(************************************************************************)
(*         *   The Coq Proof Assistant / The Coq Development Team       *)
(*  v      *         Copyright INRIA, CNRS and contributors             *)
(* <O___,, * (see version control and CREDITS file for authors & dates) *)
(*   \VV/  **************************************************************)
(*    //   *    This file is distributed under the terms of the         *)
(*         *     GNU Lesser General Public License Version 2.1          *)
(*         *     (see LICENSE file for the text of the license)         *)
(************************************************************************)

open Pp
open CErrors
open Util
open Names
open Constr
open EConstr
open Declarations
open Tactypes
open Proofview
open Proofview.Notations
open Tacmach

module RelDecl = Context.Rel.Declaration
module NamedDecl = Context.Named.Declaration

(*********************)
(*   Tacticals       *)
(*********************)

exception FailError of int * Pp.t Lazy.t

let catch_failerror (e, info) =
  match e with
  | FailError (lvl,s) when lvl > 0 ->
    tclZERO ~info (FailError (lvl - 1, s))
  | e ->
    Control.check_for_interrupt ();
    tclUNIT ()

(************************************************************************)
(* Elimination Tacticals                                                *)
(************************************************************************)

(* The following tacticals allow to apply a tactic to the
   branches generated by the application of an elimination
  tactic.

  Two auxiliary types --branch_args and branch_assumptions-- are
  used to keep track of some information about the ``branches'' of
  the elimination. *)

let fix_empty_or_and_pattern nv l =
  (* 1- The syntax does not distinguish between "[ ]" for one clause with no
     names and "[ ]" for no clause at all *)
  (* 2- More generally, we admit "[ ]" for any disjunctive pattern of
     arbitrary length *)
  match l with
  | IntroOrPattern [[]] -> IntroOrPattern (List.make nv [])
  | _ -> l

let check_or_and_pattern_size ?loc check_and names branchsigns =
  let n = Array.length branchsigns in
  let msg p1 p2 = strbrk "a conjunctive pattern made of " ++ int p1 ++ (if p1 == p2 then mt () else str " or " ++ int p2) ++ str " patterns" in
  let err1 p1 p2 =
    user_err ?loc  (str "Expects " ++ msg p1 p2 ++ str ".") in
  let errn n =
    user_err ?loc  (str "Expects a disjunctive pattern with " ++ int n
        ++ str " branches.") in
  let err1' p1 p2 =
    user_err ?loc  (strbrk "Expects a disjunctive pattern with 1 branch or " ++ msg p1 p2 ++ str ".") in
  let errforthcoming ?loc =
    user_err ?loc  (strbrk "Unexpected non atomic pattern.") in
  match names with
  | IntroAndPattern l ->
      if not (Int.equal n 1) then errn n;
      let l' = List.filter CAst.(function {v=IntroForthcoming _} -> true | {v=IntroNaming _} | {v=IntroAction _} -> false) l in
      if l' != [] then errforthcoming ?loc:(List.hd l').CAst.loc;
      if check_and then
        let p1 = List.count (fun x -> x) branchsigns.(0) in
        let p2 = List.length branchsigns.(0) in
        let p = List.length l in
        if not (Int.equal p p1 || Int.equal p p2) then err1 p1 p2;
        if Int.equal p p1 then
          IntroAndPattern
            (List.extend branchsigns.(0) (CAst.make @@ IntroNaming Namegen.IntroAnonymous) l)
        else
          names
      else
        names
  | IntroOrPattern ll ->
      if not (Int.equal n (List.length ll)) then
        if Int.equal n 1 then
          let p1 = List.count (fun x -> x) branchsigns.(0) in
          let p2 = List.length branchsigns.(0) in
          err1' p1 p2 else errn n;
      names

let get_and_check_or_and_pattern_gen ?loc check_and names branchsigns =
  let names = check_or_and_pattern_size ?loc check_and names branchsigns in
  match names with
  | IntroAndPattern l -> [|l|]
  | IntroOrPattern l -> Array.of_list l

let get_and_check_or_and_pattern ?loc = get_and_check_or_and_pattern_gen ?loc true

let compute_induction_names check_and branchletsigns = function
  | None ->
      Array.make (Array.length branchletsigns) []
  | Some {CAst.loc;v=names} ->
      let names = fix_empty_or_and_pattern (Array.length branchletsigns) names in
      get_and_check_or_and_pattern_gen check_and ?loc names branchletsigns

(* Compute the let-in signature of case analysis or standard induction scheme *)
let compute_constructor_signatures env ~rec_flag ((_,k as ity),u) =
  let rec analrec c recargs =
    match c, recargs with
    | RelDecl.LocalAssum _ :: c, recarg::rest ->
        let rest = analrec c rest in
        begin match Declareops.dest_recarg recarg with
        | Norec | Nested _  -> true :: rest
        | Mrec (_,j)  ->
            if rec_flag && Int.equal j k then true :: true :: rest
            else true :: rest
        end
    | RelDecl.LocalDef _ :: c, rest -> false :: analrec c rest
    | [], [] -> []
    | _ -> anomaly (Pp.str "compute_constructor_signatures.")
  in
  let (mib,mip) = Inductive.lookup_mind_specif env ity in
  let map (ctx, _) = List.skipn (Context.Rel.length mib.mind_params_ctxt) (List.rev ctx) in
  let lc = Array.map map mip.mind_nf_lc in
  let lrecargs = Declareops.dest_subterms mip.mind_recargs in
  Array.map2 analrec lc lrecargs

let tclIDTAC = tclUNIT ()

let tclTHEN t1 t2 =
  t1 <*> t2

let tclFAILn ?info lvl msg =
  let info = match info with
    (* If the backtrace points here it means the caller didn't save
        the backtrace correctly *)
    | None -> Exninfo.reify ()
    | Some info -> info
  in
  tclZERO ~info (FailError (lvl,lazy msg))

let tclFAIL ?info msg = tclFAILn ?info 0 msg

let tclZEROMSG ?info ?loc msg =
  let info = match info with
    (* If the backtrace points here it means the caller didn't save
        the backtrace correctly *)
    | None -> Exninfo.reify ()
    | Some info -> info
  in
  let info = match loc with
  | None -> info
  | Some loc -> Loc.add_loc info loc
  in
  let err = UserError msg in
  tclZERO ~info err

(* spiwack: I chose to give the Ltac + the same semantics as
    [Proofview.tclOR], however, for consistency with the or-else
    tactical, we may consider wrapping the first argument with
    [tclPROGRESS]. It strikes me as a bad idea, but consistency can be
    considered valuable. *)
let tclOR t1 t2 =
  tclINDEPENDENT begin
    Proofview.tclOR
      t1
      begin fun e ->
        catch_failerror e <*> t2
      end
  end

let tclORD t1 t2 =
  tclINDEPENDENT begin
    Proofview.tclOR
      t1
      begin fun e ->
        catch_failerror e <*> t2 ()
      end
  end

let tclONCE = Proofview.tclONCE

let tclEXACTLY_ONCE t = Proofview.tclEXACTLY_ONCE (FailError(0,lazy (assert false))) t

let tclIFCATCH t tt te =
  tclINDEPENDENT begin
    Proofview.tclIFCATCH t
      tt
      (fun e -> catch_failerror e <*> te ())
  end

let tclORELSE0 t1 t2 =
  tclINDEPENDENT begin
    tclORELSE
      t1
      begin fun e ->
        catch_failerror e <*> t2
      end
  end

let tclORELSE0L t1 t2 =
  tclINDEPENDENTL begin
    tclORELSE
      t1
      begin fun e ->
        catch_failerror e <*> t2
      end
  end

let tclORELSE t1 t2 =
  tclORELSE0 (tclPROGRESS t1) t2

let tclTHENS3PARTS t1 l1 repeat l2 =
  tclINDEPENDENT begin
    t1 <*>
      Proofview.tclORELSE (* converts the [SizeMismatch] error into an ltac error *)
        begin tclEXTEND (Array.to_list l1) repeat (Array.to_list l2) end
        begin function (e, info) -> match e with
          | SizeMismatch (i,_)->
              let errmsg =
                str"Incorrect number of goals" ++ spc() ++
                str"(expected "++int i++str(String.plural i " tactic") ++ str")"
              in
              tclFAIL errmsg
          | reraise -> tclZERO ~info reraise
        end
  end
let tclTHENSFIRSTn t1 l repeat =
  tclTHENS3PARTS t1 l repeat [||]
let tclTHENFIRSTn t1 l =
  tclTHENSFIRSTn t1 l (tclUNIT())
let tclTHENFIRST t1 t2 =
  tclTHENFIRSTn t1 [|t2|]

let tclBINDFIRST t1 t2 =
  t1 >>= fun ans ->
  Proofview.Unsafe.tclGETGOALS >>= fun gls ->
  match gls with
  | [] -> tclFAIL (str "Expect at least one goal.")
  | hd::tl ->
  Proofview.Unsafe.tclSETGOALS [hd] <*> t2 ans >>= fun ans ->
  Proofview.Unsafe.tclNEWGOALS tl <*>
  Proofview.tclUNIT ans

let tclTHENSLASTn t1 repeat l =
  tclTHENS3PARTS t1 [||] repeat l

let tclTHENLASTn t1 l =
  tclTHENS3PARTS t1 [||] (tclUNIT()) l
let tclTHENLAST t1 t2 = tclTHENLASTn t1 [|t2|]

let option_of_failure f x = try Some (f x) with Failure _ -> None

let tclBINDLAST t1 t2 =
  t1 >>= fun ans ->
  Proofview.Unsafe.tclGETGOALS >>= fun gls ->
  match option_of_failure List.sep_last gls with
  | None -> tclFAIL (str "Expect at least one goal.")
  | Some (last,firstn) ->
  Proofview.Unsafe.tclSETGOALS [last] <*> t2 ans >>= fun ans ->
  Proofview.Unsafe.tclGETGOALS >>= fun newgls ->
  tclEVARMAP >>= fun sigma ->
  let firstn = Proofview.Unsafe.undefined sigma firstn in
  Proofview.Unsafe.tclSETGOALS (firstn@newgls) <*>
  Proofview.tclUNIT ans

let tclTHENS t l =
  tclINDEPENDENT begin
    t <*>Proofview.tclORELSE (* converts the [SizeMismatch] error into an ltac error *)
        begin tclDISPATCH l end
        begin function (e, info) -> match e with
          | SizeMismatch (i,_)->
              let errmsg =
                str"Incorrect number of goals" ++ spc() ++
                str"(expected "++int i++str(String.plural i " tactic") ++ str")"
              in
              tclFAIL errmsg
          | reraise -> tclZERO ~info reraise
        end
  end
let tclTHENLIST l =
  List.fold_left tclTHEN (tclUNIT()) l


(* [tclMAP f [x1..xn]] builds [(f x1);(f x2);...(f xn)] *)
let tclMAP tacfun l =
  List.fold_right (fun x -> (tclTHEN (tacfun x))) l (tclUNIT())

let tclTRY t =
  tclORELSE0 t (tclUNIT ())

let tclTRYb t =
  tclORELSE0L (t <*> tclUNIT true) (tclUNIT false)

let tclIFTHENELSE t1 t2 t3 =
  tclINDEPENDENT begin
    Proofview.tclIFCATCH t1
      (fun () -> t2)
      (fun (e, info) -> Proofview.tclORELSE t3 (fun e' -> tclZERO ~info e))
  end
let tclIFTHENSVELSE t1 a t3 =
  Proofview.tclIFCATCH t1
    (fun () -> tclDISPATCH (Array.to_list a))
    (fun _ -> t3)
let tclIFTHENFIRSTELSE t1 t2 t3 =
  Proofview.tclIFCATCH t1
    (fun () -> tclEXTEND [t2] (tclUNIT ()) [])
    (fun _ -> t3)
let tclIFTHENTRYELSEMUST t1 t2 =
  tclIFTHENELSE t1 (tclTRY t2) t2
let tclIFTHENFIRSTTRYELSEMUST t1 t2 =
  tclIFTHENFIRSTELSE t1 (tclTRY t2) t2

(* Try the first tactic that does not fail in a list of tactics *)
let rec tclFIRST = function
  | [] ->
    let info = Exninfo.reify () in
    tclZEROMSG ~info (str"No applicable tactic.")
  | t::rest -> tclORELSE0 t (tclFIRST rest)

let rec tclFIRST_PROGRESS_ON tac = function
  | []    -> tclFAIL (str "No applicable tactic")
  | [a]   -> tac a (* so that returned failure is the one from last item *)
  | a::tl -> tclORELSE (tac a) (tclFIRST_PROGRESS_ON tac tl)

let rec tclDO n t =
  if n < 0 then
    let info = Exninfo.reify () in
    tclZEROMSG ~info (str"Wrong argument : Do needs a positive integer.")
  else if n = 0 then tclUNIT ()
  else if n = 1 then t
  else
    (* Thunk to avoid stack overflow with large n *)
    tclTHEN t (tclUNIT () >>= fun () -> (tclDO (n-1) t))

let rec tclREPEAT0 t =
  tclINDEPENDENT begin
    Proofview.tclIFCATCH t
      (fun () -> tclCHECKINTERRUPT <*> tclREPEAT0 t)
      (fun e -> catch_failerror e <*> tclUNIT ())
  end
let tclREPEAT t =
  tclREPEAT0 (tclPROGRESS t)
let rec tclREPEAT_MAIN0 t =
  Proofview.tclIFCATCH t
    (fun () -> tclTRYFOCUS 1 1 (tclREPEAT_MAIN0 t))
    (fun e -> catch_failerror e <*> tclUNIT ())
let tclREPEAT_MAIN t =
  tclREPEAT_MAIN0 (tclPROGRESS t)

let tclCOMPLETE t =
  t >>= fun res ->
    (tclINDEPENDENT
        (let info = Exninfo.reify () in
        tclZEROMSG ~info (str"Proof is not complete."))
    ) <*>
      tclUNIT res

(* Try the first that solves the current goal *)
let tclSOLVE tacl = tclFIRST (List.map tclCOMPLETE tacl)

let tclPROGRESS t =
  Proofview.tclINDEPENDENT (Proofview.tclPROGRESS t)

(* Check that holes in arguments have been resolved *)

let check_evars env sigma extsigma origsigma =
  (* origsigma ⊆ extsigma ⊆ sigma *)
  let reachable = lazy (Evarutil.reachable_from_evars sigma
                          (Evar.Map.domain (Evd.undefined_map origsigma))) in
  let rec is_undefined_up_to_restriction sigma evk =
    if Evd.mem origsigma evk then None else
    let EvarInfo evi = Evd.find sigma evk in
    match Evd.evar_body evi with
    | Evd.Evar_empty -> Some (evk, Evd.EvarInfo evi)
    | Evd.Evar_defined c -> match Constr.kind (EConstr.Unsafe.to_constr c) with
      | Evar (evk,l) -> is_undefined_up_to_restriction sigma evk
      | _ ->
        (* We make the assumption that there is no way to refine an
          evar remaining after typing from the initial term given to
          apply/elim and co tactics, is it correct? *)
        None in
  if Evd.undefined_map extsigma == Evd.undefined_map origsigma then ()
  else
  let rest =
    Evd.fold_undefined (fun evk evi acc ->
      match is_undefined_up_to_restriction sigma evk with
      | Some (evk',evi) ->
          (* If [evk'] descends from [evk] which descends itself from
            an originally undefined evar in [origsigma], it is a not
            a fresh undefined hole from [sigma]. *)
          if Evar.Set.mem evk (Lazy.force reachable) then acc
          else (evk',evi)::acc
      | _ -> acc)
      extsigma []
  in
  match rest with
  | [] -> ()
  | (evk, EvarInfo evi) :: _ ->
    let (loc,_) = Evd.evar_source evi in
    Pretype_errors.error_unsolvable_implicit ?loc env sigma evk None

let tclMAPDELAYEDWITHHOLES accept_unresolved_holes l tac =
  let rec aux = function
    | [] -> tclUNIT ()
    | x :: l ->
      Proofview.Goal.enter begin fun gl ->
        let env = Proofview.Goal.env gl in
        let sigma_initial = Proofview.Goal.sigma gl in
        let (sigma, x) = x env sigma_initial in
        Proofview.Unsafe.tclEVARS sigma <*> tac x >>= fun () -> aux l >>= fun () ->
        if accept_unresolved_holes then
          tclUNIT ()
        else
          tclEVARMAP >>= fun sigma_final ->
          try
            let () = check_evars env sigma_final sigma sigma_initial in
            tclUNIT ()
          with e when CErrors.noncritical e ->
            let e, info = Exninfo.capture e in
            tclZERO ~info e
        end in
  aux l

(* The following is basically
  tclMAPDELAYEDWITHHOLES accept_unresolved_holes [fun _ _ -> (sigma,())] (fun () -> tac)
  but with value not necessarily in unit *)

let tclWITHHOLES accept_unresolved_holes tac sigma =
  tclEVARMAP >>= fun sigma_initial ->
    if sigma == sigma_initial then tac
    else
      let check_evars_if x =
        if not accept_unresolved_holes then
          tclEVARMAP >>= fun sigma_final ->
            tclENV >>= fun env ->
              try
                let () = check_evars env sigma_final sigma sigma_initial in
                tclUNIT x
              with e when CErrors.noncritical e ->
                let e, info = Exninfo.capture e in
                tclZERO ~info e
        else
          tclUNIT x
      in
      Proofview.Unsafe.tclEVARS sigma <*> tac >>= check_evars_if

let tclDELAYEDWITHHOLES check x tac =
  Proofview.Goal.enter begin fun gl ->
    let env = Proofview.Goal.env gl in
    let sigma = Proofview.Goal.sigma gl in
    let (sigma, x) = x env sigma in
    tclWITHHOLES check (tac x) sigma
  end

let tclTIMEOUT n t =
  Proofview.tclOR
    (Proofview.tclTIMEOUT n t)
    begin function (e, info) -> match e with
      | Logic_monad.Tac_Timeout as e ->
        let info = Exninfo.reify () in
        Proofview.tclZERO ~info (FailError (0,lazy (CErrors.print e)))
      | e -> Proofview.tclZERO ~info e
    end

let tclTIME s t =
  Proofview.tclTIME s t

let nthDecl m gl =
  let hyps = Proofview.Goal.hyps gl in
  try
    List.nth hyps (m-1)
  with Failure _ -> CErrors.user_err Pp.(str "No such assumption.")

let nLastDecls gl n =
  try List.firstn n (Proofview.Goal.hyps gl)
  with Failure _ -> CErrors.user_err Pp.(str "Not enough hypotheses in the goal.")

let nthHypId m gl =
  (* We only use [id] *)
  nthDecl m gl |> NamedDecl.get_id
let nthHyp m gl =
  mkVar (nthHypId m gl)

let onNthHypId m tac =
  Proofview.Goal.enter begin fun gl -> tac (nthHypId m gl) end
let onNthHyp m tac =
  Proofview.Goal.enter begin fun gl -> tac (nthHyp m gl) end

let onLastHypId = onNthHypId 1
let onLastHyp   = onNthHyp 1

let onNthDecl m tac =
  Proofview.Goal.enter begin fun gl ->
    Proofview.tclUNIT (nthDecl m gl) >>= tac
  end
let onLastDecl  = onNthDecl 1

let nLastHypsId gl n = List.map (NamedDecl.get_id) (nLastDecls gl n)
let nLastHyps gl n = List.map mkVar (nLastHypsId gl n)

let ifOnHyp pred tac1 tac2 id =
  Proofview.Goal.enter begin fun gl ->
  let typ = Tacmach.pf_get_hyp_typ id gl in
  if pf_apply pred gl (id,typ) then
    tac1 id
  else
    tac2 id
  end

let onHyps find tac = Proofview.Goal.enter begin fun gl -> tac (find gl) end

let onNLastDecls n tac  = onHyps (fun gl -> nLastDecls gl n) tac
let onNLastHypsId n tac = onHyps (fun gl -> nLastHypsId gl n) tac
let onNLastHyps n tac   = onHyps (fun gl -> nLastHyps gl n) tac

let afterHyp id tac =
  Proofview.Goal.enter begin fun gl ->
  let hyps = Proofview.Goal.hyps gl in
  let rem, _ = List.split_when (NamedDecl.get_id %> Id.equal id) hyps in
  tac rem
  end

let fullGoal gl =
  let hyps = Tacmach.pf_ids_of_hyps gl in
  None :: List.map Option.make hyps

let tryAllHyps tac =
  Proofview.Goal.enter begin fun gl ->
  let hyps = Tacmach.pf_ids_of_hyps gl in
  tclFIRST_PROGRESS_ON tac hyps
  end
let tryAllHypsAndConcl tac =
  Proofview.Goal.enter begin fun gl ->
    tclFIRST_PROGRESS_ON tac (fullGoal gl)
  end

let onClause tac cl =
  Proofview.Goal.enter begin fun gl ->
  let hyps = Tacmach.pf_ids_of_hyps gl in
  tclMAP tac (Locusops.simple_clause_of (fun () -> hyps) cl)
  end

let fullGoal gl = None :: List.map Option.make (Tacmach.pf_ids_of_hyps gl)
let onAllHyps tac =
  Proofview.Goal.enter begin fun gl ->
    tclMAP tac (Tacmach.pf_ids_of_hyps gl)
    end
let onAllHypsAndConcl tac =
  Proofview.Goal.enter begin fun gl ->
    tclMAP tac (fullGoal gl)
    end

let elimination_sort_of_goal gl =
  (* Retyping will expand evars anyway. *)
  let c = Proofview.Goal.concl gl in
  pf_apply Retyping.get_sort_family_of gl c

let elimination_sort_of_hyp id gl =
  (* Retyping will expand evars anyway. *)
  let c = pf_get_hyp_typ id gl in
  pf_apply Retyping.get_sort_family_of gl c

let elimination_sort_of_clause id gl = match id with
| None -> elimination_sort_of_goal gl
| Some id -> elimination_sort_of_hyp id gl

let pf_constr_of_global ref =
  Proofview.tclEVARMAP >>= fun sigma ->
  Proofview.tclENV >>= fun env ->
  let (sigma, c) = Evd.fresh_global env sigma ref in
  Proofview.Unsafe.tclEVARS sigma <*> Proofview.tclUNIT c

let tclTYPEOFTHEN ?refresh c tac =
  Proofview.Goal.enter (fun gl ->
    let env = Proofview.Goal.env gl in
    let sigma = Proofview.Goal.sigma gl in
    let (sigma, t) = Typing.type_of ?refresh env sigma c in
    Proofview.Unsafe.tclEVARS sigma <*> tac sigma t)

let tclSELECT = Goal_select.tclSELECT
