//========================================================================
// ScriptExports.cpp
//
// Part of the GameCode4 Application
//
// GameCode4 is the sample application that encapsulates much of the source code
// discussed in "Game Coding Complete - 4th Edition" by Mike McShaffry and David
// "Rez" Graham, published by Charles River Media. 
// ISBN-10: 1133776574 | ISBN-13: 978-1133776574
//
// If this source code has found it's way to you, and you think it has helped you
// in any way, do the authors a favor and buy a new copy of the book - there are 
// detailed explanations in it that compliment this code well. Buy a copy at Amazon.com
// by clicking here: 
//    http://www.amazon.com/gp/product/1133776574/ref=olp_product_details?ie=UTF8&me=&seller=
//
// There's a companion web site at http://www.mcshaffry.com/GameCode/
// 
// The source code is managed and maintained through Google Code: 
//    http://code.google.com/p/gamecode4/
//
// (c) Copyright 2012 Michael L. McShaffry and David Graham
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser GPL v3
// as published by the Free Software Foundation.
//
// This program 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 
// http://www.gnu.org/licenses/lgpl-3.0.txt for more details.
//
// You should have received a copy of the GNU Lesser GPL v3
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
//
//========================================================================

#include "../Unix/GameCodeStd.h"
#include "../ResourceCache/ResCache.h"
#include "ScriptExports.h"
#include "LuaStateManager.h"
#include "../EventManager/Events.h"

#include <sol/sol.hpp>
#include <set>


//---------------------------------------------------------------------------------------------------------------------
// This is the C++ listener proxy for script event listeners.  It pairs a single event type with a Lua callback 
// function.  Note that this event can be defined in C++ or Lua.  It may also be sent from C++ or Lua.
// 
// The Lua callback function should take in a table with the event data.  The return value is ignored.
// function Callback(eventData)
// 
// Chapter 12, page 384
//---------------------------------------------------------------------------------------------------------------------
class ScriptEventListener
{
	EventType m_eventType;
	sol::protected_function m_scriptCallbackFunction;

public:
	explicit ScriptEventListener(const EventType& eventType, const sol::function scriptCallbackFunction);
	~ScriptEventListener(void);
	EventListenerDelegate GetDelegate(void) { return MakeDelegate(this, &ScriptEventListener::ScriptEventDelegate); }
	void ScriptEventDelegate(IEventDataPtr pEventPtr);
};


//---------------------------------------------------------------------------------------------------------------------
// This class manages the C++ ScriptListener objects needed for script event listeners.
// Chapter 12, page 385
//---------------------------------------------------------------------------------------------------------------------
class ScriptEventListenerMgr
{
	typedef std::set<ScriptEventListener*> ScriptEventListenerSet;
	ScriptEventListenerSet m_listeners;

public:
	~ScriptEventListenerMgr(void);
	void AddListener(ScriptEventListener* pListener);
	void DestroyListener(ScriptEventListener* pListener);
};


//---------------------------------------------------------------------------------------------------------------------
// Prototypes for the functions to export.                              - Chapter 12, page 368
//---------------------------------------------------------------------------------------------------------------------
class InternalScriptExports
{
	static ScriptEventListenerMgr* s_pScriptEventListenerMgr;
	
public:
	static bool Init(void);
	static void Destroy(void);

	// resource loading
	static bool LoadAndExecuteScriptResource(const char* scriptResource);

	// event system
	static unsigned long RegisterEventListener(EventType eventType, sol::function callbackFunction);
	static bool QueueEvent(EventType eventType, sol::object eventData);

	// misc
	static void LuaLog(sol::object text);

private:
	static std::shared_ptr<ScriptEvent> BuildEvent(EventType eventType, sol::object& eventData);
};

ScriptEventListenerMgr* InternalScriptExports::s_pScriptEventListenerMgr = NULL;




//---------------------------------------------------------------------------------------------------------------------
// Destructor
//---------------------------------------------------------------------------------------------------------------------
ScriptEventListenerMgr::~ScriptEventListenerMgr(void)
{
	for (auto it = m_listeners.begin(); it != m_listeners.end(); ++it)
	{
		ScriptEventListener* pListener = (*it);
		delete pListener;
	}
	m_listeners.clear();
}

//---------------------------------------------------------------------------------------------------------------------
// Adds a new listener
//---------------------------------------------------------------------------------------------------------------------
void ScriptEventListenerMgr::AddListener(ScriptEventListener* pListener)
{
	m_listeners.insert(pListener);
}


//---------------------------------------------------------------------------------------------------------------------
// Event Listener
//---------------------------------------------------------------------------------------------------------------------
ScriptEventListener::ScriptEventListener(const EventType& eventType, const sol::function scriptCallbackFunction)
	: m_scriptCallbackFunction(scriptCallbackFunction)
{
	m_eventType = eventType;
}

ScriptEventListener::~ScriptEventListener(void)
{
	IEventManager* pEventMgr = IEventManager::Get();
	if (pEventMgr)
		pEventMgr->VRemoveListener(GetDelegate(), m_eventType);
}

void ScriptEventListener::ScriptEventDelegate(IEventDataPtr pEvent)
{
	GCC_ASSERT(m_scriptCallbackFunction.valid());  // this should never happen since it's validated before even creating this object

	// call the lua function
	std::shared_ptr<ScriptEvent> pScriptEvent = static_pointer_cast<ScriptEvent>(pEvent);
	sol::function Callback = m_scriptCallbackFunction;
	Callback(pScriptEvent->GetEventData());
}

//---------------------------------------------------------------------------------------------------------------------
// Initializes the script export system
//---------------------------------------------------------------------------------------------------------------------
bool InternalScriptExports::Init(void)
{
	GCC_ASSERT(s_pScriptEventListenerMgr == NULL);
	s_pScriptEventListenerMgr = GCC_NEW ScriptEventListenerMgr;
	
	return true;
}

//---------------------------------------------------------------------------------------------------------------------
// Destroys the script export system
//---------------------------------------------------------------------------------------------------------------------
void InternalScriptExports::Destroy(void)
{
	GCC_ASSERT(s_pScriptEventListenerMgr != NULL);
	SAFE_DELETE(s_pScriptEventListenerMgr);
}



//---------------------------------------------------------------------------------------------------------------------
// Loads a script resource then executes it.  This is used by the require() function in script (defined in 
// PreInit.lua).
//---------------------------------------------------------------------------------------------------------------------
bool InternalScriptExports::LoadAndExecuteScriptResource(const char* scriptResource)
{
	Resource resource(scriptResource);
	std::shared_ptr<ResHandle> pResourceHandle = g_pApp->m_ResCache->GetHandle(&resource);
	if (pResourceHandle)
		return true;
	return false;
}

//---------------------------------------------------------------------------------------------------------------------
// Queue's an event from the script.  Returns true if the event was sent, false if not.
//---------------------------------------------------------------------------------------------------------------------
bool InternalScriptExports::QueueEvent(EventType eventType, sol::object eventData)
{
	std::shared_ptr<ScriptEvent> pEvent(BuildEvent(eventType, eventData));
	if (pEvent)
	{
		IEventManager::Get()->VQueueEvent(pEvent);
		return true;
	}
	return false;
}

//---------------------------------------------------------------------------------------------------------------------
// Builds the event to be sent or queued
//---------------------------------------------------------------------------------------------------------------------
std::shared_ptr<ScriptEvent> InternalScriptExports::BuildEvent(EventType eventType, sol::object& eventData)
{
	// create the event from the event type
	std::shared_ptr<ScriptEvent> pEvent(ScriptEvent::CreateEventFromScript(eventType));
	if (!pEvent)
		return std::shared_ptr<ScriptEvent>();

	// set the event data that was passed in
	if (!pEvent->SetEventData(eventData))
	{
		return std::shared_ptr<ScriptEvent>();
	}

	return pEvent;
}



//---------------------------------------------------------------------------------------------------------------------
// Instantiates a C++ ScriptListener object, inserts it into the manager, and returns a handle to it.  The script 
// should maintain the handle if it needs to remove the listener at some point.  Otherwise, the listener will be 
// destroyed when the program exits.
//---------------------------------------------------------------------------------------------------------------------
unsigned long InternalScriptExports::RegisterEventListener(EventType eventType, sol::function callbackFunction)
{
	GCC_ASSERT(s_pScriptEventListenerMgr);

	if (callbackFunction.valid())
	{
		// create the C++ listener proxy and set it to listen for the event
		ScriptEventListener* pListener = GCC_NEW ScriptEventListener(eventType, callbackFunction);
		s_pScriptEventListenerMgr->AddListener(pListener);
		IEventManager::Get()->VAddListener(pListener->GetDelegate(), eventType);

		// convert the pointer to an unsigned long to use as the handle
		unsigned long handle = reinterpret_cast<unsigned long>(pListener);
		return handle;
	}

	GCC_ERROR("Attempting to register script event listener with invalid callback function");
	return 0;
}

void InternalScriptExports::LuaLog(sol::object text)
{
	if (text.is<std::string>())
	{
		GCC_LOG("Lua", text.as<std::string>());
	}
	else
	{
		const char* typeName = lua_typename(text.lua_state(), static_cast<int>(text.get_type()));
		GCC_LOG("Lua", "<" + std::string(typeName) + ">");
	}
}

//---------------------------------------------------------------------------------------------------------------------
// This function registers all the ScriptExports functions with the scripting system.  It is called in 
// Application::Init().
//---------------------------------------------------------------------------------------------------------------------
void ScriptExports::Register(void)
{
	sol::state_view lua = LuaStateManager::Get()->GetLuaState();
	sol::global_table globals = lua.globals();

	// init	
	InternalScriptExports::Init();

	// resource loading
	globals["LoadAndExecuteScriptResource"] = &InternalScriptExports::LoadAndExecuteScriptResource;

	// actors
	// globals.RegisterDirect("CreateActor", &InternalScriptExports::CreateActor);

	// event system
	globals["RegisterEventListener"] = &InternalScriptExports::RegisterEventListener;
	// globals.RegisterDirect("RemoveEventListener", &InternalScriptExports::RemoveEventListener);
	globals["QueueEvent"] = &InternalScriptExports::QueueEvent;
	// globals.RegisterDirect("TriggerEvent", &InternalScriptExports::TriggerEvent);
	
	// process system
	// globals.RegisterDirect("AttachProcess", &InternalScriptExports::AttachScriptProcess);

    // math
    // LuaPlus::LuaObject mathTable = globals.GetByName("GccMath");
    // GCC_ASSERT(mathTable.IsTable());
    // mathTable.RegisterDirect("GetYRotationFromVector", &InternalScriptExports::GetYRotationFromVector);
    // mathTable.RegisterDirect("WrapPi", &InternalScriptExports::WrapPi);
    // mathTable.RegisterDirect("GetVectorFromRotation", &InternalScriptExports::GetVectorFromRotation);
	
	// misc
	globals["Log"] = &InternalScriptExports::LuaLog;
    // globals.RegisterDirect("GetTickCount", &InternalScriptExports::GetTickCount);

	// Physics
	// globals.RegisterDirect("ApplyForce", &InternalScriptExports::ApplyForce);
	// globals.RegisterDirect("ApplyTorque", &InternalScriptExports::ApplyTorque);
}

//---------------------------------------------------------------------------------------------------------------------
// This function unregisters all the ScriptExports functions and gives any underlying systems a chance to destroy 
// themselves.  It is called in the Application destructor.
//---------------------------------------------------------------------------------------------------------------------
void ScriptExports::Unregister(void)
{
	InternalScriptExports::Destroy();
}