/*

  This file is part of solidity.

  solidity 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.

  solidity 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 solidity.  If not, see <http://www.gnu.org/licenses/>.

*/

// SPDX-License-Identifier: GPL-3.0

#include <libsolidity/formal/SymbolicState.h>

#include <libsolidity/formal/SymbolicTypes.h>

#include <libsolidity/formal/EncodingContext.h>

#include <libsolidity/formal/SMTEncoder.h>

using namespace std;

using namespace solidity;

using namespace solidity::smtutil;

using namespace solidity::frontend::smt;

BlockchainVariable::BlockchainVariable(

  string _name,

  map<string, smtutil::SortPointer> _members,

  EncodingContext& _context

):

  m_name(move(_name)),

  m_members(move(_members)),

  m_context(_context)

{

  vector<string> members;

  vector<SortPointer> sorts;

  for (auto const& [component, sort]: m_members)

  {

    members.emplace_back(component);

    sorts.emplace_back(sort);

    m_componentIndices[component] = static_cast<unsigned>(members.size() - 1);

  }

  m_tuple = make_unique<SymbolicTupleVariable>(

    make_shared<smtutil::TupleSort>(m_name + "_type", members, sorts),

    m_name,

    m_context

  );

}

smtutil::Expression BlockchainVariable::member(string const& _member) const

{

  return m_tuple->component(m_componentIndices.at(_member));

}

smtutil::Expression BlockchainVariable::assignMember(string const& _member, smtutil::Expression const& _value)

{

  vector<smtutil::Expression> args;

  for (auto const& m: m_members)

    if (m.first == _member)

      args.emplace_back(_value);

    else

      args.emplace_back(member(m.first));

  m_tuple->increaseIndex();

  auto tuple = m_tuple->currentValue();

  auto sortExpr = smtutil::Expression(make_shared<smtutil::SortSort>(tuple.sort), tuple.name);

  m_context.addAssertion(tuple == smtutil::Expression::tuple_constructor(sortExpr, args));

  return m_tuple->currentValue();

}

void SymbolicState::reset()

{

  m_error.resetIndex();

  m_thisAddress.resetIndex();

  m_state.reset();

  m_tx.reset();

  m_crypto.reset();

  if (m_abi)

    m_abi->reset();

}

smtutil::Expression SymbolicState::balances() const

{

  return m_state.member("balances");

}

smtutil::Expression SymbolicState::balance() const

{

  return balance(thisAddress());

}

smtutil::Expression SymbolicState::balance(smtutil::Expression _address) const

{

  return smtutil::Expression::select(balances(), move(_address));

}

smtutil::Expression SymbolicState::blockhash(smtutil::Expression _blockNumber) const

{

  return smtutil::Expression::select(m_tx.member("blockhash"), move(_blockNumber));

}

void SymbolicState::newBalances()

{

  auto tupleSort = dynamic_pointer_cast<TupleSort>(stateSort());

  auto balanceSort = tupleSort->components.at(tupleSort->memberToIndex.at("balances"));

  SymbolicVariable newBalances(balanceSort, "fresh_balances_" + to_string(m_context.newUniqueId()), m_context);

  m_state.assignMember("balances", newBalances.currentValue());

}

void SymbolicState::transfer(smtutil::Expression _from, smtutil::Expression _to, smtutil::Expression _value)

{

  unsigned indexBefore = m_state.index();

  addBalance(_from, 0 - _value);

  addBalance(_to, move(_value));

  unsigned indexAfter = m_state.index();

  solAssert(indexAfter > indexBefore, "");

  m_state.newVar();

  /// Do not apply the transfer operation if _from == _to.

  auto newState = smtutil::Expression::ite(

    move(_from) == move(_to),

    m_state.value(indexBefore),

    m_state.value(indexAfter)

  );

  m_context.addAssertion(m_state.value() == newState);

}

void SymbolicState::addBalance(smtutil::Expression _address, smtutil::Expression _value)

{

  auto newBalances = smtutil::Expression::store(

    balances(),

    _address,

    balance(_address) + move(_value)

  );

  m_state.assignMember("balances", newBalances);

}

smtutil::Expression SymbolicState::txMember(string const& _member) const

{

  return m_tx.member(_member);

}

smtutil::Expression SymbolicState::txTypeConstraints() const

{

  return

    smt::symbolicUnknownConstraints(m_tx.member("block.basefee"), TypeProvider::uint256()) &&

    smt::symbolicUnknownConstraints(m_tx.member("block.chainid"), TypeProvider::uint256()) &&

    smt::symbolicUnknownConstraints(m_tx.member("block.coinbase"), TypeProvider::address()) &&

    smt::symbolicUnknownConstraints(m_tx.member("block.difficulty"), TypeProvider::uint256()) &&

    smt::symbolicUnknownConstraints(m_tx.member("block.gaslimit"), TypeProvider::uint256()) &&

    smt::symbolicUnknownConstraints(m_tx.member("block.number"), TypeProvider::uint256()) &&

    smt::symbolicUnknownConstraints(m_tx.member("block.timestamp"), TypeProvider::uint256()) &&

    smt::symbolicUnknownConstraints(m_tx.member("msg.sender"), TypeProvider::address()) &&

    smt::symbolicUnknownConstraints(m_tx.member("msg.value"), TypeProvider::uint256()) &&

    smt::symbolicUnknownConstraints(m_tx.member("tx.origin"), TypeProvider::address()) &&

    smt::symbolicUnknownConstraints(m_tx.member("tx.gasprice"), TypeProvider::uint256());

}

smtutil::Expression SymbolicState::txNonPayableConstraint() const

{

  return m_tx.member("msg.value") == 0;

}

smtutil::Expression SymbolicState::txFunctionConstraints(FunctionDefinition const& _function) const

{

  smtutil::Expression conj = _function.isPayable() ? smtutil::Expression(true) : txNonPayableConstraint();

  if (_function.isPartOfExternalInterface())

  {

    auto sig = TypeProvider::function(_function)->externalIdentifier();

    conj = conj && m_tx.member("msg.sig") == sig;

    auto b0 = sig >> (3 * 8);

    auto b1 = (sig & 0x00ff0000) >> (2 * 8);

    auto b2 = (sig & 0x0000ff00) >> (1 * 8);

    auto b3 = (sig & 0x000000ff);

    auto data = smtutil::Expression::tuple_get(m_tx.member("msg.data"), 0);

    conj = conj && smtutil::Expression::select(data, 0) == b0;

    conj = conj && smtutil::Expression::select(data, 1) == b1;

    conj = conj && smtutil::Expression::select(data, 2) == b2;

    conj = conj && smtutil::Expression::select(data, 3) == b3;

    auto length = smtutil::Expression::tuple_get(m_tx.member("msg.data"), 1);

    // TODO add ABI size of function input parameters here \/

    conj = conj && length >= 4;

  }

  return conj;

}

void SymbolicState::prepareForSourceUnit(SourceUnit const& _source)

{

  set<FunctionCall const*> abiCalls = SMTEncoder::collectABICalls(&_source);

  for (auto const& source: _source.referencedSourceUnits(true))

    abiCalls += SMTEncoder::collectABICalls(source);

  buildABIFunctions(abiCalls);

}

/// Private helpers.

void SymbolicState::buildABIFunctions(set<FunctionCall const*> const& _abiFunctions)

{

  map<string, SortPointer> functions;

  for (auto const* funCall: _abiFunctions)

  {

    auto t = dynamic_cast<FunctionType const*>(funCall->expression().annotation().type);

    auto const& args = funCall->sortedArguments();

    auto const& paramTypes = t->parameterTypes();

    auto const& returnTypes = t->returnParameterTypes();

    auto argTypes = [](auto const& _args) {

      return util::applyMap(_args, [](auto arg) { return arg->annotation().type; });

    };

    /// Since each abi.* function may have a different number of input/output parameters,

    /// we generically compute those types.

    vector<frontend::Type const*> inTypes;

    vector<frontend::Type const*> outTypes;

    if (t->kind() == FunctionType::Kind::ABIDecode)

    {

      /// abi.decode : (bytes, tuple_of_types(return_types)) -> (return_types)

      solAssert(args.size() == 2, "Unexpected number of arguments for abi.decode");

      inTypes.emplace_back(TypeProvider::bytesMemory());

      auto argType = args.at(1)->annotation().type;

      if (auto const* tupleType = dynamic_cast<TupleType const*>(argType))

        for (auto componentType: tupleType->components())

        {

          auto typeType = dynamic_cast<TypeType const*>(componentType);

          solAssert(typeType, "");

          outTypes.emplace_back(typeType->actualType());

        }

      else if (auto const* typeType = dynamic_cast<TypeType const*>(argType))

        outTypes.emplace_back(typeType->actualType());

      else

        solAssert(false, "Unexpected argument of abi.decode");

    }

    else if (t->kind() == FunctionType::Kind::ABIEncodeCall)

    {

      // abi.encodeCall : (functionPointer, tuple_of_args_or_one_non_tuple_arg(arguments)) -> bytes

      solAssert(args.size() == 2, "Unexpected number of arguments for abi.encodeCall");

      outTypes.emplace_back(TypeProvider::bytesMemory());

      inTypes.emplace_back(args.at(0)->annotation().type);

      inTypes.emplace_back(args.at(1)->annotation().type);

    }

    else

    {

      outTypes = returnTypes;

      if (

        t->kind() == FunctionType::Kind::ABIEncodeWithSelector ||

        t->kind() == FunctionType::Kind::ABIEncodeWithSignature

      )

      {

        /// abi.encodeWithSelector : (bytes4, one_or_more_types) -> bytes

        /// abi.encodeWithSignature : (string, one_or_more_types) -> bytes

        inTypes.emplace_back(paramTypes.front());

        inTypes += argTypes(vector<ASTPointer<Expression const>>(args.begin() + 1, args.end()));

      }

      else

      {

        /// abi.encode/abi.encodePacked : one_or_more_types -> bytes

        solAssert(

          t->kind() == FunctionType::Kind::ABIEncode ||

          t->kind() == FunctionType::Kind::ABIEncodePacked,

          ""

        );

        inTypes = argTypes(args);

      }

    }

    /// Rational numbers and string literals add the concrete values to the type name,

    /// so we replace them by uint256 and bytes since those are the same as their SMT types.

    /// TODO we could also replace all types by their ABI type.

    auto replaceTypes = [](auto& _types) {

      for (auto& t: _types)

        if (t->category() == frontend::Type::Category::RationalNumber)

          t = TypeProvider::uint256();

        else if (t->category() == frontend::Type::Category::StringLiteral)

          t = TypeProvider::bytesMemory();

        else if (auto userType = dynamic_cast<UserDefinedValueType const*>(t))

          t = &userType->underlyingType();

    };

    replaceTypes(inTypes);

    replaceTypes(outTypes);

    auto name = t->richIdentifier();

    for (auto paramType: inTypes + outTypes)

      name += "_" + paramType->richIdentifier();

    m_abiMembers[funCall] = {name, inTypes, outTypes};

    if (functions.count(name))

      continue;

    /// If there is only one input or output parameter, we use that type directly.

    /// Otherwise we create a tuple wrapping the necessary input or output types.

    auto typesToSort = [](auto const& _types, string const& _name) -> shared_ptr<Sort> {

      if (_types.size() == 1)

        return smtSortAbstractFunction(*_types.front());

      vector<string> inNames;

      vector<SortPointer> sorts;

      for (unsigned i = 0; i < _types.size(); ++i)

      {

        inNames.emplace_back(_name + "_input_" + to_string(i));

        sorts.emplace_back(smtSortAbstractFunction(*_types.at(i)));

      }

      return make_shared<smtutil::TupleSort>(

        _name + "_input",

        inNames,

        sorts

      );

    };

    auto functionSort = make_shared<smtutil::ArraySort>(

      typesToSort(inTypes, name),

      typesToSort(outTypes, name)

    );

    functions[name] = functionSort;

  }

  m_abi = make_unique<BlockchainVariable>("abi", move(functions), m_context);

}

smtutil::Expression SymbolicState::abiFunction(frontend::FunctionCall const* _funCall)

{

  solAssert(m_abi, "");

  return m_abi->member(get<0>(m_abiMembers.at(_funCall)));

}

SymbolicState::SymbolicABIFunction const& SymbolicState::abiFunctionTypes(FunctionCall const* _funCall) const

{

  return m_abiMembers.at(_funCall);

}