/*

  * Copyright (C) 2004-2012 David Anderson

  *

  * This file is part of SourcePawn.

  *

  * SourcePawn is free software: you can redistribute it and/or modify it under

  * the terms of the GNU General Public License as published by the Free

  * Software Foundation, either version 3 of the License, or (at your option)

  * any later version.

  * 

  * SourcePawn is distributed in the hope that it will be useful, but WITHOUT ANY

  * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

  * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

  *

  * You should have received a copy of the GNU General Public License along with

  * SourcePawn. If not, see http://www.gnu.org/licenses/.

  */

 #ifndef _include_sourcepawn3_api_h_

 #define _include_sourcepawn3_api_h_

 #include <assert.h>

 #include <stddef.h>

 #include "../include/keima_util.h"

 namespace ke {

 class Zone;

 class Object;

 class HandleScope;

 class HeapRoot;

 }

 namespace Ke {

 class Function;

 /*

  * A Handle is a safe pointer that holds an object reference, such that it

  * can be scanned and potentially moved by the garbage collector.

  */

 template <typename T>

 class Handle

 {

   protected:

     template <typename S> void typeCheck() {

         while (false) {

             T *v1 = NULL;

             S *v2 = NULL;

             v1 = v2;

             (void)v1;

         }

     }

   public:

     Handle()

       : obj_(NULL)

     {

     }

     template <typename S> Handle(Handle<S> other)

       : obj_(reinterpret_cast<S *>(*other))

     {

         typeCheck<S>();

     }

     explicit Handle(T *obj)

       : obj_(obj)

     {

     }

     T *operator ->() const {

         return obj_;

     }

     T *operator *() const {

         return obj_;

     }

     operator bool () const {

         return !!obj_;

     }

   protected:

     T *obj_;

 };

 /*

  * A local variable that roots an object. Locals are owned by the nearest

  * HandleScope, and as soon as that HandleScope dies, all its Locals are

  * no longer available.

  */

 template <typename T>

 class Local : public Handle<T>

 {

   public:

     Local()

       : Handle<T>()

     {

     }

     template <typename S> Local(Local<S> other)

       : Handle<T>(reinterpret_cast<T *>(*other))

     {

         typeCheck<S>();

     }

     template <typename S> Local(S *other)

       : Handle<T>(other)

     {

     }

 };

 /*

  * A non-local variable that outlives HandleScopes. A Root is reference-

  * counted. When its reference count reaches 0, the Root is removed.

  */

 template <typename T>

 class Root : public Handle<T>

 {

   public:

     Root<T>()

       : Handle<T>()

     {

     }

     Root<T>(const Root<T> &other)

       : Handle<T>(reinterpret_cast<T *>(*other))

     {

         incref();

     }

     explicit Root(ke::HeapRoot *obj)

       : Handle<T>(reinterpret_cast<T *>(obj))

     {

 		incref();

     }

     static inline Root<T> New(Handle<T> other);

     ~Root() {

         decref();

     }

     Root<T> &operator =(const Root<T> &other) {

         decref();

         obj_ = other.obj_;

 		incref();

         return *this;

     }

   private:

     void incref();

     void decref();

 };

 /*

  * A HandleScope is where Local roots are allcoated. When the HandleScope

  * is destroyed, all Handles created under it are also destroyed. HandleScopes

  * may only be allocated on the stack, in LIFO order.

  */

 class HandleScope

 {

   protected:

     ke::Zone *zone_;

     ke::Object **position_;

     HandleScope *prev_;

     HandleScope(ke::Zone *zone, ke::Object **position, HandleScope *prev)

       : zone_(zone),

         position_(position),

         prev_(prev)

     {

     }

   public:

     HandleScope();

     ~HandleScope();

     static ke::Object **CreateHandle(ke::Object *obj);

   private:

     // Disallow silly stuff.

     HandleScope(const HandleScope &);

     void operator =(const HandleScope &);

     void *operator new (size_t size);

     void operator delete(void *, size_t);

 };

 class Parameter;

 // A string is an immutable UTF8 buffer.

 class KE_EXPORT String

 {

   public:

     // Returns the length of the string, in bytes.

     unsigned length();

     // Returns the character buffer of the string, or NULL on failure. If the

     // string is interned, chars() is guaranteed to succeed.

     const char *chars();

 };

 // A function is an executable unit of code.

 class KE_EXPORT Function

 {

   public:

     // Returns the name of a function, which may be NULL. If not NULL, the

     // string is guaranteed to be interned.

     Local<String> name();

 };

 // A native is an ISourcePawnEngine-compatible function provided by C++.

 class KE_EXPORT Native

 {

   public:

     // Returns the name of a native, which is never NULL. The string is

     // guaranteed to be interned.

     Local<String> name();

     // Returns the function pointer of the native.

     void *function();

     // Sets the function pointer of the native.

     void bind(void *function);

 };

 // A module represents a single compiled file, and contains functions and

 // global variables for that file (as well as exported types).

 class KE_EXPORT Module

 {

   public:

     // Returns publics that are based on forwards.

     unsigned numPublics();

     Local<Function> getPublic(unsigned index);

     // Returns natives.

     unsigned numNatives();

     Local<Native> getNative(unsigned index);

     // Sets the native identity pointer, which is passed as the first argument

     // to natives.

     void setNativeIdentity(void *ptr);

 };

 class Keima

 {

   public:

     /*

      * Initializes the Keima engine. This must be called exactly once before any

      * other Keima functions are called. After this, it is safe to use Keima

      * on the calling thread.

      */

     static bool Initialize();

     /*

      * Shuts down the Keima engine and frees data structures on all threads.

      */

     static void Shutdown();

     /*

      * Searches the call stack and returns true if the given module has any

      * active code running. This is an O(n) algorithm.

      */

     static bool IsInCallStack(Handle<Module> module);

     /*

      * Reclaim as much memory as possible. This pauses the calling thread

      * until garbage collection completes.

      */

     static void CollectGarbage();

     /*

      * Clear any pending exception.

      */

     static void ClearPendingException();

     /*

      * Type checks a function against given parameters.

      */

     static bool CheckInvokeTypes(Handle<Function> fun, const Parameter *params, unsigned nparams);

     /*

      * Executes a function with the given parameters. This interface is

      * intended for compatibility with SourceMod's ISourcePawnEngine2 and

      * should not be used otherwise, since it is intended to support only

      * a small subset of the core language.

      */

     static bool Invoke(Handle<Function> fun, const Parameter *params, unsigned nparams, int *result);

 };

 /*

  * Suppresses exceptions. This is useful for calling API functions. When this

  * in scope, errors will be reported, but the exception will be cleared after.

  */

 class AutoClearExceptions

 {

   public:

     ~AutoClearExceptions()

     {

         Keima::ClearPendingException();

     }

 };

 // Argument-passing interface for Invoke().

 class Parameter

 {

   public:

     enum Type {

         Int,

         Float,

         IntRef,

         FloatRef,

         Array,

         CharArray

     };

     Parameter()

     {

     }

     Parameter(int i)

       : type_(Int)

     {

         u.i = i;

     }

     Parameter(int *i, bool writeback)

       : type_(IntRef),

         writeback_(writeback)

     {

         u.ip = i;

     }

     Parameter(float f)

       : type_(Float)

     {

         u.f = f;

     }

     Parameter(float *f, bool writeback)

       : type_(FloatRef),

         writeback_(writeback)

     {

         u.fp = f;

     }

     Parameter(Type type, void *buffer, size_t length, bool writeback)

       : type_(type),

         writeback_(writeback),

         length_(length)

     {

         assert(type == Array || type == CharArray);

         u.buffer = buffer;

     }

     Type type() const {

         return type_;

     }

     int i32() const {

         assert(type() == Int);

         return u.i;

     }

     float f() const {

         assert(type() == Float);

         return u.f;

     }

     int *i32p() const {

         assert(type() == IntRef);

         return u.ip;

     }

     float *fp() const {

         assert(type() == FloatRef);

         return u.fp;

     }

     bool writeback() const {

         assert(type() >= IntRef && type() <= CharArray);

         return writeback_;

     }

     size_t length() const {

         return length_;

     }

     void *buffer() const {

         assert(type() == Array || type() == CharArray);

         return u.buffer;

     }

   private:

     Type type_;

     bool writeback_;

     size_t length_;

     union {

         int i;

         float f;

         int *ip;

         float *fp;

         void *buffer;

     } u;

 };

 /*

  * Compiles a file and returns a Module.

  */

 extern Local<Module> Compile(const char *path);

 class Internals

 {

     template <typename T> friend class Root;

   private:

     static ke::HeapRoot *NewHeapRoot(ke::Object **objp);

     static void IncRef(ke::HeapRoot *root);

     static void DecRef(ke::HeapRoot *root);

 };

 template <typename T> Root<T>

 Root<T>::New(Handle<T> other)

 {

     if (!other)

         return Root<T>();

     ke::Object **ptr = reinterpret_cast<ke::Object **>(*other);

     return Root<T>(Internals::NewHeapRoot(ptr));

 }

 template <typename T> void

 Root<T>::incref()

 {

     if (!*this)

         return;

     ke::HeapRoot *ptr = reinterpret_cast<ke::HeapRoot *>(**this);

     Internals::IncRef(ptr);

 }

 template <typename T> void

 Root<T>::decref()

 {

     if (!*this)

         return;

     ke::HeapRoot *ptr = reinterpret_cast<ke::HeapRoot *>(**this);

     Internals::DecRef(ptr);

 }

 }

 #endif // _include_sourcepawn3_api_h_