(************************************************************************)
(*         *   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 CErrors

(** The type of parsing attribute data *)
type vernac_flag_type =
  | FlagIdent of string
  | FlagString of string

type vernac_flags = vernac_flag list
and vernac_flag = string * vernac_flag_value
and vernac_flag_value =
  | VernacFlagEmpty
  | VernacFlagLeaf of vernac_flag_type
  | VernacFlagList of vernac_flags

let pr_vernac_flag_leaf = function
  | FlagIdent b -> Pp.str b
  | FlagString s -> Pp.(quote (str s))

let rec pr_vernac_flag_value = let open Pp in function
  | VernacFlagEmpty -> mt ()
  | VernacFlagLeaf l -> str "=" ++ pr_vernac_flag_leaf l
  | VernacFlagList s -> surround (prlist_with_sep pr_comma pr_vernac_flag s)
and pr_vernac_flag (s, arguments) =
  let open Pp in
  str s ++ (pr_vernac_flag_value arguments)

let warn_unsupported_attributes =
  CWarnings.create ~name:"unsupported-attributes" ~category:"parsing" ~default:CWarnings.AsError
    (fun atts ->
       let keys = List.map fst atts in
       let keys = List.sort_uniq String.compare keys in
       let conj = match keys with [_] -> "this attribute: " | _ -> "these attributes: " in
       Pp.(str "This command does not support " ++ str conj ++ prlist str keys ++ str"."))

let unsupported_attributes = function
  | [] -> ()
  | atts -> warn_unsupported_attributes atts

type 'a key_parser = 'a option -> vernac_flag_value -> 'a

type 'a attribute = vernac_flags -> vernac_flags * 'a

let parse_with_extra (p:'a attribute) (atts:vernac_flags) : vernac_flags * 'a =
  p atts

let parse_drop_extra att atts =
  snd (parse_with_extra att atts)

let parse (p:'a attribute) atts : 'a =
  let extra, v = parse_with_extra p atts in
  unsupported_attributes extra;
  v

let make_attribute x = x

module Notations = struct

  type 'a t = 'a attribute

  let return x = fun atts -> atts, x

  let (>>=) att f =
    fun atts ->
      let atts, v = att atts in
      f v atts

  let (>>) p1 p2 =
    fun atts ->
      let atts, () = p1 atts in
      p2 atts

  let map f att =
    fun atts ->
      let atts, v = att atts in
      atts, f v

  let (++) (p1:'a attribute) (p2:'b attribute) : ('a*'b) attribute =
    fun atts ->
      let atts, v1 = p1 atts in
      let atts, v2 = p2 atts in
      atts, (v1, v2)

end
open Notations

let assert_empty k v =
  if v <> VernacFlagEmpty
  then user_err Pp.(str "Attribute " ++ str k ++ str " does not accept arguments")

let error_twice ~name : 'a =
  user_err Pp.(str "Attribute for " ++ str name ++ str " specified twice.")

let assert_once ~name prev =
  if Option.has_some prev then
    error_twice ~name

let attribute_of_list (l:(string * 'a key_parser) list) : 'a option attribute =
  let rec p extra v = function
    | [] -> List.rev extra, v
    | (key, attv as att) :: rem ->
      (match CList.assoc_f String.equal key l with
       | exception Not_found -> p (att::extra) v rem
       | parser ->
         let v = Some (parser v attv) in
         p extra v rem)
  in
  p [] None

let single_key_parser ~name ~key v prev args =
  assert_empty key args;
  assert_once ~name prev;
  v

let pr_possible_values ~values =
  Pp.(str "{" ++ prlist_with_sep pr_comma str (List.map fst values) ++ str "}")

(** [key_value_attribute ~key ~default ~values] parses a attribute [key=value]
  with possible [key] [value] in [values], [default] is for compatibility for users
  doing [qualif(key)] which is parsed as [qualif(key=default)] *)
let key_value_attribute ~key ~default ~(values : (string * 'a) list) : 'a option attribute =
  let parser = function
    | Some v ->
      CErrors.user_err Pp.(str "key '" ++ str key ++ str "' has been already set.")
    | None ->
      begin function
        | VernacFlagLeaf (FlagIdent b) ->
          begin match CList.assoc_f String.equal b values with
            | exception Not_found ->
              CErrors.user_err
                Pp.(str "Invalid value '" ++ str b ++ str "' for key " ++ str key ++ fnl () ++
                    str "use one of " ++ pr_possible_values ~values)
            | value -> value
          end
        | VernacFlagEmpty ->
          default
        | err ->
          CErrors.user_err
            Pp.(str "Invalid syntax " ++ pr_vernac_flag (key, err) ++ str ", try "
                ++ str key ++ str "=" ++ pr_possible_values ~values ++ str " instead.")
      end
  in
  attribute_of_list [key, parser]

let bool_attribute ~name : bool option attribute =
  let values = ["yes", true; "no", false] in
  key_value_attribute ~key:name ~default:true ~values

let legacy_bool_attribute ~name ~on ~off : bool option attribute =
  attribute_of_list
    [(on, single_key_parser ~name ~key:on true);
     (off, single_key_parser ~name ~key:off false)]

(* important note: we use on as the default for the new bool_attribute ! *)
let deprecated_bool_attribute_warning =
  CWarnings.create
    ~name:"deprecated-attribute-syntax"
    ~category:"parsing"
    ~default:CWarnings.Enabled
    (fun name ->
       Pp.(str "Syntax for switching off boolean attributes has been updated, use " ++ str name ++ str "=no instead."))

let deprecated_bool_attribute ~name ~on ~off : bool option attribute =
  bool_attribute ~name:on ++ legacy_bool_attribute ~name ~on ~off |> map (function
      | None, None ->
        None
      | None, Some v ->
        deprecated_bool_attribute_warning name;
        Some v
      | Some v, None -> Some v
      | Some v1, Some v2 ->
        CErrors.user_err
          Pp.(str "attribute " ++ str name ++
              str ": cannot specify legacy and modern syntax at the same time.")
    )

(* Variant of the [bool] attribute with only two values (bool has three). *)
let get_bool_value ~key ~default =
  function
  | VernacFlagEmpty -> default
  | VernacFlagList [ "true", VernacFlagEmpty ] ->
    deprecated_bool_attribute_warning key;
    true
  | VernacFlagList [ "false", VernacFlagEmpty ] ->
    deprecated_bool_attribute_warning key;
    false
  | VernacFlagLeaf (FlagIdent "yes") ->
    true
  | VernacFlagLeaf (FlagIdent "no") ->
    false
  | _ -> user_err Pp.(str "Attribute " ++ str key ++ str " only accepts boolean values.")

let enable_attribute ~key ~default : bool attribute =
  fun atts ->
  let default = default () in
  let this, extra = List.partition (fun (k, _) -> String.equal key k) atts in
  extra,
  match this with
  | [] -> default
  | [ _, value ] -> get_bool_value ~key ~default:true value
  | _ -> error_twice ~name:key

let qualify_attribute qual (parser:'a attribute) : 'a attribute =
  fun atts ->
    let rec extract extra qualified = function
      | [] -> List.rev extra, List.flatten (List.rev qualified)
      | (key,attv) :: rem when String.equal key qual ->
        (match attv with
         | VernacFlagEmpty | VernacFlagLeaf _ ->
           CErrors.user_err ~hdr:"qualified_attribute"
             Pp.(str "Malformed attribute " ++ str qual ++ str ": attribute list expected.")
         | VernacFlagList atts ->
           extract extra (atts::qualified) rem)
      | att :: rem -> extract (att::extra) qualified rem
    in
    let extra, qualified = extract [] [] atts in
    let rem, v = parser qualified in
    let extra = if rem = [] then extra else (qual, VernacFlagList rem) :: extra in
    extra, v

(** [program_mode] tells that Program mode has been activated, either
    globally via [Set Program] or locally via the Program command prefix. *)

let program_mode_option_name = ["Program";"Mode"]
let program_mode = ref false

let () = let open Goptions in
  declare_bool_option
    { optdepr  = false;
      optkey   = program_mode_option_name;
      optread  = (fun () -> !program_mode);
      optwrite = (fun b -> program_mode:=b) }

let program =
  enable_attribute ~key:"program" ~default:(fun () -> !program_mode)

(* This is a bit complex as the grammar in g_vernac.mlg doesn't
   distingish between the boolean and ternary case.*)
let option_locality_parser =
  let name = "Locality" in
  attribute_of_list [
    ("local", single_key_parser ~name ~key:"local" Goptions.OptLocal)
  ; ("global", single_key_parser ~name ~key:"global" Goptions.OptGlobal)
  ; ("export", single_key_parser ~name ~key:"export" Goptions.OptExport)
  ]

let option_locality =
  option_locality_parser >>= function
  | None -> return Goptions.OptDefault
  | Some l -> return l

(* locality is supposed to be true when local, false when global *)
let locality =
  let locality_to_bool =
    function
    | Goptions.OptLocal ->
      true
    | Goptions.OptGlobal ->
      false
    | Goptions.OptExport ->
      CErrors.user_err Pp.(str "export attribute not supported here")
    | Goptions.OptDefault ->
      CErrors.user_err Pp.(str "default attribute not supported here")
  in
  option_locality_parser >>= function l ->
    return (Option.map locality_to_bool l)

let ukey = "universes"

let universe_polymorphism_option_name = ["Universe"; "Polymorphism"]
let is_universe_polymorphism =
  let b = ref false in
  let () = let open Goptions in
    declare_bool_option
      { optdepr  = false;
        optkey   = universe_polymorphism_option_name;
        optread  = (fun () -> !b);
        optwrite = ((:=) b) }
  in
  fun () -> !b

let polymorphic_base =
  deprecated_bool_attribute
    ~name:"Polymorphism"
    ~on:"polymorphic" ~off:"monomorphic" >>= function
  | Some b -> return b
  | None -> return (is_universe_polymorphism())

let template =
  qualify_attribute ukey
    (deprecated_bool_attribute
       ~name:"Template"
       ~on:"template" ~off:"notemplate")

let polymorphic =
  qualify_attribute ukey polymorphic_base

let deprecation_parser : Deprecation.t key_parser = fun orig args ->
  assert_once ~name:"deprecation" orig;
  match args with
  | VernacFlagList [ "since", VernacFlagLeaf (FlagString since) ; "note", VernacFlagLeaf (FlagString note) ]
  | VernacFlagList [ "note", VernacFlagLeaf (FlagString note) ; "since", VernacFlagLeaf (FlagString since) ] ->
    Deprecation.make ~since ~note ()
  | VernacFlagList [ "since", VernacFlagLeaf (FlagString since) ] ->
    Deprecation.make ~since ()
  | VernacFlagList [ "note", VernacFlagLeaf (FlagString note) ] ->
    Deprecation.make ~note ()
  |  _ -> CErrors.user_err (Pp.str "Ill formed “deprecated” attribute")

let deprecation = attribute_of_list ["deprecated",deprecation_parser]

let only_locality atts = parse locality atts

let only_polymorphism atts = parse polymorphic atts


let vernac_polymorphic_flag = ukey, VernacFlagList ["polymorphic", VernacFlagEmpty]
let vernac_monomorphic_flag = ukey, VernacFlagList ["polymorphic", VernacFlagLeaf (FlagIdent "no")]

let canonical_field =
  enable_attribute ~key:"canonical" ~default:(fun () -> true)
let canonical_instance =
  enable_attribute ~key:"canonical" ~default:(fun () -> false)

let uses_parser : string key_parser = fun orig args ->
  assert_once ~name:"using" orig;
  match args with
  | VernacFlagLeaf (FlagString str) -> str
  |  _ -> CErrors.user_err (Pp.str "Ill formed \"using\" attribute")

let using = attribute_of_list ["using",uses_parser]