT] " : "  NORMAL] ") << i.first << ": " << std::dec << r[1].toInt<u256>() << "@" << r[0].toInt<u256>();
			if (r.itemCount() == 3)
			{
				_out << " *" << r[2].toHash<h256>();
				TrieDB<h256, Overlay> memdb(const_cast<Overlay*>(&_s.m_db), r[2].toHash<h256>());		// promise we won't alter the overlay! :)
				std::map<u256, u256> mem;
				for (auto const& j: memdb)
				{
					_out << std::endl << "    [" << j.first << ":" << toHex(j.second) << "]";
					mem[j.first] = RLP(j.second).toInt<u256>();
				}
				_out << std::endl << mem;
			}
			_out << std::endl;
		}
		else
			d.insert(i.first);
	}
	for (auto i: _s.m_cache)
		if (i.second.type() == AddressType::Dead)
			_out << "[XXX " << i.first << std::endl;
		else
		{
			_out << (d.count(i.first) ? "[ !  " : "[ *  ") << (i.second.type() == AddressType::Contract ? "CONTRACT] " : "  NORMAL] ") << i.first << ": " << std::dec << i.second.nonce() << "@" << i.second.balance();
			if (i.second.type() == AddressType::Contract)
			{
				if (i.second.isComplete())
				{
					_out << std::endl << i.second.memory();
				}
				else
				{
					_out << " *" << i.second.oldRoot();
					TrieDB<h256, Overlay> memdb(const_cast<Overlay*>(&_s.m_db), i.second.oldRoot());		// promise we won't alter the overlay! :)
					std::map<u256, u256> mem;
					for (auto const& j: memdb)
					{
						_out << std::endl << "    [" << j.first << ":" << toHex(j.second) << "]";
						mem[j.first] = RLP(j.second).toInt<u256>();
					}
					_out << std::endl << mem;
				}
			}
			_out << std::endl;
		}
	return _out;
}

template <class DB>
void commit(std::map<Address, AddressState> const& _cache, DB& _db, TrieDB<Address, DB>& _state)
{
	for (auto const& i: _cache)
		if (i.second.type() == AddressType::Dead)
			_state.remove(i.first);
		else
		{
			RLPStream s(i.second.type() == AddressType::Contract ? 3 : 2);
			s << i.second.balance() << i.second.nonce();
			if (i.second.type() == AddressType::Contract)
			{
				if (i.second.isComplete())
				{
					TrieDB<h256, DB> memdb(&_db);
					memdb.init();
					for (auto const& j: i.second.memory())
						if (j.second)
							memdb.insert(j.first, rlp(j.second));
					s << memdb.root();
					if (i.second.freshCode())
					{
						h256 ch = sha3(i.second.code());
						_db.insert(ch, &i.second.code());
						s << ch;
					}
					else
						s << i.second.codeHash();
				}
				else
					s << i.second.oldRoot() << i.second.codeHash();
			}
			_state.insert(i.first, &s.out());
		}
}

}