/**

 * vim: set ts=4 :

 * =============================================================================

 * SourceMod

 * Copyright (C) 2004-2008 AlliedModders LLC.  All rights reserved.

 * =============================================================================

 *

 * This program is free software; you can redistribute it and/or modify it under

 * the terms of the GNU General Public License, version 3.0, 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 the GNU General Public License for more

 * details.

 *

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

 * this program.  If not, see <http://www.gnu.org/licenses/>.

 *

 * As a special exception, AlliedModders LLC gives you permission to link the

 * code of this program (as well as its derivative works) to "Half-Life 2," the

 * "Source Engine," the "SourcePawn JIT," and any Game MODs that run on software

 * by the Valve Corporation.  You must obey the GNU General Public License in

 * all respects for all other code used.  Additionally, AlliedModders LLC grants

 * this exception to all derivative works.  AlliedModders LLC defines further

 * exceptions, found in LICENSE.txt (as of this writing, version JULY-31-2007),

 * or <http://www.sourcemod.net/license.php>.

 *

 * Version: $Id$

 */

#ifndef _INCLUDE_SOURCEMOD_MODULE_INTERFACE_H_

#define _INCLUDE_SOURCEMOD_MODULE_INTERFACE_H_

#include <IShareSys.h>

#include <ILibrarySys.h>

/**

 * @file IExtensionSys.h

 * @brief Defines the interface for loading/unloading/managing extensions.

 */

namespace SourceMod

{

	class IExtensionInterface;

	typedef void *		ITERATOR;		/**< Generic pointer for dependency iterators */

	/** 

	 * @brief Encapsulates an IExtensionInterface and its dependencies.

	 */

	class IExtension

	{

	public:

		/**

		 * @brief Returns whether or not the extension is properly loaded.

		 */

		virtual bool IsLoaded() =0;

		/**

		 * @brief Returns the extension's API interface

		 *

		 * @return			An IExtensionInterface pointer.

		 */

		virtual IExtensionInterface *GetAPI() =0;

		/**

		 * @brief Returns the filename of the extension, relative to the

		 * extension folder.   If the extension is an "external" extension, 

		 * the file path is specified by the extension itself, and may be 

		 * arbitrary (not real).

		 *

		 * @return			A string containing the extension file name.

		 */

		virtual const char *GetFilename() =0;

		/**

		 * @brief Returns the extension's identity token.

		 *

		 * @return			An IdentityToken_t pointer.

		 */

		virtual IdentityToken_t *GetIdentity() =0;

		/**

		 * @brief Retrieves the extension dependency list for this extension.

		 *

		 * @param pOwner		Optional pointer to store the first interface's owner.

		 * @param pInterface	Optional pointer to store the first interface.

		 * @return				An ITERATOR pointer for the results, or NULL if no results at all.

		 */

		virtual ITERATOR *FindFirstDependency(IExtension **pOwner, SMInterface **pInterface) =0;

		/**

		 * @brief Finds the next dependency in the dependency list.

		 *

		 * @param iter			Pointer to iterator from FindFirstDependency.

		 * @param pOwner		Optional pointer to store the interface's owner.

		 * @param pInterface	Optional pointer to store the interface.

		 * @return				True if there are more results after this, false otherwise.

		 */

		virtual bool FindNextDependency(ITERATOR *iter, IExtension **pOwner, SMInterface **pInterface) =0;

		/**

		 * @brief Frees an ITERATOR handle from FindFirstDependency.

		 *

		 * @param iter			Pointer to iterator to free.

		 */

		virtual void FreeDependencyIterator(ITERATOR *iter) =0;

		/**

		 * @brief Queries the extension to see its run state.

		 *

		 * @param error			Error buffer (may be NULL).

		 * @param maxlength		Maximum length of buffer.

		 * @return				True if extension is okay, false if not okay.

		 */

		virtual bool IsRunning(char *error, size_t maxlength) =0;

		/**

		 * @brief Returns whether the extension is local (from the extensions 

		 * folder), or is from an external source (such as Metamod:Source).

		 *

		 * @return				True if from an external source, 

		 *						false if local to SourceMod.

		 */

		virtual bool IsExternal() =0;

	};

	/**

	 * @brief Version code of the IExtensionInterface API itself.

	 *

	 * Note: This is bumped when IShareSys is changed, because IShareSys 

	 * itself is not versioned.

	 */

	#define SMINTERFACE_EXTENSIONAPI_VERSION	3

	/**

	 * @brief The interface an extension must expose.

	 */

	class IExtensionInterface

	{

	public:

		/** Returns the interface API version */

		virtual unsigned int GetExtensionVersion()

		{

			return SMINTERFACE_EXTENSIONAPI_VERSION;

		}

	public:

		/**

		 * @brief Called when the extension is loaded.

		 * 

		 * @param me		Pointer back to extension.

		 * @param sys		Pointer to interface sharing system of SourceMod.

		 * @param error		Error buffer to print back to, if any.

		 * @param maxlength	Maximum size of error buffer.

		 * @param late		If this extension was loaded "late" (i.e. manually).

		 * @return			True if load should continue, false otherwise.

		 */

		virtual bool OnExtensionLoad(IExtension *me,

			IShareSys *sys, 

			char *error, 

			size_t maxlength, 

			bool late) =0;

		/**

		 * @brief Called when the extension is about to be unloaded.

		 */

		virtual void OnExtensionUnload() =0;

		/**

		 * @brief Called when all extensions are loaded (loading cycle is done).

		 * If loaded late, this will be called right after OnExtensionLoad().

		 */

		virtual void OnExtensionsAllLoaded() =0;

		/**

		 * @brief Called when your pause state is about to change.

		 * 

		 * @param pause		True if pausing, false if unpausing.

		 */

		virtual void OnExtensionPauseChange(bool pause) =0;

		/**

		 * @brief Asks the extension whether it's safe to remove an external 

		 * interface it's using.  If it's not safe, return false, and the 

		 * extension will be unloaded afterwards.

		 *

		 * NOTE: It is important to also hook NotifyInterfaceDrop() in order to clean up resources.

		 *

		 * @param pInterface		Pointer to interface being dropped.

		 * @return					True to continue, false to unload this extension afterwards.

		 */

		virtual bool QueryInterfaceDrop(SMInterface *pInterface)

		{

			return false;

		}

		/**

		 * @brief Notifies the extension that an external interface it uses is being removed.

		 *

		 * @param pInterface		Pointer to interface being dropped.

		 */

		virtual void NotifyInterfaceDrop(SMInterface *pInterface)

		{

		}

		/**

		 * @brief Return false to tell Core that your extension should be considered unusable.

		 *

		 * @param error				Error buffer.

		 * @param maxlength			Size of error buffer.

		 * @return					True on success, false otherwise.

		 */

		virtual bool QueryRunning(char *error, size_t maxlength)

		{

			return true;

		}

	public:

		/**

		 * @brief For extensions loaded through SourceMod, this should return true 

		 * if the extension needs to attach to Metamod:Source.  If the extension 

		 * is loaded through Metamod:Source, and uses SourceMod optionally, it must 

		 * return false.

		 *

		 * @return					True if Metamod:Source is needed.

		 */

		virtual bool IsMetamodExtension() =0;

		/**

		 * @brief Must return a string containing the extension's short name.

		 *

		 * @return					String containing extension name.

		 */

		virtual const char *GetExtensionName() =0;

		/**

		 * @brief Must return a string containing the extension's URL.

		 *

		 * @return					String containing extension URL.

		 */

		virtual const char *GetExtensionURL() =0;

		/**

		 * @brief Must return a string containing a short identifier tag.

		 *

		 * @return					String containing extension tag.

		 */

		virtual const char *GetExtensionTag() =0;

		/**

		 * @brief Must return a string containing a short author identifier.

		 *

		 * @return					String containing extension author.

		 */

		virtual const char *GetExtensionAuthor() =0;

		/**

		 * @brief Must return a string containing version information.

		 *

		 * Any version string format can be used, however, SourceMod 

		 * makes a special guarantee version numbers in the form of 

		 * A.B.C.D will always be fully displayed, where:

		 * 

		 * A is a major version number of at most one digit.

		 * B is a minor version number of at most two digits.

		 * C is a minor version number of at most two digits.

		 * D is a build number of at most 5 digits.

		 *

		 * Thus, thirteen characters of display is guaranteed.

		 *

		 * @return					String containing extension version.

		 */

		virtual const char *GetExtensionVerString() =0;

		/**

		 * @brief Must return a string containing description text.

		 *

		 * The description text may be longer than the other identifiers, 

		 * as it is only displayed when viewing one extension at a time.

		 * However, it should not have newlines, or any other characters 

		 * which would otherwise disrupt the display pattern.

		 * 

		 * @return					String containing extension description.

		 */

		virtual const char *GetExtensionDescription() =0;

		/**

		 * @brief Must return a string containing the compilation date.

		 *

		 * @return					String containing the compilation date.

		 */

		virtual const char *GetExtensionDateString() =0;

	};

	/**

	 * @brief Returned via OnMetamodQuery() to get an IExtensionManager pointer.

	 */

	#define SOURCEMOD_INTERFACE_EXTENSIONS				"SM_ExtensionManager"

	/**

	 * @brief Fired through OnMetamodQuery() to notify plugins that SourceMod is 

	 * loaded.  

	 *

	 * Plugins should not return an interface pointer or IFACE_OK, instead, 

	 * they should attach as needed by searching for SOURCEMOD_INTERFACE_EXTENSIONS.

	 *

	 * This may be fired more than once; if already attached, an extension should 

	 * not attempt to re-attach.  The purpose of this is to notify Metamod:Source 

	 * plugins which load after SourceMod loads.

	 */

	#define SOURCEMOD_NOTICE_EXTENSIONS					"SM_ExtensionsAttachable"

	#define SMINTERFACE_EXTENSIONMANAGER_NAME			"IExtensionManager"

	#define SMINTERFACE_EXTENSIONMANAGER_VERSION		2

	/**

	 * @brief Manages the loading/unloading of extensions.

	 */

	class IExtensionManager : public SMInterface

	{

	public:

		virtual const char *GetInterfaceName()

		{

			return SMINTERFACE_EXTENSIONMANAGER_NAME;

		}

		virtual unsigned int GetInterfaceVersion()

		{

			return SMINTERFACE_EXTENSIONMANAGER_VERSION;

		}

		virtual bool IsVersionCompatible(unsigned int version)

		{

			if (version < 2)

			{

				return false;

			}

			return SMInterface::IsVersionCompatible(version);

		}

	public:

		/**

		 * @brief Loads a extension into the extension system.

		 *

		 * @param path			Path to extension file, relative to the 

		 *						extensions folder.

		 * @param error			Error buffer.

		 * @param maxlength		Maximum error buffer length.

		 * @return				New IExtension on success, NULL on failure.

		 *						If	NULL is returned, the error buffer will be 

		 *						filled with a null-terminated string.

		 */

		virtual IExtension *LoadExtension(const char *path, 

			char *error,

			size_t maxlength) =0;

		/**

		 * @brief Loads an extension into the extension system, directly, 

		 * as an external extension.  

		 *

		 * The extension receives all normal callbacks.  However, it is 

		 * never opened via LoadLibrary/dlopen or closed via FreeLibrary

		 * or dlclose.

		 *

		 * @param pInterface	Pointer to an IExtensionInterface instance.

		 * @param filepath		Relative path to the extension's file, from 

		 * 						mod folder.

		 * @param filename		Name to use to uniquely identify the extension. 

		 *						The name should be generic, without any 

		 *						platform-specific suffices.  For example, 

		 *						sdktools.ext instead of sdktools.ext.so.

		 *						This filename is used to detect if the 

		 *						extension is already loaded, and to verify 

		 *						plugins that require the same extension.

		 * @param error			Buffer to store error message.

		 * @param maxlength		Maximum size of the error buffer.

		 * @return				IExtension pointer on success, NULL on failure.

		 *						If NULL is returned, the error buffer will be 

		 *						filled with a null-terminated string.

		 */

		virtual IExtension *LoadExternal(IExtensionInterface *pInterface,

			const char *filepath,

			const char *filename,

			char *error,

			size_t maxlength) =0;

		/**

		 * @brief Attempts to unload an extension.  External extensions must 

		 * call this before unloading.

		 *

		 * @param pExt			IExtension pointer.

		 * @return				True if successful, false otherwise.

		 */

		virtual bool UnloadExtension(IExtension *pExt) =0;

	};

	#define SM_IFACEPAIR(name) SMINTERFACE_##name##_NAME, SMINTERFACE_##name##_VERSION

	#define SM_FIND_IFACE_OR_FAIL(prefix, variable, errbuf, errsize) \

		if (!sharesys->RequestInterface(SM_IFACEPAIR(prefix), myself, (SMInterface **)&variable)) \

		{ \

			if (errbuf) \

			{ \

				size_t len = snprintf(errbuf, \

					errsize, \

					"Could not find interface: %s (version: %d)", \

					SM_IFACEPAIR(prefix)); \

				if (len >= errsize) \

				{ \

					errbuf[errsize - 1] = '\0'; \

				} \

			} \

			return false; \

		}

	#define SM_FIND_IFACE(prefix, variable) \

		sharesys->RequestInterface(SM_IFACEPAIR(prefix), myself, (SMInterface **)&variable);

}

#endif //_INCLUDE_SOURCEMOD_MODULE_INTERFACE_H_