/*

  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/ConditionalSimplifier.h>

#include <libyul/optimiser/Semantics.h>

#include <libyul/AST.h>

#include <libyul/optimiser/NameCollector.h>

#include <libyul/ControlFlowSideEffectsCollector.h>

#include <libsolutil/CommonData.h>

using namespace solidity;

using namespace solidity::yul;

using namespace solidity::util;

void ConditionalSimplifier::run(OptimiserStepContext& _context, Block& _ast)

{

  ConditionalSimplifier{

    _context.dialect,

    ControlFlowSideEffectsCollector{_context.dialect, _ast}.functionSideEffectsNamed()

  }(_ast);

}

void ConditionalSimplifier::operator()(Switch& _switch)

{

  visit(*_switch.expression);

  if (!std::holds_alternative<Identifier>(*_switch.expression))

  {

    ASTModifier::operator()(_switch);

    return;

  }

  YulName expr = std::get<Identifier>(*_switch.expression).name;

  for (auto& _case: _switch.cases)

  {

    if (_case.value)

    {

      (*this)(*_case.value);

      _case.body.statements.insert(_case.body.statements.begin(),

        Assignment{

          _case.body.debugData,

          {Identifier{_case.body.debugData, expr}},

          std::make_unique<Expression>(*_case.value)

        }

      );

    }

    (*this)(_case.body);

  }

}

void ConditionalSimplifier::operator()(Block& _block)

{

  iterateReplacing(

    _block.statements,

    [&](Statement& _s) -> std::optional<std::vector<Statement>>

    {

      visit(_s);

      if (std::holds_alternative<If>(_s))

      {

        If& _if = std::get<If>(_s);

        if (

          std::holds_alternative<Identifier>(*_if.condition) &&

          !_if.body.statements.empty() &&

          TerminationFinder(m_dialect, &m_functionSideEffects).controlFlowKind(_if.body.statements.back()) !=

            TerminationFinder::ControlFlow::FlowOut

        )

        {

          YulName condition = std::get<Identifier>(*_if.condition).name;

          langutil::DebugData::ConstPtr debugData = _if.debugData;

          return make_vector<Statement>(

            std::move(_s),

            Assignment{

              debugData,

              {Identifier{debugData, condition}},

              std::make_unique<Expression>(m_dialect.zeroLiteral())

            }

          );

        }

      }

      return {};

    }

  );

}