err_man.erl

%% Author: Francesco
%% Created: May 27, 2009
%% Description: TODO: Add description to man
-module(err_man).

%%
%% Include files
%%

%%
%% Exported Functions
%%
-export([err_man_life/5]).

%%
%% API Functions
%%

%%%%%%%%%%% err_man_life( PARENT, CHILDREN, NODES, NUM_N, NUM_C, DEPTH, INPUT, ERROR_TREE_ROOT, TWIN)
%% param:
%%      PARENT: Father's PID
%%      CHILDREN : a list containing the subtree's PIDs
%%	NODES : a list containing the nodes' PIDs handled by this manager
%%	DEPTH : the depth in the tree
%%	TWIN : is the associate manager in the winner tree
%% receives:
%%	+ {decrease_error, PARENT ,ALPHA}
%%		- comunicates to decrease error of a factor ALPHA to all the subtree	
%% sends:
%%		- PARENT ! { my_error , self (), MAX }
%%
%%
%% Sends distance request to all the nodes in NODES and asks for the sub_winner and sub_runner to the subtrees in CHILDREN
%% Combines all and sends a message to the father comunicating his winner and runner.

err_man_life(PARENT, CHILDREN, NODES, DEPTH, TWIN) ->
    receive
      {set_twin, NEW_TWIN} ->
	  err_man_life(PARENT, CHILDREN, NODES, DEPTH, NEW_TWIN);
      {removeNode, NodePID} ->
	  io:format("E_M ~p ERR:I received Remove Node :~p~n",
		    [self(), NodePID]),
	  TWIN ! {removeNode, NodePID},
	  err_man_life(PARENT, CHILDREN,
		       lists:delete(NodePID, NODES), DEPTH, TWIN);
      {addNode,
       NEW_NODE} -> %% this is received just form the tree
	  io:format("E_M Received add_node~n "),
	  NEW_NODES_LIST = NODES ++
			     [NEW_NODE],%%TODO i've to remember to call the function with this NEW_NODES_LIST
	  TWIN ! {update_add_node, NEW_NODE},
	  io:format("E_M ~p Received add_node , i've told "
		    "my twin ~p , my nodes :~w~n",
		    [self(), TWIN, NEW_NODES_LIST]),
	  err_man_life(PARENT, CHILDREN, NEW_NODES_LIST, DEPTH,
		       TWIN);  %%TODO i've to add this in the win_man
      {decrease_error, PARENT, ALPHA} ->
	  io:format("E_M ~p Received decrease_error, i'll "
		    "tell everyone:~n",
		    [self()]),
	  tell_everyone(CHILDREN,
			{decrease_Error, self(), ALPHA}),
	  tell_everyone(NODES, {decrease_error, self(), ALPHA}),
	  err_man_life(PARENT, CHILDREN, NODES, DEPTH, TWIN);
      {request_decreased_error, PARENT, ALPHA} ->
	  io:format("E_M ~p Received request_decreased_error, "
		    "i begin calculate the max:~n",
		    [self()]),
	  tell_everyone(CHILDREN,
			{request_decreased_error, self(),
			 ALPHA}),  %% the same function, but we can't unify the lists
	  tell_everyone(NODES,
			{request_decreased_error, self(), ALPHA}),
	  io:format("E_M ~p I asked about the error. My Nodes: "
		    "~w My CHildren: ~w:~n",
		    [self(), NODES, CHILDREN]),
	  %% NUM_ANSWERS_ARRIVING is a number that tell how many distances to wait
	  NUM_ANSWERS_ARRIVING = length(NODES) + length(CHILDREN),
	  io:format("E_M ~p Waits : ~p~n",
		    [self(), NUM_ANSWERS_ARRIVING]),
	  %% MAX is a tuple { {NODE, ERROR} }
	  %% TODO maybe i should call compute_max(NUM_ANSWERS_ARRIVING) and then a subfuntion adds the inital phoonies {0.0},{0.0}
	  MAX = compute_max(NUM_ANSWERS_ARRIVING),
	  io:format("E_M ~p My error: ~w~n", [self(), MAX]),
	  PARENT ! {my_error, self(), MAX},
	  err_man_life(PARENT, CHILDREN, NODES, DEPTH, TWIN);
      {move_nodes_start, NEW_NODE, DIRECTIONS} ->
	  L_DIR = length(DIRECTIONS),
	  [NEXT_D | OTHER_DIRECTIONS] = DIRECTIONS,
	  NODES_PACKAGE = NODES ++ [NEW_NODE],
	  io:format("E_M ~p Received move_node_start, i'll "
		    "pass :~w~n",
		    [self(), NODES_PACKAGE]),
	  NEW_NODES_LIST = [],
	  TWIN !
	    {reset_nodes_list},    %% TODO tell the twin the news !
	  if L_DIR == 1 ->   %%  TODO adds a new manager
		 NEW_CHILDREN_LIST = CHILDREN ++
				       [add_manager(DEPTH + 1, TWIN)];
	     true -> NEW_CHILDREN_LIST = CHILDREN
	  end,
	  %%spreads the messages down the tree
	  lists:nth(NEXT_D, CHILDREN) !
	    {move_nodes, NODES_PACKAGE, OTHER_DIRECTIONS},
	  err_man_life(PARENT, NEW_CHILDREN_LIST, NEW_NODES_LIST,
		       DEPTH, TWIN);
      {move_nodes, NODES_PACK,
       DIRECTIONS} ->   %% By-passing manager
	  io:format("E_M ~p Received move_node, i'll pass "
		    ":~w~n",
		    [self(), NODES_PACK]),
	  L_DIR = length(DIRECTIONS),
	  [NEXT_D | OTHER_DIRECTIONS] = DIRECTIONS,
	  case L_DIR %% check how long is the directions list
	      of
	    1 ->    %% if is 1 adds a new manager	
		NEW_NODES_LIST = NODES,
		NEW_CHILDREN_LIST = CHILDREN ++
				      [add_manager(DEPTH + 1, TWIN)],
		lists:nth(NEXT_D, CHILDREN) !
		  {move_nodes, NODES_PACK, OTHER_DIRECTIONS};
	    0 ->    %% if is zero adds the nodes package to his NODES list
		NEW_CHILDREN_LIST = CHILDREN,
		NEW_NODES_LIST = NODES_PACK,
		tell_everyone(NEW_NODES_LIST, {set_parent, self()}),
		TWIN ! {update_add_nodes_pack, NODES_PACK}
	  end,
	  err_man_life(PARENT, NEW_CHILDREN_LIST, NEW_NODES_LIST,
		       DEPTH, TWIN)
    end.

%%%%%%%%%%%%%%% ask_for_min(NODESLIST, RETURN_PID, INPUT) %%%%%%%%%%%%%%
%% 	- sends recursively a message {request_distance, RETURN_PID, INPUT} to every emelement of NODES (a node's PID List)

tell_everyone([], _MESSAGE) -> ok;
tell_everyone([HEAD | TAIL], MESSAGE) ->
    HEAD ! MESSAGE, tell_everyone(TAIL, MESSAGE).

%%%%%%% compute_max(NODES_REMAINING, TEMP_WIN, TEMP_RUN)%%%%%%%%%%%%%%%%
%%
%%	In this case the node's max and the runner's max can be computed in the same way, receiving the same message
%%
%%	params:
%%		NODES_REMAINING is the number on nodes/messages to receive
%%		TEMP_MAX is a tuple { MAX_ERR_NODE_PID , ERROR } storing the temporary best
%%		
%%
%%	returns: a tuple { MAX_ERR_NODE_PID , ERROR} }
%%
%%	receives:
%%		 + recursively the error from all the NODES_REMAINING nodes in the form {my_error, self(), ERROR }
%%		 	- updates the temporary winner and runner
%%

compute_max(NUM_ANSWERS_ARRIVING) ->
    compute_max(NUM_ANSWERS_ARRIVING,
		{0, 0}).  %% TODO think about this

compute_max(0, TEMP_MAX) -> TEMP_MAX;
compute_max(NOD_OR_CHILD_REMAINING, TEMP_MAX) ->
    %%io:format("I'm in compute_max ~p~n",[self()]),			
    receive
      {my_decreased_error, NodePID, ERROR} ->
	  %%io:format("I received form ~p the error ~p~n",[NodePID,ERROR]),			
	  ERR_TEMP_MAX = element(2, TEMP_MAX),
	  if ERR_TEMP_MAX < ERROR ->
		 %% if is big enough to be the next max
		 compute_max(NOD_OR_CHILD_REMAINING - 1,
			     {NodePID, ERROR});
	     true ->
		 compute_max(NOD_OR_CHILD_REMAINING - 1, TEMP_MAX)
	  end
    end.

%%addNode_TWIN_NODES_VERSION( NEW_NODE_PID, TWIN) ->

        %% comunicates to add new node to the twin

%%	TWIN ! { update_add_node, NEW_NODE_PID },
%%
%%	receive
%%		{update_new_node_confirm , WIN_NEW_PID } ->
%%				NEW_NODE_PID ! { set_twin, WIN_NEW_PID }
%%		after 4000 ->
%%			io:format("~w :I've added a node but I didn't receive confirmation from my twin ~w~n",self(),TWIN)
%%
%%	end
%%
%%.

add_manager(DEPTH, TWIN) ->
    NEW_MAN = spawn(err_man, err_man_life,
		    [self(),  % new parent
		     [],     % new NODES list
		     [],     % new CHILDREN list	
		     DEPTH, % new DEPTH
		     0]),    %%  New TWIN, 0 is temporary, until i receive the confirmation from the win_tree
    TWIN ! {update_add_manager, NEW_MAN, self()},
    receive
      {update_add_manager_confirm, WIN_TWIN} ->
	  NEW_MAN ! {set_twin, WIN_TWIN}, NEW_MAN
      after 4000 ->
		io:format("E_M ~p :I've added a node but I didn't "
			  "receive confirmation from my twin ~p~n",
			  self(), TWIN)
    end.