open Ast
open Data
open Util

(* Utility : find declaration of a const / a node *)

let find_const_decl p id =
  match List.find (function
                   | AST_const_decl (c, _) when c.name = id -> true
                   | _ -> false) 
                  p with
  | AST_const_decl d -> d
  | _ -> assert false

let find_node_decl p id =
  match List.find (function
                   | AST_node_decl (c, _) when c.name = id -> true
                   | _ -> false) 
                  p with
  | AST_node_decl d -> d
  | _ -> assert false

(* Expression evaluation *)

(*
  eval_expr : calc_map -> state -> string -> expr ext -> (state * value)
*)
let rec eval_expr c scope st exp =
  let sub_eval = eval_expr c scope in
  match fst exp with
  | AST_identifier (id, _) ->
    begin try let st, v = get_var st c (scope^"/"^id) in st, [v]
    with No_variable _ -> let st, v = get_var st c ("cst/"^id) in st, [v]
    end
  (* on numerical values *)
  | AST_int_const (i, _) -> st, [VInt (int_of_string i)]
  | AST_real_const (r, _) -> st, [VReal (float_of_string r)]
  | AST_unary(AST_UPLUS, e) -> sub_eval st e
  | AST_unary(AST_UMINUS, e) ->
    begin match sub_eval st e with
    | st, [VInt x] -> st, [VInt (-x)]
    | st, [VReal x] -> st, [VReal(-. x)]
    | _ -> type_error "Unary on non-numerical."
    end
  | AST_binary(op, e1, e2) ->
    let st, v1 = sub_eval st e1 in
    let st, v2 = sub_eval st e2 in
    let iop, fop = match op with
    | AST_PLUS -> (+), (+.)
    | AST_MINUS -> (-), (-.)
    | AST_MUL -> ( * ), ( *. )
    | AST_DIV -> (/), (/.)
    | AST_MOD -> (mod), mod_float
    in
    begin match v1, v2 with
    | [VInt a], [VInt b] -> st, [VInt (iop a b)]
    | [VReal a], [VReal b] -> st, [VReal(fop a b)]
    | _ -> type_error "Invalid arguments for numerical binary."
    end
  (* on boolean values *)
  | AST_bool_const b -> st, [VBool b]
  | AST_binary_rel(op, e1, e2) ->
    let st, v1 = sub_eval st e1 in
    let st, v2 = sub_eval st e2 in
    let r = match op with
    | AST_EQ -> (=)     | AST_NE -> (<>)
    | AST_LT -> (<)     | AST_LE -> (<=)
    | AST_GT -> (>)     | AST_GE -> (>=)
    in
    begin match v1, v2 with
    | [VInt a], [VInt b] -> st, [VBool (r a b)]
    | [VReal a], [VReal b] -> st, [VBool (r a b)]
    | [VBool a], [VBool b] -> st, [VBool (r a b)]
    | _ -> type_error "Invalid arguments for binary relation."
    end
  | AST_binary_bool(op, e1, e2) ->
    let st, v1 = sub_eval st e1 in
    let st, v2 = sub_eval st e2 in
    let r = match op with
    | AST_AND -> (&&)   | AST_OR -> (||)
    in
    begin match v1, v2 with
    | [VBool a], [VBool b] -> st, [VBool (r a b)]
    | _ -> type_error "Invalid arguments for boolean relation."
    end
  | AST_not(e) ->
    begin match sub_eval st e with
    | st, [VBool b] -> st, [VBool (not b)]
    | _ -> type_error "Invalid arguments for boolean negation."
    end
  (* temporal primitives *)
  | AST_pre(exp, n) ->
    begin try match VarMap.find (scope^"/"^n) st with
      | VPrevious x -> st, x
      | _ -> st, []
    with Not_found -> st, []
    end
  | AST_arrow(before, after) -> 
    begin try match VarMap.find (scope^"/init") st with
    | VBool true -> sub_eval st before
    | VBool false -> sub_eval st after
    | _ -> assert false
    with Not_found -> assert false
    end
  (* other *)
  | AST_if(cond, a, b) ->
    let st, cv = sub_eval st cond in
    begin match cv with
    | [VBool true] -> sub_eval st a
    | [VBool false] -> sub_eval st b
    | _ -> type_error "Invalid condition in if."
    end
  | AST_instance((f, _), args, id) -> not_implemented "instance"

(* Constant calculation *)

let rec calc_const d st c =
  match eval_expr c "cst" st d.value with
  | st, [v] -> VarMap.add ("cst/"^d.name) v st
  | _ -> type_error ("Cannot assign tuple to constant" ^ d.name)

let program_consts p =
  let cdecl = List.fold_left
    (fun l d -> match d with
      | AST_const_decl (d, _) -> d::l
      | _ -> l)
    [] p
  in
  let ccmap = List.fold_left
    (fun c d -> VarMap.add ("cst/"^d.name) (F (calc_const d)) c)
    VarMap.empty cdecl
  in
  List.fold_left
    (fun st d -> let st, _ = get_var st ccmap ("cst/"^d.name) in st)
    VarMap.empty
    cdecl

(* Program execution *)

(* subscopes :
      prog -> expr ext -> (id * eqs * (id * expr ext) list) list
*)
let rec subscopes p e = match fst e with
  | AST_identifier _ | AST_int_const _ | AST_real_const _ | AST_bool_const _ -> []
  | AST_unary (_, e') | AST_pre (e', _) | AST_not e' -> subscopes p e'
  | AST_binary(_, e1, e2) | AST_binary_rel (_, e1, e2) | AST_binary_bool (_, e1, e2)
  | AST_arrow(e1, e2) ->
    subscopes p e1 @ subscopes p e2
  | AST_if(e1, e2, e3) ->
    subscopes p e1 @ subscopes p e2 @ subscopes p e3
  | AST_instance((f, _), args, id) ->
    let more = List.flatten (List.map (subscopes p) args) in
    let (node, _) = find_node_decl p f in
    let args_x = List.map2 (fun id arg -> id, arg) node.args args in
    (id, node.body, args_x)::more

(* extract_pre : expr ext -> (id * expr ext) list *)
let rec extract_pre e = match fst e with
  | AST_identifier _ | AST_int_const _ | AST_real_const _ | AST_bool_const _ -> []
  | AST_unary (_, e') | AST_not e' -> extract_pre e'
  | AST_binary(_, e1, e2) | AST_binary_rel (_, e1, e2) | AST_binary_bool (_, e1, e2)
  | AST_arrow(e1, e2) ->
    extract_pre e1 @ extract_pre e2
  | AST_if(e1, e2, e3) ->
    extract_pre e1 @ extract_pre e2 @ extract_pre e3
  | AST_instance((f, _), args, id) ->
    List.flatten (List.map extract_pre args)
  | AST_pre(e', n) ->
    (n, e')::(extract_pre e')


(* build calc map *)
let rec build_prog_ccmap p scope eqs st =
  let add_eq c eq = match fst eq with
    | AST_assign(vars, e) ->
      let calc st c =
        let st, vals = eval_expr c scope st e in
        List.fold_left2
          (fun st (id,_) v -> VarMap.add (scope^"/"^id) v st)
          st vars vals
      in
      let c = List.fold_left (fun c (id, _) -> VarMap.add (scope^"/"^id) (F calc) c) c vars in

      let add_subscope c (ss_id, ss_eqs, ss_args) =
        let c = VarMap.merge (fun _ a b -> match a, b with
          | Some x, None -> Some x
          | None, Some y -> Some y
          | _ -> assert false) c
          (build_prog_ccmap p (scope^"/"^ss_id) ss_eqs st)
        in
        let add_v c ((_, (id, _), _), eq) =
          let calc st c =
            let st, vals = eval_expr c scope st eq in
            match vals with
            | [v] -> VarMap.add (scope^"/"^ss_id^"/"^id) v st
            | _ -> type_error "invalid arity"
          in
          VarMap.add (scope^"/"^ss_id^"/"^id) (F calc) c
        in
        List.fold_left add_v c ss_args
      in
      List.fold_left add_subscope c (subscopes p e)
    | AST_assume _ | AST_guarantee _ -> c
    | AST_automaton _ -> not_implemented "build_prog_ccmap for automaton"
  in
  List.fold_left add_eq VarMap.empty eqs

let extract_next_state active p scope eqs st ccmap =
  let csts = VarMap.filter
    (fun k _ -> String.length k > 4 && String.sub k 0 4 = "cst/")
    st
  in
  let rec aux active scope eqs st nst =
    let r = VarMap.add (scope^"/init")
        (if active then VBool false
          else try VarMap.find (scope^"/init") st with Not_found -> assert false)
        nst
    in
    let add_subscopes active =
      List.fold_left (fun (st, nst) (ss_id, ss_eqs, _) ->
        aux active (scope^"/"^ss_id) ss_eqs st nst)
    in
    let add_eq (st, nst) eq = match fst eq with
      | AST_assign(vars, e) ->
        let st, nst = add_subscopes active (st, nst) (subscopes p e) in
        List.fold_left (fun (st, nst) (pn, pe) ->
            let st, v = if active then eval_expr ccmap scope st pe
              else st,
                try match VarMap.find (scope^"/"^pn) st with VPrevious x -> x | _ -> []
                with Not_found -> []
            in
            st, VarMap.add (scope^"/"^pn) (VPrevious v) nst)
          (st, nst) (extract_pre e)
      | AST_assume _ | AST_guarantee _ -> st, nst
      | AST_automaton _ -> not_implemented "extract_next_state automaton"
    in
    List.fold_left add_eq (st, r) eqs
  in aux active scope eqs st csts

let program_init_state p root_node =
  let (n, _) = find_node_decl p root_node in
  let rec prog_init_state_aux st p scope eqs =
    let st = VarMap.add (scope^"/init") (VBool true) st in
    let add_subscopes =
      List.fold_left (fun st (ss_id, ss_eqs, _) -> prog_init_state_aux st p (scope^"/"^ss_id) ss_eqs)
    in
    List.fold_left (fun st eq -> match fst eq with
        | AST_assign(_, e) -> add_subscopes st (subscopes p e)
        | AST_assume _ | AST_guarantee _ -> st
        | AST_automaton _ -> not_implemented "prog_init_state_aux automaton")
      st eqs
  in
    prog_init_state_aux (program_consts p) p "" n.body


let program_step p st inputs root_node =
  let (n, _) = find_node_decl p root_node in
  let st = List.fold_left
    (fun st (n, v) -> VarMap.add ("/"^n) v st) st inputs in

  let ccmap = build_prog_ccmap p "" n.body st in

  let st = List.fold_left
    (fun st (_, (id, _), _) -> let st, _ = get_var st ccmap ("/"^id) in st)
    st n.ret in
  let outputs = List.map
    (fun (_, (id, _), _) -> let _, v = get_var st ccmap ("/"^id) in (id, v))
    n.ret in
  let st, next_st = extract_next_state true p "" n.body st ccmap in

  st, outputs, next_st