Rewrite get_trending_topics method to sql

hive/db/schema.py

@@ -769,6 +769,7 @@ def setup_runtime_code(db):
         "postgrest/utilities/list_comments.sql",
         "postgrest/database_api/database_api_list_comments.sql",
         "postgrest/bridge_api/bridge_api_list_subscribers.sql",
+        "postgrest/bridge_api/bridge_api_get_trending_topics.sql",
     ]
 
     sql_scripts_dir_path = Path(__file__).parent / 'sql_scripts'

hive/db/sql_scripts/postgrest/bridge_api/bridge_api_get_trending_topics.sql

@@ -0,0 +1,51 @@
+DROP FUNCTION IF EXISTS hivemind_endpoints.bridge_api_get_trending_topics;
+CREATE FUNCTION hivemind_endpoints.bridge_api_get_trending_topics(IN _json_is_object BOOLEAN, IN _params JSONB)
+RETURNS JSONB
+LANGUAGE 'plpgsql'
+STABLE
+AS
+$$
+DECLARE
+    _limit INTEGER := 10;
+    _observer TEXT;
+    _lowest_community_rank INTEGER := 2147483647; -- MAX INT
+    _fallback_tags_array TEXT[] := ARRAY['food', 'music', 'newsteem', 'crypto', 'gaming', 'travel', 'photography'];
+    result JSONB;
+BEGIN
+    PERFORM hivemind_postgrest_utilities.validate_json_parameters(_json_is_object, _params, '{"limit", "observer"}', '{"number", "string"}');
+
+    _limit := hivemind_postgrest_utilities.parse_integer_argument_from_json(_params, _json_is_object, 'limit', 0, False);
+    _limit := hivemind_postgrest_utilities.valid_number(_limit, 10, 1, 25, 'limit');
+
+    _observer := hivemind_postgrest_utilities.parse_string_argument_from_json(_params, _json_is_object, 'observer', 1, False);
+    PERFORM hivemind_postgrest_utilities.valid_account(_observer, True);
+
+    WITH main_communities AS (
+        SELECT jsonb_build_array(
+                    community_data->>0,
+                    COALESCE(NULLIF(community_data->>1, ''), community_data->>0)
+               ) AS entry,
+               rank
+        FROM (
+            SELECT community_data, rank
+            FROM hivemind_postgrest_utilities.list_top_communities(_limit)
+        ) AS subquery
+    ),
+    fallback_tags AS (
+        SELECT jsonb_build_array(tag, '#' || tag) AS entry,
+               _lowest_community_rank - ROW_NUMBER() OVER (ORDER BY array_position(_fallback_tags_array, tag)) AS rank
+        FROM unnest(_fallback_tags_array) AS tag
+    ),
+    combined_results AS (
+        (
+            SELECT entry, rank FROM main_communities
+            UNION ALL
+            SELECT entry, rank FROM fallback_tags
+        ) ORDER BY rank LIMIT _limit
+    )
+
+    SELECT jsonb_agg(entry ORDER BY rank) INTO result FROM combined_results;
+    RETURN result;
+END
+$$
+;

hive/db/sql_scripts/postgrest/utilities/get_api_method.sql

@@ -129,6 +129,8 @@ BEGIN
       result := hivemind_endpoints.bridge_api_post_notifications(__json_with_params_is_object, __params);
     WHEN __method_type = 'list_subscribers' THEN
       result := hivemind_endpoints.bridge_api_list_subscribers(__json_with_params_is_object, __params);
+    WHEN __method_type = 'get_trending_topics' THEN
+      result := hivemind_endpoints.bridge_api_get_trending_topics(__json_with_params_is_object, __params);
     ELSE
       RAISE EXCEPTION '%', hivemind_postgrest_utilities.raise_method_not_found_exception(__method_type);
   END CASE;