%% Copyright (c) 2012-2018, DNSimple Corporation
%%
%% Permission to use, copy, modify, and/or distribute this software for any
%% purpose with or without fee is hereby granted, provided that the above
%% copyright notice and this permission notice appear in all copies.
%%
%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

%% @doc Funcions for loading zones from local or remote sources.
-module(erldns_zone_loader).

-export([load_zones/0]).

-define(FILENAME, "zones.json").

% Public API

%% @doc Load zones from a file. The default file name is "zones.json".
-spec load_zones() -> {ok, integer()} | {err,  atom()}.
load_zones() ->
  case file:read_file(filename()) of
    {ok, Binary} ->
      lager:debug("Parsing zones JSON"),
      JsonZones = jsx:decode(Binary),
      lager:debug("Putting zones into cache"),
      lists:foreach(
        fun(JsonZone) ->
            Zone = erldns_zone_parser:zone_to_erlang(JsonZone),
            case erldns_zone_cache:put_zone(Zone) of
              {error, Reason} -> lager:error("Failed to load zone (reason: ~p)", [JsonZone, Reason]);
              _ -> ok
            end
        end, JsonZones),
      lager:info("Loaded zones (count: ~p)", [length(JsonZones)]),
      {ok, length(JsonZones)};
    {error, Reason} ->
      lager:error("Failed to load zones (reason: ~p)", [Reason]),
      {err, Reason}
  end.

% Internal API
filename() ->
  case application:get_env(erldns, zones) of
    {ok, Filename} -> Filename;
    _ -> ?FILENAME
  end.