=begin comment

 This file is part of Deliantra, the Roguelike Realtime MMORPG.
  
 Copyright (©) 2005,2006,2007,2008,2009 Marc Alexander Lehmann / Robin Redeker / the Deliantra team
  
 Deliantra is free software: you can redistribute it and/or modify it under
 the terms of the Affero GNU General Public License as published by the
 Free Software Foundation, either version 3 of the License, or (at your
 option) any later version.
  
 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 Affero GNU General Public License
 and the GNU General Public License along with this program. If not, see
 <http://www.gnu.org/licenses/>.
  
 The authors can be reached via e-mail to <support@deliantra.net>

=end comment

=head1 DELIANTRA PLUG-IN EVENTS

This document briefly describes each plug-in event. It is also used to
generate the event-list itself, so is always complete. Be careful wehn
changing it, though.

=head2 NOTATION

The event description below uses a variant of the forth stack notation -
an opening parenthesis followed by the type of each parameter, optionally
followed by two dashes and the returning parameters. If the latter part is
missing, the event will be invoked but cannot change wether the event gets
processed.

Return values are given by overriding (in Perl by calling C<cf::override>)
with the return values, which will both stop further event processing and
tell the caller that it wants to override normal processing.

Even if no return values are supported, a plug-in can override (e.g. using
C<cf::override> in Perl) event processing, basically short-circuiting
it. For example, if you override from within a player BIRTH event,
nothing much will happen with respect to the built-in processing, but if
you override from within a player TELL event, the tell will be ignored
(presumably your plug-in took care of it).


=head2 ATTACHABLE EVENTS

No time to document this, screw me.

=head3 instantiate (object init-args...)

An object was instantiated.

For objects, this event occurs when a map is loaded for the first time
when it was instantiated from an archetype, or when the object was created
dynamically. The arguments are as specified in the C<attach> attribute of
the object or archetype.

This is useful to initialise any per-object state you might need.

=head3 reattach	(object)

Invoked whenever attachments/plug-ins need to get reattached to the
object. This usually happens when it was loaded from disk, or when the
server was reloaded. This event will only be generated if the object has
attachments.

=head3 clone (object destination)

An object with _attached plugin_ is cloned, that is, a copy was made. The
copy automatically has all attachments the original object had. The perl
variables get copied in a shallow way (references are shared between
instances). If this is not the behaviour you need, you have to adjust the
B<destination> object as you see fit.

=head3 destroy (object -- )

Invoked when the deliantra object gets destroyed, and only when the object
has a handler for this event. This event can occur many times, as its
called when the in-memory object is destroyed, not when the object itself
dies.


=head2 OBJECT EVENTS

Object events always relate to a specific object, which is always the
first argument. Not all events get generated for every object, some are
specific to an object type.

=head3 add_bonus (item creator difficulty max_magic flags -- )

A basic item has been created (e.g. for shops, monsters drops etc.)
that needs bonus values applied. The B<creator> object is a template
object that can be used to inherit stuff (and can be NULL). Flags is a
combination of GT_ENVIRONMENT (???) or GT_STARTEQUIP (set FLAG_STARTEQUIP
on item or set its value to 0) or GT_MINIMAL (???)

When overriden, built-in bonus generation is skipped, otherwise
treasure generation continues as it would without this hook.

In general, if flags != 0 or creator != 0 you should just return and leave
item generation to the standard code.

=head3 remove (object -- )

Invoked before the object is removed from its environment.

=head3 insert (object -- )

Called after the object was inserted into a container or map.

=head3 tick (object -- )

Invoked whenever the object "ticks", i.e. has positive B<speed_left>. Only
during ticks should an objetc process any movement or other events.

=head3 kill (object hitter -- )

Invoked whenever an object was killed (hp < 0 caused by an attack) and is
about to get removed. Overriding processing will skip removal, but to do
this successfully you have to keep the object from dieing, otherwise the
event gets invoked again and again.

=head3 apply (object who -- applytype)

Invoked whenever the object is being applied in some way. The applytype is one of:

=over 4

=item B<0> player or monster can't apply objects of that type

=item B<1> has been applied, or there was an error applying the object

=item B<2> objects of that type can't be applied if not in inventory

=back

=head3 reset (object)

Invoked whenever the object is initialised on a map after it was
loaded. This can be used to emulate shop-floor behaviour for example.

=head3 throw (object thrower)

Invoked when an B<object> is thrown by B<thrower>.

=head3 stop (object -- )

Invoked when a thrown B<object> (arrow, other stuff) hits something and is
thus being "stopped".

=head3 can_apply (who object -- reason)

=head3 can_be_applied (object who -- reason)

Check wether the B<object> can be applied/readied/etc. by the
object B<who> and return reason otherwise. Reason is a bitset composed of
C<CAN_APPLY_*>-flags.

=head3 be_ready (object who -- success)

=head3 ready (who object -- success)

Invoked whenever an B<object> is being applied by object B<who>. See
I<can_apply> for an alternative if you just want to check wether something
can apply an object.

=head3 be_unready (object who -- deleted)

=head3 unready (who object -- deleted)

Unwield/unapply/unready the given spell/weapon/skill/etc. B<object>,
currently applied by B<who>. If your override, make sure you give 'who'
(if it is a player) an indication of whats wrong. Must return true if the
object was freed.

=head3 use_skill (skill who part direction stringarg -- )

Invoked whenever a skill is used by somebody or something.

=head3 cast_spell (spell owner casting_object direction stringarg -- )

Invoked whenever a given spell is cast by B<casting_object> (used by
B<owner>).

=head3 drop (object who -- )

Invoked whenever an item gets dropped by somebody, e.g. as a result of a
drop command.

=head3 drop_on (floor object who -- )

Invoked whenever some B<object> is being dropped on the B<floor> object.

=head3 say (object player message)

Invoked whenever the I<object> can hear a B<message> being said by
B<player> in its vicinity.

=head3 monster_move (monster enemy -- )

Invoked whenever the B<monster> tries to move, just after B<enemy> and
other parameters have been determined, but before movement is actually
executed.

=head3 attack (object hitter -- damage)

Object gets attacked by somebody - when overriden, should return the
damage that has been dealt.

=head3 skill_attack (attacker victim message skill -- success)

Invoked whenever an B<attacker> attacks B<victim> using a B<skill> (skill
can be C<undef>). B<message> is the message that describes the attack when
damage is done.

=head3 weapon_attack (weapon hitter victim)

Invoked whenever an object is used as a B<weapon> by B<hitter> to attack
B<victim>.

=head3 inscribe_note (book pl message skill -- )

Used whenever a book gets inscribed with a message.

=head3 trigger (object who -- )

Invoked whenever a lever-like B<object> has been activated/triggered in some
(manual) way.

=head3 move_trigger (object victim originator -- )

Invoked whenever a trap-like B<object> has been activated, usually by
moving onto it. This includes not just traps, but also buttons, holes,
signs and similar stuff.

=head3 open (container who -- )

Invoked whenever a container gets opened. When overriden, the container will not
get opened, but you must tell op about the reason.

=head3 close (container who -- )

Invoked whenever a container gets closed. When overriden, the container
will not get closed, but you must tell op about the reason. This event
is not crash-safe, i.e. containers might be closed due to a server crash
without this event being invoked.

=head3 blocked_move (self who -- do_blocked)

Invoked when an C<who> tries to move to the same space as C<self>,
C<self>'s C<move_block> causes blocked movement for C<who> and nothing
else explicitly allows movement to this space.

Should return true when C<who> is blocked, i.e., should not be allowed to
move onto C<self>.

When not overriding, normal blocked_move (blocked_link) processing will
happen.


=head2 GLOBAL EVENTS

Global events have no relation to specific objects.

=head3 cleanup ()

Called when the server is cleaning up, just before it calls exit.

=head3 clock ()

Is invoked on every server tick, usually every 0.12 seconds.

=head3 resource_update ()

Is invoked after each time the server reloads its resources, which is
usually one of the earliest things it does when starting up.


=head2 PLAYER EVENTS

Player events always have a player object as first argument.

=head3 birth (player)

Invoked as very first thing after creating a player.

=head3 quit (player)

Invoked wheneever a player quits, before actually removing him/her.

=head3 kick (player params -- )

Invoked when the given player is being kicked, before the kick is
executed.

=head3 load (player -- )

Invoked whenever after a player has been loaded from disk, but before
actual activation/login.

=head3 save (player -- )

Invoked just before a player gets serialised.

=head3 save_done (player -- )

Invoked just after a player was serialised.

=head3 connect (player -- )

Invoked just after the player object was connected to a client.

=head3 disconnect (player -- )

Invoked just before the player gets disconnected from the client.

=head3 login (player)

Invoked whenever a player logs in.

=head3 logout (player cleanly -- )

Invoked whenever a player logs out, gets disconnected etc.

=head3 death (player)

Invoked whenever a player dies, before the death actually gets processed.

=head3 map_change (player newmap x y -- )

Invoked before a player moves from one map to another, can override the movement.

=head3 region_change (player newregion oldregion -- )

Invoked when a player entered a new region. Cannot be overriden.

=head3 command (player command args -- time)

Execute a user command sent by the client - this is invoked for I<all>
command,s so should not normally be hooked.

=head3 unknown_command (player command args -- time)

Execute a user command sent by the client that isn't known to the
server. Programmable plug-ins usually handle this event internally.

=head3 extcmd (player string)

Invoked whenever a client issues the C<extcmd> protocol command.
Programmable plug-ins usually handle this event internally.

=head3 move (player direction -- )

Called whenever the player is supposed to move or attack. The handler
must handle the cases of speed_left or weapon_sp_left being negative,
fire being on, is responsible for decreaseing the speed_left value
on successful moves etc. etc.. When overriden, must return a boolean
indicating wether a move could be effected.

=head3 pray_altar (player altar skill -- )

Invoked whenever the B<player> prays over an B<altar>, using the given B<skill>.

=head3 tell (player name message -- )

Invoked whenever the player uses the B<tell> or B<reply> command, before
it gets processed.

=head3 told (player player message -- )

Invoked right before a message is being told to a player using B<tell> or
B<reply>.

=head3 say (player message --)

=head3 chat (player message --)

=head3 shout (player message --)

Invoked whenever the player uses the B<say>, B<chat> or B<shout> command,
before it gets processed.

=head3 build (player builder map x y --)

Players tries to build using C<builder> at (map+x+y). Is invoked after the
usual sanity checks, so the coordinates are valid.


=head2 MAP EVENTS

These events are generally dependent on a map and thus all have a map
as first argument.

=head3 instantiate (map)

Original B<map> has been loaded (e.g. on first use, or after a map
reset).

=head3 swapin (map)

Invoked when a previously swapped-out temporary B<map> has been loaded again.

=head3 swapout (map)

Invoked after a B<map> has been swapped out to disk.

=head3 reset (map)

Invoked when a B<map> gets reset.

=head3 clean (map)

Invoked when a temporary B<map> gets deleted on-disk.

=head3 enter (map player x y -- )

Invoked whenever a player tries to enter the B<map>, while he/she is still
on the old map. Overriding means the player won't be able to enter, and,
if newmap/x/y are given, will be redirected to that map instead.

=head3 leave (map player -- )

Invoked whenever a player tries to leave the B<map>. Overriding means the
player won't be able to leave.

=head3 trigger (map connection state what? who? -- )

Invoked whenever something activates a B<connection> on the B<map>. If B<state>
is true the connection was 'state' and if false it is 'released'.


=head2 CLIENT EVENTS

These events are very similar to player events, but they are might be
handled asynchronously as soon as the command reaches the server, even when
the player hasn't logged in yet (meaning there is no player yet).

=head3 connect (client -- )

Called as soon as a new connection to the server is established. Should
not be overriden.

=head3 version (client string -- )

Called as soon as the version command from the client is received
(normally the very first command sent).

=head3 setup (client string -- )

Client sent the setup command to negotiate parameters. Handling is
mandatory and done by F<login.ext>.

=head3 addme (client -- )

The client sent an addme, thus ending the initial handshaking. Handling is mandatory
and done by F<login.ext>.

=head3 reply (client replystring -- )

Called when the client submits a reply in the ST_CUSTOM state. Usually
handled internally by language plugins.

=head3 exticmd (client string -- )

Like C<extcmd>, but can be called before a player has logged in.

Programmable plug-ins usually handle this event internally.

=head3 client_destroy (client -- )

Invoked when the client gets destroyed.