/*
 * InspIRCd -- Internet Relay Chat Daemon
 *
 *   Copyright (C) 2009 Daniel De Graaf <danieldg@inspircd.org>
 *   Copyright (C) 2004-2006, 2008 Craig Edwards <craigedwards@brainbox.cc>
 *   Copyright (C) 2007 Robin Burchell <robin+git@viroteck.net>
 *   Copyright (C) 2007 Dennis Friis <peavey@inspircd.org>
 *
 * This file is part of InspIRCd.  InspIRCd 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 <http://www.gnu.org/licenses/>.
 */


#pragma once

#include "ctables.h"

/**
 * Holds the values for different type of modes
 * that can exist, USER or CHANNEL type.
 */
enum ModeType
{
	/** User mode */
	MODETYPE_USER = 0,
	/** Channel mode */
	MODETYPE_CHANNEL = 1
};

/**
 * Holds mode actions - modes can be allowed or denied.
 */
enum ModeAction
{
	MODEACTION_DENY = 0, /* Drop the mode change, AND a parameter if its a parameterized mode */
	MODEACTION_ALLOW = 1 /* Allow the mode */
};

/**
 * Used to mask off the mode types in the mode handler
 * array. Used in a simple two instruction hashing function
 * "(modeletter - 65) OR mask"
 */
enum ModeMasks
{
	MASK_USER = 128,	/* A user mode */
	MASK_CHANNEL = 0	/* A channel mode */
};

/**
 * These fixed values can be used to proportionally compare module-defined prefixes to known values.
 * For example, if your module queries a Channel, and is told that user 'joebloggs' has the prefix
 * '$', and you dont know what $ means, then you can compare it to these three values to determine
 * its worth against them. For example if '$' had a value of 15000, you would know it is of higher
 * status than voice, but lower status than halfop.
 * No two modes should have equal prefix values.
 */
enum PrefixModeValue
{
	/* +v */
	VOICE_VALUE	=	10000,
	/* +h */
	HALFOP_VALUE	=	20000,
	/* +o */
	OP_VALUE	=	30000
};

enum ParamSpec
{
	/** No parameters */
	PARAM_NONE,
	/** Parameter required on mode setting only */
	PARAM_SETONLY,
	/** Parameter always required */
	PARAM_ALWAYS
};

/** Each mode is implemented by ONE ModeHandler class.
 * You must derive ModeHandler and add the child class to
 * the list of modes handled by the ircd, using
 * ModeParser::AddMode. When the mode you implement is
 * set by a user, the virtual function OnModeChange is
 * called. If you specify a value greater than 0 for
 * parameters_on or parameters_off, then when the mode is
 * set or unset respectively, std::string &parameter will
 * contain the parameter given by the user, else it will
 * contain an empty string. You may alter this parameter
 * string, and if you alter it to an empty string, and your
 * mode is expected to have a parameter, then this is
 * equivalent to returning MODEACTION_DENY.
 */
class CoreExport ModeHandler : public ServiceProvider
{
 public:
	enum Class
	{
		MC_PREFIX,
		MC_OTHER
	};

 protected:
	/**
	 * The mode parameter translation type
	 */
	TranslateType m_paramtype;

	/** What kind of parameters does the mode take?
	 */
	ParamSpec parameters_taken;

	/**
	 * The mode letter you're implementing.
	 */
	char mode;

	/** Mode prefix, or 0
	 */
	char prefix;

	/**
	 * True if the mode requires oper status
	 * to set.
	 */
	bool oper;

	/**
	 * Mode is a 'list' mode. The behaviour
	 * of your mode is now set entirely within
	 * the class as of the 1.1 api, rather than
	 * inside the mode parser as in the 1.0 api,
	 * so the only use of this value (along with
	 * IsListMode()) is for the core to determine
	 * wether your module can produce 'lists' or not
	 * (e.g. banlists, etc)
	 */
	bool list;

	/**
	 * The mode type, either MODETYPE_USER or
	 * MODETYPE_CHANNEL.
	 */
	ModeType m_type;

	/** The object type of this mode handler
	 */
	const Class type_id;

	/** The prefix char needed on channel to use this mode,
	 * only checked for channel modes
	 */
	int levelrequired;

	/** The prefix rank of this mode, used to compare prefix
	 * modes
	 */
	unsigned int prefixrank;

 public:
	/**
	 * The constructor for ModeHandler initalizes the mode handler.
	 * The constructor of any class you derive from ModeHandler should
	 * probably call this constructor with the parameters set correctly.
	 * @param me The module which created this mode
	 * @param name A one-word name for the mode
	 * @param modeletter The mode letter you wish to handle
	 * @param params Parameters taken by the mode
	 * @param type Type of the mode (MODETYPE_USER or MODETYPE_CHANNEL)
	 * @param mclass The object type of this mode handler, one of ModeHandler::Class
	 */
	ModeHandler(Module* me, const std::string& name, char modeletter, ParamSpec params, ModeType type, Class mclass = MC_OTHER);
	virtual CullResult cull();
	virtual ~ModeHandler();
	/**
	 * Returns true if the mode is a list mode
	 */
	bool IsListMode() const { return list; }
	/**
	 * Mode prefix or 0. If this is defined, you should
	 * also implement GetPrefixRank() to return an integer
	 * value for this mode prefix.
	 */
	inline char GetPrefix() const { return prefix; }
	/**
	 * Get the 'value' of this modes prefix.
	 * determines which to display when there are multiple.
	 * The mode with the highest value is ranked first. See the
	 * PrefixModeValue enum and Channel::GetPrefixValue() for
	 * more information.
	 */
	unsigned int GetPrefixRank() const { return prefixrank; }
	/**
	 * Returns the mode's type
	 */
	inline ModeType GetModeType() const { return m_type; }
	/**
	 * Returns the mode's parameter translation type
	 */
	inline TranslateType GetTranslateType() const { return m_paramtype; }
	/**
	 * Returns true if the mode can only be set/unset by an oper
	 */
	inline bool NeedsOper() const { return oper; }
	/**
	 * Returns the number of parameters for the mode. Any non-zero
	 * value should be considered to be equivalent to one.
	 * @param adding If this is true, the number of parameters required to set the mode should be returned, otherwise the number of parameters required to unset the mode shall be returned.
	 * @return The number of parameters the mode expects
	 */
	int GetNumParams(bool adding);
	/**
	 * Returns the mode character this handler handles.
	 * @return The mode character
	 */
	inline char GetModeChar() { return mode; }

	/** For user modes, return the current parameter, if any
	 */
	virtual std::string GetUserParameter(User* useor);

	/**
	 * Called when a channel mode change access check for your mode occurs.
	 * @param source Contains the user setting the mode.
	 * @param channel contains the destination channel the modes are being set on.
	 * @param parameter The parameter for your mode. This is modifiable.
	 * @param adding This value is true when the mode is being set, or false when it is being unset.
	 * @return allow, deny, or passthru to check against the required level
	 */
	virtual ModResult AccessCheck(User* source, Channel* channel, std::string &parameter, bool adding);

	/**
	 * Called when a mode change for your mode occurs.
	 * @param source Contains the user setting the mode.
	 * @param dest For usermodes, contains the destination user the mode is being set on. For channelmodes, this is an undefined value.
	 * @param channel For channel modes, contains the destination channel the modes are being set on. For usermodes, this is an undefined value.
	 * @param parameter The parameter for your mode, if you indicated that your mode requires a parameter when being set or unset. Note that
	 * if you alter this value, the new value becomes the one displayed and send out to the network, also, if you set this to an empty string
	 * but you specified your mode REQUIRES a parameter, this is equivalent to returning MODEACTION_DENY and will prevent the mode from being
	 * displayed.
	 * @param adding This value is true when the mode is being set, or false when it is being unset.
	 * @return MODEACTION_ALLOW to allow the mode, or MODEACTION_DENY to prevent the mode, also see the description of 'parameter'.
	 */
	virtual ModeAction OnModeChange(User* source, User* dest, Channel* channel, std::string &parameter, bool adding); /* Can change the mode parameter as its a ref */
	/**
	 * If your mode is a listmode, then this method will be called for displaying an item list, e.g. on MODE \#channel +modechar
	 * without any parameter or other modes in the command.
	 * @param user The user issuing the command
	 * @param channel The channel they're requesting an item list of (e.g. a banlist, or an exception list etc)
	 */
	virtual void DisplayList(User* user, Channel* channel);

	/** In the event that the mode should be given a parameter, and no parameter was provided, this method is called.
	 * This allows you to give special information to the user, or handle this any way you like.
	 * @param user The user issuing the mode change
	 * @param dest For user mode changes, the target of the mode. For channel mode changes, NULL.
	 * @param channel For channel mode changes, the target of the mode. For user mode changes, NULL.
	 */
	virtual void OnParameterMissing(User* user, User* dest, Channel* channel);

	/**
	 * If your mode is a listmode, this method will be called to display an empty list (just the end of list numeric)
	 * @param user The user issuing the command
	 * @param channel The channel tehy're requesting an item list of (e.g. a banlist, or an exception list etc)
	 */
	virtual void DisplayEmptyList(User* user, Channel* channel);

	/**
	 * If your mode needs special action during a server sync to determine which side wins when comparing timestamps,
	 * override this function and use it to return true or false. The default implementation just returns true if
	 * theirs < ours. This will only be called for non-listmodes with parameters, when adding the mode and where
	 * theirs == ours (therefore the default implementation will always return false).
	 * @param their_param Their parameter if the mode has a parameter
	 * @param our_param Our parameter if the mode has a parameter
	 * @param channel The channel we are checking against
	 * @return True if the other side wins the merge, false if we win the merge for this mode.
	 */
	virtual bool ResolveModeConflict(std::string &their_param, const std::string &our_param, Channel* channel);

	/**
	 * When a MODETYPE_USER mode handler is being removed, the core will call this method for every user on the server.
	 * The usermode will be removed using the appropiate server mode using InspIRCd::SendMode().
	 * @param user The user which the server wants to remove your mode from
	 */
	void RemoveMode(User* user);

	/**
	 * When a MODETYPE_CHANNEL mode handler is being removed, the server will call this method for every channel on the server.
	 * The mode handler has to populate the given modestacker with mode changes that remove the mode from the channel.
	 * The default implementation of this method can remove all kinds of channel modes except listmodes.
	 * In the case of listmodes, the entire list of items must be added to the modestacker (which is handled by ListModeBase,
	 * so if you inherit from it or your mode can be removed by the default implementation then you do not have to implement
	 * this function).
	 * @param channel The channel which the server wants to remove your mode from
	 * @param stack The mode stack to add the mode change to
	 */
	virtual void RemoveMode(Channel* channel, irc::modestacker& stack);

	inline unsigned int GetLevelRequired() const { return levelrequired; }
};

/**
 * Prefix modes are channel modes that grant a specific rank to members having prefix mode set.
 * They require a parameter when setting and unsetting; the parameter is always a member of the channel.
 * A prefix mode may be set on any number of members on a channel, but for a given member a given prefix
 * mode is either set or not set, in other words members cannot have the same prefix mode set more than once.
 *
 * A rank of a member is defined as the rank given by the 'strongest' prefix mode that member has.
 * Other parts of the IRCd use this rank to determine whether a channel action is allowable for a user or not.
 * The rank of a prefix mode is constant, i.e. the same rank value is given to all users having that prefix mode set.
 *
 * Note that it is possible that the same action requires a different rank on a different channel;
 * for example changing the topic on a channel having +t set requires a rank that is >= than the rank of a halfop,
 * but there is no such restriction when +t isn't set.
 */
class PrefixMode : public ModeHandler
{
 public:
	/**
	 * Constructor
	 * @param Creator The module creating this mode
	 * @param Name The user-friendly one word name of the prefix mode, e.g.: "op", "voice"
	 * @param ModeLetter The mode letter of this mode
	 */
	PrefixMode(Module* Creator, const std::string& Name, char ModeLetter);

	/**
	 * Handles setting and unsetting the prefix mode.
	 * Finds the given member of the given channel, if it's not found an error message is sent to 'source'
	 * and MODEACTION_DENY is returned. Otherwise the mode change is attempted.
	 * @param source Source of the mode change, an error message is sent to this user if the target is not found
	 * @param dest Unused
	 * @param channel The channel the mode change is happening on
	 * @param param The nickname or uuid of the target user
	 * @param adding True when the mode is being set, false when it is being unset
	 * @return MODEACTION_ALLOW if the change happened, MODEACTION_DENY if no change happened
	 * The latter occurs either when the member cannot be found or when the member already has this prefix set
	 * (when setting) or doesn't have this prefix set (when unsetting).
	 */
	ModeAction OnModeChange(User* source, User* dest, Channel* channel, std::string& param, bool adding);

	/**
	 * Removes this prefix mode from all users on the given channel
	 * @param chan The channel which the server wants to remove your mode from
	 * @param stack The mode stack to add the mode change to
	 */
	void RemoveMode(Channel* chan, irc::modestacker& stack);
};

/** A prebuilt mode handler which handles a simple user mode, e.g. no parameters, usable by any user, with no extra
 * behaviour to the mode beyond the basic setting and unsetting of the mode, not allowing the mode to be set if it
 * is already set and not allowing it to be unset if it is already unset.
 * An example of a simple user mode is user mode +w.
 */
class CoreExport SimpleUserModeHandler : public ModeHandler
{
 public:
	SimpleUserModeHandler(Module* Creator, const std::string& Name, char modeletter)
		: ModeHandler(Creator, Name, modeletter, PARAM_NONE, MODETYPE_USER) {}
	virtual ~SimpleUserModeHandler() {}
	virtual ModeAction OnModeChange(User* source, User* dest, Channel* channel, std::string &parameter, bool adding);
};

/** A prebuilt mode handler which handles a simple channel mode, e.g. no parameters, usable by any user, with no extra
 * behaviour to the mode beyond the basic setting and unsetting of the mode, not allowing the mode to be set if it
 * is already set and not allowing it to be unset if it is already unset.
 * An example of a simple channel mode is channel mode +s.
 */
class CoreExport SimpleChannelModeHandler : public ModeHandler
{
 public:
	SimpleChannelModeHandler(Module* Creator, const std::string& Name, char modeletter)
		: ModeHandler(Creator, Name, modeletter, PARAM_NONE, MODETYPE_CHANNEL) {}
	virtual ~SimpleChannelModeHandler() {}
	virtual ModeAction OnModeChange(User* source, User* dest, Channel* channel, std::string &parameter, bool adding);
};

class CoreExport ParamChannelModeHandler : public ModeHandler
{
 public:
	ParamChannelModeHandler(Module* Creator, const std::string& Name, char modeletter)
		: ModeHandler(Creator, Name, modeletter, PARAM_SETONLY, MODETYPE_CHANNEL) {}
	virtual ModeAction OnModeChange(User* source, User* dest, Channel* channel, std::string &parameter, bool adding);
	/** Validate the parameter - you may change the value to normalize it. Return true if it is valid. */
	virtual bool ParamValidate(std::string& parameter);
};

/**
 * The ModeWatcher class can be used to alter the behaviour of a mode implemented
 * by the core or by another module. To use ModeWatcher, derive a class from it,
 * and attach it to the mode using Server::AddModeWatcher and Server::DelModeWatcher.
 * A ModeWatcher will be called both before and after the mode change.
 */
class CoreExport ModeWatcher : public classbase
{
 private:
	/**
	 * The mode name this class is watching
	 */
	const std::string mode;

	/**
	 * The mode type being watched (user or channel)
	 */
	ModeType m_type;

 public:
	ModuleRef creator;
	/**
	 * The constructor initializes the mode and the mode type
	 */
	ModeWatcher(Module* creator, const std::string& modename, ModeType type);
	/**
	 * The default destructor does nothing.
	 */
	virtual ~ModeWatcher();

	/**
	 * Get the mode name being watched
	 * @return The mode name being watched
	 */
	const std::string& GetModeName() const { return mode; }

	/**
	 * Get the mode type being watched
	 * @return The mode type being watched (user or channel)
	 */
	ModeType GetModeType();

	/**
	 * Before the mode character is processed by its handler, this method will be called.
	 * @param source The sender of the mode
	 * @param dest The target user for the mode, if you are watching a user mode
	 * @param channel The target channel for the mode, if you are watching a channel mode
	 * @param parameter The parameter of the mode, if the mode is supposed to have a parameter.
	 * If you alter the parameter you are given, the mode handler will see your atered version
	 * when it handles the mode.
	 * @param adding True if the mode is being added and false if it is being removed
	 * @return True to allow the mode change to go ahead, false to abort it. If you abort the
	 * change, the mode handler (and ModeWatcher::AfterMode()) will never see the mode change.
	 */
	virtual bool BeforeMode(User* source, User* dest, Channel* channel, std::string& parameter, bool adding);
	/**
	 * After the mode character has been processed by the ModeHandler, this method will be called.
	 * @param source The sender of the mode
	 * @param dest The target user for the mode, if you are watching a user mode
	 * @param channel The target channel for the mode, if you are watching a channel mode
	 * @param parameter The parameter of the mode, if the mode is supposed to have a parameter.
	 * You cannot alter the parameter here, as the mode handler has already processed it.
	 * @param adding True if the mode is being added and false if it is being removed
	 */
	virtual void AfterMode(User* source, User* dest, Channel* channel, const std::string& parameter, bool adding);
};

typedef std::multimap<std::string, ModeWatcher*>::iterator ModeWatchIter;

/** The mode parser handles routing of modes and handling of mode strings.
 * It marshalls, controls and maintains both ModeWatcher and ModeHandler classes,
 * parses client to server MODE strings for user and channel modes, and performs
 * processing for the 004 mode list numeric, amongst other things.
 */
class CoreExport ModeParser
{
 private:
	/** Mode handlers for each mode, to access a handler subtract
	 * 65 from the ascii value of the mode letter.
	 * The upper bit of the value indicates if its a usermode
	 * or a channel mode, so we have 256 of them not 64.
	 */
	ModeHandler* modehandlers[256];

	/** Mode watcher classes
	 */
	std::multimap<std::string, ModeWatcher*> modewatchermap;

	/** Displays the current modes of a channel or user.
	 * Used by ModeParser::Process.
	 */
	void DisplayCurrentModes(User *user, User* targetuser, Channel* targetchannel, const char* text);
	/** Displays the value of a list mode
	 * Used by ModeParser::Process.
	 */
	void DisplayListModes(User* user, Channel* chan, std::string &mode_sequence);

	/**
	 * Attempts to apply a mode change to a user or channel
	 */
	ModeAction TryMode(User* user, User* targu, Channel* targc, bool adding, unsigned char mode, std::string &param, bool SkipACL);

	/** Returns a list of user or channel mode characters.
	 * Used for constructing the parts of the mode list in the 004 numeric.
	 * @param mt Controls whether to list user modes or channel modes
	 * @param needparam Return modes only if they require a parameter to be set
	 * @return The available mode letters that satisfy the given conditions
	 */
	std::string CreateModeList(ModeType mt, bool needparam = false);

	/** Recreate the cached mode list that is displayed in the 004 numeric
	 * in Cached004ModeList.
	 * Called when a mode handler is added or removed.
	 */
	void RecreateModeListFor004Numeric();

	/** The string representing the last set of modes to be parsed.
	 * Use GetLastParse() to get this value, to be used for  display purposes.
	 */
	std::string LastParse;
	std::vector<std::string> LastParseParams;
	std::vector<TranslateType> LastParseTranslate;

	unsigned int sent[256];

	unsigned int seq;

	/** Cached mode list for use in 004 numeric
	 */
	std::string Cached004ModeList;

 public:
	typedef unsigned int ModeProcessFlag;
	enum ModeProcessFlags
	{
		/** If only this flag is specified, the mode change will be global
		 * and parameter modes will have their parameters explicitly set
		 * (not merged). This is the default.
		 */
		MODE_NONE = 0,

		/** If this flag is set then the parameters of non-listmodes will be
		 * merged according to their conflict resolution rules.
		 * Does not affect user modes, channel modes without a parameter and
		 * listmodes.
		 */
		MODE_MERGE = 1,

		/** If this flag is set then the mode change won't be handed over to
		 * the linking module to be sent to other servers, but will be processed
		 * locally and sent to local user(s) as usual.
		 */
		MODE_LOCALONLY = 2
	};

	ModeParser();
	~ModeParser();

	/** Initialize all built-in modes
	 */
	static void InitBuiltinModes();

	/** Tidy a banmask. This makes a banmask 'acceptable' if fields are left out.
	 * E.g.
	 *
	 * nick -> nick!*@*
	 *
	 * nick!ident -> nick!ident@*
	 *
	 * host.name -> *!*\@host.name
	 *
	 * ident@host.name -> *!ident\@host.name
	 *
	 * This method can be used on both IPV4 and IPV6 user masks.
	 */
	static void CleanMask(std::string &mask);
	/** Get the last string to be processed, as it was sent to the user or channel.
	 * Use this to display a string you just sent to be parsed, as the actual output
	 * may be different to what you sent after it has been 'cleaned up' by the parser.
	 * @return Last parsed string, as seen by users.
	 */
	const std::string& GetLastParse() const { return LastParse; }
	const std::vector<std::string>& GetLastParseParams() { return LastParseParams; }
	const std::vector<TranslateType>& GetLastParseTranslate() { return LastParseTranslate; }
	/** Add a mode to the mode parser.
	 * @return True if the mode was successfully added.
	 */
	bool AddMode(ModeHandler* mh);
	/** Delete a mode from the mode parser.
	 * When a mode is deleted, the mode handler will be called
	 * for every user (if it is a user mode) or for every  channel
	 * (if it is a channel mode) to unset the mode on all objects.
	 * This prevents modes staying in the system which no longer exist.
	 * @param mh The mode handler to remove
	 * @return True if the mode was successfully removed.
	 */
	bool DelMode(ModeHandler* mh);

	/** Add a mode watcher.
	 * A mode watcher is triggered before and after a mode handler is
	 * triggered. See the documentation of class ModeWatcher for more
	 * information.
	 * @param mw The ModeWatcher you want to add
	 */
	void AddModeWatcher(ModeWatcher* mw);

	/** Delete a mode watcher.
	 * A mode watcher is triggered before and after a mode handler is
	 * triggered. See the documentation of class ModeWatcher for more
	 * information.
	 * @param mw The ModeWatcher you want to delete
	 * @return True if the ModeWatcher was deleted correctly
	 */
	bool DelModeWatcher(ModeWatcher* mw);
	/** Process a set of mode changes from a server or user.
	 * @param parameters The parameters of the mode change, in the format
	 * they would be from a MODE command.
	 * @param user The source of the mode change, can be a server user.
	 * @param flags Optional flags controlling how the mode change is processed,
	 * defaults to MODE_NONE.
	 */
	void Process(const std::vector<std::string>& parameters, User* user, ModeProcessFlag flags = MODE_NONE);

	/** Find the mode handler for a given mode and type.
	 * @param modeletter mode letter to search for
	 * @param mt type of mode to search for, user or channel
	 * @returns a pointer to a ModeHandler class, or NULL of there isnt a handler for the given mode
	 */
	ModeHandler* FindMode(unsigned const char modeletter, ModeType mt);

	/** Find a mode handler by its prefix.
	 * If there is no mode handler with the given prefix, NULL will be returned.
	 * @param pfxletter The prefix to find, e.g. '@'
	 * @return The mode handler which handles this prefix, or NULL if there is none.
	 */
	ModeHandler* FindPrefix(unsigned const char pfxletter);

	/** Returns a list of modes, space seperated by type:
	 * 1. User modes
	 * 2. Channel modes
	 * 3. Channel modes that require a parameter when set
	 * This is sent to users as the last part of the 004 numeric
	 */
	const std::string& GetModeListFor004Numeric();

	/** Generates a list of modes, comma seperated by type:
	 *  1; Listmodes EXCEPT those with a prefix
	 *  2; Modes that take a param when adding or removing
	 *  3; Modes that only take a param when adding
	 *  4; Modes that dont take a param
	 */
	std::string GiveModeList(ModeMasks m);

	/** This returns the PREFIX=(ohv)@%+ section of the 005 numeric, or
	 * just the "@%+" part if the parameter false
	 */
	std::string BuildPrefixes(bool lettersAndModes = true);
};

inline const std::string& ModeParser::GetModeListFor004Numeric()
{
	return Cached004ModeList;
}