%%%-------------------------------------------------------------------
%%% @doc Обработчик полнотекстового поиска (клиентский API).
%%%
%%% GET – выполняет поиск по календарям и событиям.
%%% @end
%%%-------------------------------------------------------------------
-module(handler_search).
-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/search">>,
      method      => <<"GET">>,
      description => <<"Search calendars and events. Empty query (auth only) returns discovery tops by rating; use q/tags/geo/from/to for filtered search.">>,
      tags        => [<<"Search">>],
      parameters  => [
        #{name => <<"type">>,  in => <<"query">>, schema => #{type => string, enum => [<<"calendar">>, <<"event">>]}, description => <<"Type of entities to search">>},
        #{name => <<"q">>,     in => <<"query">>, schema => #{type => string}, description => <<"Search query">>},
        #{name => <<"limit">>, in => <<"query">>, schema => #{type => integer}, description => <<"Maximum results per page">>},
        #{name => <<"offset">>, in => <<"query">>, schema => #{type => integer}, description => <<"Offset for pagination">>},
        #{name => <<"tags">>,  in => <<"query">>, schema => #{type => string}, description => <<"Comma-separated tags">>},
        #{name => <<"sort">>,  in => <<"query">>, schema => #{type => string, enum => [<<"start_time">>, <<"created_at">>, <<"title">>]}, description => <<"Field to sort by">>},
        #{name => <<"order">>, in => <<"query">>, schema => #{type => string, enum => [<<"asc">>, <<"desc">>]}, description => <<"Sort order">>},
        #{name => <<"lat">>,   in => <<"query">>, schema => #{type => number, format => float}, description => <<"Latitude for geo search">>},
        #{name => <<"lon">>,   in => <<"query">>, schema => #{type => number, format => float}, description => <<"Longitude for geo search">>},
        #{name => <<"radius">>, in => <<"query">>, schema => #{type => integer}, description => <<"Radius in km for geo search">>},
        #{name => <<"from">>,  in => <<"query">>, schema => #{type => string, format => <<"date-time">>}, description => <<"Start datetime (ISO8601)">>},
        #{name => <<"to">>,    in => <<"query">>, schema => #{type => string, format => <<"date-time">>}, description => <<"End datetime (ISO8601)">>}
      ],
      responses => #{
        200 => #{
          description => <<"Search results with pagination">>,
          content     => #{<<"application/json">> => #{schema => #{
            type       => object,
            properties => #{
              total   => #{type => integer},
              limit   => #{type => integer},
              offset  => #{type => integer},
              results => #{type => array, items => #{type => object}}
            }
          }}}
        },
        400 => #{description => <<"Invalid parameters">>},
        500 => #{description => <<"Search failed">>}
      }
    }
  ].

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

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

%% @doc GET /v1/search — полнотекстовый поиск с фильтрами.
-spec search(cowboy_req:req()) -> {ok, binary(), cowboy_req:req()}.
search(Req) ->
  case handler_utils:auth_user(Req) of
    {ok, UserId, Req1} ->
      Qs = cowboy_req:parse_qs(Req1),
      Type  = proplists:get_value(<<"type">>, Qs, undefined),
      Query = proplists:get_value(<<"q">>, Qs, undefined),
      Params = parse_params(Qs),
      case logic_search:search(Type, Query, UserId, Params) of
        {ok, Total, Results} ->
          Response = #{
            total   => Total,
            limit   => maps:get(limit, Params, 20),
            offset  => maps:get(offset, Params, 0),
            results => Results
          },
          handler_utils:send_json(Req1, 200, Response);
        {error, _} ->
          handler_utils:send_error(Req1, 500, <<"Search failed">>)
      end;
    {error, Code, Message, Req1} ->
      handler_utils:send_error(Req1, Code, Message)
  end.

%%%===================================================================
%%% Внутренние функции
%%%===================================================================

%% @private Собирает карту параметров для поискового движка.
%% Не кладёт sort/tags/geo/даты, если их нет в QS — иначе
%% logic_search:is_discovery_request/2 никогда не сработает (Back#50).
-spec parse_params(cowboy_req:qs()) -> map().
parse_params(Qs) ->
  Params0 = #{
    limit  => parse_int_param(Qs, <<"limit">>, 20),
    offset => parse_int_param(Qs, <<"offset">>, 0)
  },
  Params1 = case proplists:get_value(<<"tags">>, Qs) of
              undefined -> Params0;
              <<>> -> Params0;
              Tags -> Params0#{tags => Tags}
            end,
  Params2 = case proplists:get_value(<<"sort">>, Qs) of
              undefined -> Params1;
              <<>> -> Params1;
              Sort ->
                Order = case proplists:get_value(<<"order">>, Qs) of
                          undefined -> <<"asc">>;
                          <<>> -> <<"asc">>;
                          O -> O
                        end,
                Params1#{sort => Sort, order => Order}
            end,
  Params3 = case {parse_float_param(Qs, <<"lat">>), parse_float_param(Qs, <<"lon">>)} of
              {{ok, Lat}, {ok, Lon}} ->
                Radius = parse_int_param(Qs, <<"radius">>, 10),
                Params2#{lat => Lat, lon => Lon, radius => Radius};
              _ -> Params2
            end,
  case {parse_datetime_param(Qs, <<"from">>), parse_datetime_param(Qs, <<"to">>)} of
    {{ok, From}, {ok, To}} -> Params3#{from => From, to => To};
    {{ok, From}, error}    -> Params3#{from => From};
    {error, {ok, To}}      -> Params3#{to => To};
    _                      -> Params3
  end.

-spec parse_int_param(cowboy_req:qs(), binary(), integer()) -> integer().
parse_int_param(Qs, Key, Default) ->
  handler_utils:parse_int_qs(proplists:get_value(Key, Qs), Default).

-spec parse_float_param(cowboy_req:qs(), binary()) -> {ok, float()} | error.
parse_float_param(Qs, Key) ->
  case proplists:get_value(Key, Qs) of
    undefined -> error;
    Val -> {ok, binary_to_float(Val)}
  end.

-spec parse_datetime_param(cowboy_req:qs(), binary()) -> {ok, calendar:datetime()} | error.
parse_datetime_param(Qs, Key) ->
  case proplists:get_value(Key, Qs) of
    undefined -> error;
    Val -> handler_utils:parse_datetime(Val)
  end.