(*
 * Copyright (C) 2003-2004:
 *    Stefano Zacchiroli <zack@cs.unibo.it>
 *    for the HELM Team http://helm.cs.unibo.it/
 *
 *  This file is part of HELM, an Hypertextual, Electronic
 *  Library of Mathematics, developed at the Computer Science
 *  Department, University of Bologna, Italy.
 *
 *  HELM is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version 2
 *  of the License, or (at your option) any later version.
 *
 *  HELM is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with HELM; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 *  MA  02111-1307, USA.
 *
 *  For details, see the HELM World-Wide-Web page,
 *  http://helm.cs.unibo.it/
 *)

open Printf

open Http_getter_common
open Http_getter_misc
open Http_getter_types

exception Not_implemented of string
exception UnexpectedGetterOutput

(* resolve_result is needed because it is not possible to raise *)
(* an exception in a pxp ever-processing callback. Too bad.     *)
type resolve_result =
  | Unknown
  | Exception of exn
  | Resolved of string

type logger_callback = HelmLogger.html_tag -> unit

let stdout_logger tag =  print_string (HelmLogger.string_of_html_tag tag)

let not_implemented s = raise (Not_implemented ("Http_getter." ^ s))

let (index_line_sep_RE, index_sep_RE, trailing_types_RE,
    heading_cic_RE, heading_theory_RE, heading_nuprl_RE,
    heading_rdf_cic_RE, heading_rdf_theory_RE) =
  (Pcre.regexp "[ \t]+", Pcre.regexp "\r\n|\r|\n",
  Pcre.regexp "\\.types$",
  Pcre.regexp "^cic:", Pcre.regexp "^theory:", Pcre.regexp "^nuprl:",
  Pcre.regexp "^helm:rdf.*//cic:", Pcre.regexp "^helm:rdf.*//theory:")

  (* global maps, shared by all threads *)

let cic_map =
  lazy (new Http_getter_map.map (Lazy.force Http_getter_env.cic_dbm))
let nuprl_map =
  lazy (new Http_getter_map.map (Lazy.force Http_getter_env.nuprl_dbm))
let rdf_map =
  lazy (new Http_getter_map.map (Lazy.force Http_getter_env.rdf_dbm))
let xsl_map =
  lazy (new Http_getter_map.map (Lazy.force Http_getter_env.xsl_dbm))

let maps = [ cic_map; nuprl_map; rdf_map; xsl_map ]
let close_maps () = List.iter (fun m -> (Lazy.force m) # close) maps
let clear_maps () = List.iter (fun m -> (Lazy.force m) # clear) maps
let sync_maps  () = List.iter (fun m -> (Lazy.force m) # sync) maps

let map_of_uri = function
  | uri when is_cic_uri uri -> Lazy.force cic_map
  | uri when is_nuprl_uri uri -> Lazy.force nuprl_map
  | uri when is_rdf_uri uri -> Lazy.force rdf_map
  | uri when is_xsl_uri uri -> Lazy.force xsl_map
  | uri -> raise (Unresolvable_URI uri)

let update_from_server logger server_url = (* use global maps *)
  Http_getter_logger.log ("Updating information from " ^ server_url);
  let xml_url_of_uri = function
      (* TODO missing sanity checks on server_url, e.g. it can contains $1 *)
    | uri when (Pcre.pmatch ~rex:heading_cic_RE uri) ->
        Pcre.replace ~rex:heading_cic_RE ~templ:server_url uri
    | uri when (Pcre.pmatch ~rex:heading_theory_RE uri) ->
        Pcre.replace ~rex:heading_theory_RE ~templ:server_url uri
    | uri when (Pcre.pmatch ~rex:heading_nuprl_RE uri) ->
        Pcre.replace ~rex:heading_nuprl_RE ~templ:server_url uri
    | uri -> raise (Invalid_URI uri)
  in
  let rdf_url_of_uri = function (* TODO as above *)
    | uri when (Pcre.pmatch ~rex:heading_rdf_cic_RE uri) ->
        Pcre.replace ~rex:heading_rdf_cic_RE ~templ:server_url uri
    | uri when (Pcre.pmatch ~rex:heading_rdf_theory_RE uri) ->
        Pcre.replace ~rex:heading_rdf_theory_RE ~templ:server_url uri
    | uri -> raise (Invalid_URI uri)
  in
  logger (`T ("Processing server: " ^ server_url));
  logger `BR;
  let (xml_index, rdf_index, xsl_index) =
    (* TODO keeps index in memory, is better to keep them on temp files? *)
    (http_get (server_url ^ "/" ^ (Lazy.force Http_getter_env.xml_index)),
     http_get (server_url ^ "/" ^ (Lazy.force Http_getter_env.rdf_index)),
     http_get (server_url ^ "/" ^ (Lazy.force Http_getter_env.xsl_index)))
  in
  if (xml_index = None && rdf_index = None && xsl_index = None) then
    Http_getter_logger.log (sprintf "Warning: useless server %s" server_url);
  (match xml_index with
  | Some xml_index ->
      logger (`T "- Updating XML db ...");
(*       logger `BR; *)
      List.iter
        (function
          | l when is_blank_line l -> ()  (* skip blank and commented lines *)
          | l ->
              (try
                (match Pcre.split ~rex:index_line_sep_RE l with
                | [uri; "gz"] ->
                   assert (is_cic_uri uri || is_nuprl_uri uri) ;
                   (map_of_uri uri)#replace
                    uri ((xml_url_of_uri uri) ^ ".xml.gz")
                | [uri] ->
                   assert (is_cic_uri uri || is_nuprl_uri uri) ;
                   (map_of_uri uri)#replace
                    uri ((xml_url_of_uri uri) ^ ".xml")
                | _ ->
                    logger (`T ("Ignoring invalid line: '" ^ l));
                    logger `BR)
              with Invalid_URI uri ->
                logger (`T ("Ignoring invalid XML URI: '" ^ l));
                logger `BR))
        (Pcre.split ~rex:index_sep_RE xml_index); (* xml_index lines *)
      logger (`T "All done");
      logger `BR
  | None -> ());
  (match rdf_index with
  | Some rdf_index ->
      logger (`T "- Updating RDF db ...");
(*       logger `BR; *)
      List.iter
        (fun l ->
          try
            (match Pcre.split ~rex:index_line_sep_RE l with
            | [uri; "gz"] ->
                (Lazy.force rdf_map) # replace uri
                  ((rdf_url_of_uri uri) ^ ".xml.gz")
            | [uri] ->
                (Lazy.force rdf_map) # replace uri
                  ((rdf_url_of_uri uri) ^ ".xml")
            | _ ->
                logger (`T ("Ignoring invalid line: '" ^ l));
                logger `BR)
          with Invalid_URI uri ->
            logger (`T ("Ignoring invalid RDF URI: '" ^ l));
            logger `BR)
        (Pcre.split ~rex:index_sep_RE rdf_index); (* rdf_index lines *)
      logger (`T "All done");
      logger `BR
  | None -> ());
  (match xsl_index with
  | Some xsl_index ->
      logger (`T "- Updating XSLT db ...");
(*       logger `BR; *)
      List.iter
        (fun l -> (Lazy.force xsl_map) # replace l (server_url ^ "/" ^ l))
        (Pcre.split ~rex:index_sep_RE xsl_index);
      logger (`T "All done");
      logger `BR
  | None -> ());
  Http_getter_logger.log "done with this server"

let update_from_all_servers logger () =  (* use global maps *)
  clear_maps ();
  List.iter
    (update_from_server logger)
      (* reverse order: 1st server is the most important one *)
    (List.map snd (List.rev (Http_getter_env.servers ())));
  sync_maps ()

let update_from_one_server ?(logger = fun _ -> ()) server_url =
  update_from_server logger server_url

let temp_file_of_uri uri =
  let flat_string s s' c =
    let cs = String.copy s in
    for i = 0 to (String.length s) - 1 do
      if String.contains s' s.[i] then cs.[i] <- c
    done;
    cs
  in
  let user = try Unix.getlogin () with _ -> "" in
  Filename.open_temp_file (user ^ flat_string uri ".-=:;!?/&" '_') ""

  (* should we use a remote getter or not *)
let remote () =
  try
    Helm_registry.get "getter.mode" = "remote"
  with Helm_registry.Key_not_found _ -> false
let getter_url () = Helm_registry.get "getter.url"

(* Remote interface: getter methods implemented using a remote getter *)

  (* <TODO> *)
let getxslt_remote ~patch_dtd uri = not_implemented "getxslt_remote"
let getdtd_remote ~patch_dtd uri = not_implemented "getdtd_remote"
let clean_cache_remote () = not_implemented "clean_cache_remote"
let list_servers_remote () = not_implemented "list_servers_remote"
let add_server_remote ~logger ~position name =
  not_implemented "add_server_remote"
let remove_server_remote ~logger position =
  not_implemented "remove_server_remote"
let getalluris_remote () = not_implemented "getalluris_remote"
let getallrdfuris_remote () = not_implemented "getallrdfuris_remote"
let ls_remote lsuri = not_implemented "ls_remote"
  (* </TODO> *)

let resolve_remote uri =
  (* deliver resolve request to http_getter *)
  let doc = ClientHTTP.get (sprintf "%sresolve?uri=%s" (getter_url ()) uri) in
  let res = ref Unknown in
   Pxp_ev_parser.process_entity PxpHelmConf.pxp_config (`Entry_content [])
    (Pxp_ev_parser.create_entity_manager ~is_document:true
      PxpHelmConf.pxp_config (Pxp_yacc.from_string doc))
    (function
      | Pxp_types.E_start_tag ("url",["value",url],_,_) -> res := Resolved url
      | Pxp_types.E_start_tag ("unresolvable",[],_,_) ->
          res := Exception (Unresolvable_URI uri)
      | Pxp_types.E_start_tag ("not_found",[],_,_) ->
          res := Exception (Key_not_found uri)
      | Pxp_types.E_start_tag (x,_,_,_) -> 
	  res := Exception UnexpectedGetterOutput
      | _ -> ());
   match !res with
   | Unknown -> raise UnexpectedGetterOutput
   | Exception e -> raise e
   | Resolved url -> url

let register_remote ~uri ~url =
  ClientHTTP.send (sprintf "%sregister?uri=%s&url=%s" (getter_url ()) uri url)

let unregister_remote uri =
  ClientHTTP.send (sprintf "%sunregister?uri=%s" (getter_url ()) uri)

let update_remote logger  () =
  let answer = ClientHTTP.get (getter_url () ^ "update") in
  logger (`T answer);
  logger `BR

let getxml_remote ~format ~patch_dtd uri =
  ClientHTTP.get_and_save_to_tmp
    (sprintf "%sgetxml?uri=%s&format=%s&patch_dtd=%s"
      (getter_url ()) uri
      (match format with `Normal -> "normal" | `Gzipped -> "gzipped")
      (match patch_dtd with true -> "yes" | false -> "no"))

(* API *)

let help () = Http_getter_const.usage_string (Http_getter_env.env_to_string ())

let resolve uri =
  if remote () then
    resolve_remote uri
  else
    (map_of_uri uri)#resolve uri
	
let register ~uri ~url =
  if remote () then
    register_remote ~uri ~url
  else
    (map_of_uri uri)#add uri url

let unregister uri =
  if remote () then
    unregister_remote uri
  else
    try
      (map_of_uri uri)#remove uri
    with Key_not_found _ -> ()

let update ?(logger = fun _ -> ()) () =
  if remote () then
    update_remote logger ()
  else
    update_from_all_servers logger ()

let getxml ?(format = `Normal) ?(patch_dtd = true) uri =
  if remote () then
    getxml_remote ~format ~patch_dtd uri
  else begin
    Http_getter_logger.log ~level:2 ("getxml: " ^ uri);
    let url = resolve uri in
    Http_getter_logger.log ~level:2 ("resolved_uri: " ^ url) ;
    let (fname, outchan) = temp_file_of_uri uri in
    Http_getter_cache.respond_xml ~via_http:false ~enc:format ~patch:patch_dtd
      ~uri ~url outchan;
    close_out outchan;
    fname
  end

let getxslt ?(patch_dtd = true) uri =
  if remote () then
    getxslt_remote ~patch_dtd uri
  else begin
    
    let url = resolve uri in
    let (fname, outchan) = temp_file_of_uri uri in
    Http_getter_cache.respond_xsl ~via_http:false ~url ~patch:patch_dtd outchan;
    close_out outchan;
    fname
  end

let getdtd ?(patch_dtd = true) uri =
  if remote () then
    getdtd_remote ~patch_dtd uri
  else begin
    let url = Lazy.force Http_getter_env.dtd_dir ^ "/" ^ uri in
    let (fname, outchan) = temp_file_of_uri uri in
    Http_getter_cache.respond_dtd ~via_http:false ~url ~patch:patch_dtd outchan;
    close_out outchan;
    fname
  end

let clean_cache () =
  if remote () then
    clean_cache_remote ()
  else
    Http_getter_cache.clean ()

let list_servers () =
  if remote () then
    list_servers_remote ()
  else
    Http_getter_env.servers ()

let add_server ?(logger = fun _ -> ()) ?(position = 0) name =
  if remote () then
    add_server_remote ~logger ~position name
  else begin
    if position = 0 then begin
      Http_getter_env.add_server ~position:0 name;
      update_from_one_server ~logger name (* quick update (new server only) *)
    end else if position > 0 then begin
      Http_getter_env.add_server ~position name;
      update ~logger ()
    end else  (* already checked by parse_position *)
      assert false
  end

let has_server position = List.mem_assoc position (Http_getter_env.servers ())

let remove_server ?(logger = fun _ -> ()) position =
  if remote () then
    remove_server_remote ~logger ()
  else begin
    let server_name =
      try
        List.assoc position (Http_getter_env.servers ())
      with Not_found ->
        raise (Invalid_argument (sprintf "no server with position %d" position))
    in
    Http_getter_env.remove_server position;
    update ~logger ()
  end

let return_uris map filter =
  let uris = ref [] in
  map#iter (fun uri _ -> if filter uri then uris := uri :: !uris);
  List.rev !uris

let getalluris () =
  if remote () then
    getalluris_remote ()
  else
    let filter uri =
      (Pcre.pmatch ~rex:heading_cic_RE uri)
(*       && not (Pcre.pmatch ~rex:trailing_types_RE uri) *)
    in
    return_uris (Lazy.force cic_map) filter

let getallrdfuris classs =
  if remote () then
    getallrdfuris_remote ()
  else
    let filter =
      let base = "^helm:rdf:www\\.cs\\.unibo\\.it/helm/rdf/" in
      match classs with
      | `Forward -> (fun uri -> Pcre.pmatch ~pat:(base ^ "forward") uri)
      | `Backward -> (fun uri -> Pcre.pmatch ~pat:(base ^ "backward") uri)
    in
    return_uris (Lazy.force rdf_map) filter

let ls =
  let (++) (oldann, oldtypes, oldbody, oldtree)
           (newann, newtypes, newbody, newtree) =
    ((if newann   > oldann    then newann   else oldann),
     (if newtypes > oldtypes  then newtypes else oldtypes),
     (if newbody  > oldbody   then newbody  else oldbody),
     (if newtree  > oldtree   then newtree  else oldtree))
  in
  let basepart_RE =
    Pcre.regexp
      "^([^.]*\\.[^.]*)((\\.body)|(\\.proof_tree)|(\\.types))?(\\.ann)?$"
  in
  let (types_RE, types_ann_RE, body_RE, body_ann_RE,
       proof_tree_RE, proof_tree_ann_RE, trailing_slash_RE, theory_RE) =
    (Pcre.regexp "\\.types$", Pcre.regexp "\\.types\\.ann$",
     Pcre.regexp "\\.body$", Pcre.regexp "\\.body\\.ann$",
     Pcre.regexp "\\.proof_tree$", Pcre.regexp "\\.proof_tree\\.ann$",
     Pcre.regexp "/$", Pcre.regexp "\\.theory$")
  in
  let (slash_RE, til_slash_RE, no_slashes_RE) =
    (Pcre.regexp "/", Pcre.regexp "^.*/", Pcre.regexp "^[^/]*$")
  in
  fun regexp ->
    if remote () then
      ls_remote regexp
    else begin
      let looking_for_dir = Pcre.pmatch ~rex:trailing_slash_RE regexp in
      let pat = Pcre.replace ~rex:trailing_slash_RE ("^" ^ regexp) in
      let (dir_RE, dir_RE2, obj_RE, orig_theory_RE) =
        Pcre.regexp (pat ^ "/"), Pcre.regexp (pat ^ "/[^/]*"),
        Pcre.regexp (pat ^ "(\\.|$)"), Pcre.regexp (pat ^ ".theory$")
      in
      let dirs = ref StringSet.empty in
      let objs = Hashtbl.create 17 in
      let store_dir d =
        dirs := StringSet.add (List.hd (Pcre.split ~rex:slash_RE d)) !dirs
      in
      let store_obj o =
        let basepart = Pcre.replace ~rex:basepart_RE ~templ:"$1" o in
        let no_flags = false, No, No, No in
        let oldflags =
          try
            Hashtbl.find objs basepart
          with Not_found -> (* no ann, no types, no body, no proof tree *)
            no_flags
        in
        let newflags =
          match o with
          | s when Pcre.pmatch ~rex:types_RE s          -> (false, Yes, No, No)
          | s when Pcre.pmatch ~rex:types_ann_RE s      -> (true,  Ann, No, No)
          | s when Pcre.pmatch ~rex:body_RE s           -> (false, No, Yes, No)
          | s when Pcre.pmatch ~rex:body_ann_RE s       -> (true,  No, Ann, No)
          | s when Pcre.pmatch ~rex:proof_tree_RE s     -> (false, No, No, Yes)
          | s when Pcre.pmatch ~rex:proof_tree_ann_RE s -> (true,  No, No, Ann)
          | s -> no_flags
        in
        Hashtbl.replace objs basepart (oldflags ++ newflags)
      in
      (* Variables used in backward compatibility code to map
         theory:/path/t.theory into theory:/path/t/index.theory
         when cic:/path/t/ exists *)
      let the_candidate_for_remapping =
       (* CSC: Here I am making a strong assumption: the pattern
          can be only of the form  [^:]*:/path where path is
          NOT a regular expression *)
       "theory:" ^ Pcre.replace ~rex:(Pcre.regexp "[^:]*:") pat
      in
      let index_not_generated_yet = ref true in
      let valid_candidates = ref [] in
      let candidates_found = ref [] in
      (Lazy.force cic_map) # iter
        (* BLEARGH Dbm module lacks support for fold-like functions *)
        (fun key _ ->
          match key with
          | uri when looking_for_dir && Pcre.pmatch ~rex:dir_RE uri ->
              (* directory hit *)
              let localpart = Pcre.replace ~rex:dir_RE uri in
              if Pcre.pmatch ~rex:no_slashes_RE localpart then
               begin
                (* Backward compatibility code to map
		   theory:/path/t.theory into theory:/path/t/index.theory
		   when cic:/path/t/ exists *)
                if Pcre.pmatch ~rex:theory_RE localpart then
                 candidates_found := (uri,localpart) :: !candidates_found
                else
                 store_obj localpart

               end
              else
               begin
                store_dir localpart ;
                if String.sub uri 0 3 = "cic" then
                 let dir_found = ref "" in
                 let _ =
                  Pcre.substitute_first ~rex:dir_RE2
                   ~subst:(fun s -> dir_found := s; "") uri in
                 let dir =
                  "theory" ^ String.sub !dir_found 3
                   (String.length !dir_found - 3) ^ ".theory" in
                 if not (List.mem dir !valid_candidates) then
                 valid_candidates := dir::!valid_candidates
               end
          | uri when (not looking_for_dir) && Pcre.pmatch ~rex:obj_RE  uri ->
              (* file hit *)
              store_obj (Pcre.replace ~rex:til_slash_RE uri)
          | uri -> (* miss *)
             if !index_not_generated_yet &&
	        Pcre.pmatch ~rex:orig_theory_RE uri
             then
              (index_not_generated_yet := false ;
               store_obj "index.theory"));
      List.iter
       (fun (uri,localpart) ->
         if not (List.mem uri !valid_candidates) then
          store_obj localpart
       ) !candidates_found ;
      let ls_items = ref [] in
      StringSet.iter (fun dir -> ls_items := Ls_section dir :: !ls_items) !dirs;
      Http_getter_misc.hashtbl_sorted_iter
        (fun uri (annflag, typesflag, bodyflag, treeflag) ->
          ls_items :=
            Ls_object {
              uri = uri; ann = annflag;
              types = typesflag; body = bodyflag; proof_tree = treeflag
            } :: !ls_items)
        objs;
      List.rev !ls_items
    end

  (* Shorthands from now on *)

let getxml' uri = getxml (UriManager.string_of_uri uri)
let resolve' uri = resolve (UriManager.string_of_uri uri)
let register' uri url = register ~uri:(UriManager.string_of_uri uri) ~url
let init () =
  Http_getter_logger.set_log_level
    (Helm_registry.get_opt_default Helm_registry.get_int 1 "getter.log_level");
  Http_getter_logger.set_log_file
    (Helm_registry.get_opt Helm_registry.get_string "getter.log_file");
  Http_getter_env.reload ()