/*
	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 <unordered_map>
#include <libdevcore/Common.h>
#include <libdevcore/RLP.h>
#include <libdevcore/TrieDB.h>
#include <libdevcrypto/OverlayDB.h>
#include <libethcore/Exceptions.h>
#include <libethcore/BlockInfo.h>
#include <libethcore/ProofOfWork.h>
#include <libethcore/Miner.h>
#include <libevm/ExtVMFace.h>
#include "TransactionQueue.h"
#include "Account.h"
#include "Transaction.h"
#include "TransactionReceipt.h"
#include "AccountDiff.h"

namespace dev
{

namespace test { class ImportTest; class StateLoader; }

namespace eth
{

class BlockChain;
class State;

struct StateChat: public LogChannel { static const char* name(); static const int verbosity = 4; };
struct StateTrace: public LogChannel { static const char* name(); static const int verbosity = 5; };
struct StateDetail: public LogChannel { static const char* name(); static const int verbosity = 14; };
struct StateSafeExceptions: public LogChannel { static const char* name(); static const int verbosity = 21; };

enum class BaseState
{
	PreExisting,
	Empty,
	CanonGenesis
};

enum class TransactionPriority
{
	Lowest = 0,
	Low = 2,
	Medium = 4,
	High = 6,
	Highest = 8
};

class GasPricer
{
public:
	GasPricer() = default;
	virtual ~GasPricer() = default;

	virtual u256 ask(State const&) const = 0;
	virtual u256 bid(TransactionPriority _p = TransactionPriority::Medium) const = 0;

	virtual void update(BlockChain const&) {}
};

class TrivialGasPricer: public GasPricer
{
protected:
	u256 ask(State const&) const override { return 10 * szabo; }
	u256 bid(TransactionPriority = TransactionPriority::Medium) const override { return 10 * szabo; }
};

enum class Permanence
{
	Reverted,
	Committed
};

/**
 * @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
{
	friend class ExtVM;
	friend class dev::test::ImportTest;
	friend class dev::test::StateLoader;
	friend class Executive;

public:
	/// Default constructor; creates with a blank database prepopulated with the genesis block.
	State(): State(OverlayDB(), BaseState::Empty) {}

	/// Basic state object from database.
	/// Use the default when you already have a database and you just want to make a State object
	/// which uses it. If you have no preexisting database then set BaseState to something other
	/// than BaseState::PreExisting in order to prepopulate the Trie.
	/// You can also set the coinbase address.
	explicit State(OverlayDB const& _db, BaseState _bs = BaseState::PreExisting, Address _coinbaseAddress = Address());

	/// Construct state object from arbitrary point in blockchain.
	State(OverlayDB const& _db, BlockChain const& _bc, h256 _hash, ImportRequirements::value _ir = ImportRequirements::Default);

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

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

	~State();

	/// 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 OverlayDB openDB(std::string _path, WithExisting _we = WithExisting::Trust);
	static OverlayDB openDB(WithExisting _we = WithExisting::Trust) { return openDB(std::string(), _we); }
	OverlayDB const& db() const { return m_db; }
	OverlayDB& db() { return m_db; }

	/// @returns the set containing all addresses currently in use in Ethereum.
	/// @throws InterfaceNotSupported if compiled without ETH_FATDB.
	std::unordered_map<Address, u256> addresses() const;

	/// Get the header information on the present block.
	BlockInfo const& info() const { return m_currentBlock; }

	/// @brief Checks that mining the current object will result in a valid block.
	/// Effectively attempts to import the serialised block.
	/// @returns true if all is ok. If it's false, worry.
	bool amIJustParanoid(BlockChain const& _bc);

	/// 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.
	void commitToMine(BlockChain const& _bc);

	/// @returns true iff commitToMine() has been called without any subsequest transactions added &c.
	bool isCommittedToMine() const { return m_committedToMine; }

	/// Pass in a solution to the proof-of-work.
	/// @returns true iff we were previously committed to mining.
	template <class PoW>
	bool completeMine(typename PoW::Solution const& _result)
	{
		if (!m_committedToMine)
			return false;

		PoW::assignResult(_result, m_currentBlock);

		cnote << "Completed" << m_currentBlock.headerHash(WithoutNonce) << m_currentBlock.nonce << m_currentBlock.difficulty << PoW::verify(m_currentBlock);

		completeMine();

		return true;
	}

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

	/// Sync our transactions, killing those from the queue that we have and assimilating those that we don't.
	/// @returns a list of receipts one for each transaction placed from the queue into the state and bool, true iff there are more transactions to be processed.
	std::pair<TransactionReceipts, bool> sync(BlockChain const& _bc, TransactionQueue& _tq, GasPricer const& _gp, unsigned _msTimeout = 100);

	/// Execute a given transaction.
	/// This will append @a _t to the transaction list and change the state accordingly.
	ExecutionResult execute(LastHashes const& _lh, Transaction const& _t, Permanence _p = Permanence::Committed);

	/// Get the remaining gas limit in this block.
	u256 gasLimitRemaining() const { return m_currentBlock.gasLimit - gasUsed(); }

	/// Check if the address is in use.
	bool addressInUse(Address _address) const;

	/// Check if the address contains executable code.
	bool addressHasCode(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);

	/**
	 * @brief Transfers "the balance @a _value between two accounts.
	 * @param _from Account from which @a _value will be deducted.
	 * @param _to Account to which @a _value will be added.
	 * @param _value Amount to be transferred.
	 */
	void transferBalance(Address _from, Address _to, u256 _value) { subBalance(_from, _value); addBalance(_to, _value); }

	/// Get the root of the storage of an account.
	h256 storageRoot(Address _contract) const;

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

	/// Set the value of a storage position of an account.
	void setStorage(Address _contract, u256 _location, u256 _value) { m_cache[_contract].setStorage(_location, _value); }

	/// Create a new contract.
	Address newContract(u256 _balance, bytes const& _code);

	/// Get the storage of an account.
	/// @note This is expensive. Don't use it unless you need to.
	/// @returns std::unordered_map<u256, u256> if no account exists at that address.
	std::unordered_map<u256, u256> storage(Address _contract) const;

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

	/// Get the code hash of an account.
	/// @returns EmptySHA3 if no account exists at that address or if there is no code associated with the address.
	h256 codeHash(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; }

	/// Get the list of hashes of pending transactions.
	h256Hash const& pendingHashes() const { return m_transactionSet; }

	/// Get the transaction receipt for the transaction of the given index.
	TransactionReceipt const& receipt(unsigned _i) const { return m_receipts[_i]; }

	/// Get the list of pending transactions.
	LogEntries const& log(unsigned _i) const { return m_receipts[_i].log(); }

	/// Get the bloom filter of all logs that happened in the block.
	LogBloom logBloom() const;

	/// Get the bloom filter of a particular transaction that happened in the block.
	LogBloom const& logBloom(unsigned _i) const { return m_receipts[_i].bloom(); }

	/// Get the State immediately after the given number of pending transactions have been applied.
	/// If (_i == 0) returns the initial state of the block.
	/// If (_i == pending().size()) returns the final state of the block, prior to rewards.
	State fromPending(unsigned _i) const;

	/// @returns the StateDiff caused by the pending transaction of index @a _i.
	StateDiff pendingDiff(unsigned _i) const { return fromPending(_i).diff(fromPending(_i + 1)); }

	/// @return the difference between this state (origin) and @a _c (destination).
	StateDiff diff(State const& _c) const;

	/// 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, BlockInfo const& _bi = BlockInfo(), ImportRequirements::value _ir = ImportRequirements::Default);

	/// Execute all transactions within a given block.
	/// @returns the additional total difficulty.
	u256 enactOn(bytesConstRef _block, BlockInfo const& _bi, BlockChain const& _bc, ImportRequirements::value _ir = ImportRequirements::Default);

	/// Returns back to a pristine state after having done a playback.
	/// @arg _fullCommit if true flush everything out to disk. If false, this effectively only validates
	/// the block since all state changes are ultimately reversed.
	void cleanup(bool _fullCommit);

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

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

private:
	/** Commit to DB and build the final block if the previous call to mine()'s result is completion.
	 * Typically looks like:
	 * @code
	 * while (notYetMined)
	 * {
	 * // lock
	 * commitToMine(_blockChain);  // will call uncommitToMine if a repeat.
	 * completeMine();
	 * // unlock
	 * @endcode
	 */
	void completeMine();

	/// Undo the changes to the state for committing to mine.
	void uncommitToMine();

	/// 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 _requireCode, bool _forceCreate) const;

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

	/// Execute the given block, assuming it corresponds to m_currentBlock.
	/// Throws on failure.
	u256 enact(bytesConstRef _block, BlockChain const& _bc, ImportRequirements::value _ir = ImportRequirements::Default);

	/// Finalise the block, applying the earned rewards.
	void applyRewards(std::vector<BlockInfo> const& _uncleBlockHeaders);

	/// @returns gas used by transactions thus far executed.
	u256 gasUsed() const { return m_receipts.size() ? m_receipts.back().gasUsed() : 0; }

	/// Debugging only. Good for checking the Trie is in shape.
	bool isTrieGood(bool _enforceRefs, bool _requireNoLeftOvers) const;
	/// Debugging only. Good for checking the Trie is in shape.
	void paranoia(std::string const& _when, bool _enforceRefs = false) const;

	OverlayDB m_db;								///< Our overlay for the state tree.
	SecureTrieDB<Address, OverlayDB> m_state;	///< Our state tree, as an OverlayDB DB.
	Transactions m_transactions;				///< The current list of transactions that we've included in the state.
	TransactionReceipts m_receipts;				///< The corresponding list of transaction receipts.
	h256Hash m_transactionSet;					///< The set of transaction hashes that we've included in the state.
	OverlayDB m_lastTx;

	mutable std::unordered_map<Address, Account> 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.
	bool m_committedToMine = false;				///< Have we committed to mine on the present m_currentBlock?

	bytes m_currentTxs;							///< The RLP-encoded block of transactions.
	bytes m_currentUncles;						///< The RLP-encoded block of uncles.

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

	u256 m_blockReward;

	static std::string c_defaultPath;

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

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

template <class DB>
void commit(std::unordered_map<Address, Account> const& _cache, DB& _db, SecureTrieDB<Address, DB>& _state)
{
	for (auto const& i: _cache)
		if (i.second.isDirty())
		{
			if (!i.second.isAlive())
				_state.remove(i.first);
			else
			{
				RLPStream s(4);
				s << i.second.nonce() << i.second.balance();

				if (i.second.storageOverlay().empty())
				{
					assert(i.second.baseRoot());
					s.append(i.second.baseRoot());
				}
				else
				{
					SecureTrieDB<h256, DB> storageDB(&_db, i.second.baseRoot());
					for (auto const& j: i.second.storageOverlay())
						if (j.second)
							storageDB.insert(j.first, rlp(j.second));
						else
							storageDB.remove(j.first);
					assert(storageDB.root());
					s.append(storageDB.root());
				}

				if (i.second.isFreshCode())
				{
					h256 ch = sha3(i.second.code());
					_db.insert(ch, &i.second.code());
					s << ch;
				}
				else
					s << i.second.codeHash();

				_state.insert(i.first, &s.out());
			}
		}
}

}
}