(* mclu: Mini Cloud
 * Copyright (C) 2014-2015 Red Hat Inc.
 *
 * 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; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *)

(* Parsing /etc/mclu.conf *)

open Printf

(* blank line *)
let is_blank_line =
  let rex = Pcre.regexp "^\\s*$" in
  Pcre.pmatch ~rex

(* comment *)
let is_comment =
  let rex = Pcre.regexp "^\\s*#" in
  Pcre.pmatch ~rex

(* [header] *)
let is_header =
  let rex = Pcre.regexp "^\\s*\\[(\\w+)\\]\\s*$" in
  fun line ->
    try
      let subs = Pcre.exec ~rex line in
      Some (Pcre.get_substring subs 1)
    with
      Not_found -> None

let ws_rex = Pcre.regexp "\\s+"

type node = {
  hostname : string;
  libvirt_uri : string;
  mac_addr : string option;
}

let _nodes : node list ref = ref []

let load_configuration config_file =
  let chan =
    try open_in config_file
    with Sys_error msg ->
      eprintf "mclu: %s: cannot open configuration file: %s\n" config_file msg;
      exit 1 in
  let rec loop section =
    let line = input_line chan in
    if is_blank_line line || is_comment line then
      loop section
    else (
      match is_header line with
      | Some "nodes" ->
        loop `Nodes
      | Some section ->
        (* Ignore unknown sections and keep going. *)
        printf "mclu: %s: warning: ignoring unknown section [%s]\n"
          config_file section;
        loop `Unknown
      | None ->
        (* How we parse lines within sections depends on the header. *)
        match section with
        | `Nodes ->
          (* If we're in the [nodes] section, parse "hostname [key=value].." *)
          (match Pcre.split ~rex:ws_rex line with
          | [] -> assert false
          | hostname :: defs ->
            let node = {
              hostname = hostname;
              libvirt_uri = sprintf "qemu+ssh://root@%s/system" hostname;
              mac_addr = None
            } in
            let node = List.fold_left (
              fun node def ->
                match Pcre.split ~pat:"=" ~max:2 def with
                | ["mac"; value] -> { node with mac_addr = Some value }
                | ["uri"; value] -> { node with libvirt_uri = value }
                | [_] -> node           (* key with no value - ignore *)
                | [_; _] -> node        (* unknown key=value - ignore *)
                | _ -> assert false
            ) node defs in
            _nodes := node :: !_nodes;
            loop section
          )
        | `Global
        | `Unknown ->
          (* Ignore the line. *)
          printf "mclu: %s: warning: ignoring `%s'\n" config_file line;
          loop section
    )
  in
  (try
     loop `Global
   with End_of_file -> ()
  );
  close_in chan;

  _nodes := List.rev !_nodes

(* Get list of nodes. *)
let nodes () = !_nodes