%% @private
%%% @doc Cowboy Swagger Handler. This handler exposes a GET operation
%%%      to enable `swagger.json' to be retrieved from embedded
%%%      Swagger-UI (located in `priv/swagger' folder).
-module(cowboy_swagger_json_handler).

%% Cowboy callbacks
-export([init/2, content_types_provided/2]).

-behaviour(cowboy_rest).

%% Handlers
-export([handle_get/2]).

-type options() ::
    #{server => ranch:ref(),
      host => cowboy_swagger_handler:route_match(),
      _ => _}.

-export_type([options/0, state/0]).

-type state() :: options().

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%%% Cowboy Callbacks
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-spec init(cowboy_req:req(), options()) -> {cowboy_rest, cowboy_req:req(), state()}.
init(Req, Opts) ->
    State = Opts,
    {cowboy_rest, Req, State}.

-spec content_types_provided(cowboy_req:req(), state()) ->
                                {[{binary(), atom()}], cowboy_req:req(), state()}.
content_types_provided(Req, State) ->
    {[{<<"application/json">>, handle_get}], Req, State}.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%% Handlers
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

-spec handle_get(cowboy_req:req(), state()) -> {iodata(), cowboy_req:req(), state()}.
handle_get(Req, State) ->
    Server = maps:get(server, State, '_'),
    HostMatch = maps:get(host, State, '_'),
    Trails = trails:all(Server, HostMatch),
    {cowboy_swagger:to_json(Server, Trails), Req, State}.