(* COCANWIKI - a wiki written in Objective CAML.
 * Written by Richard W.M. Jones <rich@merjis.com>.
 * Copyright (C) 2004 Merjis Ltd.
 * $Id: cocanwiki_template.ml,v 1.2 2004/10/23 10:13:20 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.
 *
 * This module wraps around the Template library.  It provides caching
 * of templates and fills in standard fields on a host-specific basis.
 *
 *)

open Unix

open Cocanwiki_files
open Cocanwiki_strings

(* This is used to generate the id fields from URLs on the site menu. *)
let id_of_url 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

let base =
  let base =
    try Sys.getenv "COCANWIKI_TEMPLATES"
    with Not_found -> "/usr/share/cocanwiki/templates" in
  let is_dir path =
    try (Unix.stat path).Unix.st_kind = Unix.S_DIR
    with Unix.Unix_error _ -> false in
  if not (is_dir base) then
    failwith ("environment variable $COCANWIKI_TEMPLATES " ^
	      "must be set to point to my 'templates' directory " ^
	      "(see README file for more details)");
  base

(* The webserver gets restarted regularly enough that this is reasonable. *)
let { tm_year = year } = gmtime (time ())
let year = year + 1900

(* Cache of precompiled templates, arranged by full path. *)
let cache = Hashtbl.create 32

let _get_template filename =
  let path = base // filename in
  let stat = Unix.stat path in
  let mtime = stat.st_mtime in

  try
    let template, old_mtime = Hashtbl.find cache path in
    if old_mtime < mtime then (
      (* The template has changed on disk since it was compiled.  Reload. *)
      let template = Template.template path in
      Hashtbl.replace cache path (template, mtime);
      template
    ) else
      template
  with
      Not_found ->
	(* Template not seen before, so load it. *)
	let template = Template.template path in
	Hashtbl.replace cache path (template, mtime);
	template

let get_template ?page (dbh : Dbi.connection) hostid filename =
  let template = _get_template filename in

  (* Get standard fields concerning this host from the database. *)
  let sth =
    dbh#prepare_cached
      "select h.theme_css, p.name, p.url
         from hosts h left outer join powered_by p on h.powered_by = p.id
        where h.id = ?" in
  sth#execute [`Int hostid];

  let theme_css, powered_by_name, powered_by_url =
    match sth#fetch1 () with
      | [ a; b; c] -> a, b, c
      | _ -> assert false in
  let theme_css =
    match theme_css with
      | `Null -> "/_css/standard.css"
      | `String file -> file
      | _ -> assert false in
  let powered_by_name, powered_by_url =
    match powered_by_name, powered_by_url with
      | `Null, `Null ->
	  let url = "http://sandbox.merjis.com/" in
	  let name = Cocanwiki_version.package ^ " " ^
		     Cocanwiki_version.version in
	  name, url
      | `String name, `String url -> name, url
      | _ -> assert false in

  template#set "theme_css" theme_css;
  template#set "powered_by_name" powered_by_name;
  template#set "powered_by_url" powered_by_url;

  (* Site menu. *)
  let sth = dbh#prepare_cached "select url, label, ordering from sitemenu
                                 where hostid = ? order by ordering" in
  sth#execute [`Int hostid];

  let is_homepage =
    match page with
      | None -> false
      | Some "index" -> true
      | _ -> false in
  template#conditional "is_homepage" is_homepage;

  let table = sth#map (function [`String url; `String label; _] ->
			 let is_linked =
			   match page with
			     | None -> true
			     | Some page when page = url -> false
			     | _ -> true in
			 let id = id_of_url url in
			 [ "url", Template.VarString url;
			   "label", Template.VarString label;
			   "is_linked", Template.VarConditional is_linked;
			   "id", Template.VarString id ]
			 | _ -> assert false) in

  template#table "sitemenu" table;

  (* Wiki version. *)
  template#set "cocanwiki_package" Cocanwiki_version.package;
  template#set "cocanwiki_version" Cocanwiki_version.version;

  (* Copyright year. *)
  template#set "year" (string_of_int year);

  template