%%%-------------------------------------------------------------------
%%% @doc Обработчик конкретного бронирования (клиентский API).
%%%
%%% GET    – получить информацию о бронировании.
%%% PUT    – подтвердить или отклонить бронирование (владельцем).
%%% DELETE – отменить бронирование (участником).
%%% @end
%%%-------------------------------------------------------------------
-module(handler_booking_by_id).
-behaviour(cowboy_handler).

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

-include("records.hrl").

%%% cowboy_handler callback
-spec init(cowboy_req:req(), any()) -> {ok, cowboy_req:req(), any()}.
init(Req, _Opts) ->
  case cowboy_req:method(Req) of
    <<"GET">>    -> get_booking(Req);
    <<"PUT">>    -> update_booking(Req);
    <<"DELETE">> -> cancel_booking(Req);
    _            -> handler_utils:send_error(Req, 405, <<"Method not allowed">>)
  end.

%%% Swagger metadata
-spec trails() -> [map()].
trails() ->
  BaseParams = [
    #{
      name        => <<"id">>,
      in          => <<"path">>,
      description => <<"Booking ID">>,
      required    => true,
      schema      => #{type => string}
    }
  ],
  [
    #{  % GET by id
      path        => <<"/v1/bookings/:id">>,
      method      => <<"GET">>,
      description => <<"Get booking by ID">>,
      tags        => [<<"Bookings">>],
      parameters  => BaseParams,
      responses   => #{
        200 => #{
          description => <<"Booking details">>,
          content     => #{<<"application/json">> => #{schema => booking_schema()}}
        },
        404 => #{description => <<"Booking not found">>}
      }
    },
    #{  % PUT update (confirm/decline)
      path        => <<"/v1/bookings/:id">>,
      method      => <<"PUT">>,
      description => <<"Confirm or decline a booking (owner)">>,
      tags        => [<<"Bookings">>],
      parameters  => BaseParams,
      requestBody => #{
        required => true,
        content  => #{<<"application/json">> => #{schema => booking_update_schema()}}
      },
      responses => #{
        200 => #{description => <<"Booking updated">>},
        400 => #{description => <<"Invalid action">>},
        404 => #{description => <<"Booking not found">>}
      }
    },
    #{  % DELETE cancel
      path        => <<"/v1/bookings/:id">>,
      method      => <<"DELETE">>,
      description => <<"Cancel booking (participant)">>,
      tags        => [<<"Bookings">>],
      parameters  => BaseParams,
      responses => #{
        200 => #{description => <<"Booking cancelled">>},
        404 => #{description => <<"Booking not found">>}
      }
    }
  ].

booking_schema() ->
  #{
    type       => object,
    properties => #{
      id            => #{type => string},
      event_id      => #{type => string},
      user_id       => #{type => string},
      status        => #{type => string, enum => [<<"pending">>, <<"confirmed">>, <<"cancelled">>]},
      notes         => #{type => string, nullable => true},
      reminder_sent => #{type => boolean},
      confirmed_at  => #{type => string, format => <<"date-time">>, nullable => true},
      created_at    => #{type => string, format => <<"date-time">>},
      updated_at    => #{type => string, format => <<"date-time">>}
    }
  }.

booking_update_schema() ->
  #{
    type       => object,
    required   => [<<"action">>],
    properties => #{
      action => #{type => string, enum => [<<"confirm">>, <<"decline">>]}
    }
  }.

%%% Internal functions

%% @doc Получить бронирование по ID.
-spec get_booking(cowboy_req:req()) -> {ok, binary(), cowboy_req:req()}.
get_booking(Req) ->
  case handler_utils:auth_user(Req) of
    {ok, UserId, Req1} ->
      BookingId = cowboy_req:binding(id, Req1),
      case logic_booking:get_booking(UserId, BookingId) of
        {ok, Booking} ->
          handler_utils:send_json(Req1, 200, booking_to_json(Booking));
        {error, access_denied} ->
          handler_utils:send_error(Req1, 403, <<"Access denied">>);
        {error, not_found} ->
          handler_utils:send_error(Req1, 404, <<"Booking not found">>);
        {error, _} ->
          handler_utils:send_error(Req1, 500, <<"Internal server error">>)
      end;
    {error, Code, Message, Req1} ->
      handler_utils:send_error(Req1, Code, Message)
  end.

%% @doc Подтвердить или отклонить бронирование (владельцем).
-spec update_booking(cowboy_req:req()) -> {ok, binary(), cowboy_req:req()}.
update_booking(Req) ->
  case handler_utils:auth_user(Req) of
    {ok, UserId, Req1} ->
      BookingId = cowboy_req:binding(id, Req1),
      {ok, Body, Req2} = cowboy_req:read_body(Req1),
      try jsx:decode(Body, [return_maps]) of
        #{<<"action">> := Action} when Action =:= <<"confirm">>; Action =:= <<"decline">> ->
          ActionAtom = binary_to_existing_atom(Action, utf8),
          case logic_booking:confirm_booking(UserId, BookingId, ActionAtom) of
            {ok, Booking} ->
              handler_utils:send_json(Req2, 200, booking_to_json(Booking));
            {error, access_denied} ->
              handler_utils:send_error(Req2, 403, <<"Access denied">>);
            {error, not_found} ->
              handler_utils:send_error(Req2, 404, <<"Booking not found">>);
            {error, _} ->
              handler_utils:send_error(Req2, 500, <<"Internal server error">>)
          end;
        _ ->
          handler_utils:send_error(Req2, 400, <<"Missing or invalid 'action' field. Use 'confirm' or 'decline'">>)
      catch
        _:_ -> handler_utils:send_error(Req2, 400, <<"Invalid JSON format">>)
      end;
    {error, Code, Message, Req1} ->
      handler_utils:send_error(Req1, Code, Message)
  end.

%% @doc Отменить бронирование (участником).
-spec cancel_booking(cowboy_req:req()) -> {ok, binary(), cowboy_req:req()}.
cancel_booking(Req) ->
  case handler_utils:auth_user(Req) of
    {ok, UserId, Req1} ->
      BookingId = cowboy_req:binding(id, Req1),
      case logic_booking:cancel_booking(BookingId, UserId) of
        {ok, Booking} ->
          handler_utils:send_json(Req1, 200, booking_to_json(Booking));
        {error, access_denied} ->
          handler_utils:send_error(Req1, 403, <<"Access denied">>);
        {error, not_found} ->
          handler_utils:send_error(Req1, 404, <<"Booking not found">>);
        {error, _} ->
          handler_utils:send_error(Req1, 500, <<"Internal server error">>)
      end;
    {error, Code, Message, Req1} ->
      handler_utils:send_error(Req1, Code, Message)
  end.

%% @private Формирует JSON-представление записи #booking{}.
%% Учитывает все поля из records.hrl.
-spec booking_to_json(#booking{}) -> map().
booking_to_json(Booking) ->
  #{
    id            => Booking#booking.id,
    event_id      => Booking#booking.event_id,
    user_id       => Booking#booking.user_id,
    status        => Booking#booking.status,
    notes         => Booking#booking.notes,
    reminder_sent => Booking#booking.reminder_sent,
    confirmed_at  => case Booking#booking.confirmed_at of
                       undefined -> null;
                       Dt        -> handler_utils:datetime_to_iso8601(Dt)
                     end,
    created_at    => handler_utils:datetime_to_iso8601(Booking#booking.created_at),
    updated_at    => handler_utils:datetime_to_iso8601(Booking#booking.updated_at)
  }.