#ifndef SASS_EVAL_H

#define SASS_EVAL_H

#include "ast.hpp"

#include "context.hpp"

#include "listize.hpp"

#include "operation.hpp"

#include "environment.hpp"

namespace Sass {

  class Expand;

  class Context;

  class Eval : public Operation_CRTP<Expression_Ptr, Eval> {

   private:

    Expression_Ptr fallback_impl(AST_Node_Ptr n);

   public:

    Expand&  exp;

    Context& ctx;

    Eval(Expand& exp);

    ~Eval();

    bool force;

    bool is_in_comment;

    bool is_in_selector_schema;

    Boolean_Obj bool_true;

    Boolean_Obj bool_false;

    Env* environment();

    Backtrace* backtrace();

    Selector_List_Obj selector();

    // for evaluating function bodies

    Expression_Ptr operator()(Block_Ptr);

    Expression_Ptr operator()(Assignment_Ptr);

    Expression_Ptr operator()(If_Ptr);

    Expression_Ptr operator()(For_Ptr);

    Expression_Ptr operator()(Each_Ptr);

    Expression_Ptr operator()(While_Ptr);

    Expression_Ptr operator()(Return_Ptr);

    Expression_Ptr operator()(Warning_Ptr);

    Expression_Ptr operator()(Error_Ptr);

    Expression_Ptr operator()(Debug_Ptr);

    Expression_Ptr operator()(List_Ptr);

    Expression_Ptr operator()(Map_Ptr);

    Expression_Ptr operator()(Binary_Expression_Ptr);

    Expression_Ptr operator()(Unary_Expression_Ptr);

    Expression_Ptr operator()(Function_Call_Ptr);

    Expression_Ptr operator()(Function_Call_Schema_Ptr);

    Expression_Ptr operator()(Variable_Ptr);

    Expression_Ptr operator()(Number_Ptr);

    Expression_Ptr operator()(Color_Ptr);

    Expression_Ptr operator()(Boolean_Ptr);

    Expression_Ptr operator()(String_Schema_Ptr);

    Expression_Ptr operator()(String_Quoted_Ptr);

    Expression_Ptr operator()(String_Constant_Ptr);

    // Expression_Ptr operator()(Selector_List_Ptr);

    Media_Query_Ptr operator()(Media_Query_Ptr);

    Expression_Ptr operator()(Media_Query_Expression_Ptr);

    Expression_Ptr operator()(At_Root_Query_Ptr);

    Expression_Ptr operator()(Supports_Operator_Ptr);

    Expression_Ptr operator()(Supports_Negation_Ptr);

    Expression_Ptr operator()(Supports_Declaration_Ptr);

    Expression_Ptr operator()(Supports_Interpolation_Ptr);

    Expression_Ptr operator()(Null_Ptr);

    Expression_Ptr operator()(Argument_Ptr);

    Expression_Ptr operator()(Arguments_Ptr);

    Expression_Ptr operator()(Comment_Ptr);

    // these will return selectors

    Selector_List_Ptr operator()(Selector_List_Ptr);

    Selector_List_Ptr operator()(Complex_Selector_Ptr);

    Attribute_Selector_Ptr operator()(Attribute_Selector_Ptr);

    // they don't have any specific implementatio (yet)

    Element_Selector_Ptr operator()(Element_Selector_Ptr s) { return s; };

    Pseudo_Selector_Ptr operator()(Pseudo_Selector_Ptr s) { return s; };

    Wrapped_Selector_Ptr operator()(Wrapped_Selector_Ptr s) { return s; };

    Class_Selector_Ptr operator()(Class_Selector_Ptr s) { return s; };

    Id_Selector_Ptr operator()(Id_Selector_Ptr s) { return s; };

    Placeholder_Selector_Ptr operator()(Placeholder_Selector_Ptr s) { return s; };

    // actual evaluated selectors

    Selector_List_Ptr operator()(Selector_Schema_Ptr);

    Expression_Ptr operator()(Parent_Selector_Ptr);

    template <typename U>

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

    // -- only need to define two comparisons, and the rest can be implemented in terms of them

    static bool eq(Expression_Obj, Expression_Obj);

    static bool lt(Expression_Obj, Expression_Obj, std::string op);

    // -- arithmetic on the combinations that matter

    static Value_Ptr op_numbers(enum Sass_OP, const Number&, const Number&, struct Sass_Inspect_Options opt, const ParserState& pstate);

    static Value_Ptr op_number_color(enum Sass_OP, const Number&, const Color&, struct Sass_Inspect_Options opt, const ParserState& pstate);

    static Value_Ptr op_color_number(enum Sass_OP, const Color&, const Number&, struct Sass_Inspect_Options opt, const ParserState& pstate);

    static Value_Ptr op_colors(enum Sass_OP, const Color&, const Color&, struct Sass_Inspect_Options opt, const ParserState& pstate);

    static Value_Ptr op_strings(Sass::Operand, Value&, Value&, struct Sass_Inspect_Options opt, const ParserState& pstate, bool interpolant = false);

  private:

    void interpolation(Context& ctx, std::string& res, Expression_Obj ex, bool into_quotes, bool was_itpl = false);

  };

  Expression_Ptr cval_to_astnode(union Sass_Value* v, Backtrace* backtrace, ParserState pstate = ParserState("[AST]"));

}

#endif