-module(rinder).
-export([naive/2, mp/2, mp/3,kmpsupply/1]).
naive(X,T) ->
% API entry: converts the lists/strings to tuples, computes the sizes,
% and calls the real function with args X, T, size(X), size(T), I and J [loop counters].
  XX=list_to_tuple(X),
  TT=list_to_tuple(T),
  M=size(XX),
  N=size(TT),
  log_to_screen("Going with ~p/~p ~p/~p~n",[XX,M,TT,N]),
  log_to_screen("Maximum iterations: ~p~n",[N*M-M*M+M]),
  naive(XX,TT,M,N,1,1).

naive(X,T,M,N,I,J) when I>M ->
% finished: found an occurence at pos j-m
  J-M;
naive(X,T,M,N,I,J) when J>N ->
% finished. Not found
  -1;
naive(X,T,M,N,I,J) ->
% Main loop.
  Cond=element(I,X),
  Cond2=element(J,T),
  case Cond2 of
    Cond ->
      naive(X,T,M,N,I+1,J+1);
    _ ->
      naive(X,T,M,N,1,J-I+2)
  end.

mpsupply(X) ->
  XX=list_to_tuple(X),
  mp_supply(XX,size(XX)-1,1,[0]).
mp_supply(X,M,J,S) when J>M ->
  list_to_tuple(S);
mp_supply(X,M,J,S) ->
  I=mp__supply(X,M,J,S,element(J,list_to_tuple(S))),
  mp_supply(X,M,J+1,lists:flatten([S,I+1])).
mp__supply(X,M,J,S,I) ->
  case I of
    0 -> I;
    _ ->
      Cond=element(I,X),
      Cond2=element(J,X),
      case Cond of
        Cond2 ->
          I;
        _ ->
          mp__supply(X,M,J,S,element(I,list_to_tuple(S)))
      end
  end.

mp(X,T) ->
% API entry: converts the lists/strings to tuples, computes the sizes, and the supply function
% and calls the real function with args X, T, size(X), size(T),
% I and J [loop counters], and the supply function [as a tuple].
% Of course, since the next API entry does all this, just call it with J = 1
  mp(X,T,1).

mp(X,T,J) ->
% same API entry as above with J [start position in the source string T] preset:
% aka look for the *next* occurence
% rinder:mp("cab","acabacabacab"). ==> 2
% rinder:mp("cab","acabacabacab",3). ==> 6
% rinder:mp("cab","acabacabacab",7). ==> 10
% rinder:mp("cab","acabacabacab",11). ==> -1
  XX=list_to_tuple(X),
  TT=list_to_tuple(T),
  M=size(XX),
  N=size(TT),
  S=mpsupply(X),
  mp(XX,M,TT,N,1,J,S).
mp(X,M,T,N,I,J,S) when I>M ->
% finished. Found an occurence of x in t at position j-m
  J-M;
mp(X,M,T,N,I,J,S) when J>N ->
% finished. Not found.
  -1;
mp(X,M,T,N,I,J,S) ->
% main loop
  case I of
    0 -> mp(X,M,T,N,I+1,J+1,S);
    _ ->
      Cond=element(J,T),
      Cond2=element(I,X),
      case Cond of
        Cond2 -> mp(X,M,T,N,I+1,J+1,S);
            _ -> mp(X,M,T,N,element(I,S),J,S)
      end
  end.



log_to_screen(A,B) -> io:format(A,B).