(**************************************************************************)
(*                                                                        *)
(*  MiniLustre                                                            *)
(*                                                                        *)
(*  Author : Marc Pouzet                                                  *)
(*  Organization : Demons, LRI, University of Paris-Sud, Orsay            *)
(*                                                                        *)
(**************************************************************************)

(* clock checking *)

(* $Id$ *)

open Misc
open Ident
open Minils
open Global
open Location

type error = | Etypeclash of ct * ct

exception TypingError of error
exception Unify

let error kind = raise (TypingError(kind))

let message e kind =
  begin match kind with
      Etypeclash(actual_ct, expected_ct) ->
	Printf.eprintf "%aClock Clash: this expression has clock %a, \n\
                  but is expected to have clock %a.\n" 
	  Printer.print_exp e
	  Printer.print_clock actual_ct
	  Printer.print_clock expected_ct
  end;
  raise Error
    
let index = ref 0
let gen_index () = incr index; !index
let new_var () = Cvar { contents = Cindex (gen_index ()) }

let rec repr ck =
  match ck with
      Cbase | Con _ | Cvar { contents = Cindex _ } -> ck
    | Cvar ({ contents = Clink(ck) } as link) ->
	let ck = repr ck in
	link.contents <- Clink(ck);
	ck
  
let rec occur_check index ck =
  let ck = repr ck in
    match ck with
      Cbase -> ()
    | Cvar { contents = Cindex n } when index <> n -> ()
    | Con(ck, _, _) -> occur_check index ck
    | _ -> raise Unify

let rec ck_value ck =
  match ck with
    | Cbase | Con _ | Cvar { contents = Cindex _ } -> ck
    | Cvar { contents = Clink(ck) } ->
	ck_value ck

let rec unify t1 t2 =
  if t1 == t2 then ()
  else match t1, t2 with
      Ck(ck1), Ck(ck2) -> unify_ck ck1 ck2
    | Cprod(ct_list1), Cprod(ct_list2) ->
	begin try
	  List.iter2 unify ct_list1 ct_list2
	with
	    _ -> raise Unify
	end
    | _ -> raise Unify

and unify_ck ck1 ck2 =
  let ck1 = repr ck1 in
  let ck2 = repr ck2 in
  if ck1 == ck2 then ()
  else match ck1, ck2 with
      Cbase, Cbase -> ()
    | Cvar { contents = Cindex n1 }, Cvar { contents = Cindex n2 } 
	when n1 = n2 -> ()
    | Cvar ({ contents = Cindex n1 } as v), _ ->
	occur_check n1 ck2;
	v.contents <- Clink(ck2)
    | _, Cvar ({contents = Cindex n2 } as v) ->
	occur_check n2 ck1;
	v.contents <- Clink(ck1)
    | Con(ck1, c1, n1), Con(ck2, c2, n2) when (c1 = c2) & (n1 = n2) ->
	unify_ck ck1 ck2
    | _ -> raise Unify
    
let rec eq ck1 ck2 =
  match repr ck1, repr ck2 with
    | Cbase, Cbase -> true
    | Cvar { contents = Cindex n1 }, Cvar { contents = Cindex n2 } -> true
    | Con(ck1, _, n1), Con(ck2, _, n2) when (n1 = n2) -> eq ck1 ck2
    | _ -> false
	
let rec unify t1 t2 =
  match t1, t2 with
      Ck(ck1), Ck(ck2) -> unify_ck ck1 ck2
    | Cprod(t1_list), Cprod(t2_list) -> unify_list t1_list t2_list
    | _ -> raise Unify

and unify_list t1_list t2_list =
  try
    List.iter2 unify t1_list t2_list
  with
      _ -> raise Unify
	
let rec skeleton ck = function
  | Tprod(ty_list) -> Cprod(List.map (skeleton ck) ty_list)
  | Tbase _ -> Ck(ck)

let ckofct = function
  | Ck(ck) -> repr ck
  | Cprod(ct_list) -> Cbase

let prod = function
  | [] -> assert false
  | [ty] -> ty
  | ty_list -> Tprod(ty_list)
	
let typ_of_name h x = Env.find x h

let rec typing h e =
  let ct = match e.e_desc with
    | Econst _ | Econstvar _ -> Ck(new_var ())
    | Evar(x) -> Ck(typ_of_name h x)
    | Efby(c, e) -> typing h e
    | Etuple(e_list) ->
	Cprod(List.map (typing h) e_list)
    | Eop(_,_, e_list) ->
	let ck = new_var () in
	  List.iter (expect h (Ck(ck))) e_list;
	  skeleton ck e.e_ty
    | Eapp(_,_, e_list) ->
	let ck_r = new_var () in
	List.iter (expect h (Ck(ck_r))) e_list;
	skeleton ck_r e.e_ty
    | Eevery(_,_, e_list, n) ->
	let ck_r = typ_of_name h n in
	List.iter (expect h (Ck(ck_r))) e_list;
	skeleton ck_r e.e_ty
    | Ewhen(e, c, n) ->
	let ck_n = typ_of_name h n in
	expect h (skeleton ck_n e.e_ty) e;
	skeleton (Con(ck_n, c, n)) e.e_ty
    | Eifthenelse(e1, e2, e3) ->
	let ck = new_var () in
	let ct = skeleton  ck e.e_ty in
	expect h (Ck(ck)) e1;
	expect h ct e2;
	expect h ct e3; ct
    | Emerge(n, c_e_list) ->
	let ck_c = typ_of_name h n in
	typing_c_e_list h ck_c n c_e_list;
	skeleton ck_c e.e_ty
    | Efield(e1,n) ->
	let ck = new_var () in
	let ct = skeleton ck e1.e_ty in
	expect h (Ck(ck)) e1;
	ct
    | Estruct(l) ->
	let ck = new_var () in
	List.iter
	  (fun (n,e) ->
	     let ct = skeleton ck e.e_ty in
	     expect h ct e)
	  l;
	Ck(ck)
  (*Array operators*)
    | Earray e_list ->
	let ck = new_var () in
	  List.iter (expect h (Ck(ck))) e_list;
	  skeleton ck e.e_ty
    | Erepeat (_,e) -> 
	typing h e
    | Eselect (_,e) -> 
	typing h e
    | Eselect_dyn (e_list, _, e, defe) -> 
	let ck = new_var () in
	let ct = skeleton  ck e.e_ty in
	expect h ct e;
	List.iter (expect h ct) e_list;
	ct
    | Eupdate (_, e1, e2) | Efield_update (_, e1, e2) ->
	let ck = new_var () in
	let ct = skeleton ck e.e_ty in
	expect h (Ck(ck)) e1;
	expect h ct e2; 
	ct
    | Eselect_slice (_ , _, e) -> 
	typing h e
    | Econcat (e1, e2) ->
	let ck = new_var () in
	let ct = skeleton ck e.e_ty in
	expect h (Ck(ck)) e1;
	expect h ct e2; 
	ct
    | Eiterator (_, f, _, _, e_list, _) ->  
	let ck_r = new_var () in
	  List.iter (expect h (Ck(ck_r))) e_list;
	  skeleton ck_r e.e_ty
    | Ereset_mem (_, _, x) -> assert false
  in
  e.e_ck <- ckofct ct;
  ct      

and expect h expected_ty e =
  let actual_ty = typing h e in
    try unify actual_ty expected_ty
    with Unify -> message e (Etypeclash(actual_ty, expected_ty))
  
and typing_c_e_list h ck_c n c_e_list =
  let rec typrec = function
    | [] -> ()
    | (c, e) :: c_e_list ->
         expect h (skeleton (Con(ck_c, c, n)) e.e_ty) e;
         typrec c_e_list in
    typrec c_e_list

let rec typing_pat h = function
  | Evarpat(x) -> Ck(typ_of_name h x)
  | Etuplepat(pat_list) -> Cprod(List.map (typing_pat h) pat_list)

let typing_eqs h eq_list =
  List.iter 
    (fun { p_lhs = pat; p_rhs = e } ->
       (match e.e_desc with
	  | Ereset_mem (_, _, x) -> 
	      let ck = typ_of_name h x in
		e.e_ck <- ck;
	  | _ -> 
	      let ty_pat = typing_pat h pat in
		try
		  expect h ty_pat e
		with Error ->
		  (* DEBUG *)
		  Printf.eprintf "Complete expression: %a\n"
		    Printer.print_exp e;
		  Printf.eprintf "Clock pattern: %a\n"
		    Printer.print_clock ty_pat;
		  raise Error
       )
    ) eq_list
    
let build h dec =
  List.fold_left (fun h { v_name = n } -> Env.add n (new_var ()) h) h dec    

let sbuild h dec base =
  List.fold_left (fun h { v_name = n } -> Env.add n base h) h dec    

let typing_contract h contract base =
  match contract with
    | None -> h
    | Some { c_local = l_list;
	     c_eq = eq_list;
	     c_assume = e_a;
	     c_enforce = e_g;
	     c_controllables = c_list } ->
	let h = sbuild h c_list base in
	let h' = build h l_list in
	typing_eqs h' eq_list;
	(* assumption *)
	expect h' (Ck base) e_a;
	(* property *)
	expect h' (Ck base) e_g;
	h

let typing_node ({ n_name = f; n_input = i_list; n_output = o_list;
		  n_contract = contract;
		  n_local = l_list; n_equs = eq_list } as node) =
  let base = Cbase in
  let h = sbuild Env.empty i_list base in
  let h = sbuild h o_list base in
  
  let h = typing_contract h contract base in

  let h = build h l_list in
    typing_eqs h eq_list;
    
    (*update clock info in variables descriptions *)
    let set_clock vd = 
      { vd with v_clock = ck_value (Env.find vd.v_name h) } in 
      
      { node with n_input = List.map set_clock i_list;
	  n_output = List.map set_clock o_list;
	  n_local = List.map set_clock l_list; }
    

let program ({ p_nodes = p_node_list } as p) =
 { p with p_nodes = List.map typing_node p_node_list }