From fc38f63497afd54d557bacec21b6dd10247e2e6e Mon Sep 17 00:00:00 2001
From: Aleksey Sabilin <aleksey@sabilin.com>
Date: Mon, 20 Jul 2026 14:04:56 +0300
Subject: [PATCH] fix: only add search filters present in QS so empty GET hits
 discovery tops. Refs EventHub/EventHubBack#50

---
 src/handlers/handler_search.erl | 44 ++++++++++++++++++++++-----------
 1 file changed, 29 insertions(+), 15 deletions(-)

diff --git a/src/handlers/handler_search.erl b/src/handlers/handler_search.erl
index 022a6ce..4e86691 100644
--- a/src/handlers/handler_search.erl
+++ b/src/handlers/handler_search.erl
@@ -101,28 +101,42 @@ search(Req) ->
 %%%===================================================================
 
 %% @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) ->
-  Params = #{
+  Params0 = #{
     limit  => parse_int_param(Qs, <<"limit">>, 20),
-    offset => parse_int_param(Qs, <<"offset">>, 0),
-    tags   => proplists:get_value(<<"tags">>, Qs),
-    sort   => proplists:get_value(<<"sort">>, Qs, <<"start_time">>),
-    order  => proplists:get_value(<<"order">>, Qs, <<"asc">>)
+    offset => parse_int_param(Qs, <<"offset">>, 0)
   },
-  Params1 = case {parse_float_param(Qs, <<"lat">>), parse_float_param(Qs, <<"lon">>)} of
+  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),
-                Params#{lat => Lat, lon => Lon, radius => Radius};
-              _ -> Params
+                Params2#{lat => Lat, lon => Lon, radius => Radius};
+              _ -> Params2
             end,
-  Params2 = case {parse_datetime_param(Qs, <<"from">>), parse_datetime_param(Qs, <<"to">>)} of
-              {{ok, From}, {ok, To}} -> Params1#{from => From, to => To};
-              {{ok, From}, error}    -> Params1#{from => From};
-              {error, {ok, To}}      -> Params1#{to => To};
-              _                      -> Params1
-            end,
-  Params2.
+  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) ->