/* 

  MicroSam in Picat.

  Simplified version of SAM (Script Applier Mechanism).

  This Picat version is based on the Prolog code from
  Leon S. Sterling: "The Art of Prolog", 2nd edition,
  page 274ff.

  This Picat model was created by Hakan Kjellerstrand, hakank@gmail.com
  See also my Picat page: http://www.hakank.org/picat/

*/


% import util.
% import cp.


main => go.

go ?=> 
   test_mcsam(Name,UnderstoodStory),
   writeln(name=Name),
   % writeln(understoodStory=UnderstoodStory),
   foreach(S in UnderstoodStory) writeln(S) end,
   nl,
   fail.

go => true.

mcsam(Story,Script) =>  
   find(Story,Script,Defaults),
   match(Script,Story),
   name_defaults(Defaults).

find(Story,Script,Defaults) => 
   filler(Slot,Story),
   trigger(Slot,Name),
   script(Name,Script,Defaults).

/*
   match(Script,Story) =>
      Story is a subsequence of Script.
*/
match(_Script,Story) ?=> Story = [].
match(LineScript,LineStory) ?=> 
    LineScript = [Line|Script],
    LineStory = [Line|Story],
    match(Script,Story).
match(LineScript, LineStory) => 
    LineScript = [_Line|Script],
    LineStory = Story,
    match(Script,Story).

/*
   filler(Slot,Story) =>
      Slot is a word in Story.
*/

filler(Slot,Story) => 
   member([_Action|Args],Story),
   member(Slot,Args),
   nonvar(Slot).

/*
   name_defaults(Defaults) =>
      Unifies default pairs in Defaults.
*/

name_defaults(Defaults) ?=> 
   Defaults = [].
name_defaults(Defaults) ?=>  
   Defaults = [[N,N]|L],
   name_defaults(L).
name_defaults(Defaults) =>  
   Defaults = [[N1,N2]|L],
   N1 != N2, 
   name_defaults(L).


%
% Program 14.17 (page 277)
%
% The story is
%    "John went to Leones, ate a hamburger, and left."
% 
test_mcsam(Name,UnderstoodStory) =>
   story(Name,Story), 
   mcsam(Story,UnderstoodStory).

story(Name, Story) ?=> 
   Name=test,
   Story=[[ptrans, john, john, _X1, leones],
          [ingest, _X2, hamburger, _X3],
          [ptrans, Actor, Actor, _X4, _X5] ].

script(Name, Script, Defaults) => 
   Name = restaurant,
   Script = 
   [ [ptrans, Actor, Actor, Earlier_place, Restaurant],
     [ptrans, Actor, Actor, Door, Seat],
     [mtrans, Actor, Waiter, Food],
     [ingest, Actor, Food, [mouth, Actor] ],
     [atrans, Actor, Money, Actor, Waiter],
     [ptrans, Actor, Actor, Restaurant, Gone] ],
   Defaults = [ [Actor, customer], [Earlier_place, place1],
     [Restaurant, restaurant], [Door, door],
     [Seat, seat], [Food, meal], [Waiter, waiter],
     [Money, check], [Gone, place2] ].

trigger(Slot, Name) ?=> 
   Slot = leones, 
   Name=restaurant.  
trigger(Slot, Name) => 
   Slot = waiter, 
   Name = restaurant.