/*
 * Anope IRC Services
 *
 * Copyright (C) 2003-2017 Anope Team <team@anope.org>
 *
 * This file is part of Anope. Anope 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, version 2.
 *
 * 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 see <http://www.gnu.org/licenses/>.
 */

#pragma once

#include "serialize.h"
#include "base.h"
#include "modes.h"
#include "timers.h"
#include "logger.h"
#include "extensible.h"
#include "version.h"

class ModuleDef;
struct ModuleVersionC;

enum
{
	ANOPE_MODAPI_VER = 1
};

struct AnopeModule
{
	unsigned int api_version;
	ModuleDef* (*init)();
	void (*fini)(ModuleDef *);
	ModuleVersionC (*version)();
};

class ModuleDef
{
	std::vector<Anope::string> dependencies;

 public:
	virtual ~ModuleDef() = default;
	virtual Module *Create(const Anope::string &modname, const Anope::string &creator) anope_abstract;
	virtual void Destroy(Module *) anope_abstract;
	virtual void BuildModuleInfo() anope_abstract;

	void Depends(const Anope::string &modname);
	const std::vector<Anope::string> &GetDependencies();
};

template<class ModuleClass> void ModuleInfo(ModuleDef *moddef) { }

/** This definition is used as shorthand for the various classes
 * and functions needed to make a module loadable by the OS.
 */
#define MODULE_INIT(ModuleClass) \
	class ModuleClass ## ModuleDef : public ModuleDef \
	{ \
		Module *Create(const Anope::string &modname, const Anope::string &creator) override \
		{ \
			return new ModuleClass(modname, creator); \
		} \
		void Destroy(Module *module) override \
		{ \
			delete module; \
		} \
		void BuildModuleInfo() override \
		{ \
			ModuleInfo<ModuleClass>(this); \
		} \
	}; \
	static ModuleDef *CreateModuleDef() \
	{ \
		return new ModuleClass ## ModuleDef(); \
	} \
	static void DeleteModuleDef(ModuleDef *def) \
	{ \
		delete def; \
	} \
	static ModuleVersionC AnopeModuleVersion() \
	{ \
		ModuleVersionC ver; \
		ver.version_major = VERSION_MAJOR; \
		ver.version_minor = VERSION_MINOR; \
		ver.version_patch = VERSION_PATCH; \
		return ver; \
	} \
	extern "C" DllExport struct AnopeModule AnopeMod; \
	struct AnopeModule AnopeMod = \
	{ \
		ANOPE_MODAPI_VER, \
		CreateModuleDef, \
		DeleteModuleDef, \
		AnopeModuleVersion \
	};

enum class ModuleReturn
{
	OK,
	PARAMS,
	EXISTS,
	NOEXIST,
	NOLOAD,
	UNKNOWN,
	FILE_IO,
	EXCEPTION,
	VERSION
};

/* Module types, in the order in which they are unloaded. The order these are in is IMPORTANT */
enum
{
	MT_BEGIN,
	/* Module is 3rd party. All 3rd party modules should set this. Mutually exclusive to VENDOR. */
	THIRD = 1 << 0,
	/* A vendor module, which is made and shipped by Anope. Mutually exclusive to THIRD. */
	VENDOR = 1 << 1,
	/* Extra module not required for standard use. Probably requires external dependencies.
	 * This module does something extreme enough that we want it to show in the default /os modlist command
	 */
	EXTRA = 1 << 2,
	/* Module provides access to a database */
	DATABASE = 1 << 3,
	/* Module provides encryption */
	ENCRYPTION = 1 << 4,
	/* Module provides a pseudoclient */
	PSEUDOCLIENT = 1 << 5,
	/* Module provides IRCd protocol support */
	PROTOCOL = 1 << 6,
	MT_END = 1 << 7
};
typedef unsigned short ModType;

struct ModuleVersionC
{
	int version_major, version_minor, version_patch;
};

/** Returned by Module::GetVersion, used to see what version of Anope
 * a module is compiled against.
 */
class ModuleVersion
{
 private:
	int version_major;
	int version_minor;
	int version_patch;

 public:
	ModuleVersion(const ModuleVersionC &);

	/** Get the major version of Anope this was built against
	 * @return The major version
	 */
	int GetMajor() const;

	/** Get the minor version of Anope this was built against
	 * @return The minor version
	 */
	int GetMinor() const;

	/** Get the patch version this was built against
	 * @return The patch version
	 */
	int GetPatch() const;
};

/** Every module in Anope is actually a class.
 */
class CoreExport Module : public Extensible
{
 private:
	bool permanent;
 public:
	/** The module name (e.g. os_modload)
	 */
	Anope::string name;

	/** What type this module is
	 */
	ModType type;

	/** The temporary path/filename
	 */
	Anope::string filename;

	/** Handle for this module, obtained from dlopen()
	 */
	void *handle;

	ModuleDef *def = nullptr;
	AnopeModule *module = nullptr;

	/** Time this module was created
	 */
	time_t created;

	/** Version of this module
	 */
	Anope::string version;

	/** Author of the module
	 */
	Anope::string author;

	Logger logger;

	/** Creates and initialises a new module.
	 * @param modname The module name
	 * @param loadernick The nickname of the user loading the module.
	 * @param type The module type
	 */
	Module(const Anope::string &modname, const Anope::string &loadernick, ModType type = THIRD);

	/** Destroys a module, freeing resources it has allocated.
	 */
	virtual ~Module();

	const Anope::string &GetName() const;

	/** Toggles the permanent flag on a module. If a module is permanent,
	 * then it may not be unloaded.
	 *
	 * Naturally, this setting should be used sparingly!
	 *
	 * @param state True if this module should be permanent, false else.
	 */
	void SetPermanent(bool state);

	/** Retrieves whether or not a given module is permanent.
	 * @return true if the module is permanent, false else.
	 */
	bool GetPermanent() const;

	/** Set the modules version info.
	 * @param version the version of the module
	 */
	void SetVersion(const Anope::string &version);

	/** Set the modules author info
	 * @param author the author of the module
	 */
	void SetAuthor(const Anope::string &author);

	/** Get the version of Anope this module was
	 * compiled against
	 * @return The version
	 */
	ModuleVersion GetVersion() const;

	virtual void OnReload(Configuration::Conf *conf) { }
};

/** Used to manage modules.
 */
class CoreExport ModuleManager
{
 public:
 	/** List of all modules loaded in Anope
	 */
	static std::list<Module *> Modules;

#ifdef _WIN32
	/** Clean up the module runtime directory
	 */
	static void CleanupRuntimeDirectory();
#endif

	/** Loads a given module.
	 * @param m the module to load
	 * @param u the user who loaded it, NULL for auto-load
	 * @return MOD_ERR_OK on success, anything else on fail
	 */
	static ModuleReturn LoadModule(const Anope::string &modname, User *u);

	/** Unload the given module.
	 * @param m the module to unload
	 * @param u the user who unloaded it
	 * @return MOD_ERR_OK on success, anything else on fail
	 */
	static ModuleReturn UnloadModule(Module *m, User * u);

	/** Find a module
	 * @param name The module name
	 * @return The module
	 */
	static Module *FindModule(const Anope::string &name);

	/** Find the first module of a certain type
	 * @param type The module type
	 * @return The module
	 */
	static Module *FindFirstOf(ModType type);

	/** Checks whether this version of Anope is at least major.minor.patch.build
	 * Throws a ModuleException if not
	 * @param major The major version
	 * @param minor The minor vesion
	 * @param patch The patch version
	 */
	static void RequireVersion(int major, int minor, int patch);

	/** Unloading all modules except the protocol module.
	 */
	static void UnloadAll();

 private:
	/** Call the module_delete function to safely delete the module
	 * @param m the module to delete
	 * @return MOD_ERR_OK on success, anything else on fail
	 */
	static ModuleReturn DeleteModule(Module *m);
};