-module(primes).
-export([start/0,
	 primes/0,sieve/1,allNumbers/1]).

start() ->
    P=spawn(primes,primes,[]),
    %P=spawn(primes,filterStart,[2]),
    show(P,1).

show(P,M) ->
    P!{get,self()},
    receive
	N -> io:format("Step ~w: ~w~n",[M,N]),
	     case N>80000000 of
		 false -> show(P,M+1);
		 true  -> ok
	     end
    end.

nextNumber(N,GenPid) ->
    GenPid!{get,self()},
    receive
	M -> case M rem N of
		 0 ->
		     nextNumber(N,GenPid);
		 _ ->
		     M
	     end
    end.

allNumbers(N) ->
    receive
	{get,P} ->
	    P!N,
	    allNumbers(N+1)
    end.

sieve(Numbers) ->
    receive
	{get,P} -> Numbers!{get,self()},
		   receive
		       Primzahl -> 
			   NextPrim=spawn(primes,sieve,[self()]),
			   P!{primzahl,Primzahl,NextPrim},
			   numbers(Primzahl,Numbers)
		   end
    end.

numbers(Primzahl,Numbers) ->
    receive
	{get,P} -> P!nextNumber(Primzahl,Numbers),
		   numbers(Primzahl,Numbers)
    end.

primes() ->
    AllNumbers=spawn(primes,allNumbers,[2]),
    Primes=spawn(primes,sieve,[AllNumbers]),
    collectAllPrimes(Primes).

collectAllPrimes(P) ->
    receive
	{get,P1} ->
	    P!{get,self()},
	    receive
		{primzahl,Primzahl,P2} -> 
		    P1!Primzahl,
		    collectAllPrimes(P2)
	    end
    end.