(* Copyright (C) 2004-2005, HELM Team.
 * 
 * This file is part of HELM, an Hypertextual, Electronic
 * Library of Mathematics, developed at the Computer Science
 * Department, University of Bologna, Italy.
 * 
 * HELM is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * HELM is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with HELM; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA  02111-1307, USA.
 * 
 * For details, see the HELM World-Wide-Web page,
 * http://helm.cs.unibo.it/
 *)

open Printf

module Ast = CicNotationPt
module Env = CicNotationEnv

let unopt_names names env =
  let rec aux acc = function
    | (name, (ty, v)) :: tl when List.mem name names ->
        (match ty, v with
        | Env.OptType ty, Env.OptValue (Some v) ->
            aux ((name, (ty, v)) :: acc) tl
        | _ -> assert false)
    | _ :: tl -> aux acc tl
      (* some pattern may contain only meta names, thus we trash all others *)
    | [] -> acc
  in
  aux [] env

let head_names names env =
  let rec aux acc = function
    | (name, (ty, v)) :: tl when List.mem name names ->
        (match ty, v with
        | Env.ListType ty, Env.ListValue (v :: _) ->
            aux ((name, (ty, v)) :: acc) tl
        | _ -> assert false)
    | _ :: tl -> aux acc tl
      (* base pattern may contain only meta names, thus we trash all others *)
    | [] -> acc
  in
  aux [] env

let tail_names names env =
  let rec aux acc = function
    | (name, (ty, v)) :: tl when List.mem name names ->
        (match ty, v with
        | Env.ListType ty, Env.ListValue (_ :: vtl) ->
            aux ((name, (Env.ListType ty, Env.ListValue vtl)) :: acc) tl
        | _ -> assert false)
    | binding :: tl -> aux (binding :: acc) tl
    | [] -> acc
  in
  aux [] env

let instantiate_level2 env term =
  let fresh_env = ref [] in
  let lookup_fresh_name n =
    try
      List.assoc n !fresh_env
    with Not_found ->
      let new_name = CicNotationUtil.fresh_name () in
      fresh_env := (n, new_name) :: !fresh_env;
      new_name
  in
  let rec aux env term =
    match term with
    | Ast.AttributedTerm (_, term) -> aux env term
    | Ast.Appl terms -> Ast.Appl (List.map (aux env) terms)
    | Ast.Binder (binder, var, body) ->
        Ast.Binder (binder, aux_capture_var env var, aux env body)
    | Ast.Case (term, indty, outty_opt, patterns) ->
        Ast.Case (aux env term, indty, aux_opt env outty_opt,
          List.map (aux_branch env) patterns)
    | Ast.LetIn (var, t1, t2) ->
        Ast.LetIn (aux_capture_var env var, aux env t1, aux env t2)
    | Ast.LetRec (kind, definitions, body) ->
        Ast.LetRec (kind, List.map (aux_definition env) definitions,
          aux env body)
    | Ast.Uri (name, None) -> Ast.Uri (name, None)
    | Ast.Uri (name, Some substs) ->
        Ast.Uri (name, Some (aux_substs env substs))
    | Ast.Ident (name, Some substs) ->
        Ast.Ident (name, Some (aux_substs env substs))
    | Ast.Meta (index, substs) -> Ast.Meta (index, aux_meta_substs env substs)

    | Ast.Implicit
    | Ast.Ident _
    | Ast.Num _
    | Ast.Sort _
    | Ast.Symbol _
    | Ast.UserInput -> term

    | Ast.Magic magic -> aux_magic env magic
    | Ast.Variable var -> aux_variable env var

    | _ -> assert false
  and aux_opt env = function
    | Some term -> Some (aux env term)
    | None -> None
  and aux_capture_var env (name, ty_opt) = (aux env name, aux_opt env ty_opt)
  and aux_branch env (pattern, term) =
    (aux_pattern env pattern, aux env term)
  and aux_pattern env (head, vars) =
    (head, List.map (aux_capture_var env) vars)
  and aux_definition env (var, term, i) =
    (aux_capture_var env var, aux env term, i)
  and aux_substs env substs =
    List.map (fun (name, term) -> (name, aux env term)) substs
  and aux_meta_substs env meta_substs = List.map (aux_opt env) meta_substs
  and aux_variable env = function
    | Ast.NumVar name -> Ast.Num (Env.lookup_num env name, 0)
    | Ast.IdentVar name -> Ast.Ident (Env.lookup_string env name, None)
    | Ast.TermVar name -> Env.lookup_term env name
    | Ast.FreshVar name -> Ast.Ident (lookup_fresh_name name, None)
    | Ast.Ascription (term, name) -> assert false
  and aux_magic env = function
    | Ast.Default (some_pattern, none_pattern) ->
        (match CicNotationUtil.names_of_term some_pattern with
        | [] -> assert false (* some pattern must contain at least 1 name *)
        | (name :: _) as names ->
            (match Env.lookup_value env name with
            | Env.OptValue (Some _) ->
                (* assumption: if "name" above is bound to Some _, then all
                 * names returned by "meta_names_of" are bound to Some _ as well
                 *)
                aux (unopt_names names env) some_pattern
            | Env.OptValue None -> aux env none_pattern
            | _ -> assert false))
    | Ast.Fold (`Left, base_pattern, names, rec_pattern) ->
        let acc_name = List.hd names in (* names can't be empty, cfr. parser *)
        let meta_names =
          List.filter ((<>) acc_name)
            (CicNotationUtil.names_of_term rec_pattern)
        in
        (match meta_names with
        | [] -> assert false (* as above *)
        | (name :: _) as names ->
            let rec instantiate_fold_left acc env' =
              match Env.lookup_value env' name with
              | Env.ListValue (_ :: _) ->
                  instantiate_fold_left 
                    (let acc_binding =
                      acc_name, (Env.TermType, Env.TermValue acc)
                     in
                     aux (acc_binding :: head_names names env') rec_pattern)
                    (tail_names names env')
              | Env.ListValue [] -> acc
              | _ -> assert false
            in
            instantiate_fold_left (aux env base_pattern) env)
    | Ast.Fold (`Right, base_pattern, names, rec_pattern) ->
        let acc_name = List.hd names in (* names can't be empty, cfr. parser *)
        let meta_names =
          List.filter ((<>) acc_name)
            (CicNotationUtil.names_of_term rec_pattern)
        in
        (match meta_names with
        | [] -> assert false (* as above *)
        | (name :: _) as names ->
            let rec instantiate_fold_right env' =
              match Env.lookup_value env' name with
              | Env.ListValue (_ :: _) ->
                  let acc = instantiate_fold_right (tail_names names env') in
                  let acc_binding =
                    acc_name, (Env.TermType, Env.TermValue acc)
                  in
                  aux (acc_binding :: head_names names env') rec_pattern
              | Env.ListValue [] -> aux env base_pattern
              | _ -> assert false
            in
            instantiate_fold_right env)
    | Ast.If (_, p_true, p_false) as t ->
        aux env (CicNotationUtil.find_branch (Ast.Magic t))
    | Ast.Fail -> assert false
    | _ -> assert false
  in
  aux env term

let instantiate_appl_pattern env appl_pattern =
  let lookup name =
    try List.assoc name env
    with Not_found ->
      prerr_endline (sprintf "Name %s not found" name);
      assert false
  in
  let rec aux = function
    | Ast.UriPattern uri -> CicUtil.term_of_uri uri
    | Ast.ImplicitPattern -> Cic.Implicit None
    | Ast.VarPattern name -> lookup name
    | Ast.ApplPattern terms -> Cic.Appl (List.map aux terms)
  in
  aux appl_pattern