-module(handler_subscription).
-include("records.hrl").

-export([init/2]).

init(Req, Opts) ->
  handle(Req, Opts).

handle(Req, _Opts) ->
  case cowboy_req:method(Req) of
    <<"GET">> -> get_subscription(Req);
    <<"POST">> -> create_subscription(Req);
    _ -> send_error(Req, 405, <<"Method not allowed">>)
  end.

%% GET /v1/subscription - получить подписку текущего пользователя
get_subscription(Req) ->
  case handler_auth:authenticate(Req) of
    {ok, UserId, Req1} ->
      case logic_subscription:get_user_subscription(UserId) of
        {ok, Subscription} ->
          send_json(Req1, 200, Subscription);
        {error, _} ->
          send_error(Req1, 500, <<"Internal server error">>)
      end;
    {error, Code, Message, Req1} ->
      send_error(Req1, Code, Message)
  end.

%% POST /v1/subscription - активировать подписку
create_subscription(Req) ->
  case handler_auth:authenticate(Req) of
    {ok, UserId, Req1} ->
      {ok, Body, Req2} = cowboy_req:read_body(Req1),
      try jsx:decode(Body, [return_maps]) of
        Decoded when is_map(Decoded) ->
          case Decoded of
            #{<<"action">> := <<"start_trial">>} ->
              case logic_subscription:start_trial(UserId) of
                {ok, Subscription} ->
                  Response = subscription_to_json(Subscription),
                  send_json(Req2, 201, Response);
                {error, already_has_subscription} ->
                  send_error(Req2, 409, <<"Already has active subscription">>);
                {error, _} ->
                  send_error(Req2, 500, <<"Internal server error">>)
              end;
            #{<<"action">> := <<"activate">>, <<"plan">> := PlanBin} ->
              Plan = parse_plan(PlanBin),
              PaymentInfo = maps:get(<<"payment_info">>, Decoded, #{}),
              case logic_subscription:activate_subscription(UserId, Plan, PaymentInfo) of
                {ok, Subscription} ->
                  Response = subscription_to_json(Subscription),
                  send_json(Req2, 201, Response);
                {error, payment_failed} ->
                  send_error(Req2, 402, <<"Payment failed">>);
                {error, _} ->
                  send_error(Req2, 500, <<"Internal server error">>)
              end;
            _ ->
              send_error(Req2, 400, <<"Invalid action. Use 'start_trial' or 'activate'">>)
          end;
        _ ->
          send_error(Req2, 400, <<"Invalid JSON">>)
      catch
        _:_ ->
          send_error(Req2, 400, <<"Invalid JSON format">>)
      end;
    {error, Code, Message, Req1} ->
      send_error(Req1, Code, Message)
  end.

%% Вспомогательные функции
parse_plan(<<"monthly">>) -> monthly;
parse_plan(<<"quarterly">>) -> quarterly;
parse_plan(<<"biannual">>) -> biannual;
parse_plan(<<"annual">>) -> annual;
parse_plan(_) -> monthly.

subscription_to_json(Subscription) when is_tuple(Subscription) ->
  #{
    id => Subscription#subscription.id,
    plan => Subscription#subscription.plan,
    status => Subscription#subscription.status,
    trial_used => Subscription#subscription.trial_used,
    started_at => datetime_to_iso8601(Subscription#subscription.started_at),
    expires_at => datetime_to_iso8601(Subscription#subscription.expires_at)
  };
subscription_to_json(Subscription) when is_map(Subscription) ->
  Subscription.

datetime_to_iso8601({{Year, Month, Day}, {Hour, Minute, Second}}) ->
  iolist_to_binary(io_lib:format("~4..0B-~2..0B-~2..0BT~2..0B:~2..0B:~2..0BZ",
    [Year, Month, Day, Hour, Minute, Second])).

send_json(Req, Status, Data) ->
  Body = jsx:encode(Data),
  cowboy_req:reply(Status, #{<<"content-type">> => <<"application/json">>}, Body, Req),
  {ok, Body, []}.

send_error(Req, Status, Message) ->
  Body = jsx:encode(#{error => Message}),
  cowboy_req:reply(Status, #{<<"content-type">> => <<"application/json">>}, Body, Req),
  {ok, Body, []}.