/*

  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 <libyul/optimiser/VarNameCleaner.h>

#include <libyul/optimiser/OptimizerUtilities.h>

#include <libyul/AST.h>

#include <libyul/Dialect.h>

#include <algorithm>

#include <cctype>

#include <climits>

#include <iterator>

#include <string>

#include <regex>

#include <limits>

using namespace std;

using namespace solidity::yul;

VarNameCleaner::VarNameCleaner(

  Block const& _ast,

  Dialect const& _dialect,

  set<YulString> _namesToKeep

):

  m_dialect{_dialect},

  m_namesToKeep{std::move(_namesToKeep)},

  m_translatedNames{}

{

  for (auto const& statement: _ast.statements)

    if (holds_alternative<FunctionDefinition>(statement))

      m_namesToKeep.insert(std::get<FunctionDefinition>(statement).name);

  m_usedNames = m_namesToKeep;

}

void VarNameCleaner::operator()(FunctionDefinition& _funDef)

{

  yulAssert(!m_insideFunction, "");

  m_insideFunction = true;

  set<YulString> globalUsedNames = std::move(m_usedNames);

  m_usedNames = m_namesToKeep;

  map<YulString, YulString> globalTranslatedNames;

  swap(globalTranslatedNames, m_translatedNames);

  renameVariables(_funDef.parameters);

  renameVariables(_funDef.returnVariables);

  ASTModifier::operator()(_funDef);

  swap(globalUsedNames, m_usedNames);

  swap(globalTranslatedNames, m_translatedNames);

  m_insideFunction = false;

}

void VarNameCleaner::operator()(VariableDeclaration& _varDecl)

{

  renameVariables(_varDecl.variables);

  ASTModifier::operator()(_varDecl);

}

void VarNameCleaner::renameVariables(vector<TypedName>& _variables)

{

  for (TypedName& typedName: _variables)

  {

    auto newName = findCleanName(typedName.name);

    if (newName != typedName.name)

    {

      m_translatedNames[typedName.name] = newName;

      typedName.name = newName;

    }

    m_usedNames.insert(typedName.name);

  }

}

void VarNameCleaner::operator()(Identifier& _identifier)

{

  auto name = m_translatedNames.find(_identifier.name);

  if (name != m_translatedNames.end())

    _identifier.name = name->second;

}

YulString VarNameCleaner::findCleanName(YulString const& _name) const

{

  auto newName = stripSuffix(_name);

  if (!isUsedName(newName))

    return newName;

  // create new name with suffix (by finding a free identifier)

  for (size_t i = 1; i < numeric_limits<decltype(i)>::max(); ++i)

  {

    YulString newNameSuffixed = YulString{newName.str() + "_" + to_string(i)};

    if (!isUsedName(newNameSuffixed))

      return newNameSuffixed;

  }

  yulAssert(false, "Exhausted by attempting to find an available suffix.");

}

bool VarNameCleaner::isUsedName(YulString const& _name) const

{

  return isRestrictedIdentifier(m_dialect, _name) || m_usedNames.count(_name);

}

YulString VarNameCleaner::stripSuffix(YulString const& _name) const

{

  static regex const suffixRegex("(_+[0-9]+)+$");

  smatch suffixMatch;

  if (regex_search(_name.str(), suffixMatch, suffixRegex))

    return {YulString{suffixMatch.prefix().str()}};

  return _name;

}