/*********************                                                        */
/*! \file ite_removal.cpp
 ** \verbatim
 ** Original author: Dejan Jovanovic
 ** Major contributors: Andrew Reynolds, Morgan Deters
 ** Minor contributors (to current version): Clark Barrett
 ** This file is part of the CVC4 project.
 ** Copyright (c) 2009-2013  New York University and The University of Iowa
 ** See the file COPYING in the top-level source directory for licensing
 ** information.\endverbatim
 **
 ** \brief Removal of term ITEs
 **
 ** Removal of term ITEs.
 **/

#include <vector>

#include "util/ite_removal.h"
#include "theory/rewriter.h"
#include "expr/command.h"
#include "theory/quantifiers/options.h"

using namespace CVC4;
using namespace std;

namespace CVC4 {

void RemoveITE::run(std::vector<Node>& output, IteSkolemMap& iteSkolemMap)
{
  for (unsigned i = 0, i_end = output.size(); i < i_end; ++ i) {
    std::vector<Node> quantVar;
    output[i] = run(output[i], output, iteSkolemMap, quantVar);
  }
}

Node RemoveITE::run(TNode node, std::vector<Node>& output,
                    IteSkolemMap& iteSkolemMap, std::vector<Node>& quantVar) {
  // Current node
  Debug("ite") << "removeITEs(" << node << ")" << endl;

  // The result may be cached already
  NodeManager *nodeManager = NodeManager::currentNM();
  ITECache::iterator i = d_iteCache.find(node);
  if(i != d_iteCache.end()) {
    Node cachedRewrite = (*i).second;
    Debug("ite") << "removeITEs: in-cache: " << cachedRewrite << endl;
    return cachedRewrite.isNull() ? Node(node) : cachedRewrite;
  }

  // If an ITE replace it
  if(node.getKind() == kind::ITE) {
    TypeNode nodeType = node.getType();
    if(!nodeType.isBoolean()) {
      Node skolem;
      // Make the skolem to represent the ITE
      if( quantVar.empty() ){
        skolem = nodeManager->mkSkolem("termITE_$$", nodeType, "a variable introduced due to term-level ITE removal");
      }else{
        //if in the scope of free variables, make a skolem operator
        vector< TypeNode > argTypes;
        for( size_t i=0; i<quantVar.size(); i++ ){
          argTypes.push_back( quantVar[i].getType() );
        }
        TypeNode typ = NodeManager::currentNM()->mkFunctionType( argTypes, nodeType );
        Node op = NodeManager::currentNM()->mkSkolem( "termITEop_$$", typ, "a function variable introduced due to term-level ITE removal" );
        vector< Node > funcArgs;
        funcArgs.push_back( op );
        funcArgs.insert( funcArgs.end(), quantVar.begin(), quantVar.end() );
        skolem = NodeManager::currentNM()->mkNode( kind::APPLY_UF, funcArgs );
      }

      // The new assertion
      Node newAssertion =
        nodeManager->mkNode(kind::ITE, node[0], skolem.eqNode(node[1]),
                            skolem.eqNode(node[2]));
      Debug("ite") << "removeITEs(" << node << ") => " << newAssertion << endl;

      // Attach the skolem
      d_iteCache[node] = skolem;

      // Remove ITEs from the new assertion, rewrite it and push it to the output
      newAssertion = run(newAssertion, output, iteSkolemMap, quantVar);

      if( !quantVar.empty() ){
        //if in the scope of free variables, it is a quantified assertion
        vector< Node > children;
        children.push_back( NodeManager::currentNM()->mkNode( kind::BOUND_VAR_LIST, quantVar ) );
        children.push_back( newAssertion );
        newAssertion = NodeManager::currentNM()->mkNode( kind::FORALL, children );
      }

      iteSkolemMap[skolem] = output.size();
      output.push_back(newAssertion);

      // The representation is now the skolem
      return skolem;
    }
  }

  // If not an ITE, go deep
  if( ( node.getKind() != kind::FORALL || options::iteRemoveQuant() ) &&
      node.getKind() != kind::EXISTS &&
      node.getKind() != kind::REWRITE_RULE ) {
    std::vector< Node > newQuantVar;
    newQuantVar.insert( newQuantVar.end(), quantVar.begin(), quantVar.end() );
    if( node.getKind()==kind::FORALL ){
      for( size_t i=0; i<node[0].getNumChildren(); i++ ){
        newQuantVar.push_back( node[0][i] );
      }
    }
    vector<Node> newChildren;
    bool somethingChanged = false;
    if(node.getMetaKind() == kind::metakind::PARAMETERIZED) {
      newChildren.push_back(node.getOperator());
    }
    // Remove the ITEs from the children
    for(TNode::const_iterator it = node.begin(), end = node.end(); it != end; ++it) {
      Node newChild = run(*it, output, iteSkolemMap, newQuantVar);
      somethingChanged |= (newChild != *it);
      newChildren.push_back(newChild);
    }

    // If changes, we rewrite
    if(somethingChanged) {
      Node cachedRewrite = nodeManager->mkNode(node.getKind(), newChildren);
      d_iteCache[node] = cachedRewrite;
      return cachedRewrite;
    } else {
      d_iteCache[node] = Node::null();
      return node;
    }
  } else {
    d_iteCache[node] = Node::null();
    return node;
  }
}

}/* CVC4 namespace */