(* 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.
 *)

(* Templates. *)

open Utils

open Printf

let template_dir =
  try Sys.getenv "MCLU_PATH"
  with Not_found -> Config.pkgdatadir // "templates"

let templates () =
  let files = Sys.readdir template_dir in
  let files = Array.to_list files in
  let files = List.map ((//) template_dir) files in
  let files =
    List.filter (fun name -> Filename.check_suffix name ".template") files in
  let templates =
    List.map (
      fun filename ->
        let name = Filename.basename filename in
        let name = Filename.chop_suffix name ".template" in
        (name, filename)
    ) files in
  List.sort compare templates

let template_names () = List.map fst (templates ())

let run_template ~verbose filename subcmd args =
  let cmd =
    sprintf "%s %s %s" (quote filename) (quote subcmd)
      (String.concat " " (List.map quote args)) in
  if verbose then printf "%s\n%!" cmd;
  let chan = Unix.open_process_in cmd in
  let lines = ref [] in
  (try while true do lines := input_line chan :: !lines done
   with End_of_file -> ());
  let lines = List.rev !lines in
  let stat = Unix.close_process_in chan in
  (match stat with
  | Unix.WEXITED 0 -> Some lines
  | Unix.WEXITED 2 -> None
  | Unix.WEXITED i ->
    eprintf "mclu: template '%s' subcmd '%s' exited with error %d\n"
      filename subcmd i;
    exit 1
  | Unix.WSIGNALED i ->
    eprintf "mclu: template '%s' subcmd '%s' killed by signal %d\n"
      filename subcmd i;
    exit 1
  | Unix.WSTOPPED i ->
    eprintf "mclu: template '%s' subcmd '%s' stopped by signal %d\n"
      filename subcmd i;
    exit 1
  )

type template_info = {
  base_image : string;
  guest_arch : string option;
  minimum_memory : int64 option;
  recommended_memory : int64 option;
  minimum_size : int64 option;
  disk_bus : string option;
  network_model : string option;
  has_xml_target : bool;
  needs_external_kernel : bool;
  cmdline : string option;
}

let probe ?(verbose = false) filename =
  (* Check the template is a template. *)
  (match run_template ~verbose filename "probe" [] with
  | Some ["hello"] -> ()
  | _ ->
    eprintf "mclu: file %s is not an mclu template\n" filename;
    exit 1
  );

  (* Probe for various properties. *)
  let base_image =
    match run_template ~verbose filename "base-image" [] with
    | Some [answer] -> answer
    | _ ->
      eprintf "mclu: cannot parse '%s base-image'\n" filename;
      exit 1 in
  let guest_arch =
    match run_template ~verbose filename "guest-arch" [] with
    | Some [arch] -> Some arch
    | _ -> None in
  let minimum_memory =
    match run_template ~verbose filename "minimum-memory" [] with
    | Some [memory] ->
      (try Some (bytes_of_human_size memory)
       with Not_found ->
         eprintf "mclu: cannot parse output of '%s minimum-memory'\n"
           filename;
         exit 1
      );
    | _ -> None in
  let recommended_memory =
    match run_template ~verbose filename "recommended-memory" [] with
    | Some [memory] ->
      (try Some (bytes_of_human_size memory)
       with Not_found ->
         eprintf "mclu: cannot parse output of '%s recommended-memory'\n"
           filename;
         exit 1
      );
    | _ -> None in
  let minimum_size =
    match run_template ~verbose filename "minimum-size" [] with
    | Some [size] ->
      (try Some (bytes_of_human_size size)
       with Not_found ->
         eprintf "mclu: cannot parse output of '%s minimum-size'\n"
           filename;
         exit 1
      );
    | _ -> None in
  let disk_bus =
    match run_template ~verbose filename "disk-bus" [] with
    | Some [answer] -> Some answer
    | _ -> None in
  let network_model =
    match run_template ~verbose filename "network-model" [] with
    | Some [answer] -> Some answer
    | _ -> None in

  let has_xml_target = run_template ~verbose filename "xml" [] <> None in

  let needs_external_kernel =
    match run_template ~verbose filename "needs-external-kernel" [] with
    | None -> false
    | Some ["1"|"yes"] -> true
    | Some _ -> false in

  let cmdline =
    match run_template ~verbose filename "cmdline" [] with
    | Some [cmdline] -> Some cmdline
    | _ -> None in

  if not needs_external_kernel && cmdline <> None then (
    eprintf "mclu: template cannot set 'cmdline' unless 'needs-external-kernel' is 'yes'.\n";
    exit 1
  );

  { base_image = base_image;
    guest_arch = guest_arch;
    minimum_memory = minimum_memory;
    recommended_memory = recommended_memory;
    minimum_size = minimum_size;
    disk_bus = disk_bus;
    network_model = network_model;
    has_xml_target = has_xml_target;
    needs_external_kernel = needs_external_kernel;
    cmdline = cmdline }