#ifndef SASS_EXTEND_H

#define SASS_EXTEND_H

#include <string>

#include <set>

#include "ast.hpp"

#include "node.hpp"

#include "operation.hpp"

#include "subset_map.hpp"

#include "ast_fwd_decl.hpp"

namespace Sass {

  Node subweave(Node& one, Node& two);

  class Extend : public Operation_CRTP<void, Extend> {

    Subset_Map& subset_map;

    void fallback_impl(AST_Node_Ptr n) { }

  private:

    std::unordered_map<

      Selector_List_Obj, // key

      Selector_List_Obj, // value

      HashNodes, // hasher

      CompareNodes // compare

    > memoizeList;

    std::unordered_map<

      Complex_Selector_Obj, // key

      Node, // value

      HashNodes, // hasher

      CompareNodes // compare

    > memoizeComplex;

    /* this turned out to be too much overhead

       re-evaluate once we store an ast selector

    std::unordered_map<

      Compound_Selector_Obj, // key

      Node, // value

      HashNodes, // hasher

      CompareNodes // compare

    > memoizeCompound;

    */

    void extendObjectWithSelectorAndBlock(Ruleset_Ptr pObject);

    Node extendComplexSelector(Complex_Selector_Ptr sel, CompoundSelectorSet& seen, bool isReplace, bool isOriginal);

    Node extendCompoundSelector(Compound_Selector_Ptr sel, CompoundSelectorSet& seen, bool isReplace);

    bool complexSelectorHasExtension(Complex_Selector_Ptr selector, CompoundSelectorSet& seen);

    Node trim(Node& seqses, bool isReplace);

    Node weave(Node& path);

  public:

    Selector_List_Ptr extendSelectorList(Selector_List_Obj pSelectorList, bool isReplace, bool& extendedSomething, CompoundSelectorSet& seen);

    Selector_List_Ptr extendSelectorList(Selector_List_Obj pSelectorList, bool isReplace = false) {

      bool extendedSomething = false;

      CompoundSelectorSet seen;

      return extendSelectorList(pSelectorList, isReplace, extendedSomething, seen);

    }

    Selector_List_Ptr extendSelectorList(Selector_List_Obj pSelectorList, CompoundSelectorSet& seen) {

      bool isReplace = false;

      bool extendedSomething = false;

      return extendSelectorList(pSelectorList, isReplace, extendedSomething, seen);

    }

    Extend(Subset_Map&);

    ~Extend() { }

    void operator()(Block_Ptr);

    void operator()(Ruleset_Ptr);

    void operator()(Supports_Block_Ptr);

    void operator()(Media_Block_Ptr);

    void operator()(Directive_Ptr);

    template <typename U>

    void fallback(U x) { return fallback_impl(x); }

  };

}

#endif