#ifdef GEN_INTELLISENSE_DIRECTIVES
#pragma once
#include "types.hpp"
#include "gen/ecode.hpp"
#include "gen/eoperator.hpp"
#include "gen/especifier.hpp"
#endif

struct AST;
struct AST_Body;
struct AST_Attributes;
struct AST_Comment;
struct AST_Constructor;
// struct AST_BaseClass;
struct AST_Class;
struct AST_Define;
struct AST_Destructor;
struct AST_Enum;
struct AST_Exec;
struct AST_Extern;
struct AST_Include;
struct AST_Friend;
struct AST_Fn;
struct AST_Module;
struct AST_NS;
struct AST_Operator;
struct AST_OpCast;
struct AST_Param;
struct AST_Pragma;
struct AST_PreprocessCond;
struct AST_Specifiers;

#if GEN_EXECUTION_EXPRESSION_SUPPORT
struct AST_Expr;
struct AST_Expr_Assign;
struct AST_Expr_Alignof;
struct AST_Expr_Binary;
struct AST_Expr_CStyleCast;
struct AST_Expr_FunctionalCast;
struct AST_Expr_CppCast;
struct AST_Expr_ProcCall;
struct AST_Expr_Decltype;
struct AST_Expr_Comma;  // TODO(Ed) : This is a binary op not sure if it needs its own AST...
struct AST_Expr_AMS;    // Access Member Symbol
struct AST_Expr_Sizeof;
struct AST_Expr_Subscript;
struct AST_Expr_Ternary;
struct AST_Expr_UnaryPrefix;
struct AST_Expr_UnaryPostfix;
struct AST_Expr_Element;

struct AST_Stmt;
struct AST_Stmt_Break;
struct AST_Stmt_Case;
struct AST_Stmt_Continue;
struct AST_Stmt_Decl;
struct AST_Stmt_Do;
struct AST_Stmt_Expr;  // TODO(Ed) : Is this distinction needed? (Should it be a flag instead?)
struct AST_Stmt_Else;
struct AST_Stmt_If;
struct AST_Stmt_For;
struct AST_Stmt_Goto;
struct AST_Stmt_Label;
struct AST_Stmt_Switch;
struct AST_Stmt_While;
#endif

struct AST_Struct;
struct AST_Template;
struct AST_Type;
struct AST_Typedef;
struct AST_Union;
struct AST_Using;
struct AST_Var;

#if GEN_COMPILER_C
#define Define_Code(Type) typedef AST_##Type* Code##Type
#else
#define Define_Code(Type) struct Code##Type
#endif

#if GEN_COMPILER_C
typedef AST* code;
#else
struct Code;
#endif
Define_Code(Body);
// These are to offer ease of use and optionally strong type safety for the AST.
Define_Code(Attributes);
// struct CodeBaseClass;
Define_Code(Comment);
Define_Code(Class);
Define_Code(Constructor);
Define_Code(Define);
Define_Code(Destructor);
Define_Code(Enum);
Define_Code(Exec);
Define_Code(Extern);
Define_Code(Include);
Define_Code(Friend);
Define_Code(Fn);
Define_Code(Module);
Define_Code(NS);
Define_Code(Operator);
Define_Code(OpCast);
Define_Code(Param);
Define_Code(PreprocessCond);
Define_Code(Pragma);
Define_Code(Specifiers);

#if GEN_EXECUTION_EXPRESSION_SUPPORT
Define_Code(Expr);
Define_Code(Expr_Assign);
Define_Code(Expr_Alignof);
Define_Code(Expr_Binary);
Define_Code(Expr_CStyleCast);
Define_Code(Expr_FunctionalCast);
Define_Code(Expr_CppCast);
Define_Code(Expr_Element);
Define_Code(Expr_ProcCall);
Define_Code(Expr_Decltype);
Define_Code(Expr_Comma);
Define_Code(Expr_AMS); // Access Member Symbol
Define_Code(Expr_Sizeof);
Define_Code(Expr_Subscript);
Define_Code(Expr_Ternary);
Define_Code(Expr_UnaryPrefix);
Define_Code(Expr_UnaryPostfix);

Define_Code(Stmt);
Define_Code(Stmt_Break);
Define_Code(Stmt_Case);
Define_Code(Stmt_Continue);
Define_Code(Stmt_Decl);
Define_Code(Stmt_Do);
Define_Code(Stmt_Expr);
Define_Code(Stmt_Else);
Define_Code(Stmt_If);
Define_Code(Stmt_For);
Define_Code(Stmt_Goto);
Define_Code(Stmt_Label);
Define_Code(Stmt_Switch);
Define_Code(Stmt_While);
#endif

Define_Code(Struct);
Define_Code(Template);
Define_Code(Type);
Define_Code(Typedef);
Define_Code(Union);
Define_Code(Using);
Define_Code(Var);
#undef Define_Code

namespace parser
{
	struct Token;
}

#if ! GEN_COMPILER_C
template< class Type> forceinline Type tmpl_cast( Code self ) { return * rcast( Type*, & self ); }
#endif

char const* debug_str (Code code);
Code        duplicate (Code code);
bool        is_equal  (Code code, Code other);
bool        is_body   (Code code);
bool        is_valid  (Code code);
void        set_global(Code code);
String      to_string (Code code);

#if ! GEN_COMPILER_C
/*
	AST* wrapper
	- Not constantly have to append the '*' as this is written often..
	- Allows for implicit conversion to any of the ASTs (raw or filtered).
*/
struct Code
{
	AST* ast;

#	define Using_Code( Typename )                                                     \
	char const* debug_str()                { return GEN_NS debug_str(* this); }       \
	Code        duplicate()                { return GEN_NS duplicate(* this); }	      \
	bool        is_equal( Code other )     { return GEN_NS is_equal(* this, other); } \
	bool        is_body()                  { return GEN_NS is_body(* this); }         \
	bool        is_valid()                 { return GEN_NS is_valid(* this); }        \
	void        set_global()               { return GEN_NS set_global(* this); }

#	define Using_CodeOps( Typename )                                         \
	Typename&   operator = ( AST* other );                                   \
	Typename&   operator = ( Code other );                                   \
	bool        operator ==( Code other ) { return (AST*)ast == other.ast; } \
	bool        operator !=( Code other ) { return (AST*)ast != other.ast; } \
	operator bool();

#if GEN_SUPPORT_CPP_MEMBER_FEATURES
	Using_Code( Code );
	String to_string() { return GEN_NS to_string(* this); }
#endif

	Using_CodeOps( Code );

	AST* operator ->() { return ast; }
	Code& operator ++();

	// TODO(Ed) : Remove this overload.
	auto& operator*()
	{
		local_persist thread_local
		Code NullRef = { nullptr };

		if ( ast == nullptr )
			return NullRef;

		return *this;
	}

#ifdef GEN_ENFORCE_STRONG_CODE_TYPES
#	define operator explicit operator
#endif
	operator CodeBody() const;
	operator CodeAttributes() const;
	// operator CodeBaseClass() const;
	operator CodeComment() const;
	operator CodeClass() const;
	operator CodeConstructor() const;
	operator CodeDefine() const;
	operator CodeDestructor() const;
	operator CodeExec() const;
	operator CodeEnum() const;
	operator CodeExtern() const;
	operator CodeInclude() const;
	operator CodeFriend() const;
	operator CodeFn() const;
	operator CodeModule() const;
	operator CodeNS() const;
	operator CodeOperator() const;
	operator CodeOpCast() const;
	operator CodeParam() const;
	operator CodePragma() const;
	operator CodePreprocessCond() const;
	operator CodeSpecifiers() const;
	operator CodeStruct() const;
	operator CodeTemplate() const;
	operator CodeType() const;
	operator CodeTypedef() const;
	operator CodeUnion() const;
	operator CodeUsing() const;
	operator CodeVar() const;
	#undef operator
};
#endif

#pragma region Statics
// Used to identify ASTs that should always be duplicated. (Global constant ASTs)
extern Code Code_Global;

// Used to identify invalid generated code.
extern Code Code_Invalid;
#pragma endregion Statics

struct Code_POD
{
	AST* ast;
};

static_assert( sizeof(Code) == sizeof(Code_POD), "ERROR: Code is not POD" );

// Desired width of the AST data structure.
constexpr int const AST_POD_Size = 128;

void        append       ( AST* self, AST* other );
char const* debug_str    ( AST* self );
AST*        duplicate    ( AST* self );
Code*       entry        ( AST* self, u32 idx );
bool        has_entries  ( AST* self );
bool        is_body      ( AST* self );
bool        is_equal     ( AST* self, AST* other );
String      to_string    ( AST* self );
void        to_string    ( AST* self, String* result );
char const* type_str     ( AST* self );
bool        validate_body( AST* self );

#if GEN_CPP_SUPPORT_REFERENCES
void        append   ( AST& self, AST& other ) { return append(& self, & other); }
bool        is_body  ( AST& self )             { return is_body(& self); }
bool        is_equal ( AST& self, AST& other ) { return is_equal(& self, & other); }
char const* debug_str( AST& self )             { return debug_str( & self ); }
String      to_string( AST& self )             { return to_string( & self ); }
char const* type_str ( AST& self )             { return type_str( & self ); }
#endif

constexpr static
int AST_ArrSpecs_Cap =
(
		AST_POD_Size
		- sizeof(AST*) * 3
		- sizeof(parser::Token*)
		- sizeof(AST*)
		- sizeof(StringCached)
		- sizeof(CodeT)
		- sizeof(ModuleFlag)
		- sizeof(int)
)
/ sizeof(int) - 1; // -1 for 4 extra bytes

/*
	Simple AST POD with functionality to seralize into C++ syntax.
*/
struct AST
{
#if GEN_SUPPORT_CPP_MEMBER_FEATURES
#	pragma region Member Functions
	void        append     ( AST* other )  { GEN_NS append(this, other); }
	char const* debug_str  ()              { return GEN_NS debug_str(this); }
	AST*        duplicate  ()              { return GEN_NS duplicate(this); }
	Code*       entry      ( u32 idx )     { return GEN_NS entry(this, idx); }
	bool        has_entries()              { return GEN_NS has_entries(this); }
	bool        is_equal   ( AST* other )  { return GEN_NS is_equal(this, other); }
	bool        is_body()                  { return GEN_NS is_body(this); }
	char const* type_str()                 { return GEN_NS type_str(this); }
	bool        validate_body()            { return GEN_NS validate_body(this); }

	String to_string()                 { return GEN_NS to_string(this); }
	void   to_string( String& result ) { return GEN_NS to_string(this, & result); }

#	pragma endregion Member Functions
#endif

	operator Code();
	operator CodeBody();
	operator CodeAttributes();
	// operator CodeBaseClass();
	operator CodeComment();
	operator CodeConstructor();
	operator CodeDestructor();
	operator CodeClass();
	operator CodeDefine();
	operator CodeEnum();
	operator CodeExec();
	operator CodeExtern();
	operator CodeInclude();
	operator CodeFriend();
	operator CodeFn();
	operator CodeModule();
	operator CodeNS();
	operator CodeOperator();
	operator CodeOpCast();
	operator CodeParam();
	operator CodePragma();
	operator CodePreprocessCond();
	operator CodeSpecifiers();
	operator CodeStruct();
	operator CodeTemplate();
	operator CodeType();
	operator CodeTypedef();
	operator CodeUnion();
	operator CodeUsing();
	operator CodeVar();

	union {
		struct
		{
			AST*      InlineCmt;       // Class, Constructor, Destructor, Enum, Friend, Functon, Operator, OpCast, Struct, Typedef, Using, Variable
			AST*      Attributes;      // Class, Enum, Function, Struct, Typedef, Union, Using, Variable
			AST*      Specs;           // Destructor, Function, Operator, Typename, Variable
			union {
				AST*  InitializerList; // Constructor
				AST*  ParentType;      // Class, Struct, ParentType->Next has a possible list of interfaces.
				AST*  ReturnType;      // Function, Operator, Typename
				AST*  UnderlyingType;  // Enum, Typedef
				AST*  ValueType;       // Parameter, Variable
			};
			union {
				AST*  Macro;           // Parameter
				AST*  BitfieldSize;    // Variable (Class/Struct Data Member)
				AST*  Params;          // Constructor, Function, Operator, Template, Typename
			};
			union {
				AST*  ArrExpr;          // Typename
				AST*  Body;             // Class, Constructor, Destructor, Enum, Friend, Function, Namespace, Struct, Union
				AST*  Declaration;      // Friend, Template
				AST*  Value;            // Parameter, Variable
			};
			union {
				AST*  NextVar;          // Variable; Possible way to handle comma separated variables declarations. ( , NextVar->Specs NextVar->Name NextVar->ArrExpr = NextVar->Value )
				AST*  SuffixSpecs;      // Only used with typenames, to store the function suffix if typename is function signature. ( May not be needed )
				AST*  PostNameMacro;     // Only used with parameters for specifically UE_REQUIRES (Thanks Unreal)
			};
		};
		StringCached  Content;          // Attributes, Comment, Execution, Include
		struct {
			SpecifierT ArrSpecs[AST_ArrSpecs_Cap]; // Specifiers
			AST*       NextSpecs;              // Specifiers; If ArrSpecs is full, then NextSpecs is used.
		};
	};
	union {
		AST* Prev;
		AST* Front;
		AST* Last;
	};
	union {
		AST* Next;
		AST* Back;
	};
	parser::Token*    Token; // Reference to starting token, only avaialble if it was derived from parsing.
	AST*              Parent;
	StringCached      Name;
	CodeT             Type;
//	CodeFlag          CodeFlags;
	ModuleFlag        ModuleFlags;
	union {
		b32           IsFunction;  // Used by typedef to not serialize the name field.
		b32           IsParamPack; // Used by typename to know if type should be considered a parameter pack.
		OperatorT     Op;
		AccessSpec    ParentAccess;
		s32           NumEntries;
		s32           VarConstructorInit;  // Used by variables to know that initialization is using a constructor expression instead of an assignment expression.
		b32           EnumUnderlyingMacro; // Used by enums incase the user wants to wrap underlying type specification in a macro
	};
};

struct AST_POD
{
	union {
		struct
		{
			AST*      InlineCmt;       // Class, Constructor, Destructor, Enum, Friend, Functon, Operator, OpCast, Struct, Typedef, Using, Variable
			AST*      Attributes;      // Class, Enum, Function, Struct, Typedef, Union, Using, Variable
			AST*      Specs;           // Destructor, Function, Operator, Typename, Variable
			union {
				AST*  InitializerList; // Constructor
				AST*  ParentType;      // Class, Struct, ParentType->Next has a possible list of interfaces.
				AST*  ReturnType;      // Function, Operator, Typename
				AST*  UnderlyingType;  // Enum, Typedef
				AST*  ValueType;       // Parameter, Variable
			};
			union {
				AST*  Macro;           // Parameter
				AST*  BitfieldSize;    // Variable (Class/Struct Data Member)
				AST*  Params;          // Constructor, Function, Operator, Template, Typename
			};
			union {
				AST*  ArrExpr;          // Typename
				AST*  Body;             // Class, Constructr, Destructor, Enum, Friend, Function, Namespace, Struct, Union
				AST*  Declaration;      // Friend, Template
				AST*  Value;            // Parameter, Variable
			};
			union {
				AST*  NextVar;          // Variable; Possible way to handle comma separated variables declarations. ( , NextVar->Specs NextVar->Name NextVar->ArrExpr = NextVar->Value )
				AST*  SuffixSpecs;      // Only used with typenames, to store the function suffix if typename is function signature. ( May not be needed )
				AST*  PostNameMacro;    // Only used with parameters for specifically UE_REQUIRES (Thanks Unreal)
			};
		};
		StringCached  Content;          // Attributes, Comment, Execution, Include
		struct {
			SpecifierT ArrSpecs[AST_ArrSpecs_Cap]; // Specifiers
			AST*       NextSpecs;                   // Specifiers; If ArrSpecs is full, then NextSpecs is used.
		};
	};
	union {
		AST* Prev;
		AST* Front;
		AST* Last;
	};
	union {
		AST* Next;
		AST* Back;
	};
	parser::Token*    Token; // Reference to starting token, only avaialble if it was derived from parsing.
	AST*              Parent;
	StringCached      Name;
	CodeT             Type;
	CodeFlag          CodeFlags;
	ModuleFlag        ModuleFlags;
	union {
		b32           IsFunction;  // Used by typedef to not serialize the name field.
		b32           IsParamPack; // Used by typename to know if type should be considered a parameter pack.
		OperatorT     Op;
		AccessSpec    ParentAccess;
		s32           NumEntries;
		s32           VarConstructorInit; // Used by variables to know that initialization is using a constructor expression instead of an assignment expression.
	};
};

// Its intended for the AST to have equivalent size to its POD.
// All extra functionality within the AST namespace should just be syntatic sugar.
static_assert( sizeof(AST)     == sizeof(AST_POD), "ERROR: AST IS NOT POD" );
static_assert( sizeof(AST_POD) == AST_POD_Size,    "ERROR: AST POD is not size of AST_POD_Size" );

// Used when the its desired when omission is allowed in a definition.
#define NoCode      { nullptr }
#define InvalidCode (* Code_Invalid.ast) // Uses an implicitly overloaded cast from the AST to the desired code type.