%%%-------------------------------------------------------------------
%%% @doc Административный обработчик списка администраторов.
%%% GET  – список всех администраторов (доступен всем администраторам).
%%% POST – создать нового администратора (только для superadmin).
%%% @end
%%%-------------------------------------------------------------------
-module(admin_handler_admins).
-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">>  -> list_admins(Req);
    <<"POST">> -> create_admin(Req);
    _ -> handler_utils:send_error(Req, 405, <<"Method not allowed">>)
  end.

%%% Swagger metadata
-spec trails() -> [map()].
trails() ->
  ListGet = #{
    path => <<"/v1/admin/admins">>,
    method => <<"GET">>,
    description => <<"List all admins (any admin)">>,
    tags => [<<"Admins">>],
    parameters => [
      #{name => <<"role">>,   in => <<"query">>, schema => #{type => string}},
      #{name => <<"status">>, in => <<"query">>, schema => #{type => string}},
      #{name => <<"q">>,      in => <<"query">>, schema => #{type => string}, description => <<"Search by email or nickname">>},
      #{name => <<"sort">>,   in => <<"query">>, schema => #{type => string, enum => [<<"email">>, <<"role">>, <<"created_at">>]}, description => <<"Sort field">>},
      #{name => <<"order">>,  in => <<"query">>, schema => #{type => string, enum => [<<"asc">>, <<"desc">>]}, description => <<"Sort order">>},
      #{name => <<"limit">>,  in => <<"query">>, schema => #{type => integer}},
      #{name => <<"offset">>, in => <<"query">>, schema => #{type => integer}}
    ],
    responses => #{
      200 => #{
        description => <<"Array of admins">>,
        content => #{<<"application/json">> => #{schema => #{
          type => array,
          items => admin_schema()
        }}}
      }
    }
  },
  PostCreate = #{
    path => <<"/v1/admin/admins">>,
    method => <<"POST">>,
    description => <<"Create a new admin (superadmin only)">>,
    tags => [<<"Admins">>],
    requestBody => #{
      required => true,
      content => #{<<"application/json">> => #{schema => #{
        type => object,
        required => [<<"email">>, <<"password">>, <<"role">>],
        properties => #{
          email    => #{type => string, format => <<"email">>},
          password => #{type => string},
          role     => #{type => string, enum => [<<"superadmin">>, <<"admin">>, <<"moderator">>, <<"support">>]}
        }
      }}}
    },
    responses => #{
      201 => #{description => <<"Admin created">>},
      400 => #{description => <<"Invalid fields">>},
      403 => #{description => <<"Only superadmin can create admins">>},
      409 => #{description => <<"Email already exists">>}
    }
  },
  [ListGet, PostCreate].

-spec admin_schema() -> map().
admin_schema() ->
  #{
    type => object,
    properties => #{
      id          => #{type => string},
      email       => #{type => string, format => <<"email">>},
      role        => #{type => string, enum => [<<"superadmin">>, <<"admin">>, <<"moderator">>, <<"support">>]},
      status      => #{type => string, enum => [<<"active">>, <<"blocked">>]},
      nickname    => #{type => string, nullable => true},
      avatar_url  => #{type => string, nullable => true},
      timezone    => #{type => string, nullable => true},
      language    => #{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">>}
    }
  }.

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

%% @doc GET /v1/admin/admins – список администраторов (доступен всем администраторам).
-spec list_admins(cowboy_req:req()) -> {ok, binary(), cowboy_req:req()}.
list_admins(Req) ->
  case handler_utils:auth_admin(Req) of
    {ok, _AdminId, Req1} ->
      Filters = parse_admin_filters(Req1),
      Pagination = handler_utils:parse_pagination_params(Req1),
      {ok, Total, Admins} = logic_admin:list_admins(Filters, Pagination),
      Json = [handler_utils:admin_to_json(A) || A <- Admins],
      ExtraHeaders = handler_utils:pagination_headers(Pagination, Total),
      handler_utils:send_json(Req1, 200, Json, ExtraHeaders);
    {error, Code, Msg, Req1} ->
      handler_utils:send_error(Req1, Code, Msg)
  end.

%% @doc POST /v1/admin/admins – создание администратора (только суперадмин).
-spec create_admin(cowboy_req:req()) -> {ok, binary(), cowboy_req:req()}.
create_admin(Req) ->
  case handler_utils:is_superadmin(Req) of
    {ok, SuperAdminId, Req1} ->
      {ok, Body, Req2} = cowboy_req:read_body(Req1),
      try jsx:decode(Body, [return_maps]) of
        #{<<"email">> := Email, <<"password">> := Password, <<"role">> := RoleBin} ->
          Role = try binary_to_existing_atom(RoleBin, utf8)
                 catch error:badarg -> undefined
                 end,
          case Role of
            undefined ->
              handler_utils:send_error(Req2, 400, <<"Invalid role">>);
            _ ->
              case logic_admin:create_admin(Email, Password, Role) of
                {ok, Admin} ->
                  % Аудит создания администратора
                  admin_utils:log_admin_action(SuperAdminId, <<"create_admin">>, <<"admin">>, Email, Req2),
                  handler_utils:send_json(Req2, 201, handler_utils:admin_to_json(Admin));
                {error, email_exists} ->
                  handler_utils:send_error(Req2, 409, <<"Email already exists">>);
                {error, invalid_role} ->
                  handler_utils:send_error(Req2, 400, <<"Invalid role">>);
                {error, _} ->
                  handler_utils:send_error(Req2, 500, <<"Internal server error">>)
              end
          end;
        _ ->
          handler_utils:send_error(Req2, 400, <<"Missing fields">>)
      catch
        _:_ -> handler_utils:send_error(Req1, 400, <<"Invalid JSON">>)
      end;
    {error, Code, Msg, Req1} ->
      handler_utils:send_error(Req1, Code, Msg)
  end.

%%%===================================================================
%%% Вспомогательные функции
%%%===================================================================

%% @private Разбор query-параметров для фильтрации.
-spec parse_admin_filters(cowboy_req:req()) -> map().
parse_admin_filters(Req) ->
  Qs = cowboy_req:parse_qs(Req),
  #{
    role   => to_atom(proplists:get_value(<<"role">>, Qs)),
    status => to_atom(proplists:get_value(<<"status">>, Qs)),
    q      => proplists:get_value(<<"q">>, Qs)
  }.

%% @private Безопасное преобразование бинарного значения в атом.
to_atom(undefined) -> undefined;
to_atom(Bin) when is_binary(Bin) ->
  try binary_to_existing_atom(Bin, utf8)
  catch error:badarg -> Bin
  end.