#include "ResolvExpr/AlternativeFinder.h"
#include "ResolvExpr/Alternative.h"
#include "ResolvExpr/typeops.h"
#include "SynTree/Expression.h"
#include "TupleAssignment.h"
#include "SemanticError.h"

#include <functional>
#include <algorithm>
#include <iterator>
#include <iostream>
#include <cassert>
#include <set>

namespace Tuples {
  TupleAssignSpotter::TupleAssignSpotter( ResolvExpr::AlternativeFinder *f = 0 )
    : currentFinder(f), matcher(0), hasMatched( false ) {}

  bool TupleAssignSpotter::pointsToTuple( Expression *expr ) {
    // also check for function returning tuple of reference types
    if(AddressExpr *addr = dynamic_cast<AddressExpr *>(expr) )
      if( isTuple(addr->get_arg() ) )
	return true;
    return false;
  }

  bool TupleAssignSpotter::isTupleVar( DeclarationWithType *decl ) {
    if( dynamic_cast<TupleType *>(decl->get_type()) )
      return true;
    return false;
  }

  bool TupleAssignSpotter::isTuple( Expression *expr, bool isRight ) {
    // true if `expr' is an expression returning a tuple: tuple, tuple variable or MRV function
    if ( !expr ) return false;

    if( dynamic_cast<TupleExpr *>(expr) )
      return true;
    else if( VariableExpr *var = dynamic_cast<VariableExpr *>(expr) ) {
      if( isTupleVar(var->get_var()) )
	return true;
    }

    return false;
  }

  bool TupleAssignSpotter::match() {
    assert ( matcher != 0 );

    std::list< Expression * > new_assigns;
    if (! matcher->match(new_assigns) )
      return false;

    if( new_assigns.empty() ) return false;
    /*return */matcher->solve( new_assigns );
    if( dynamic_cast<TupleAssignSpotter::MultipleAssignMatcher *>( matcher ) ) {
      // now resolve new assignments
      std::list< Expression * > solved_assigns;
      ResolvExpr::AltList solved_alts;
      assert( currentFinder != 0 );

      ResolvExpr::AltList current;
      for( std::list< Expression * >::iterator i = new_assigns.begin(); i != new_assigns.end(); ++i ) {
	//try {
	ResolvExpr::AlternativeFinder finder( currentFinder->get_indexer(), currentFinder->get_environ() );
	finder.findWithAdjustment(*i);
	// prune expressions that don't coincide with
	ResolvExpr::AltList alts = finder.get_alternatives();
	assert( alts.size() == 1 );
	assert(alts.front().expr != 0 );
	current.push_back( finder.get_alternatives().front() );
	solved_assigns.push_back( alts.front().expr->clone() );
	//solved_assigns.back()->print(std::cerr);
	/*} catch( ... ) {
	  continue; // no reasonable alternative found
	  }*/
      }
      options.add_option( current );

      return true;
    } else { // mass assignment
      //if( new_assigns.empty() ) return false;
      std::list< Expression * > solved_assigns;
      ResolvExpr::AltList solved_alts;
      assert( currentFinder != 0 );

      ResolvExpr::AltList current;
      if ( optMass.empty() ) {
	for( std::list< Expression * >::size_type i = 0; i != new_assigns.size(); ++i )
	  optMass.push_back( ResolvExpr::AltList() );
      }
      int cnt = 0;
      for( std::list< Expression * >::iterator i = new_assigns.begin(); i != new_assigns.end(); ++i, cnt++ ) {

	ResolvExpr::AlternativeFinder finder( currentFinder->get_indexer(), currentFinder->get_environ() );
	finder.findWithAdjustment(*i);
	ResolvExpr::AltList alts = finder.get_alternatives();
	assert( alts.size() == 1 );
	assert(alts.front().expr != 0 );
	current.push_back( finder.get_alternatives().front() );
	optMass[cnt].push_back( finder.get_alternatives().front() );
	solved_assigns.push_back( alts.front().expr->clone() );
      }

      return true;
    }

    return false;
  }

  bool TupleAssignSpotter::isMVR( Expression *expr ) {
    if( expr->get_results().size() > 1 ) {
      // MVR processing
      return true;
    }
    return false;
  }

  bool TupleAssignSpotter::isTupleAssignment( UntypedExpr * expr, std::list<ResolvExpr::AltList> &possibilities ) {
    if(  NameExpr *assgnop = dynamic_cast< NameExpr * >(expr->get_function()) ) {

      if( assgnop->get_name() == std::string("?=?") ) {

	for( std::list<ResolvExpr::AltList>::iterator ali = possibilities.begin(); ali != possibilities.end(); ++ali ) {
	  assert( ali->size() == 2 );
	  ResolvExpr::AltList::iterator opit = ali->begin();
	  ResolvExpr::Alternative op1 = *opit, op2 = *(++opit);

	  if( pointsToTuple(op1.expr) ) { // also handles tuple vars
	    if ( isTuple( op2.expr, true ) )
	      matcher = new MultipleAssignMatcher(op1.expr, op2.expr);
	    else if( isMVR( op2.expr ) ) {
	      // handle MVR differently
	    } else
	      // mass assignment
	      matcher = new MassAssignMatcher(op1.expr, op2.expr);

	    std::list< ResolvExpr::AltList > options;
	    if( match() )
	      /*
	      if( hasMatched ) {
		// throw SemanticError("Ambiguous tuple assignment");
	      } else {*/
		// Matched for the first time
		hasMatched = true;
		/*} */
	  } /* else if ( isTuple( op2 ) )
	    throw SemanticError("Inapplicable tuple assignment.");
	    */
	}

	if( hasMatched ) {
	  if( dynamic_cast<TupleAssignSpotter::MultipleAssignMatcher *>( matcher ) ) {
	    //options.print( std::cerr );
	    std::list< ResolvExpr::AltList >best = options.get_best();
	    if( best.size() == 1 ) {
	      std::list<Expression *> solved_assigns;
	      for( ResolvExpr::AltList::iterator i = best.front().begin(); i != best.front().end(); ++i ){
		solved_assigns.push_back( i->expr );
	      }
	      /* assigning cost zero? */
	      currentFinder->get_alternatives().push_front( ResolvExpr::Alternative(new SolvedTupleExpr(solved_assigns/*, SolvedTupleExpr::MULTIPLE*/), currentFinder->get_environ(), ResolvExpr::Cost() ) );
	    }
	  } else {
	    assert(! optMass.empty() );
	    ResolvExpr::AltList winners;
	    for( std::vector< ResolvExpr::AltList >::iterator i = optMass.begin(); i != optMass.end(); ++i )
	      findMinCostAlt( i->begin(), i->end(), back_inserter(winners) );

	    std::list< Expression *> solved_assigns;
	    for( ResolvExpr::AltList::iterator i = winners.begin(); i != winners.end(); ++i )
	      solved_assigns.push_back( i->expr );
	    currentFinder->get_alternatives().push_front( ResolvExpr::Alternative(new SolvedTupleExpr(solved_assigns/*, SolvedTupleExpr::MASS*/), currentFinder->get_environ(), ResolvExpr::Cost() ) );
	  }
	}
      }
    }
    return hasMatched;
  }

  void TupleAssignSpotter::Matcher::init( Expression *_lhs, Expression *_rhs ) {
    lhs.clear();
    if(AddressExpr *addr = dynamic_cast<AddressExpr *>(_lhs) )
      if( TupleExpr *tuple = dynamic_cast<TupleExpr *>(addr->get_arg()) )
	std::copy( tuple->get_exprs().begin(), tuple->get_exprs().end(), back_inserter(lhs) );

    rhs.clear();
  }

  TupleAssignSpotter::Matcher::Matcher( /*TupleAssignSpotter &spot,*/ Expression *_lhs, Expression *_rhs ) /*: own_spotter(spot) */{
    init(_lhs,_rhs);
  }

  TupleAssignSpotter::MultipleAssignMatcher::MultipleAssignMatcher( Expression *_lhs, Expression *_rhs )/* : own_spotter(spot) */{
    init(_lhs,_rhs);

    if( TupleExpr *tuple = dynamic_cast<TupleExpr *>(_rhs) )
      std::copy( tuple->get_exprs().begin(), tuple->get_exprs().end(), back_inserter(rhs) );
  }

  UntypedExpr *TupleAssignSpotter::Matcher::createAssgn( Expression *left, Expression *right ) {
    if ( left && right ) {
      std::list< Expression * > args;
      args.push_back(new AddressExpr(left->clone()));  args.push_back(right->clone());
      return new UntypedExpr(new NameExpr("?=?"), args);
    } else
      throw 0; // xxx - diagnose the problem
  }

  bool TupleAssignSpotter::MassAssignMatcher::match( std::list< Expression * > &out ) {
    if ( lhs.empty() || (rhs.size() != 1) ) return false;

    for( std::list< Expression * >::iterator l = lhs.begin(); l != lhs.end(); l++ ) {
      std::list< Expression * > args;
      args.push_back( new AddressExpr(*l) );
      args.push_back( rhs.front() );
      out.push_back( new UntypedExpr(new NameExpr("?=?"), args) );
    }

    return true;
  }

  bool TupleAssignSpotter::MassAssignMatcher::solve( std::list< Expression * > &assigns ) {
    /*
    std::list< Expression * > solved_assigns;
    ResolvExpr::AltList solved_alts;
    assert( currentFinder != 0 );

    ResolvExpr::AltList current;
    if ( optMass.empty() ) {
      for( std::list< Expression * >::size_type i = 0; i != new_assigns.size(); ++i )
	optMass.push_back( ResolvExpr::AltList() );
    }
    int cnt = 0;
    for( std::list< Expression * >::iterator i = new_assigns.begin(); i != new_assigns.end(); ++i, cnt++ ) {

      ResolvExpr::AlternativeFinder finder( currentFinder->get_indexer(), currentFinder->get_environ() );
      finder.findWithAdjustment(*i);
      ResolvExpr::AltList alts = finder.get_alternatives();
      assert( alts.size() == 1 );
      assert(alts.front().expr != 0 );
      current.push_back( finder.get_alternatives().front() );
      optMass[cnt].push_back( finder.get_alternatives().front() );
      solved_assigns.push_back( alts.front().expr->clone() );
    }
    */
    return true;
  }

  bool TupleAssignSpotter::MultipleAssignMatcher::match( std::list< Expression * > &out ) {
    // need more complicated matching
    if( lhs.size() == rhs.size() ) {
      zipWith( lhs.begin(), lhs.end(), rhs.begin(), rhs.end(), back_inserter(out), TupleAssignSpotter::Matcher::createAssgn );
      return true;
    } //else
    //std::cerr << "The length of (left, right) is: (" << lhs.size() << "," << rhs.size() << ")" << std::endl;*/
    return false;
  }

  bool TupleAssignSpotter::MultipleAssignMatcher::solve( std::list< Expression * > &assigns ) {
    /*
    std::list< Expression * > solved_assigns;
    ResolvExpr::AltList solved_alts;
    assert( currentFinder != 0 );

    ResolvExpr::AltList current;
    for( std::list< Expression * >::iterator i = new_assigns.begin(); i != new_assigns.end(); ++i ) {
      //try {
      ResolvExpr::AlternativeFinder finder( currentFinder->get_indexer(), currentFinder->get_environ() );
      finder.findWithAdjustment(*i);
      // prune expressions that don't coincide with
      ResolvExpr::AltList alts = finder.get_alternatives();
      assert( alts.size() == 1 );
      assert(alts.front().expr != 0 );
      current.push_back( finder.get_alternatives().front() );
      solved_assigns.push_back( alts.front().expr->clone() );
      //solved_assigns.back()->print(std::cerr);
      //} catch( ... ) {
      //continue; // no reasonable alternative found
      //}
    }
    options.add_option( current );
    */

    return true;
  }

  void TupleAssignSpotter::Options::add_option( ResolvExpr::AltList &opt ) {
    using namespace std;

    options.push_back( opt );
    /*
      vector< Cost > costs;
      costs.reserve( opt.size() );
      transform( opt.begin(), opt.end(), back_inserter(costs), ptr_fun(extract_cost) );
    */
    // transpose matrix
    if ( costMatrix.empty() )
      for( unsigned int i = 0; i< opt.size(); ++i)
	costMatrix.push_back( vector<ResolvExpr::Cost>() );

    int cnt = 0;
    for( ResolvExpr::AltList::iterator i = opt.begin(); i != opt.end(); ++i, cnt++ )
      costMatrix[cnt].push_back( i->cost );

    return;
  }

  std::list< ResolvExpr::AltList > TupleAssignSpotter::Options::get_best() {
    using namespace std;
    using namespace ResolvExpr;
    list< ResolvExpr::AltList > ret;
    list< multiset<int> > solns;
    for( vector< vector<Cost> >::iterator i = costMatrix.begin(); i != costMatrix.end(); ++i ) {
      list<int> current;
      findMinCost( i->begin(), i->end(), back_inserter(current) );
      solns.push_back( multiset<int>(current.begin(), current.end()) );
    }
    // need to combine
    multiset<int> result;
    lift_intersection( solns.begin(), solns.end(), inserter( result, result.begin() ) );
    if( result.size() != 1 )
      throw SemanticError("Ambiguous tuple expression");
    ret.push_back(get_option( *(result.begin() )));
    return ret;
  }

  void TupleAssignSpotter::Options::print( std::ostream &ostr ) {
    using namespace std;

    for( vector< vector < ResolvExpr::Cost > >::iterator i = costMatrix.begin(); i != costMatrix.end(); ++i ) {
      for( vector < ResolvExpr::Cost >::iterator j = i->begin(); j != i->end(); ++j )
	ostr << *j << " " ;
      ostr << std::endl;
    }
    
    return;
  }

  ResolvExpr::Cost extract_cost( ResolvExpr::Alternative &alt ) {
    return alt.cost;
  }

  template< typename InputIterator, typename OutputIterator >
  void
  TupleAssignSpotter::Options::findMinCost( InputIterator begin, InputIterator end, OutputIterator out )
  {
    using namespace ResolvExpr;
    std::list<int> alternatives;

    // select the alternatives that have the minimum parameter cost
    Cost minCost = Cost::infinity;
    unsigned int index = 0;
    for( InputIterator i = begin; i != end; ++i, index++ ) {
      if( *i < minCost ) {
        minCost = *i;
        alternatives.clear();
        alternatives.push_back( index );
      } else if( *i == minCost ) {
        alternatives.push_back( index );
      }
    }
    std::copy( alternatives.begin(), alternatives.end(), out );
  }

  template< class InputIterator, class OutputIterator >
  void TupleAssignSpotter::Options::lift_intersection( InputIterator begin, InputIterator end, OutputIterator out ){
    if( begin == end ) return;
    InputIterator test = begin;

    if(++test == end)
      { copy(begin->begin(), begin->end(), out); return; }


    std::multiset<int> cur; // InputIterator::value_type::value_type
    copy( begin->begin(), begin->end(), inserter( cur, cur.begin() ) );

    while( test != end ) {
      std::multiset<int> temp;
      set_intersection( cur.begin(), cur.end(), test->begin(), test->end(), inserter(temp,temp.begin()) );
      cur.clear();
      copy( temp.begin(), temp.end(), inserter(cur,cur.begin()));
      ++test;
    }

    copy( cur.begin(), cur.end(), out );
    return;
  }


  ResolvExpr::AltList TupleAssignSpotter::Options::get_option( std::list< ResolvExpr::AltList >::size_type index ) {
    if( index >= options.size() )
      throw 0; // XXX
    std::list< ResolvExpr::AltList >::iterator it = options.begin();
    for( std::list< ResolvExpr::AltList >::size_type i = 0; i < index; ++i, ++it );
    return *it;
  }


} // namespace Tuples