(************************************************************************)
(*         *   The Coq Proof Assistant / The Coq Development Team       *)
(*  v      *   INRIA, CNRS and contributors - Copyright 1999-2018       *)
(* <O___,, *       (see CREDITS file for the list of authors)           *)
(*   \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)         *)
(************************************************************************)

(* Created by Jacek Chrzaszcz, Aug 2002 as part of the implementation of
   the Coq module system *)

(* This module provides the main entry points for type-checking basic
   declarations *)

open CErrors
open Util
open Names
open Constr
open Declarations
open Environ
open Entries
open Typeops

module NamedDecl = Context.Named.Declaration

(* Insertion of constants and parameters in environment. *)

type 'a effect_handler =
  env -> Constr.t -> 'a -> (Constr.t * Univ.ContextSet.t * int)

type _ trust =
| Pure : unit trust
| SideEffects : 'a effect_handler -> 'a trust

let skip_trusted_seff sl b e =
  let rec aux sl b e acc =
    let open Context.Rel.Declaration in
    if Int.equal sl 0 then b, e, acc
    else match kind b with
    | LetIn (n,c,ty,bo) ->
       aux (sl - 1) bo
         (Environ.push_rel (LocalDef (n,c,ty)) e) (`Let(n,c,ty)::acc)
    | App(hd,arg) ->
       begin match kind hd with
       | Lambda (n,ty,bo) ->
           aux (sl - 1) bo
             (Environ.push_rel (LocalAssum (n,ty)) e) (`Cut(n,ty,arg)::acc)
       | _ -> assert false
       end
    | _ -> assert false
    in
  aux sl b e []

let rec unzip ctx j =
  match ctx with
  | [] -> j
  | `Let (n,c,ty) :: ctx ->
      unzip ctx { j with uj_val = mkLetIn (n,c,ty,j.uj_val) }
  | `Cut (n,ty,arg) :: ctx ->
      unzip ctx { j with uj_val = mkApp (mkLambda (n,ty,j.uj_val),arg) }

let feedback_completion_typecheck =
  Option.iter (fun state_id ->
      Feedback.feedback ~id:state_id Feedback.Complete)

let abstract_constant_universes = function
  | Monomorphic_const_entry uctx ->
    Univ.empty_level_subst, Monomorphic_const uctx
  | Polymorphic_const_entry uctx ->
    let sbst, auctx = Univ.abstract_universes uctx in
    let sbst = Univ.make_instance_subst sbst in
    sbst, Polymorphic_const auctx

let infer_declaration (type a) ~(trust : a trust) env (dcl : a constant_entry) =
  match dcl with
    | ParameterEntry (ctx,(t,uctx),nl) ->
      let env = match uctx with
        | Monomorphic_const_entry uctx -> push_context_set ~strict:true uctx env
        | Polymorphic_const_entry uctx -> push_context ~strict:false uctx env
      in
      let j = infer env t in
      let usubst, univs = abstract_constant_universes uctx in
      let c = Typeops.assumption_of_judgment env j in
      let t = Constr.hcons (Vars.subst_univs_level_constr usubst c) in
      {
        Cooking.cook_body = Undef nl;
        cook_type = t;
        cook_universes = univs;
        cook_inline = false;
        cook_context = ctx;
      }

  (** Definition [c] is opaque (Qed), non polymorphic and with a specified type,
      so we delay the typing and hash consing of its body.
      Remark: when the universe quantification is given explicitly, we could
      delay even in the polymorphic case.  *)
  | DefinitionEntry ({ const_entry_type = Some typ;
                       const_entry_opaque = true;
                       const_entry_universes = Monomorphic_const_entry univs; _ } as c) ->
      let env = push_context_set ~strict:true univs env in
      let { const_entry_body = body; const_entry_feedback = feedback_id ; _ } = c in
      let tyj = infer_type env typ in
      let proofterm =
        Future.chain body (fun ((body,uctx),side_eff) ->
          (* don't redeclare universes which are declared for the type *)
          let uctx = Univ.ContextSet.diff uctx univs in
          let j, uctx = match trust with
          | Pure ->
            let env = push_context_set uctx env in
            let j = infer env body in
            let _ = judge_of_cast env j DEFAULTcast tyj in
            j, uctx
          | SideEffects handle ->
            let (body, uctx', valid_signatures) = handle env body side_eff in
            let uctx = Univ.ContextSet.union uctx uctx' in
            let env = push_context_set uctx env in
            let body,env,ectx = skip_trusted_seff valid_signatures body env in
            let j = infer env body in
            let j = unzip ectx j in
            let _ = judge_of_cast env j DEFAULTcast tyj in
            j, uctx
          in
          let c = Constr.hcons j.uj_val in
          feedback_completion_typecheck feedback_id;
          c, uctx) in
      let def = OpaqueDef (Opaqueproof.create proofterm) in
      {
        Cooking.cook_body = def;
        cook_type = typ;
        cook_universes = Monomorphic_const univs;
        cook_inline = c.const_entry_inline_code;
        cook_context = c.const_entry_secctx;
      }

  (** Other definitions have to be processed immediately. *)
  | DefinitionEntry c ->
      let { const_entry_type = typ; const_entry_opaque = opaque ; _ } = c in
      let { const_entry_body = body; const_entry_feedback = feedback_id; _ } = c in
      let (body, ctx), side_eff = Future.join body in
      let body, ctx = match trust with
      | Pure -> body, ctx
      | SideEffects handle ->
        let body, ctx', _ = handle env body side_eff in
        body, Univ.ContextSet.union ctx ctx'
      in
      let env, usubst, univs = match c.const_entry_universes with
      | Monomorphic_const_entry univs ->
        let ctx = Univ.ContextSet.union univs ctx in
        let env = push_context_set ~strict:true ctx env in
        env, Univ.empty_level_subst, Monomorphic_const ctx
      | Polymorphic_const_entry uctx ->
        (** Ensure not to generate internal constraints in polymorphic mode.
            The only way for this to happen would be that either the body
            contained deferred universes, or that it contains monomorphic
            side-effects. The first property is ruled out by upper layers,
            and the second one is ensured by the fact we currently
            unconditionally export side-effects from polymorphic definitions,
            i.e. [trust] is always [Pure]. *)
        let () = assert (Univ.ContextSet.is_empty ctx) in
        let env = push_context ~strict:false uctx env in
        let sbst, auctx = Univ.abstract_universes uctx in
        let sbst = Univ.make_instance_subst sbst in
        env, sbst, Polymorphic_const auctx
      in
      let j = infer env body in
      let typ = match typ with
        | None ->
          Vars.subst_univs_level_constr usubst j.uj_type
        | Some t ->
           let tj = infer_type env t in
           let _ = judge_of_cast env j DEFAULTcast tj in
           Vars.subst_univs_level_constr usubst t
      in
      let def = Constr.hcons (Vars.subst_univs_level_constr usubst j.uj_val) in
      let def = 
	if opaque then OpaqueDef (Opaqueproof.create (Future.from_val (def, Univ.ContextSet.empty)))
	else Def (Mod_subst.from_val def) 
      in
	feedback_completion_typecheck feedback_id;
      {
        Cooking.cook_body = def;
        cook_type = typ;
        cook_universes = univs;
        cook_inline = c.const_entry_inline_code;
        cook_context = c.const_entry_secctx;
      }

let record_aux env s_ty s_bo =
  let in_ty = keep_hyps env s_ty in
  let v =
    String.concat " "
      (CList.map_filter (fun decl ->
          let id = NamedDecl.get_id decl in
          if List.exists (NamedDecl.get_id %> Id.equal id) in_ty then None
          else Some (Id.to_string id))
        (keep_hyps env s_bo)) in
  Aux_file.record_in_aux "context_used" v

let build_constant_declaration _kn env result =
  let open Cooking in
  let typ = result.cook_type in
  let check declared inferred =
    let mk_set l = List.fold_right Id.Set.add (List.map NamedDecl.get_id l) Id.Set.empty in
    let inferred_set, declared_set = mk_set inferred, mk_set declared in
    if not (Id.Set.subset inferred_set declared_set) then
      let l = Id.Set.elements (Id.Set.diff inferred_set declared_set) in
      let n = List.length l in
      let declared_vars = Pp.pr_sequence Id.print (Id.Set.elements declared_set) in
      let inferred_vars = Pp.pr_sequence Id.print (Id.Set.elements inferred_set) in
      let missing_vars  = Pp.pr_sequence Id.print (List.rev l) in
      user_err Pp.(prlist str
         ["The following section "; (String.plural n "variable"); " ";
          (String.conjugate_verb_to_be n); " used but not declared:"] ++ fnl () ++
         missing_vars ++ str "." ++ fnl () ++ fnl () ++
         str "You can either update your proof to not depend on " ++ missing_vars ++
         str ", or you can update your Proof line from" ++ fnl () ++
         str "Proof using " ++ declared_vars ++ fnl () ++
         str "to" ++ fnl () ++
         str "Proof using " ++ inferred_vars) in
  let sort l =
    List.filter (fun decl ->
      let id = NamedDecl.get_id decl in
      List.exists (NamedDecl.get_id %> Names.Id.equal id) l)
    (named_context env) in
  (* We try to postpone the computation of used section variables *)
  let hyps, def =
    let context_ids = List.map NamedDecl.get_id (named_context env) in
    let def = result.cook_body in
    match result.cook_context with
    | None when not (List.is_empty context_ids) -> 
        (* No declared section vars, and non-empty section context:
           we must look at the body NOW, if any *)
        let ids_typ = global_vars_set env typ in
        let ids_def = match def with
        | Undef _ -> Id.Set.empty
        | Def cs -> global_vars_set env (Mod_subst.force_constr cs)
        | OpaqueDef lc ->
            let vars =
              global_vars_set env
                (Opaqueproof.force_proof (opaque_tables env) lc) in
            (* we force so that cst are added to the env immediately after *)
            ignore(Opaqueproof.force_constraints (opaque_tables env) lc);
            if !Flags.record_aux_file then record_aux env ids_typ vars;
            vars
        in
        keep_hyps env (Id.Set.union ids_typ ids_def), def
    | None ->
        if !Flags.record_aux_file then
          record_aux env Id.Set.empty Id.Set.empty;
        [], def (* Empty section context: no need to check *)
    | Some declared ->
        (* We use the declared set and chain a check of correctness *)
        sort declared,
        match def with
        | Undef _ as x -> x (* nothing to check *)
        | Def cs as x ->
            let ids_typ = global_vars_set env typ in
            let ids_def = global_vars_set env (Mod_subst.force_constr cs) in
            let inferred = keep_hyps env (Id.Set.union ids_typ ids_def) in
            check declared inferred;
            x
        | OpaqueDef lc -> (* In this case we can postpone the check *)
            OpaqueDef (Opaqueproof.iter_direct_opaque (fun c ->
              let ids_typ = global_vars_set env typ in
              let ids_def = global_vars_set env c in
              let inferred = keep_hyps env (Id.Set.union ids_typ ids_def) in
              check declared inferred) lc) in
  let univs = result.cook_universes in
  let tps = 
    let res = Cbytegen.compile_constant_body ~fail_on_error:false env univs def in
    Option.map Cemitcodes.from_val res
  in
  { const_hyps = hyps;
    const_body = def;
    const_type = typ;
    const_body_code = tps;
    const_universes = univs;
    const_inline_code = result.cook_inline;
    const_typing_flags = Environ.typing_flags env }

(*s Global and local constant declaration. *)

let translate_constant mb env kn ce =
  build_constant_declaration kn env
    (infer_declaration ~trust:mb env ce)

let translate_local_assum env t =
  let j = infer env t in
  let t = Typeops.assumption_of_judgment env j in
    t

let translate_recipe ~hcons env kn r =
  build_constant_declaration kn env (Cooking.cook_constant ~hcons r)

let translate_local_def env _id centry =
  let open Cooking in
  let body = Future.from_val ((centry.secdef_body, Univ.ContextSet.empty), ()) in
  let centry = {
    const_entry_body = body;
    const_entry_secctx = centry.secdef_secctx;
    const_entry_feedback = centry.secdef_feedback;
    const_entry_type = centry.secdef_type;
    const_entry_universes = Monomorphic_const_entry Univ.ContextSet.empty;
    const_entry_opaque = false;
    const_entry_inline_code = false;
  } in
  let decl = infer_declaration ~trust:Pure env (DefinitionEntry centry) in
  let typ = decl.cook_type in
  if Option.is_empty decl.cook_context && !Flags.record_aux_file then begin
    match decl.cook_body with
    | Undef _ -> ()
    | Def _ -> ()
    | OpaqueDef lc ->
       let ids_typ = global_vars_set env typ in
       let ids_def = global_vars_set env
         (Opaqueproof.force_proof (opaque_tables env) lc) in
       record_aux env ids_typ ids_def
  end;
  let () = match decl.cook_universes with
  | Monomorphic_const ctx -> assert (Univ.ContextSet.is_empty ctx)
  | Polymorphic_const _ -> assert false
  in
  let c = match decl.cook_body with
  | Def c -> Mod_subst.force_constr c
  | OpaqueDef o ->
    let p = Opaqueproof.force_proof (Environ.opaque_tables env) o in
    let cst = Opaqueproof.force_constraints (Environ.opaque_tables env) o in
    (** Let definitions are ensured to have no extra constraints coming from
        the body by virtue of the typing of [Entries.section_def_entry]. *)
    let () = assert (Univ.ContextSet.is_empty cst) in
    p
  | Undef _ -> assert false
  in
  c, typ

(* Insertion of inductive types. *)

let translate_mind env kn mie = Indtypes.check_inductive env kn mie