/* Spamventure! */
%% starter file by Ran Libeskind-Hadas
%% and modified by Z Dodds

/*



  Comments on your game should go here -- including how to "solve" it
     -- and anything else the graders should know (extras)



*/



% some "nice" prolog settings...  see assignment 8's
% description for the details on what these do
% -- but it's not crucial to know the details of these Prolog internals
:- set_prolog_flag( prompt_alternatives_on, groundness ).
:- set_prolog_flag(toplevel_print_options, [quoted(true), 
     portray(true), attributes(portray), max_depth(999), priority(699)]).




%% thing_at(X, Y) will be true iff thing X is at location Y.
%% player_at(X) will be true iff player is at location X.
%% The use of dynamic should be at the beginning of the file when
%% we plan to mix static and dynamic facts with the same names.

:- dynamic thing_at/2, player_at/1.

%% The player is initially at Jacobs
player_at(jacobs).

%% thing_at(X, Y) is true iff thing X is at location Y.
%% note that the key is not described at jacobs and
%% the spam is described along with west_dorm
%% both of these are problems -- you might start by considering
%% how you might fix them... (see west_dorm for a similar note)
thing_at(key, jacobs).         
thing_at(spam, west_dorm).    

%% path(X, Y, Z) is true iff there is a path from X to Z via direction Y.
path(jacobs, north, parsons).   
path(jacobs, east, west_dorm).
path(parsons, east, platt).
path(parsons, south, jacobs).
path(platt, west, parsons).
path(platt, south, west_dorm).
path(west_dorm, north, platt).
path(west_dorm, west, jacobs).

%% This is how one can take an object.
take(X) :- 
    thing_at(X, in_hand),
    nl, write('You are already holding that.'),
    nl.  /* new line */

take(X) :-
    player_at(Place),
    thing_at(X, Place),
    retract(thing_at(X, Place)),
    assert(thing_at(X, in_hand)),
    nl, write('OK you now have '),
    write(X),
    nl.


%% This is how we move.
north :- go(north).
south :- go(south).
east :- go(east).
west :- go(west).

go(Direction) :-
    player_at(Here),
    path(Here, Direction, There),
    retract(player_at(Here)),
    assert(player_at(There)),
    nl, write('OK, you are now walking to '),
    write(There), nl,
    look.

go(Direction) :-
    player_at(Here),
    \+path(Here, Direction, _),
    write('You cannot go that way.'), nl.


%% The predicates used to describe a place
look :- nl, player_at(Place), describe(Place), nl.

describe(jacobs) :- 
    write('You are in Jacobs building in CS 60.'), nl,
    write('The prof is talking about Prolog.'), nl,
    write('Prolog is so much fun!').

describe(parsons) :- 
    write('You are in the Parsons building.'), nl,
    write('There are engineers here.'), nl,
    write('One of them wants a fourier transform --'), nl,
    write('and wants it fast!').

describe(platt) :- 
    write('You are in Platt.'), nl,
    write('Jays Place has good pizza.').


%% notice that there is a problem here...
%% the can of spam is described in the description
%% of West dorm - but this means that it will
%% still be present in the description even 
%% after being picked up!
%%
%% this may be a good thing to fix to get you started!
%%

describe(west_dorm) :- 
    write('You are at West Dorm.'), nl,
    write('It is probably best not to describe this place.'), nl,
    write('There is a can of Spam at your feet!').


%% The predicates used to start the game
%% You should customize these instructions to reveal
%% the object of your adventure along with any special 
%% commands the user might need to know.
start :- instructions, look.

instructions :- nl,
    write('Welcome to Spamventure!'), nl,
    write('Type east, west, north, or south to move.'), nl,
    write('Type take(item) to take item.'), nl.