(* $Id$ *)

open Pp
open Util
open Names
open Term
open Sign
open Declarations
open Inductive
open Reduction
open Type_errors
open Typeops
open Libobject
open Lib
open Impargs
open Indrec

type strength = 
  | DischargeAt of dir_path
  | NeverDischarge

let make_strength = function
  | [] -> NeverDischarge
  | l  -> DischargeAt l

let make_strength_0 () = make_strength (Lib.cwd())

let make_strength_1 () =
  let cwd = Lib.cwd() in
  let path = try list_firstn (List.length cwd - 1) cwd with Failure _ -> [] in
  make_strength path

let make_strength_2 () =
  let cwd = Lib.cwd() in
  let path = try list_firstn (List.length cwd - 2) cwd with Failure _ -> [] in
  make_strength path


(* Section variables. *)

type section_variable_entry =
  | SectionLocalDef of constr
  | SectionLocalAssum of constr

type sticky = bool

type variable_declaration = section_variable_entry * strength * sticky

let vartab = ref (Spmap.empty : (identifier * variable_declaration) Spmap.t)

let _ = Summary.declare_summary "VARIABLE"
	  { Summary.freeze_function = (fun () -> !vartab);
	    Summary.unfreeze_function = (fun ft -> vartab := ft);
	    Summary.init_function = (fun () -> vartab := Spmap.empty);
	    Summary.survive_section = false }

let cache_variable (sp,(id,(d,_,_) as vd)) =
  if Nametab.exists_cci sp then
    errorlabstrm "cache_variable"
      [< pr_id (basename sp); 'sTR " already exists" >];
  begin match d with (* Fails if not well-typed *)
    | SectionLocalAssum ty -> Global.push_named_assum (id,ty)
    | SectionLocalDef c -> Global.push_named_def (id,c)
  end;
  Nametab.push sp (VarRef sp);
  vartab := Spmap.add sp vd !vartab

let (in_variable, out_variable) =
  let od = {
    cache_function = cache_variable;
    load_function = (fun _ -> ());
    open_function = (fun _ -> ());
    export_function = (fun x -> None) }
  in
  declare_object ("VARIABLE", od)

let declare_variable id obj =
  let sp = add_leaf id CCI (in_variable (id,obj)) in
  if is_implicit_args() then declare_var_implicits sp

(* Parameters. *)

let cache_parameter (sp,c) =
  if Nametab.exists_cci sp then
    errorlabstrm "cache_parameter"
      [< pr_id (basename sp); 'sTR " already exists" >];
  Global.add_parameter sp c;
  Nametab.push sp (ConstRef sp)

let load_parameter _ = ()

let open_parameter (sp,_) = ()
(*  Nametab.push sp (ConstRef sp)*)

let export_parameter x = Some x

let (in_parameter, out_parameter) =
  let od = {
    cache_function = cache_parameter;
    load_function = load_parameter;
    open_function = open_parameter;
    export_function = export_parameter } 
  in
  declare_object ("PARAMETER", od)

let declare_parameter id c =
  let sp = add_leaf id CCI (in_parameter c) in 
  if is_implicit_args() then declare_constant_implicits sp

(* Constants. *)

type constant_declaration_type =
  | ConstantEntry  of constant_entry
  | ConstantRecipe of Cooking.recipe

type constant_declaration = constant_declaration_type * strength

let csttab = ref (Spmap.empty : strength Spmap.t)

let _ = Summary.declare_summary "CONSTANT"
	  { Summary.freeze_function = (fun () -> !csttab);
	    Summary.unfreeze_function = (fun ft -> csttab := ft);
	    Summary.init_function = (fun () -> csttab := Spmap.empty);
	    Summary.survive_section = false }

let cache_constant (sp,(cdt,stre)) =
  if Nametab.exists_cci sp then
    errorlabstrm "cache_constant"
      [< pr_id (basename sp); 'sTR " already exists" >] ;
  begin match cdt with 
    | ConstantEntry ce -> Global.add_constant sp ce
    | ConstantRecipe r -> Global.add_discharged_constant sp r
  end;
  Nametab.push sp (ConstRef sp);
  csttab := Spmap.add sp stre !csttab

let load_constant (sp,(ce,stre)) =
  csttab := Spmap.add sp stre !csttab

let open_constant (sp,_) = ()
(*  Nametab.push sp (ConstRef sp)*)

let export_constant x = Some x

let (in_constant, out_constant) =
  let od = {
    cache_function = cache_constant;
    load_function = load_constant;
    open_function = open_constant;
    export_function = export_constant } 
  in
  declare_object ("CONSTANT", od)

let declare_constant id cd =
  let sp = add_leaf id CCI (in_constant cd) in
  if is_implicit_args() then declare_constant_implicits sp
 
(* Inductives. *)


let inductive_names sp mie =
  let names, _ = 
    List.fold_left
      (fun (names, n) (id,_,cnames,_) ->
	 let indsp = (sp,n) in
	 let names, _ =
	   List.fold_left
	     (fun (names, p) id ->
		let sp = Names.make_path (dirpath sp) id CCI in
		((sp, ConstructRef (indsp,p)) :: names, p+1))
	     (names, 1) cnames in
	 let sp = Names.make_path (dirpath sp) id CCI in
	 ((sp, IndRef indsp) :: names, n+1))
      ([], 0) mie.mind_entry_inds
  in names

let push_inductive_names sp mie =
  let _ = 
    List.fold_left
      (fun n (id,_,cnames,_) ->
	 let indsp = (sp,n) in
	 let _ =
	   List.fold_left
	     (fun p id ->
		let sp = Names.make_path (dirpath sp) id CCI in
		Nametab.push sp (ConstructRef (indsp,p)); (p+1))
	     1 cnames in
	 let sp = Names.make_path (dirpath sp) id CCI in
	 Nametab.push sp (IndRef indsp);
	 n+1)
      0 mie.mind_entry_inds
  in ()

let check_exists_inductive (sp,_) =
  if Nametab.exists_cci sp then
    errorlabstrm "cache_inductive"
      [< pr_id (basename sp); 'sTR " already exists" >]

let cache_inductive (sp,mie) =
  let names = inductive_names sp mie in
  List.iter check_exists_inductive names;
  Global.add_mind sp mie;
  List.iter (fun (sp, ref) -> Nametab.push sp ref) names

let load_inductive _ = ()

let open_inductive (sp,mie) = ()
(*  push_inductive_names sp mie *)

let export_inductive x = Some x

let (in_inductive, out_inductive) =
  let od = {
    cache_function = cache_inductive;
    load_function = load_inductive;
    open_function = open_inductive;
    export_function = export_inductive } 
  in
  declare_object ("INDUCTIVE", od)

let declare_mind mie =
  let id = match mie.mind_entry_inds with
    | (id,_,_,_)::_ -> id
    | [] -> anomaly "cannot declare an empty list of inductives"
  in
  let sp = add_leaf id CCI (in_inductive mie) in
  if is_implicit_args() then declare_mib_implicits sp;
  sp

(*s Test and access functions. *)

let is_constant sp = 
  try let _ = Global.lookup_constant sp in true with Not_found -> false

let constant_strength sp = Spmap.find sp !csttab

let constant_or_parameter_strength sp =
  try constant_strength sp with Not_found -> NeverDischarge

let get_variable sp = 
  let (id,(_,str,sticky)) = Spmap.find sp !vartab in
  let (c,ty) = Global.lookup_named id in
  ((id,c,ty),str,sticky)

let variable_strength qid =
  match Nametab.locate qid with
    | VarRef sp -> let _,(_,str,_) = Spmap.find sp !vartab in str
    | _ -> anomaly "variable_strength: not the reference to a variable"

(* Global references. *)

let first f v =
  let n = Array.length v in
  let rec look_for i =
    if i = n then raise Not_found;
    try f i v.(i) with Not_found -> look_for (succ i)
  in
  look_for 0

let mind_oper_of_id sp id mib =
  first
    (fun tyi mip ->
       if id = mip.mind_typename then 
	 IndRef (sp,tyi)
       else
	 first 
	   (fun cj cid -> 
	      if id = cid then 
		ConstructRef ((sp,tyi),succ cj) 
	      else raise Not_found) 
	   mip.mind_consnames)
    mib.mind_packets

let context_of_global_reference sigma env = function
  | EvarRef n -> (Evd.map sigma n).Evd.evar_hyps
  | VarRef sp -> [] (* Hum !, pas correct *)
  | ConstRef sp -> (Environ.lookup_constant sp env).const_hyps
  | IndRef (sp,_) -> (Environ.lookup_mind sp env).mind_hyps
  | ConstructRef ((sp,_),_) -> (Environ.lookup_mind sp env).mind_hyps

(*
let global_sp_operator env sp id =
  try

  with Not_found -> 
    let mib = 
    mind_oper_of_id sp id mib, mib.mind_hyps
*)

let occur_decl env (id,c,t) hyps =
  try
    let (c',t') = Sign.lookup_id id hyps in
    let matching_bodies = match c,c' with
      | None, _ -> true
      | Some c, None -> false
      | Some c, Some c' -> is_conv env Evd.empty c c' in
    let matching_types = 
      is_conv env Evd.empty (body_of_type t) (body_of_type t') in
    matching_types & matching_bodies
  with Not_found -> false

(*
let find_common_hyps_then_abstract c env hyps' hyps = 
  snd (fold_named_context_both_sides
	 (fun
	    (env,c) (id,_,_ as d) hyps ->
	      if occur_decl env d hyps' then 
		(Environ.push_named_decl d env,c)
	      else
		let hyps'' = List.rev (d :: hyps) in
		(env, Environ.it_mkNamedLambda_or_LetIn c hyps''))
	 hyps
	 (env,c))
*)

let rec quantify_extra_hyps c = function
  | (id,None,t)::hyps -> mkNamedLambda id t (quantify_extra_hyps c hyps)
  | (_,Some _,_)::hyps -> quantify_extra_hyps c hyps
  | [] -> c

let rec find_common_hyps_then_abstract c env hyps' = function
  | (id,_,_ as d) :: hyps when occur_decl env d hyps' ->
      find_common_hyps_then_abstract c (Environ.push_named_decl d env) hyps' hyps
  | hyps -> quantify_extra_hyps c hyps

let find_common_hyps_then_abstract c env hyps' hyps =
  find_common_hyps_then_abstract c env hyps' (List.rev hyps)

let current_section_context () =
  let current = Spmap.fold (fun _ (id,_) hyps -> id::hyps) !vartab [] in
  List.fold_right
    (fun (id,_,_ as d) hyps -> if List.mem id current then d::hyps else hyps)
    (Global.named_context ()) []

let extract_instance ref args =
  let hyps = context_of_global_reference Evd.empty (Global.env ()) ref in
  let hyps0 = current_section_context () in
  let na = Array.length args in
  let rec peel n acc = function
    | (_,None,_ as d)::hyps ->
	if List.mem d hyps0 then peel (n-1) acc hyps
	else peel (n-1) (args.(n)::acc) hyps
    | (_,Some _,_)::hyps -> peel n acc hyps
    | [] -> Array.of_list acc
  in peel (na-1) [] hyps

let constr_of_reference sigma env ref =
  let hyps = context_of_global_reference sigma env ref in
  let hyps0 = current_section_context () in
  let env0 = Environ.reset_context env in
  let args = instance_from_named_context hyps in
  let body = match ref with
    | EvarRef n -> mkEvar (n,Array.of_list args)
    | VarRef sp -> mkVar (basename sp)
    | ConstRef sp -> mkConst (sp,Array.of_list args)
    | ConstructRef sp -> mkMutConstruct (sp,Array.of_list args)
    | IndRef sp -> mkMutInd (sp,Array.of_list args)
  in
  find_common_hyps_then_abstract body env0 hyps0 hyps

let construct_absolute_reference env sp =
  let ref = Nametab.locate (qualid_of_sp sp) in
  constr_of_reference Evd.empty env ref

let construct_qualified_reference env qid =
  let ref = Nametab.locate qid in
  constr_of_reference Evd.empty env ref

let construct_reference env kind id =
  try
    let ref = Nametab.sp_of_id kind id in
    constr_of_reference Evd.empty env ref
  with Not_found ->
    mkVar (let _ = Environ.lookup_named id env in id)

let global_qualified_reference qid = 
  construct_qualified_reference (Global.env()) qid

let global_absolute_reference sp = 
  construct_absolute_reference (Global.env()) sp

let global_reference kind id = 
  construct_reference (Global.env()) kind id

(*
let global env id =
  try let _ = lookup_glob id (Environ.context env) in mkVar id
  with Not_found -> global_reference CCI id
*)
let dirpath_of_global = function
  | EvarRef n -> ["evar"]
  | VarRef sp -> dirpath sp
  | ConstRef sp -> dirpath sp
  | IndRef (sp,_) -> dirpath sp
  | ConstructRef ((sp,_),_) -> dirpath sp

let is_global id =
  try 
    let osp = Nametab.locate (make_qualid [] (string_of_id id)) in
    list_prefix_of (dirpath_of_global osp) (Lib.cwd())
  with Not_found -> 
    false

let path_of_constructor_path ((sp,tyi),ind) =
   let mib = Global.lookup_mind sp in
   let mip = mind_nth_type_packet mib tyi in 
   let (pa,_,k) = repr_path sp in 
   Names.make_path pa (mip.mind_consnames.(ind-1)) k 

let path_of_inductive_path (sp,tyi) =
  if tyi = 0 then sp
  else
    let mib = Global.lookup_mind sp in
    let mip = mind_nth_type_packet mib tyi in 
    let (pa,_,k) = repr_path sp in 
    Names.make_path pa (mip.mind_typename) k 

(* Eliminations. *)

let eliminations = [ (prop,"_ind") ; (spec,"_rec") ; (types,"_rect") ]

let elimination_suffix = function
  | Type _    -> "_rect"
  | Prop Null -> "_ind"
  | Prop Pos  -> "_rec"

let declare_eliminations sp i =
  let mib = Global.lookup_mind sp in
  let ids = ids_of_named_context mib.mind_hyps in
  if not (list_subset ids (ids_of_named_context (Global.named_context ()))) then
    error ("Declarations of elimination scheme outside the section "^
    "of the inductive definition is not implemented");
  let ctxt = instance_from_named_context mib.mind_hyps in
  let mispec = Global.lookup_mind_specif ((sp,i),Array.of_list ctxt) in 
  let mindstr = string_of_id (mis_typename mispec) in
  let declare na c =
    declare_constant (id_of_string na)
      (ConstantEntry { const_entry_body = c; const_entry_type = None }, 
       NeverDischarge);
    if Options.is_verbose() then pPNL [< 'sTR na; 'sTR " is defined" >]
  in
  let env = Global.env () in
  let sigma = Evd.empty in
  let elim_scheme = build_indrec env sigma mispec in
  let npars = mis_nparams mispec in
  let make_elim s = instanciate_indrec_scheme s npars elim_scheme in
  let kelim = mis_kelim mispec in
  List.iter
    (fun (sort,suff) -> 
       if List.mem sort kelim then declare (mindstr^suff) (make_elim sort))
    eliminations

(* Look up function for the default elimination constant *)

let lookup_eliminator env path s =
  let s = (string_of_id (basename path))^(elimination_suffix s) in
  construct_reference env (kind_of_path path) (id_of_string s)