(* COCANWIKI - a wiki written in Objective CAML.
 * Written by Richard W.M. Jones <rich@merjis.com>.
 * Copyright (C) 2004 Merjis Ltd.
 * $Id: cocanwiki.ml,v 1.10 2006/03/28 16:24:08 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_ok
open Cocanwiki_strings

(* The "host object". *)
type host_t = { hostname : string;
		canonical_hostname : string;
		edit_anon : bool;
		view_anon : bool }

(* Permissions and restrictions.
 *
 * Use the optional ~restrict parameter to register_script to restrict
 * who can use the script.  For example:
 *   register_script ~restrict:[CanEdit ; CanManageUsers] run
 *)
type permissions_t = CanView | CanEdit | CanManageUsers | CanManageContacts
		   | CanManageSite | CanEditGlobalCSS | CanImportMail

(* User preferences and other settings (some cannot be changed by the user). *)
type prefs_t = {
  email : string option;		(* Email address. *)
  email_notify : bool;			(* Email notification. *)
}

(* The "user object". *)
type user_t = Anonymous			(* Not logged in. *)
	    | User of int32 * string * permissions_t list * prefs_t
					(* Userid, name, perms, prefs. *)

let test_permission {edit_anon = edit_anon; view_anon = view_anon} perm user =
  if perm = CanEdit && edit_anon then true
  else if perm = CanView && view_anon then true
  else match user with
      Anonymous -> false
    | User (_, _, perms, _) -> List.mem perm perms

let can_edit host = test_permission host CanEdit
let can_manage_users host = test_permission host CanManageUsers
let can_manage_contacts host = test_permission host CanManageContacts
let can_manage_site host = test_permission host CanManageSite
let can_edit_global_css host = test_permission host CanEditGlobalCSS
let can_import_mail host = test_permission host CanImportMail

let get_uri_from_request r =
  try
    (* If we passed through mod_rewrite, then it saved the
     * unmodified original URL in a subprocess environment
     * variable called SCRIPT_URL:
     *)
    let tbl = Request.subprocess_env r in
    Some (Table.get tbl "SCRIPT_URL")
  with
    Not_found ->
      try
	(* Otherwise try the ordinary uri field
	 * in request_rec.
	 *)
	Some (Request.uri r)
      with Not_found ->
	None

(* Our wrapper around the standard [register_script] function.
 *
 * The optional ~restrict and ~anonymous parameters work as follows:
 *
 * By default (neither parameter given), anonymous or logged-in users
 * at any level are permitted to run the script.
 *
 * If ~anonymous:false then a user must be logged in to use the script.
 *
 * If ~restrict contains a list of permissions (eg. CanEdit, etc.) then
 * the user must have the ability to do AT LEAST ONE of those actions.
 * (Note that this does not necessarily imply that the user must be
 * logged in, because in some circumstances even anonymous users have
 * the CanEdit permission - very typical for a wiki).
 *
 * If ~anonymous:false and ~restrict is given then the user must be
 * logged in AND have the ability to do AT LEAST ONE of those actions.
 *)
let register_script ?(restrict = []) ?(anonymous = true) run =
  (* Actually register the script with the real [Registry] module. *)
  register_script
    (fun r ->
       let q = new cgi r in

       (* XXX Database pooling. *)
       let dbh = PGOCaml.connect ~database:"cocanwiki" () in
       PGOCaml.begin_work dbh;

       let exn =
	 try
	   (* Get the host ID, by comparing the Host: header with the hostnames
	    * table in the database.
	    *)
	   let hostid, hostname, canonical_hostname, edit_anon, view_anon =
	     let hostname =
	       try Request.hostname r
	       with Not_found ->
		 error ~back_button:true
		   ~title:"Browser problem" dbh (-1l) q
		   ("Your browser didn't send a \"Host\" header as part of " ^
		      "the HTTP request.  Unfortunately this web server " ^
		      "cannot handle HTTP requests without a \"Host\" " ^
		      "header.");
		 return () in
	     let hostname = String.lowercase hostname in

	     let rows =
	       PGSQL(dbh)
		 "select h.id, h.canonical_hostname, h.edit_anon, h.view_anon
                    from hostnames hn, hosts h
                   where hn.name = $hostname and hn.hostid = h.id" in

	     match rows with
	     | [id, canonical_hostname, edit_anon, view_anon] ->
		 id, hostname, canonical_hostname, edit_anon, view_anon
	     | [] ->
	       error ~back_button:true
	         ~title:"Unknown website" dbh (-1l) q
	         ("No website called \"" ^ hostname ^ "\" can be found.  " ^
		  "If you are the administrator of this site, check that " ^
		  "the hostname is listed in the \"hostnames\" table " ^
		  "in the database.");
		 return ()
	     | _ -> assert false in

	   (* Create the host object. *)
	   let host = { hostname = hostname;
			canonical_hostname = canonical_hostname;
			edit_anon = edit_anon;
			view_anon = view_anon } in

	   (* Look for the user's cookie, and determine from this the user
	    * object.
	    *)
	   let user =
	     try
	       let cookie =
		 (* Allow the user to deliberately specify an extra "cookie"
		  * parameter, which we will send back as a cookie.  This is
		  * useful for "mail my password"-type scripts.
		  *)
		 if q#param_exists "cookie" then (
		   let value = q#param "cookie" in
		   let cookie = Cookie.cookie "auth" value ~path:"/" in
		   Table.set (Request.headers_out r)
		     "Set-Cookie" cookie#to_string;
		   value
		 ) else (
		   (* Normal cookie, from the headers. *)
		   let header = Table.get (Request.headers_in r) "Cookie" in
		   let cookies = Cookie.parse header in
		   let cookie =
		     List.find (fun cookie -> cookie#name = "auth") cookies in
		   cookie#value
		 ) in

	       let rows =
		 PGSQL(dbh)
		   "select u.id, u.name, u.can_edit, u.can_manage_users,
                           u.can_manage_contacts, u.can_manage_site,
                           u.can_edit_global_css, u.can_import_mail,
                           u.email, u.email_notify
                      from usercookies uc, users u
                     where uc.cookie = $cookie
                       and uc.userid = u.id
                       and u.hostid = $hostid" in
	       match rows with
	       | [userid, name, can_edit, can_manage_users,
		  can_manage_contacts, can_manage_site,
		  can_edit_global_css, can_import_mail,
		  email, email_notify] ->
		   (* Every logged in user can view. *)
		   let perms = [CanView] in
		   let perms =
		     if can_edit then CanEdit :: perms
		     else perms in
		   let perms =
		     if can_manage_users then CanManageUsers :: perms
		     else perms in
		   let perms =
		     if can_manage_contacts then CanManageContacts :: perms
		     else perms in
		   let perms =
		     if can_manage_site then CanManageSite :: perms
		     else perms in
		   let perms =
		     if can_edit_global_css then CanEditGlobalCSS :: perms
		     else perms in
		   let perms =
		     if can_import_mail then CanImportMail :: perms
		     else perms in
		   (* Preferences. *)
		   let prefs = { email = email;
				 email_notify = email_notify; } in
		   User (userid, name, perms, prefs)
	       | [] -> raise Not_found
	       | _ -> assert false
	     with
	       Not_found -> Anonymous in

	   (* If the ~restrict parameter is given, then we want to check that
	    * the user has sufficient permission to run this script.
	    *)
	   let permitted =
	     if not anonymous && user = Anonymous then false
	     else
	       match restrict with
	       | [] -> true		(* empty list = no restrictions *)
	       | rs ->
		   List.fold_left (||) false
		     (List.map (fun r -> test_permission host r user) rs) in

	   if permitted then (
	     (* Call the actual CGI script. *)
	     run r q dbh hostid host user
	   ) else (
	     if user = Anonymous then (
	       (* Not logged in and no permission to do the requested action,
		* so redirect to the login script.  If possible set the
		* redirect parameter so that we return to the right URL.
		*)
	       let redirect = get_uri_from_request r in

	       let url =
		 "http://" ^ hostname ^ "/_login" ^
		   match redirect with
		   | None -> ""
		   | Some url -> "?redirect=" ^ Cgi_escape.escape_url url in
	       q#redirect url
	     ) else
	       error ~back_button:true
		 ~title:"Access denied"
		 dbh hostid q
		 "You do not have permission to access this part of the site."
	   );

	   None (* no exception *)
	 with
	   exn -> Some exn in

       (* XXX Connection pooling - see above. *)
       PGOCaml.close dbh;

       (* To help with debugging, if there is an exception, print some
	* extended details.
	*)
       (match exn with
	| Some exn ->
	    fprintf stderr "COCANWIKI exception: %S\n" (Std.dump exn);
	    fprintf stderr "Time: %s\n"
	      (Printer.CalendarPrinter.to_string (Calendar.now ()));
	    let hostname =
	      try Some (Request.hostname r) with Not_found -> None in
	    fprintf stderr "Host: ";
	    (match hostname with
	     | None -> fprintf stderr "not available\n"
	     | Some hostname -> fprintf stderr "%S\n" hostname
	    );
	    let uri = get_uri_from_request r in
	    fprintf stderr "Request: ";
	    (match uri with
	     | None -> fprintf stderr "not available\n"
	     | Some uri -> fprintf stderr "%S\n" uri
	    );
	| _ -> ()
       );

       (* May re-raise the caught exception. *)
       Option.may raise exn
    )

(* Convert a section name into something valid for use in <a name="...">
 * XXX This breaks horribly for non-7-bit strings.
 * XXX This is stuck here because we don't have a good place for it, and
 * because it needs to be fixed for i18n compliance.
 *)
let linkname_of_sectionname str =
  let str = String.copy str in
  for i = 0 to String.length str - 1 do
    if not (isalnum str.[i]) then str.[i] <- '_'
  done;
  str

(* List of extensions currently registered. *)
type extension_t = PGOCaml.pa_pg_data PGOCaml.t -> int32 -> string -> string
let extensions = ref ([] : (string * extension_t) list)

(* Maximum degree of redirection. *)
let max_redirect = 4