(* COCANWIKI - a wiki written in Objective CAML.
 * Written by Richard W.M. Jones <rich@merjis.com>.
 * Copyright (C) 2004 Merjis Ltd.
 * $Id: orphans.ml,v 1.4 2006/03/28 13:20:00 rich Exp $
 *
 * This program 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.
 *
 * This program 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 this program; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *)

open Apache
open Registry
open Cgi
open Printf

open Cocanwiki
open Cocanwiki_template

let run r (q : cgi) dbh hostid _ _ =
  let template = get_template dbh hostid "orphans.html" in

  (* Start with the front page, the contents of the site menu and the
   * special "copyright" page.
   *)
  let start_pages =
    PGSQL(dbh) "select url from sitemenu where hostid = $hostid" in
  let start_pages = "index" :: "copyright" :: start_pages in

  (* The find the list of orphans, we first construct the list of
   * pages reachable from the front page.  Once this list has been
   * constructed, any page not on the list is an orphan or part of
   * a group of orphans.
   *
   * XXX This does not properly handle redirects XXX
   *)
  let rec loop pages border =
    (* Preconditions:
     * pages <> []
     * border <> []
     * pages is a list of distinct pages
     * border is a list of distinct pages
     * pages @ border is a list of distinct pages
     *)
    let pages' = pages @ border in
    let border' =
      PGSQL(dbh) "select distinct to_url from links
                   where hostid = $hostid and from_url in $@border
                              and to_url not in $@pages')" in
    if border' = [] then pages'
    else loop pages' border'
  in
  let non_orphans = loop [] start_pages in

  (* Get the actual orphans, which are pages which do not appear in this list*)
  let rows = PGSQL(dbh)
    "select url, title from pages
      where hostid = $hostid
        and url is not null and redirect is null
        and url not in $@non_orphans
      order by 1" in

  let table =
    List.map (fun (page, title) ->
	       [ "page", Template.VarString page;
		 "title", Template.VarString title ]) rows in

  template#table "pages" table;

  q#template template

let () =
  register_script ~restrict:[CanView] run