(* Copyright (C) 2004-2005, HELM Team.
 * 
 * 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/
 *)

exception UnableToInclude of string

let baseuri_of_baseuri_decl st =
  match st with
  | GrafiteAst.Executable (_, GrafiteAst.Command (_, GrafiteAst.Set (_, "baseuri", buri))) ->
      Some buri
  | _ -> None

let make_absolute paths path =
   let rec aux = function
   | [] -> ignore (Unix.stat path); path
   | p :: tl ->
      let path = p ^ "/" ^ path in
       try
         ignore (Unix.stat path); path
       with Unix.Unix_error _ -> aux tl
   in
   try
     aux paths
   with Unix.Unix_error _ -> raise (UnableToInclude path)
;;
       
let baseuri_of_script ~include_paths file = 
  let file = make_absolute include_paths file in
  let uri = ref None in
  let ic = open_in file in
  let istream = Ulexing.from_utf8_channel ic in
  (try
    while true do
      try 
        let stm = GrafiteParser.parse_statement istream in
        match baseuri_of_baseuri_decl stm with
        | Some buri -> 
            let u = Http_getter_misc.strip_trailing_slash buri in
            if String.length u < 5 || String.sub u 0 5 <> "cic:/" then
              HLog.error (file ^ " sets an incorrect baseuri: " ^ buri);
            (try 
              ignore(Http_getter.resolve u)
            with
            | Http_getter_types.Unresolvable_URI _ -> 
                HLog.error (file ^ " sets an unresolvable baseuri: "^buri)
            | Http_getter_types.Key_not_found _ -> ());
            uri := Some u;
            raise End_of_file
        | None -> ()
      with
        CicNotationParser.Parse_error err ->
          HLog.error ("Unable to parse: " ^ file);
          HLog.error ("Parse error: " ^ err);
          ()
    done
  with End_of_file -> close_in ic);
  match !uri with
  | Some uri -> uri
  | None -> failwith ("No baseuri defined in " ^ file)