Generic Elevator (#1543)

     The Generic Elevator together with the Generic Elevator Call Button form a general 
purpose elevator that appears to travel between floors.
     
     The Generic Elevator is a child of the Generic Post-Apocalypse Room Class.
     
     To construct an elevator with multiple floors, create an instance of the Generic 
Elevator #1543 using something like:
     
         @create #1543 named "M of I Elevator"
     
     Each room that has access to the elevator should create a normal exit that enters 
the elevator, using an appropriate exit word like "enter" or "elevator".  This exit 
will not be usable unless the elevator is present at this floor and the door is open.
     
     The list of floors that an elevator can reach is given by the .floor_names property. 
 This property is an array of string values giving, in order, the names of floors 
that can be selected.  Similarly, the .floor_exits property gives the actual room 
numbers to be used at each of these floors.
     
     In order to call the elevator, place an instance of the Generic Elevator Call Button 
#1260 in each room:
     
         @create #1260 named "a rusted elevator call button"
     
     On each of these call buttons, use the .elevator property to associate this call 
button with the elevator it is to summon.  Similarly, use the .floor_name property 
to state the name of the floor where this button can be found.
     
     Proof by example.  The Ministry of Information Elevator is object #1531. It has three 
floors named "G", "1" and "2".  These floor labels are to the rooms numbered #1493, 
#1517, and #1524, respectively.  So #1531 has these properties to describe its floor 
choices:
     
     	; #1531.floor_names
     	=> {"G", "1", "2"}
     	; #1531.floor_exits
     	=> {#1493, #1517, #1524}
     
     For example, the call button on the "G" floor in room #1493 shows:
     
             ; #1508.floor_name
             => "G"
             #1508.elevator
             => #1531  (M of I Elevator)
     
     The property .floor_delay can be set on the elevator to change the speed of an elevator 
as it travels from floor to floor.  Currently, the default is 3.  That value is measured 
in non-blocking suspend() units.
     
     Similarly, the length of time a door will remain open before it automatically closes 
again can be adjusted by setting the .door_delay property.  Currently, the default 
is 6.
     
     Then, to add local color, one can create the appearance of an unreliable delivery 
mechanism.  By setting the .reliable property to 0, and the .odds property to a value, 
n, n > 1, the elevator will then have a 1 in n chance of NOT making it to the next 
floor.
     
     Limitations:  Although more than one user may be in the elevator at a time, there 
can be only one active destination at a time.  I didn't feel like writing the disk-scheduling 
algorithm.
     
     If things look wedged, be sure and kick the control panel...

return (this.door == 1) || (caller == this.owner);
.

if (this.door != 1)
    this:announce_all("The doors open.");
    this.exit:announce_all("The elevator doors open.");
    this.door = 1;
    fork dtask (this.door_delay)
        this:close_door();
    endfork
    this.door_task = dtask;
else
    player:tell("The doors are already open.");
endif
.

if (this.door == 1)
    this:announce_all("The doors close.");
    this.exit:announce_all("The elevator doors close.");
    this.door = 0;
    kill_task(this.door_task);
endif
.

dest_floor = args[1];
dest_n = dest_floor in this.floor_names;
cur_n = this.floor in this.floor_names;
if (dest_n == 0)
    player:tell("There is no button labeled ", dest_floor, ".");
    return;
endif
if (this.in_use)
    player:tell("Fried circuitry is only allowing one destination at a time.");
    return;
endif
this.in_use = 1;
this:close_door();
player:tell("Whirring and clanking machinery grind into motion...");
this:announce("Grinding gears and the whine of engines echo in the distance.");
if (cur_n < dest_n)
    delta = 1;
elseif (cur_n > dest_n)
    delta = -1;
endif
stopped = 0;
while ((!stopped) && (this.floor != dest_floor))
    suspend(this.floor_delay);
    cur_n = cur_n + delta;
    this.floor = this.floor_names[cur_n];
    this.exit = this.floor_exits[cur_n];
    this:announce_all(this.floor);
    if (!this.reliable)
        stopped = random(this.odds) == 1;
        if (stopped)
            this:announce_all("You hear a very strange grinding sound as the elevator 
lurches to a halt.");
        endif
    endif
endwhile
suspend(this.floor_delay);
if (stopped)
    player:tell("It's unclear if the elevator is at the right floor...");
endif
this.in_use = 0;
this:open_door();
.

calling_floor = args[1];
if (calling_floor in this.floor_names)
    if (this.door == 1)
        player:tell("The elevator is already here and the doors are open.");
    else
        if ((!this.being_called) && (!this.in_use))
            this.being_called = 1;
            this:move_to_floor(calling_floor);
            this.being_called = 0;
            if (this.floor != calling_floor)
                player:tell("Hmm.  The elevator might not have made it to this floor...");
            endif
        else
            player:tell("Seems the elevator might be in use...");
        endif
    endif
endif
.

if ((dobjstr == "") || (dobjstr == "door"))
    this:open_door();
else
    pass(@args);
endif
.

if (this.door == 1)
    dest = this.exit;
    player:moveto(dest);
    if (random(4) == 1)
        fork (this.activity_delay)
            mystery_call = random(length(this.floor_names));
            this:call_elevator(this.floor_names[mystery_call]);
        endfork
    endif
else
    player:tell("The doors are closed.");
endif
.

dest_floor = args[1];
if (dest_n = dest_floor in this.floor_names)
    player:tell("You reach out and press the ", dest_floor, " button.");
    this:announce(player.name, " presses the ", dest_floor, " button.");
    this:move_to_floor(dest_floor);
else
    player:tell("There isn't a button labeled ", dest_floor, ".");
endif
.

pass(@args);
player:tell("A panel has buttons labeled: ");
player:tell_lines(this.floor_names);
.

this.in_use = 0;
this.door = 0;
player:tell("You seem to have rattled the circuitry some.  Now give it a try.");
.

if ((length(args) == 1) && (dobjstr == "panel"))
    player:tell("A panel has buttons labeled:");
    player:tell_lines(this.floor_names);
else
    pass(@args);
endif
.