refactor: simplify report host lookup for filtered OS results

Use host and hostname values from the result iterator to resolve
the related report host, instead of querying through the result id.

Author: ozgen

src/manage_sql_report_operating_systems.c

@@ -22,33 +22,47 @@
 #include "sql.h"
 
 /**
- * @brief Get the report host for a result.
+ * @brief Get the report host matching result host information.
  *
- * @param[in]  result  Result whose related report host to return.
+ * @param[in]  report    Report containing the result.
+ * @param[in]  host      Host value from the result.
+ * @param[in]  hostname  Hostname value from the result.
  *
  * @return Related report host on success, or 0 if not found.
  */
 static report_host_t
-result_report_host (result_t result)
+result_report_host (report_t report, const char *host, const char *hostname)
 {
-  return sql_int (
-    "SELECT rh.id"
-    " FROM results r"
-    " JOIN report_hosts rh"
-    "   ON rh.report = r.report"
-    "  AND ("
-    "       (COALESCE (r.host, '') <> ''"
-    "        AND rh.host = r.host"
-    "        AND COALESCE (rh.hostname, '') = COALESCE (r.hostname, ''))"
-    "       OR"
-    "       (COALESCE (r.host, '') = ''"
-    "        AND COALESCE (r.hostname, '') <> ''"
-    "        AND COALESCE (rh.hostname, '') = COALESCE (r.hostname, ''))"
-    "      )"
-    " WHERE r.id = $1"
-    " LIMIT 1;",
-    SQL_INT_PARAM (result),
-    NULL);
+  if (report == 0)
+    return 0;
+
+  if (host && *host)
+    {
+      return sql_int_ps (
+        "SELECT id"
+        " FROM report_hosts"
+        " WHERE report = $1"
+        "   AND host = $2"
+        " LIMIT 1;",
+        SQL_RESOURCE_PARAM (report),
+        SQL_STR_PARAM (host),
+        NULL);
+    }
+
+  if (hostname && *hostname)
+    {
+      return sql_int_ps (
+        "SELECT id"
+        " FROM report_hosts"
+        " WHERE report = $1"
+        "   AND hostname = $2"
+        " LIMIT 1;",
+        SQL_RESOURCE_PARAM (report),
+        SQL_STR_PARAM (hostname),
+        NULL);
+    }
+
+  return 0;
 }
 
 /**
@@ -157,11 +171,10 @@ fill_filtered_report_host_ids (GHashTable **report_host_ids,
 
   while (next (results))
     {
-      result_t result;
       report_host_t report_host;
-
-      result = result_iterator_result (results);
-      report_host = result_report_host (result);
+      report_host = result_report_host (report,
+                                        result_iterator_host (results),
+                                        result_iterator_hostname (results));
 
       if (report_host)
         g_hash_table_add (*report_host_ids, GSIZE_TO_POINTER (report_host));