(*
 * 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 Pxp_document
open Pxp_types
open Pxp_yacc

open Http_getter_types

let version = Http_getter_const.version

let servers_file    = lazy (Helm_registry.get "getter.servers_file")
let cic_dbm         = lazy (Helm_registry.get "getter.cic_dbm")
let nuprl_dbm       = lazy (Helm_registry.get "getter.nuprl_dbm")
let rdf_dbm         = lazy (Helm_registry.get "getter.rdf_dbm")
let xsl_dbm         = lazy (Helm_registry.get "getter.xsl_dbm")
let xml_index       = lazy (Helm_registry.get "getter.xml_indexname")
let rdf_index       = lazy (Helm_registry.get "getter.rdf_indexname")
let xsl_index       = lazy (Helm_registry.get "getter.xsl_indexname")
let cic_dir         = lazy (Helm_registry.get "getter.cic_dir")
let nuprl_dir       = lazy (Helm_registry.get "getter.nuprl_dir")
let rdf_dir         = lazy (Helm_registry.get "getter.rdf_dir")
let dtd_dir         = lazy (Helm_registry.get "getter.dtd_dir")
let dtd_base_url    = lazy (Helm_registry.get "getter.dtd_base_url")
let port            = lazy (Helm_registry.get_int "getter.port")

let _servers = ref None

let servers =
 function () ->
    (match !_servers with
    | None -> failwith "Getter not yet initialized: servers not available"
    | Some servers -> servers)

let load_servers () =
  let pos = ref (-1) in
  List.rev (Http_getter_misc.fold_file
    (fun line servers ->
      if Http_getter_misc.is_blank_line line then
        servers
      else
        (incr pos; (!pos, line) :: servers))
    []
    (Lazy.force servers_file))

let reload_servers () = _servers := Some (load_servers ())

let save_servers () =
  let oc = open_out (Lazy.force servers_file) in
  List.iter (fun (_,server) -> output_string oc (server ^ "\n"))
    (servers ());
  close_out oc

let host =
  lazy
    (let buf = Buffer.create 20 in
    Shell.call ~stdout:(Shell.to_buffer buf) [Shell.cmd "hostname" ["-f"]];
    Pcre.replace ~pat:"\n+$" (Buffer.contents buf))

let my_own_url =
  lazy
    (let (host, port) = (Lazy.force host, Lazy.force port) in
    sprintf "http://%s%s" (* without trailing '/' *)
    host (if port = 80 then "" else (sprintf ":%d" port)))

let cache_mode =
  lazy
    (match String.lowercase (Helm_registry.get "getter.cache_mode") with
    | "normal" -> Enc_normal
    | "gz" -> Enc_gzipped
    | mode -> failwith ("Invalid cache mode: " ^ mode))

let reload () = reload_servers ()

let env_to_string () =
  sprintf
"HTTP Getter %s (the OCaml one!)

cic_dbm:\t%s
nuprl_dbm:\t%s
rdf_dbm:\t%s
xsl_dbm:\t%s
xml_index:\t%s
rdf_index:\t%s
xsl_index:\t%s
cic_dir:\t%s
nuprl_dir:\t%s
rdf_dir:\t%s
dtd_dir:\t%s
servers_file:\t%s
host:\t\t%s
port:\t\t%d
my_own_url:\t%s
dtd_base_url:\t%s
cache_mode:\t%s
servers:
\t%s
"
    version (Lazy.force cic_dbm) (Lazy.force nuprl_dbm) (Lazy.force rdf_dbm)
    (Lazy.force xsl_dbm) (Lazy.force xml_index)
    (Lazy.force rdf_index) (Lazy.force xsl_index) (Lazy.force cic_dir)
    (Lazy.force nuprl_dir) (Lazy.force rdf_dir)
    (Lazy.force dtd_dir) (Lazy.force servers_file) (Lazy.force host)
    (Lazy.force port) (Lazy.force my_own_url)
    (Lazy.force dtd_base_url)
    (match Lazy.force cache_mode with Enc_normal -> "Normal" | Enc_gzipped -> "GZipped")
    (String.concat "\n\t" (* (position * server) list *)
      (List.map (fun (pos, server) -> sprintf "%3d: %s" pos server)
        (servers ())))

let add_server ?position url =
  let new_servers =
    let servers = servers () in
    match position with
    | None -> servers @ [-1, url];
    | Some p when p > 0 ->
        let rec add_after pos = function
          | [] -> [-1, url]
          | hd :: tl when p = 1 -> hd :: (-1, url) :: tl
          | hd :: tl (* when p > 1 *) -> hd :: (add_after (pos - 1) tl)
        in
        add_after p servers
    | Some 0 -> (-1, url)::servers
    | Some _ -> assert false
  in
  _servers := Some new_servers;
  save_servers ();
  reload_servers ()

let remove_server position =
  _servers := Some (List.remove_assoc position (servers ()));
  save_servers ();
  reload_servers ()