%%%-------------------------------------------------------------------
%%% @doc Web Push VAPID key + subscriptions (Back#75).
%%% @end
%%%-------------------------------------------------------------------
-module(handler_push).
-behaviour(cowboy_handler).

-export([init/2, trails/0]).

-include("records.hrl").

init(Req, Opts) ->
  Path = cowboy_req:path(Req),
  Method = cowboy_req:method(Req),
  case Path of
    <<"/v1/push/vapid-public-key">> ->
      case logic_web_push:vapid_public_key() of
        {ok, Key} ->
          handler_utils:send_json(Req, 200, #{publicKey => Key});
        {error, missing} ->
          handler_utils:send_error(Req, 503, <<"VAPID not configured">>)
      end;
    <<"/v1/push/subscriptions">> ->
      case handler_utils:auth_user(Req) of
        {ok, UserId, Req1} ->
          case Method of
            <<"POST">> -> post_sub(Req1, UserId);
            <<"DELETE">> -> delete_sub(Req1, UserId);
            _ -> cowboy_req:reply(405, #{}, <<>>, Req1)
          end;
        {error, Code, Message, Req1} ->
          handler_utils:send_error(Req1, Code, Message)
      end;
    _ ->
      cowboy_req:reply(404, #{}, <<>>, Req)
  end,
  {ok, Req, Opts}.

trails() ->
  [
    #{
      path => <<"/v1/push/vapid-public-key">>,
      method => <<"GET">>,
      description => <<"VAPID public key for Web Push subscribe">>,
      tags => [<<"Notifications">>],
      responses => #{200 => #{description => <<"OK">>}, 503 => #{description => <<"Not configured">>}}
    },
    #{
      path => <<"/v1/push/subscriptions">>,
      method => <<"POST">>,
      description => <<"Register Web Push subscription">>,
      tags => [<<"Notifications">>],
      responses => #{200 => #{description => <<"OK">>}, 401 => #{description => <<"Unauthorized">>}}
    },
    #{
      path => <<"/v1/push/subscriptions">>,
      method => <<"DELETE">>,
      description => <<"Remove Web Push subscription">>,
      tags => [<<"Notifications">>],
      responses => #{204 => #{description => <<"Deleted">>}, 401 => #{description => <<"Unauthorized">>}}
    }
  ].

post_sub(Req0, UserId) ->
  {ok, Body, Req1} = cowboy_req:read_body(Req0),
  try jsx:decode(Body, [return_maps]) of
    Map when is_map(Map) ->
      Endpoint = maps:get(<<"endpoint">>, Map, undefined),
      Keys = maps:get(<<"keys">>, Map, #{}),
      P256 = maps:get(<<"p256dh">>, Keys, undefined),
      Auth = maps:get(<<"auth">>, Keys, undefined),
      case {Endpoint, P256, Auth} of
        {E, P, A} when is_binary(E), E =/= <<>>,
                       is_binary(P), P =/= <<>>,
                       is_binary(A), A =/= <<>> ->
          case core_push_subscription:upsert(UserId, E, P, A) of
            {ok, Rec} ->
              handler_utils:send_json(Req1, 200, #{
                id => Rec#push_subscription.id,
                endpoint => Rec#push_subscription.endpoint
              });
            {error, _} ->
              handler_utils:send_error(Req1, 500, <<"Save failed">>)
          end;
        _ ->
          handler_utils:send_error(Req1, 400, <<"endpoint and keys.p256dh/auth required">>)
      end;
    _ ->
      handler_utils:send_error(Req1, 400, <<"Invalid JSON">>)
  catch
    _:_ ->
      handler_utils:send_error(Req1, 400, <<"Invalid JSON format">>)
  end.

delete_sub(Req0, UserId) ->
  {ok, Body, Req1} = cowboy_req:read_body(Req0),
  try jsx:decode(Body, [return_maps]) of
    Map when is_map(Map) ->
      Endpoint = maps:get(<<"endpoint">>, Map, <<>>),
      case Endpoint of
        <<>> ->
          handler_utils:send_error(Req1, 400, <<"endpoint required">>);
        Ep ->
          _ = core_push_subscription:delete_by_endpoint(UserId, Ep),
          cowboy_req:reply(204, #{}, <<>>, Req1)
      end;
    _ ->
      handler_utils:send_error(Req1, 400, <<"Invalid JSON">>)
  catch
    _:_ ->
      handler_utils:send_error(Req1, 400, <<"Invalid JSON format">>)
  end.