#include <list>
#include <vector>
#include <cassert>
#include <algorithm>

#include "FunctionFixer.h"
#include "SynTree/Expression.h"
#include "SynTree/Declaration.h"
#include "SynTree/Type.h"

namespace ArgTweak {


  FunctionFixer::FunctionFixer( SymTab::Indexer *ind ) : index( ind )
  {
    if ( index == 0 ) index = new SymTab::Indexer();
  }

  FunctionFixer::~FunctionFixer()
  {
    delete index;
  }

  DeclarationWithType *FunctionFixer::mutate( FunctionDecl *functionDecl )
  {
    index->visit( functionDecl );
    /* check for duplicate named parameters here?  It might not be an
    error if they're never used, on the other hand, it might be to
    costly to check for duplicates every time we try a match */
    return Parent::mutate( functionDecl );
  }

  Expression *FunctionFixer::mutate( UntypedExpr *untypedExpr )
    throw ( SemanticError )
  {
    assert( untypedExpr != 0 );
    NameExpr *function;

    if ( ( function = dynamic_cast< NameExpr *>(untypedExpr->get_function()) ) != 0 )
      {
	std::list < DeclarationWithType * > options;
	index->lookupId ( function->get_name(), options );
 	for ( std::list < DeclarationWithType * >::iterator i = options.begin(); i != options.end(); i++ )
 	  {
 	    FunctionType *f;
 	    if ( ( f = dynamic_cast< FunctionType * > ( (*i)->get_type() ) ) != 0 )
 	      {
 		std::list < DeclarationWithType * > &pars = f->get_parameters();

 		bool candidateExists ;
 		for( std::list < DeclarationWithType * >::iterator p = pars.begin(); p != pars.end(); p++ )
 		  if ( ( candidateExists = align( f->get_parameters(), untypedExpr->get_args(), Matcher() ) ) ) break;

 		if ( !candidateExists ) throw SemanticError("Error in function call");
 	      }
 	  }
      }
    return untypedExpr;
  }

  template < class L1, class L2, class Helper >
  bool align( L1 &pattern, L2 &possible_permutation, Helper help )
  {
    std::map < typename Helper::key, int > positions;
    int p = 0;

    for ( typename L1::iterator i = pattern.begin(); i != pattern.end(); i++, p++ )
      if ( help.extract_key( *i ) != Helper::null_key )
	positions[ help.extract_key( *i ) ] = p;

    L2 copy_pp( possible_permutation );

    std::vector< typename L2::value_type > temp(copy_pp.size(), Helper::null_value );
    for ( typename L2::iterator i = copy_pp.begin(); i != copy_pp.end(); i++ )
      if ( positions.find( help.extract_key( *i ) ) != positions.end() ) {
	temp [ positions [ help.extract_key( *i ) ] ] = *i;
	*i = Helper::null_value;
      }

    // rest of the arguments
    int a = 0;
    bool goAhead = true;  // go ahead and change the list
    for ( typename L2::iterator i = copy_pp.begin(); i != copy_pp.end(); i++, a++ ) {
      if (  *i != Helper::null_value )
	if ( temp[a] == Helper::null_value )
	  temp[a] = *i;
	else
	  { goAhead = false; /* there's something there already */; break; }
      else
	if ( temp[a] == Helper::null_value )
	  { goAhead = false; /* can't leave empty spaces */ break; }
	else
	  ; // all good, this was filled during the first pass
      assert ( temp[a] != Helper::null_value );
    }

    // Change the original list
    if ( goAhead ) std::copy( temp.begin(), temp.end(), possible_permutation.begin() );

    return goAhead;
  }

  std::string FunctionFixer::Matcher::null_key("");
  Expression *FunctionFixer::Matcher::null_value = 0;

  std::string FunctionFixer::Matcher::extract_key ( DeclarationWithType *decl ) {
    return decl->get_name();
  }

  std::string FunctionFixer::Matcher::extract_key ( Expression *expression ) {
    if ( expression->get_argName() == 0 )
      return std::string("");
    else
      return *(expression->get_argName());
  }

} // namespace ArgTweak