/*       +------------------------------------+
 *       | Inspire Internet Relay Chat Daemon |
 *       +------------------------------------+
 *
 *  InspIRCd: (C) 2002-2011 InspIRCd Development Team
 * See: http://wiki.inspircd.org/Credits
 *
 * This program is free but copyrighted software; see
 *            the file COPYING for details.
 *
 * ---------------------------------------------------
 */

#ifndef __MODE_H
#define __MODE_H

#define MODE_ID_MAX 128

/**
 * 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 */
};

/** Mode identifier for quick lookup of modes that do not have a letter */
class ModeID
{
	unsigned char id;
 public:
	ModeID() : id(0) {}
	inline bool operator<(const ModeID& other) const { return id < other.id; }
	inline bool operator==(const ModeID& other) const { return id == other.id; }
	inline void SetID(int nid) { id = nid; }
	inline int GetID() const { return id; }
};

class ModeIDIter
{
	unsigned char current;
 public:
	ModeIDIter() : current(1) {}
	inline operator ModeID() { ModeID id; id.SetID(current); return id; }
	inline operator bool() const { return current != MODE_ID_MAX; }
	inline void operator++() { ++current; }
	inline void operator++(int) { current++; }
};

namespace irc
{
	class CoreExport modechange
	{
	 public:
		bool adding;
		ModeID mode;
		std::string value;
		modechange(ModeID id, const std::string& param = "", bool add = true)
			: adding(add), mode(id), value(param) {}
		modechange(const std::string& name, const std::string& param = "", bool add = true);
		modechange(char modechar, ModeType type, const std::string& param = "", bool add = true);
	};

	/** irc::modestacker stacks mode sequences into a list.
	 * It can then reproduce this list, clamped to a maximum of MAXMODES
	 * values per line.
	 */
	class CoreExport modestacker
	{
	 public:
		/** The mode sequence and its parameters
		 */
		std::vector<modechange> sequence;
		/** Add a mode change to this sequence */
		inline void push(const modechange& mc) { sequence.push_back(mc); }

		inline bool empty() const { return sequence.empty(); }

		/** Pop a single mode line from this stack
		 * @param format The format to use for the sequence (UID translation)
		 * @param maxlen Maximum length of the string
		 * @param maxmodes Maximum number of modes to change. 0 = MaxModes config option
		 */
		std::string popModeLine(SerializeFormat format, int maxlen = 400, int maxmodes = 0);
	};
}

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

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

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

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

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

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

	/**
	 * True if the mode requires oper status
	 * to set.
	 */
	unsigned int oper:1;

	/**
	 * True if the letter for this mode needs to stay fixed,
	 * that is, can't be changed in the configuration
	 */
	unsigned int fixed_letter:1;

	/**
	 * 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)
	 */
	unsigned int list:1;

 public:
	/** Mode is disabled by the configuration file
	 */
	unsigned int disabled:1;

	/** The mode identifier (only valid after this object has been added to ModeParser) */
	ModeID id;
	/**
	 * 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 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)
	 */
	ModeHandler(Module* me, const std::string& name, char modeletter, ParamSpec params, ModeType type);
	virtual CullResult cull();
	virtual ~ModeHandler();
	/**
	 * Returns true if the mode is a list mode
	 */
	bool IsListMode();
	/**
	 * 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.
	 */
	virtual unsigned int GetPrefixRank();
	/**
	 * 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; }

	/** Translate a parameter
	 * @param value The value being translated. If changed to empty string,
	 * the mode change will be omitted (assuming it requires a parameter)
	 * @param adding True if adding the mode
	 * @param format The target of this translation
	 */
	virtual void TranslateMode(std::string& value, bool adding, SerializeFormat format) {}

	/**
	 * 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; }

	/** Adjusts the mode character due to a configuration override.
	 * This is done during AddMode; do not change it after the mode is added.
	 */
	void AdjustModeChar(char proposed_letter);

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

	/**
	 * Populate mode list with changes required to set this mode on this channel.
	 * For non-list modes, this is the single mode change. For list modes, all list items.
	 */
	virtual void PopulateChanModes(Channel* channel, irc::modestacker& stack);

	/** For list modes, return the list */
	virtual const modelist* GetList(Channel* channel) { return NULL; }

	/**
	 * Called when a channel mode change access check for your mode occurs. This is called prior to
	 * the OnPermissionCheck hook, and before any channel rank checks.
	 */
	virtual void AccessCheck(ModePermissionData&);

	/**
	 * 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) = 0;

	/**
	 * 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.
	 * @param parameter The parameter (initially empty); if you fill this in, the mode change will be accepted
	 */
	virtual void OnParameterMissing(User* user, User* dest, Channel* channel, std::string& parameter);

	/**
	 * 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 (i.e. case sensitive string ordering).
	 * @param theirs The parameter on the remote side
	 * @param ours The parameter on the local side
	 * @return True if the other side wins the merge, false if we win the merge.
	 */
	virtual bool ParamOrder(const std::string &theirs, const std::string &ours);

	/**
	 * When a MODETYPE_USER mode handler is being removed, the server will call this method for every user on the server.
	 * Your mode handler should remove its user mode from the user by sending the appropriate server modes using
	 * InspIRCd::SendMode(). The default implementation of this method can remove simple modes which have no parameters,
	 * and can be used when your mode is of this type, otherwise you must implement a more advanced version of it to remove
	 * your mode properly from each user.
	 * @param user The user which the server wants to remove your mode from
	 */
	virtual void RemoveMode(User* user, irc::modestacker* stack = NULL);

	/**
	 * When a MODETYPE_CHANNEL mode handler is being removed, the server will call this method for every channel on the server.
	 * Your mode handler should remove its user mode from the channel by sending the appropriate server modes using
	 * InspIRCd::SendMode(). The default implementation of this method can remove simple modes which have no parameters,
	 * and can be used when your mode is of this type, otherwise you must implement a more advanced version of it to remove
	 * your mode properly from each channel. Note that in the case of listmodes, you should remove the entire list of items.
	 * @param channel The channel which the server wants to remove your mode from
	 */
	virtual void RemoveMode(Channel* channel, irc::modestacker* stack = NULL);

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

/** 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);
};

class PrefixModeHandler : public ModeHandler
{
 public:
	PrefixModeHandler(Module* Creator, const std::string& Name, char modeletter)
		: ModeHandler(Creator, Name, modeletter, PARAM_ALWAYS, MODETYPE_CHANNEL)
	{
		list = true;
		m_paramtype = TR_NICK;
	}

	virtual void RemoveMode(Channel* channel, irc::modestacker* stack);
	void RemoveMode(User* user, irc::modestacker* stack);
};

/**
 * 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
{
 protected:
	/**
	 * The mode letter this class is watching
	 */
	char 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, char modeletter, ModeType type);
	/**
	 * The default destructor does nothing.
	 */
	virtual ~ModeWatcher();

	/**
	 * Get the mode character being watched
	 * @return The mode character being watched
	 */
	char GetModeChar();
	/**
	 * 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
	 * @type The mode type, either MODETYPE_USER or MODETYPE_CHANNEL
	 * @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, ModeType type);
	/**
	 * 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
	 * @type The mode type, either MODETYPE_USER or MODETYPE_CHANNEL
	 */
	virtual void AfterMode(User* source, User* dest, Channel* channel, const std::string &parameter, bool adding, ModeType type);
};

/** 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 128.
	 */
	ModeHandler* handlers[MODE_ID_MAX];
	/** Mode watcher classes arranged in the same way as the
	 * mode handlers
	 */
	typedef std::multimap<ModeID, ModeWatcher*> ModeWatcherMap;
	ModeWatcherMap modewatchers;

	/** 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, const std::string &mode_sequence);

	/**
	 * Attempts to apply a mode change to a user or channel
	 */
	ModeAction TryMode(User* user, User* targu, Channel* targc, irc::modechange& mc, bool SkipACL);

 public:

	/** The constructor initializes all the RFC basic modes by using ModeParserAddMode().
	 */
	ModeParser();
	~ModeParser();

	/** 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);

	/** Add a mode to the mode parser.
	 * @return True if the mode was successfully added.
	 */
	void 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
	 * @return True if the ModeWatcher was added correctly
	 */
	bool 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);

	void Parse(const std::vector<std::string>& parameters, User *user, Extensible*& target, irc::modestacker& modes);

	/** Process a set of mode changes from a server or user.
	 * @param sre The source of these changes; use ServerInstance->FakeUser for server source
	 * @param target The user or channel that is being changed
	 * @param modes The modes being changed. Changes that are denied will be removed from the list.
	 * @param merge True if modes should be merged rather than just applied (used in netburst)
	 * @param skipACL True if the ACL checks should be skipped for this mode change
	 */
	void Process(User *src, Extensible* target, irc::modestacker& modes, bool merge = false, bool skipACL = false);

	void Send(User *src, Extensible* target, irc::modestacker modes);

	/** Find the mode handler for a given mode and type.
	 * @param modeletter mode letter to search for
	 * @param 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 char modeletter, ModeType mt);
	ModeHandler* FindMode(const std::string& name);
	inline ModeHandler* FindMode(ModeID id) { return handlers[id.GetID()]; }

	/** 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 char pfxletter);

	/** Returns a list of mode characters which are usermodes.
	 * This is used in the 004 numeric when users connect.
	 */
	std::string UserModeList();

	/** Returns a list of channel mode characters which are listmodes.
	 * This is used in the 004 numeric when users connect.
	 */
	std::string ChannelModeList();

	/** Returns a list of channel mode characters which take parameters.
	 * This is used in the 004 numeric when users connect.
	 */
	std::string ParaModeList();

	/** 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(ModeType m);

	static bool PrefixComparison(ModeHandler* one, ModeHandler* two);

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

#endif