(************************************************************************)
(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
(* <O___,, *   INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2010     *)
(*   \VV/  **************************************************************)
(*    //   *      This file is distributed under the terms of the       *)
(*         *       GNU Lesser General Public License Version 2.1        *)
(************************************************************************)

(*i $Id: common.ml 13420 2010-09-16 15:47:08Z letouzey $ i*)

open Pp
open Util
open Names
open Term
open Declarations
open Namegen
open Nameops
open Libnames
open Table
open Miniml
open Mlutil
open Modutil
open Mod_subst

let string_of_id id =
  let s = Names.string_of_id id in
  for i = 0 to String.length s - 2 do
    if s.[i] = '_' && s.[i+1] = '_' then warning_id s
  done;
  ascii_of_ident s

let is_mp_bound = function MPbound _ -> true | _ -> false

(*s Some pretty-print utility functions. *)

let pp_par par st = if par then str "(" ++ st ++ str ")" else st

let pp_apply st par args = match args with
  | [] -> st
  | _  -> hov 2 (pp_par par (st ++ spc () ++ prlist_with_sep spc identity args))

let pr_binding = function
  | [] -> mt ()
  | l  -> str " " ++ prlist_with_sep (fun () -> str " ") pr_id l

let fnl2 () = fnl () ++ fnl ()

let space_if = function true -> str " " | false -> mt ()

let sec_space_if = function true -> spc () | false -> mt ()

let is_digit = function
  | '0'..'9' -> true
  | _ -> false

let begins_with_CoqXX s =
  let n = String.length s in
  n >= 4 && s.[0] = 'C' && s.[1] = 'o' && s.[2] = 'q' &&
  let i = ref 3 in
  try while !i < n do
    if s.[!i] = '_' then i:=n (*Stop*)
    else if is_digit s.[!i] then incr i
    else raise Not_found
  done; true
  with Not_found -> false

let unquote s =
  if lang () <> Scheme then s
  else
    let s = String.copy s in
    for i=0 to String.length s - 1 do if s.[i] = '\'' then s.[i] <- '~' done;
    s

let rec qualify delim = function
  | [] -> assert false
  | [s] -> s
  | ""::l -> qualify delim l
  | s::l -> s^delim^(qualify delim l)

let dottify = qualify "."
let pseudo_qualify = qualify "__"

(*s Uppercase/lowercase renamings. *)

let is_upper s = match s.[0] with 'A' .. 'Z' -> true | _ -> false
let is_lower s = match s.[0] with 'a' .. 'z' | '_' -> true | _ -> false

let lowercase_id id = id_of_string (String.uncapitalize (string_of_id id))
let uppercase_id id =
  let s = string_of_id id in
  assert (s<>"");
  if s.[0] = '_' then id_of_string ("Coq_"^s)
  else id_of_string (String.capitalize s)

type kind = Term | Type | Cons | Mod

let upperkind = function
  | Type -> lang () = Haskell
  | Term -> false
  | Cons | Mod -> true

let kindcase_id k id =
  if upperkind k then uppercase_id id else lowercase_id id

(*s de Bruijn environments for programs *)

type env = identifier list * Idset.t

(*s Generic renaming issues for local variable names. *)

let rec rename_id id avoid =
  if Idset.mem id avoid then rename_id (lift_subscript id) avoid else id

let rec rename_vars avoid = function
  | [] ->
      [], avoid
  | id :: idl when id == dummy_name ->
      (* we don't rename dummy binders *)
      let (idl', avoid') = rename_vars avoid idl in
      (id :: idl', avoid')
  | id :: idl ->
      let (idl, avoid) = rename_vars avoid idl in
      let id = rename_id (lowercase_id id) avoid in
      (id :: idl, Idset.add id avoid)

let rename_tvars avoid l =
  let rec rename avoid = function
    | [] -> [],avoid
    | id :: idl ->
	let id = rename_id (lowercase_id id) avoid in
	let idl, avoid = rename (Idset.add id avoid) idl in
	(id :: idl, avoid) in
  fst (rename avoid l)

let push_vars ids (db,avoid) =
  let ids',avoid' = rename_vars avoid ids in
  ids', (ids' @ db, avoid')

let get_db_name n (db,_) =
  let id = List.nth db (pred n) in
  if id = dummy_name then id_of_string "__" else id


(*S Renamings of global objects. *)

(*s Tables of global renamings *)

let register_cleanup, do_cleanup =
  let funs = ref [] in
  (fun f -> funs:=f::!funs), (fun () -> List.iter (fun f -> f ()) !funs)

type phase = Pre | Impl | Intf

let set_phase, get_phase =
  let ph = ref Impl in ((:=) ph), (fun () -> !ph)

let set_keywords, get_keywords =
  let k = ref Idset.empty in
  ((:=) k), (fun () -> !k)

let add_global_ids, get_global_ids =
  let ids = ref Idset.empty in
  register_cleanup (fun () -> ids := get_keywords ());
  let add s = ids := Idset.add s !ids
  and get () = !ids
  in (add,get)

let empty_env () = [], get_global_ids ()

let mktable autoclean =
  let h = Hashtbl.create 97 in
  if autoclean then register_cleanup (fun () -> Hashtbl.clear h);
  (Hashtbl.add h, Hashtbl.find h, fun () -> Hashtbl.clear h)

(* A table recording objects in the first level of all MPfile *)

let add_mpfiles_content,get_mpfiles_content,clear_mpfiles_content =
  mktable false

let get_mpfiles_content mp =
  try get_mpfiles_content mp
  with Not_found -> failwith "get_mpfiles_content"

(*s The list of external modules that will be opened initially *)

let mpfiles_add, mpfiles_mem, mpfiles_list, mpfiles_clear =
  let m = ref MPset.empty in
  let add mp = m:=MPset.add mp !m
  and mem mp = MPset.mem mp !m
  and list () = MPset.elements !m
  and clear () = m:=MPset.empty
  in
  register_cleanup clear;
  (add,mem,list,clear)

(*s List of module parameters that we should alpha-rename *)

let params_ren_add, params_ren_mem =
  let m = ref MPset.empty in
  let add mp = m:=MPset.add mp !m
  and mem mp = MPset.mem mp !m
  and clear () = m:=MPset.empty
  in
  register_cleanup clear;
  (add,mem)

(*s table indicating the visible horizon at a precise moment,
    i.e. the stack of structures we are inside.

  - The sequence of [mp] parts should have the following form:
  a [MPfile] at the beginning, and then more and more [MPdot]
  over this [MPfile], or [MPbound] when inside the type of a
  module parameter.

  - the [params] are the [MPbound] when [mp] is a functor,
    the innermost [MPbound] coming first in the list.

  - The [content] part is used to record all the names already
  seen at this level.
*)

type visible_layer = { mp : module_path;
		       params : module_path list;
		       content : ((kind*string),label) Hashtbl.t }

let pop_visible, push_visible, get_visible =
  let vis = ref [] in
  register_cleanup (fun () -> vis := []);
  let pop () =
    match !vis with
      | [] -> assert false
      | v :: vl ->
	  vis := vl;
	  (* we save the 1st-level-content of MPfile for later use *)
	  if get_phase () = Impl && modular () && is_modfile v.mp
	  then add_mpfiles_content v.mp v.content
  and push mp mps =
    vis := { mp = mp; params = mps; content = Hashtbl.create 97 } :: !vis
  and get () = !vis
  in (pop,push,get)

let get_visible_mps () = List.map (function v -> v.mp) (get_visible ())
let top_visible () = match get_visible () with [] -> assert false | v::_ -> v
let top_visible_mp () = (top_visible ()).mp
let add_visible ks l = Hashtbl.add (top_visible ()).content ks l

(* table of local module wrappers used to provide non-ambiguous names *)

let add_duplicate, check_duplicate =
  let index = ref 0 and dups = ref Gmap.empty in
  register_cleanup (fun () -> index := 0; dups := Gmap.empty);
  let add mp l =
     incr index;
     let ren = "Coq__" ^ string_of_int (!index) in
     dups := Gmap.add (mp,l) ren !dups
  and check mp l = Gmap.find (mp, l) !dups
  in (add,check)

type reset_kind = AllButExternal | Everything

let reset_renaming_tables flag =
  do_cleanup ();
  if flag = Everything then clear_mpfiles_content ()

(*S Renaming functions *)

(* This function creates from [id] a correct uppercase/lowercase identifier.
   This is done by adding a [Coq_] or [coq_] prefix. To avoid potential clashes
   with previous [Coq_id] variable, these prefixes are duplicated if already
   existing. *)

let modular_rename k id =
  let s = string_of_id id in
  let prefix,is_ok =
    if upperkind k then "Coq_",is_upper else "coq_",is_lower
  in
  if not (is_ok s) ||
    (Idset.mem id (get_keywords ())) ||
    (String.length s >= 4 && String.sub s 0 4 = prefix)
  then prefix ^ s
  else s

(*s For monolithic extraction, first-level modules might have to be renamed
    with unique numbers *)

let modfstlev_rename =
  let add_prefixes,get_prefixes,_ = mktable true in
  fun l ->
    let coqid = id_of_string "Coq" in
    let id = id_of_label l in
    try
      let coqset = get_prefixes id in
      let nextcoq = next_ident_away coqid coqset in
      add_prefixes id (nextcoq::coqset);
      (string_of_id nextcoq)^"_"^(string_of_id id)
    with Not_found ->
      let s = string_of_id id in
      if is_lower s || begins_with_CoqXX s then
	(add_prefixes id [coqid]; "Coq_"^s)
      else
	(add_prefixes id []; s)

(*s Creating renaming for a [module_path] : first, the real function ... *)

let rec mp_renaming_fun mp = match mp with
  | _ when not (modular ()) && at_toplevel mp -> [""]
  | MPdot (mp,l) ->
      let lmp = mp_renaming mp in
      if lmp = [""] then (modfstlev_rename l)::lmp
      else (modular_rename Mod (id_of_label l))::lmp
  | MPbound mbid ->
      let s = modular_rename Mod (id_of_mbid mbid) in
      if not (params_ren_mem mp) then [s]
      else let i,_,_ = repr_mbid mbid in [s^"__"^string_of_int i]
  | MPfile _ ->
      assert (modular ()); (* see [at_toplevel] above *)
      assert (get_phase () = Pre);
      let current_mpfile = (list_last (get_visible ())).mp in
      if mp <> current_mpfile then mpfiles_add mp;
      [string_of_modfile mp]

(* ... and its version using a cache *)

and mp_renaming =
  let add,get,_ = mktable true in
  fun x ->
    try if is_mp_bound (base_mp x) then raise Not_found; get x
    with Not_found -> let y = mp_renaming_fun x in add x y; y

(*s Renamings creation for a [global_reference]: we build its fully-qualified
    name in a [string list] form (head is the short name). *)

let ref_renaming_fun (k,r) =
  let mp = modpath_of_r r in
  let l = mp_renaming mp in
  let l = if lang () <> Ocaml && not (modular ()) then [""] else l in
  let s =
    if l = [""] (* this happens only at toplevel of the monolithic case *)
    then
      let globs = Idset.elements (get_global_ids ()) in
      let id = next_ident_away (kindcase_id k (safe_basename_of_global r)) globs in
      string_of_id id
    else modular_rename k (safe_basename_of_global r)
  in
  add_global_ids (id_of_string s);
  s::l

(* Cached version of the last function *)

let ref_renaming =
  let add,get,_ = mktable true in
  fun x ->
    try if is_mp_bound (base_mp (modpath_of_r (snd x))) then raise Not_found; get x
    with Not_found -> let y = ref_renaming_fun x in add x y; y

(* [visible_clash mp0 (k,s)] checks if [mp0-s] of kind [k]
   can be printed as [s] in the current context of visible
   modules. More precisely, we check if there exists a
   visible [mp] that contains [s].
   The verification stops if we encounter [mp=mp0]. *)

let rec clash mem mp0 ks = function
  | [] -> false
  | mp :: _ when mp = mp0 -> false
  | mp :: _ when mem mp ks -> true
  | _ :: mpl -> clash mem mp0 ks mpl

let mpfiles_clash mp0 ks =
  clash (fun mp -> Hashtbl.mem (get_mpfiles_content mp)) mp0 ks
    (List.rev (mpfiles_list ()))

let rec params_lookup mp0 ks = function
  | [] -> false
  | param :: _ when mp0 = param -> true
  | param :: params ->
      if ks = (Mod, List.hd (mp_renaming param)) then params_ren_add param;
      params_lookup mp0 ks params

let visible_clash mp0 ks =
  let rec clash = function
    | [] -> false
    | v :: _ when v.mp = mp0 -> false
    | v :: vis ->
	let b = Hashtbl.mem v.content ks in
	if b && not (is_mp_bound mp0) then true
	else begin
	  if b then params_ren_add mp0;
	  if params_lookup mp0 ks v.params then false
	  else clash vis
	end
  in clash (get_visible ())

(* Same, but with verbose output (and mp0 shouldn't be a MPbound) *)

let visible_clash_dbg mp0 ks =
  let rec clash = function
    | [] -> None
    | v :: _ when v.mp = mp0 -> None
    | v :: vis ->
	try Some (v.mp,Hashtbl.find v.content ks)
	with Not_found ->
	  if params_lookup mp0 ks v.params then None
	  else clash vis
  in clash (get_visible ())

(* After the 1st pass, we can decide which modules will be opened initially *)

let opened_libraries () =
  if not (modular ()) then []
  else
    let used_files = mpfiles_list () in
    let used_ks = List.map (fun mp -> Mod,string_of_modfile mp) used_files in
    (* By default, we open all used files. Ambiguities will be resolved later
       by using qualified names. Nonetheless, we don't open any file A that
       contains an immediate submodule A.B hiding another file B : otherwise,
       after such an open, there's no unambiguous way to refer to objects of B. *)
    let to_open =
      List.filter
	(fun mp ->
	   not (List.exists (Hashtbl.mem (get_mpfiles_content mp)) used_ks))
	used_files
    in
    mpfiles_clear ();
    List.iter mpfiles_add to_open;
    mpfiles_list ()

(*s On-the-fly qualification issues for both monolithic or modular extraction. *)

(* [pp_ocaml_gen] below is a function that factorize the printing of both
   [global_reference] and module names for ocaml. When [k=Mod] then [olab=None],
   otherwise it contains the label of the reference to print.
   [rls] is the string list giving the qualified name, short name at the end. *)

(* In Coq, we can qualify [M.t] even if we are inside [M], but in Ocaml we
   cannot do that. So, if [t] gets hidden and we need a long name for it,
   we duplicate the _definition_ of t in a Coq__XXX module, and similarly
   for a sub-module [M.N] *)

let pp_duplicate k' prefix mp rls olab =
  let rls', lbl =
    if k'<>Mod then
      (* Here rls=[s], the ref to print is <prefix>.<s>, and olab<>None *)
      rls, Option.get olab
    else
      (* Here rls=s::rls', we search the label for s inside mp *)
      List.tl rls, get_nth_label_mp (mp_length mp - mp_length prefix) mp
  in
  try dottify (check_duplicate prefix lbl :: rls')
  with Not_found ->
    assert (get_phase () = Pre); (* otherwise it's too late *)
    add_duplicate prefix lbl; dottify rls

let fstlev_ks k = function
  | [] -> assert false
  | [s] -> k,s
  | s::_ -> Mod,s

(* [pp_ocaml_local] : [mp] has something in common with [top_visible ()]
   but isn't equal to it *)

let pp_ocaml_local k prefix mp rls olab =
  (* what is the largest prefix of [mp] that belongs to [visible]? *)
  assert (k <> Mod || mp <> prefix); (* mp as whole module isn't in itself *)
  let rls' = list_skipn (mp_length prefix) rls in
  let k's = fstlev_ks k rls' in
  (* Reference r / module path mp is of the form [<prefix>.s.<...>]. *)
  if not (visible_clash prefix k's) then dottify rls'
  else pp_duplicate (fst k's) prefix mp rls' olab

(* [pp_ocaml_bound] : [mp] starts with a [MPbound], and we are not inside
   (i.e. we are not printing the type of the module parameter) *)

let pp_ocaml_bound base rls =
  (* clash with a MPbound will be detected and fixed by renaming this MPbound *)
  if get_phase () = Pre then ignore (visible_clash base (Mod,List.hd rls));
  dottify rls

(* [pp_ocaml_extern] : [mp] isn't local, it is defined in another [MPfile]. *)

let pp_ocaml_extern k base rls = match rls with
  | [] -> assert false
  | base_s :: rls' ->
      if (not (modular ())) (* Pseudo qualification with "" *)
	|| (rls' = [])  (* Case of a file A.v used as a module later *)
	|| (not (mpfiles_mem base)) (* Module not opened *)
	|| (mpfiles_clash base (fstlev_ks k rls')) (* Conflict in opened files *)
	|| (visible_clash base (fstlev_ks k rls')) (* Local conflict *)
      then
	(* We need to fully qualify. Last clash situation is unsupported *)
	match visible_clash_dbg base (Mod,base_s) with
	  | None -> dottify rls
	  | Some (mp,l) -> error_module_clash base (MPdot (mp,l))
      else
	(* Standard situation : object in an opened file *)
	dottify rls'

(* [pp_ocaml_gen] : choosing between [pp_ocaml_extern] or [pp_ocaml_extern] *)

let pp_ocaml_gen k mp rls olab =
  match common_prefix_from_list mp (get_visible_mps ()) with
    | Some prefix -> pp_ocaml_local k prefix mp rls olab
    | None ->
	let base = base_mp mp in
	if is_mp_bound base then pp_ocaml_bound base rls
	else pp_ocaml_extern k base rls

(* For Haskell, things are simplier: we have removed (almost) all structures *)

let pp_haskell_gen k mp rls = match rls with
  | [] -> assert false
  | s::rls' ->
      (if base_mp mp <> top_visible_mp () then s ^ "." else "") ^
	(if upperkind k then "" else "_") ^ pseudo_qualify rls'

(* Main name printing function for a reference *)

let pp_global k r =
  let ls = ref_renaming (k,r) in
  assert (List.length ls > 1);
  let s = List.hd ls in
  let mp,_,l = repr_of_r r in
  if mp = top_visible_mp () then
    (* simpliest situation: definition of r (or use in the same context) *)
    (* we update the visible environment *)
    (add_visible (k,s) l; unquote s)
  else
    let rls = List.rev ls in (* for what come next it's easier this way *)
    match lang () with
      | Scheme -> unquote s (* no modular Scheme extraction... *)
      | Haskell -> if modular () then pp_haskell_gen k mp rls else s
      | Ocaml -> pp_ocaml_gen k mp rls (Some l)

(* The next function is used only in Ocaml extraction...*)

let pp_module mp =
  let ls = mp_renaming mp in
  match mp with
    | MPdot (mp0,l) when mp0 = top_visible_mp () ->
	(* simpliest situation: definition of mp (or use in the same context) *)
	(* we update the visible environment *)
	let s = List.hd ls in
	add_visible (Mod,s) l; s
    | _ -> pp_ocaml_gen Mod mp (List.rev ls) None