(* Copyright (C) 2003-2005, 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://cs.unibo.it/helm/.
 *)

module C    = Cic
module I    = CicInspect
module D    = Deannotate
module TC   = CicTypeChecker 
module Un   = CicUniv
module UM   = UriManager
module Obj  = LibraryObjects
module HObj = HelmLibraryObjects
module A    = Cic2acic
module Ut   = CicUtil
module E    = CicEnvironment
module PEH  = ProofEngineHelpers
module PER  = ProofEngineReduction
module Pp   = CicPp

module Cl   = ProceduralClassify
module T    = ProceduralTypes
module Cn   = ProceduralConversion

type status = {
   sorts : (C.id, A.sort_kind) Hashtbl.t;
   types : (C.id, A.anntypes) Hashtbl.t;
   prefix: string;
   max_depth: int option;
   depth: int;
   context: C.context;
   intros: string list
}

(* helpers ******************************************************************)

let cic = D.deannotate_term

let split2_last l1 l2 =
try
   let n = pred (List.length l1) in
   let before1, after1 = T.list_split n l1 in
   let before2, after2 = T.list_split n l2 in
   before1, before2, List.hd after1, List.hd after2
with Invalid_argument _ -> failwith "A2P.split2_last"

let string_of_head = function
   | C.ASort _         -> "sort"
   | C.AConst _        -> "const"
   | C.AMutInd _       -> "mutind"
   | C.AMutConstruct _ -> "mutconstruct"
   | C.AVar _          -> "var"
   | C.ARel _          -> "rel"
   | C.AProd _         -> "prod"
   | C.ALambda _       -> "lambda"
   | C.ALetIn _        -> "letin"
   | C.AFix _          -> "fix"
   | C.ACoFix _        -> "cofix"
   | C.AAppl _         -> "appl"
   | C.ACast _         -> "cast"
   | C.AMutCase _      -> "mutcase"
   | C.AMeta _         -> "meta"
   | C.AImplicit _     -> "implict"

let clear st = {st with intros = []}

let next st = {(clear st) with depth = succ st.depth}

let add st entry intro =
   {st with context = entry :: st.context; intros = intro :: st.intros}

let test_depth st =
try   
   let msg = Printf.sprintf "Depth %u: " st.depth in
   match st.max_depth with
      | None   -> true, "" 
      | Some d -> if st.depth < d then true, msg else false, "DEPTH EXCEDED: "
with Invalid_argument _ -> failwith "A2P.test_depth"

let is_rewrite_right = function
   | C.AConst (_, uri, []) ->
      UM.eq uri HObj.Logic.eq_ind_r_URI || Obj.is_eq_ind_r_URI uri
   | _                     -> false

let is_rewrite_left = function
   | C.AConst (_, uri, []) ->
      UM.eq uri HObj.Logic.eq_ind_URI || Obj.is_eq_ind_URI uri
   | _                     -> false

let is_fwd_rewrite_right hd tl =
   if is_rewrite_right hd then match List.nth tl 3 with
      | C.ARel _ -> true
      | _        -> false
   else false

let is_fwd_rewrite_left hd tl =
   if is_rewrite_left hd then match List.nth tl 3 with
      | C.ARel _ -> true
      | _        -> false
   else false
(*
let get_ind_name uri tno xcno =
try   
   let ts = match E.get_obj Un.empty_ugraph uri with
      | C.InductiveDefinition (ts, _, _,_), _ -> ts 
      | _                                     -> assert false
   in
   let tname, cs = match List.nth ts tno with
      | (name, _, _, cs) -> name, cs
   in
   match xcno with
      | None     -> tname
      | Some cno -> fst (List.nth cs (pred cno))
with Invalid_argument _ -> failwith "A2P.get_ind_name"
*)
let get_inner_types st v =
try
   let id = Ut.id_of_annterm v in
   try match Hashtbl.find st.types id with
      | {A.annsynthesized = st; A.annexpected = Some et} -> Some (st, et)
      | {A.annsynthesized = st; A.annexpected = None}    -> Some (st, st)
   with Not_found -> None
with Invalid_argument _ -> failwith "A2P.get_inner_types"
(*
let get_inner_sort st v =
try
   let id = Ut.id_of_annterm v in
   try Hashtbl.find st.sorts id
   with Not_found -> `Type (CicUniv.fresh())
with Invalid_argument _ -> failwith "A2P.get_sort"
*)
let get_type msg st bo =
try   
   let ty, _ = TC.type_of_aux' [] st.context (cic bo) Un.empty_ugraph in
   ty
with e -> failwith (msg ^ ": " ^ Printexc.to_string e)

(* proof construction *******************************************************)

let unused_premise = "UNUSED"

let convert st ?name v = 
   match get_inner_types st v with
      | None          -> []
      | Some (st, et) ->
         let cst, cet = cic st, cic et in
	 if PER.alpha_equivalence cst cet then [] else 
	 let e = Cn.mk_pattern 0 (T.mk_arel 1 "") in
	 match name with
	    | None    -> [T.Change (st, et, None, e, "")]
	    | Some id -> [T.Change (st, et, Some (id, id), e, ""); T.ClearBody (id, "")]

let get_intro = function 
   | C.Anonymous -> unused_premise
   | C.Name s    -> s

let mk_intros st script =
   if st.intros = [] then script else
   let count = List.length st.intros in
   T.Intros (Some count, List.rev st.intros, "") :: script

let mk_arg st = function
   | C.ARel (_, _, _, name) as what -> convert st ~name what
   | _                              -> []

let mk_fwd_rewrite st dtext name tl direction =   
   assert (List.length tl = 6);
   let what, where, predicate = List.nth tl 5, List.nth tl 3, List.nth tl 2 in
   let e = Cn.mk_pattern 1 predicate in
   match where with
      | C.ARel (_, _, _, premise) ->
         let script = mk_arg st what in
         let where = Some (premise, name) in
	 T.Rewrite (direction, what, where, e, dtext) :: script
      | _                         -> assert false

let mk_rewrite st dtext what qs tl direction = 
   assert (List.length tl = 5);
   let predicate = List.nth tl 2 in
   let e = Cn.mk_pattern 1 predicate in
   [T.Rewrite (direction, what, None, e, dtext); T.Branch (qs, "")]

let rec proc_lambda st name v t =
   let entry = Some (name, C.Decl (cic v)) in
   let intro = get_intro name in
   proc_proof (add st entry intro) t

and proc_letin st what name v t =
   let intro = get_intro name in
   let proceed, dtext = test_depth st in
   let script = if proceed then 
      let hyp, rqv = match get_inner_types st v with
         | Some (ity, _) ->
	    let rqv = match v with
               | C.AAppl (_, hd :: tl) when is_fwd_rewrite_right hd tl ->
	          mk_fwd_rewrite st dtext intro tl true
	       | C.AAppl (_, hd :: tl) when is_fwd_rewrite_left hd tl  ->
	          mk_fwd_rewrite st dtext intro tl false
	       | v                                                     ->
	          let qs = [[T.Id ""]; proc_proof (next st) v] in
	          [T.Branch (qs, ""); T.Cut (intro, ity, dtext)]
	    in
	    C.Decl (get_type "TC1" st v), rqv
	 | None          ->
	    C.Def (cic v, None), [T.LetIn (intro, v, dtext)]
      in
      let entry = Some (name, hyp) in
      let qt = proc_proof (next (add st entry intro)) t in
      List.rev_append rqv qt      
   else
      [T.Apply (what, dtext)]
   in
   mk_intros st script

and proc_rel st what = 
   let _, dtext = test_depth st in
   let text = "assumption" in
   let script = [T.Apply (what, dtext ^ text)] in 
   mk_intros st script

and proc_mutconstruct st what = 
   let _, dtext = test_depth st in
   let script = [T.Apply (what, dtext)] in 
   mk_intros st script   

and proc_appl st what hd tl =
   let proceed, dtext = test_depth st in
   let script = if proceed then
      let ty = get_type "TC2" st hd in
      let (classes, rc) as h = Cl.classify st.context ty in
      let argsno = List.length classes in
      let diff = argsno - List.length tl in
      if diff <> 0 then failwith (Printf.sprintf "NOT TOTAL: %i %s |--- %s" diff (Pp.ppcontext st.context) (Pp.ppterm (cic hd)));
      let synth = I.S.singleton 0 in
      let text = Printf.sprintf "%u %s" argsno (Cl.to_string h) in
      let script = List.rev (mk_arg st hd) @ convert st what in
      match rc with
         | Some (i, j) ->
	    let classes, tl, _, where = split2_last classes tl in
	    let script = List.rev (mk_arg st where) @ script in
	    let synth = I.S.add 1 synth in
	    let qs = proc_bkd_proofs (next st) synth classes tl in
            if is_rewrite_right hd then 
	       script @ mk_rewrite st dtext where qs tl false
	    else if is_rewrite_left hd then 
	       script @ mk_rewrite st dtext where qs tl true
	    else
	       let predicate = List.nth tl (argsno - i) in
               let e = Cn.mk_pattern 0 (T.mk_arel 1 "") (* j predicate *) in
	       let using = Some hd in
	       script @
	       [T.Elim (where, using, e, dtext ^ text); T.Branch (qs, "")]
	 | None        ->
	    let qs = proc_bkd_proofs (next st) synth classes tl in
	    script @ [T.Apply (hd, dtext ^ text); T.Branch (qs, "")]
   else
      [T.Apply (what, dtext)]
   in
   mk_intros st script

and proc_other st what =
   let text = Printf.sprintf "%s: %s" "UNEXPANDED" (string_of_head what) in
   let script = [T.Note text] in
   mk_intros st script


and proc_proof st = function
   | C.ALambda (_, name, w, t)        -> proc_lambda st name w t
   | C.ALetIn (_, name, v, t) as what -> proc_letin st what name v t
   | C.ARel _ as what                 -> proc_rel st what
   | C.AMutConstruct _ as what        -> proc_mutconstruct st what
   | C.AAppl (_, hd :: tl) as what    -> proc_appl st what hd tl
   | what                             -> proc_other st what

and proc_bkd_proofs st synth classes ts =
try 
   let _, dtext = test_depth st in   
   let aux (inv, _) v =
      if I.overlaps synth inv then None else
      if I.S.is_empty inv then Some (proc_proof st v) else
      Some [T.Apply (v, dtext ^ "dependent")]
   in
   T.list_map2_filter aux classes ts
with Invalid_argument _ -> failwith "A2P.proc_bkd_proofs"

(* object costruction *******************************************************)

let is_theorem pars =   
   List.mem (`Flavour `Theorem) pars || List.mem (`Flavour `Fact) pars || 
   List.mem (`Flavour `Remark) pars || List.mem (`Flavour `Lemma) pars

let proc_obj st = function
   | C.AConstant (_, _, s, Some v, t, [], pars) when is_theorem pars ->
      let ast = proc_proof st v in
      let count = T.count_steps 0 ast in
      let text = Printf.sprintf "tactics: %u" count in
      T.Theorem (s, t, text) :: ast @ [T.Qed ""]
   | _                                                               ->
      failwith "not a theorem"

(* interface functions ******************************************************)

let acic2procedural ~ids_to_inner_sorts ~ids_to_inner_types ?depth prefix aobj = 
   let st = {
      sorts     = ids_to_inner_sorts;
      types     = ids_to_inner_types;
      prefix    = prefix;
      max_depth = depth;
      depth     = 0;
      context   = [];
      intros    = []
   } in
   HLog.debug "Procedural: level 2 transformation";
   let steps = proc_obj st aobj in
   HLog.debug "Procedural: grafite rendering";
   List.rev (T.render_steps [] steps)