%%%-------------------------------------------------------------------
%%% @doc Обработчик профиля текущего пользователя (клиентский API).
%%%
%%% GET   – получить информацию о своём профиле.
%%% PATCH – частичное обновление профиля / смена пароля.
%%% @end
%%%-------------------------------------------------------------------
-module(handler_user_me).
-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) ->
  handle(Req, Opts).

%%% Swagger metadata
-spec trails() -> [map()].
trails() ->
  [
    #{
      path        => <<"/v1/user/me">>,
      method      => <<"GET">>,
      description => <<"Get current user profile">>,
      tags        => [<<"Users">>],
      responses   => #{
        200 => #{
          description => <<"User profile">>,
          content     => #{<<"application/json">> => #{schema => user_schema()}}
        },
        401 => #{description => <<"Unauthorized">>},
        404 => #{description => <<"User not found">>}
      }
    },
    #{
      path        => <<"/v1/user/me">>,
      method      => <<"PATCH">>,
      description => <<"Update current user profile (partial) or change password">>,
      tags        => [<<"Users">>],
      requestBody => #{
        required => true,
        content  => #{<<"application/json">> => #{schema => user_update_schema()}}
      },
      responses => #{
        200 => #{
          description => <<"Updated profile">>,
          content     => #{<<"application/json">> => #{schema => user_schema()}}
        },
        400 => #{description => <<"Invalid body / unknown field">>},
        401 => #{description => <<"Unauthorized">>},
        403 => #{description => <<"Wrong current password or account not active">>},
        404 => #{description => <<"User not found">>}
      }
    }
  ].

user_schema() ->
  #{
    type       => object,
    properties => #{
      id              => #{type => string},
      email           => #{type => string, format => <<"email">>},
      role            => #{type => string, enum => [<<"user">>, <<"bot">>]},
      status          => #{type => string, enum => [<<"active">>, <<"frozen">>, <<"deleted">>]},
      reason          => #{type => string, nullable => true},
      nickname        => #{type => string, nullable => true},
      avatar_url      => #{type => string, nullable => true},
      timezone        => #{type => string, nullable => true},
      language        => #{type => string, enum => [<<"ru">>, <<"en">>], nullable => true},
      social_links    => #{type => array, items => #{type => string}, nullable => true},
      phone           => #{type => string, nullable => true},
      preferences     => #{type => object, nullable => true},
      last_login      => #{type => string, format => <<"date-time">>},
      created_at      => #{type => string, format => <<"date-time">>},
      updated_at      => #{type => string, format => <<"date-time">>}
    }
  }.

user_update_schema() ->
  #{
    type       => object,
    properties => #{
      language         => #{type => string, enum => [<<"ru">>, <<"en">>]},
      nickname         => #{type => string, nullable => true},
      timezone         => #{type => string, nullable => true},
      phone            => #{type => string, nullable => true},
      avatar_url       => #{type => string, nullable => true},
      preferences      => #{type => object, nullable => true},
      password         => #{type => string, format => <<"password">>,
        description => <<"New password; requires current_password">>},
      current_password => #{type => string, format => <<"password">>,
        description => <<"Current password; required with password">>}
    }
  }.

%%%===================================================================
%%% HTTP-методы
%%%===================================================================

%% @private
-spec handle(cowboy_req:req(), any()) -> {ok, cowboy_req:req(), any()}.
handle(Req, _Opts) ->
  case cowboy_req:method(Req) of
    <<"GET">>   -> get_me(Req);
    <<"PATCH">> -> patch_me(Req);
    _           -> handler_utils:send_error(Req, 405, <<"Method not allowed">>)
  end.

%% @doc GET /v1/user/me — получение профиля текущего пользователя.
-spec get_me(cowboy_req:req()) -> {ok, binary(), cowboy_req:req()}.
get_me(Req) ->
  case handler_utils:auth_user(Req) of
    {ok, UserId, Req1} ->
      case core_user:get_by_id(UserId) of
        {ok, User} ->
          handler_utils:send_json(Req1, 200, handler_utils:user_to_json(User));
        {error, not_found} ->
          handler_utils:send_error(Req1, 404, <<"User not found">>)
      end;
    {error, Code, Message, Req1} ->
      handler_utils:send_error(Req1, Code, Message)
  end.

%% @doc PATCH /v1/user/me — частичное обновление профиля / смена пароля.
-spec patch_me(cowboy_req:req()) -> {ok, binary(), cowboy_req:req()}.
patch_me(Req) ->
  case handler_utils:auth_user(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 logic_user:update_me(UserId, Decoded) of
            {ok, User} ->
              handler_utils:send_json(Req2, 200, handler_utils:user_to_json(User));
            {error, not_found} ->
              handler_utils:send_error(Req2, 404, <<"User not found">>);
            {error, wrong_password} ->
              handler_utils:send_error(Req2, 403, <<"Wrong current password">>);
            {error, forbidden} ->
              handler_utils:send_error(Req2, 403, <<"Account is not active">>);
            {error, unknown_field} ->
              handler_utils:send_error(Req2, 400, <<"Unknown field">>);
            {error, empty_body} ->
              handler_utils:send_error(Req2, 400, <<"Empty update body">>);
            {error, password_pair_required} ->
              handler_utils:send_error(Req2, 400,
                <<"password and current_password must be sent together">>);
            {error, invalid_password} ->
              handler_utils:send_error(Req2, 400, <<"Invalid password fields">>);
            {error, invalid_language} ->
              handler_utils:send_error(Req2, 400, <<"language must be ru or en">>);
            {error, Reason} when is_atom(Reason) ->
              handler_utils:send_error(Req2, 400, atom_to_binary(Reason, utf8));
            {error, _} ->
              handler_utils:send_error(Req2, 400, <<"Invalid request">>)
          end;
        _ ->
          handler_utils:send_error(Req2, 400, <<"Invalid JSON">>)
      catch
        _:_ -> handler_utils:send_error(Req2, 400, <<"Invalid JSON format">>)
      end;
    {error, Code, Message, Req1} ->
      handler_utils:send_error(Req1, Code, Message)
  end.