Alerting: Reduce cyclomatic complexity of PrepareRuleGroupStatuses (#89649)

* reduce cyclomatic complexity of PrepareRuleGroupStatuses. see https://github.com/grafana/grafana/issues/88670

Signed-off-by: Syed Nihal <syed.nihal@nokia.com>

* reduce cyclomatic complexity for PrepareRuleGroupStatuses in pkg/services/ngalert/api/api_prometheus.go

Signed-off-by: Syed Nihal <syed.nihal@nokia.com>

* reduce cyclomatic complexity for PrepareRuleGroupStatuses in pkg/services/ngalert/api/api_prometheus.go

Signed-off-by: Syed Nihal <syed.nihal@nokia.com>

---------

Signed-off-by: Syed Nihal <syed.nihal@nokia.com>

pkg/services/ngalert/api/api_prometheus.go

@@ -235,9 +235,6 @@ func (srv PrometheusSrv) RouteGetRuleStatuses(c *contextmodel.ReqContext) respon
 	return response.JSON(ruleResponse.HTTPStatusCode(), ruleResponse)
 }
 
-// TODO: Refactor this function to reduce the cylomatic complexity
-//
-//nolint:gocyclo
 func PrepareRuleGroupStatuses(log log.Logger, manager state.AlertInstanceManager, store ListAlertRulesStore, opts RuleGroupStatusesOptions) apimodels.RuleResponse {
 	ruleResponse := apimodels.RuleResponse{
 		DiscoveryBase: apimodels.DiscoveryBase{
@@ -330,28 +327,7 @@ func PrepareRuleGroupStatuses(log log.Logger, manager state.AlertInstanceManager
 		ruleNamesSet[rn] = struct{}{}
 	}
 
-	// Group rules together by Namespace and Rule Group. Rules are also grouped by Org ID,
-	// but in this API all rules belong to the same organization. Also filter by rule name if
-	// it was provided as a query param.
-	groupedRules := make(map[ngmodels.AlertRuleGroupKey][]*ngmodels.AlertRule)
-	for _, rule := range ruleList {
-		if len(ruleNamesSet) > 0 {
-			if _, exists := ruleNamesSet[rule.Title]; !exists {
-				continue
-			}
-		}
-
-		groupKey := rule.GetGroupKey()
-		ruleGroup := groupedRules[groupKey]
-		ruleGroup = append(ruleGroup, rule)
-		groupedRules[groupKey] = ruleGroup
-	}
-	// Sort the rules in each rule group by index. We do this at the end instead of
-	// after each append to avoid having to sort each group multiple times.
-	for _, groupRules := range groupedRules {
-		ngmodels.AlertRulesBy(ngmodels.AlertRulesByIndex).Sort(groupRules)
-	}
-
+	groupedRules := getGroupedRules(ruleList, ruleNamesSet)
 	rulesTotals := make(map[string]int64, len(groupedRules))
 	for groupKey, rules := range groupedRules {
 		folder, ok := opts.Namespaces[groupKey.NamespaceUID]
@@ -377,27 +353,7 @@ func PrepareRuleGroupStatuses(log log.Logger, manager state.AlertInstanceManager
 		}
 
 		if len(withStates) > 0 {
-			// Filtering is weird but firing, pending, and normal filters also need to be
-			// applied to the rule. Others such as nodata and error should have no effect.
-			// This is to match the current behavior in the UI.
-			filteredRules := make([]apimodels.AlertingRule, 0, len(ruleGroup.Rules))
-			for _, rule := range ruleGroup.Rules {
-				var state *eval.State
-				switch rule.State {
-				case "normal", "inactive":
-					state = util.Pointer(eval.Normal)
-				case "alerting", "firing":
-					state = util.Pointer(eval.Alerting)
-				case "pending":
-					state = util.Pointer(eval.Pending)
-				}
-				if state != nil {
-					if _, ok := withStatesFast[*state]; ok {
-						filteredRules = append(filteredRules, rule)
-					}
-				}
-			}
-			ruleGroup.Rules = filteredRules
+			filterRules(ruleGroup, withStatesFast)
 		}
 
 		if limitRulesPerGroup > -1 && int64(len(ruleGroup.Rules)) > limitRulesPerGroup {
@@ -418,6 +374,54 @@ func PrepareRuleGroupStatuses(log log.Logger, manager state.AlertInstanceManager
 	return ruleResponse
 }
 
+func getGroupedRules(ruleList ngmodels.RulesGroup, ruleNamesSet map[string]struct{}) map[ngmodels.AlertRuleGroupKey][]*ngmodels.AlertRule {
+	// Group rules together by Namespace and Rule Group. Rules are also grouped by Org ID,
+	// but in this API all rules belong to the same organization. Also filter by rule name if
+	// it was provided as a query param.
+	groupedRules := make(map[ngmodels.AlertRuleGroupKey][]*ngmodels.AlertRule)
+	for _, rule := range ruleList {
+		if len(ruleNamesSet) > 0 {
+			if _, exists := ruleNamesSet[rule.Title]; !exists {
+				continue
+			}
+		}
+		groupKey := rule.GetGroupKey()
+		ruleGroup := groupedRules[groupKey]
+		ruleGroup = append(ruleGroup, rule)
+		groupedRules[groupKey] = ruleGroup
+	}
+	// Sort the rules in each rule group by index. We do this at the end instead of
+	// after each append to avoid having to sort each group multiple times.
+	for _, groupRules := range groupedRules {
+		ngmodels.AlertRulesBy(ngmodels.AlertRulesByIndex).Sort(groupRules)
+	}
+	return groupedRules
+}
+
+func filterRules(ruleGroup *apimodels.RuleGroup, withStatesFast map[eval.State]struct{}) {
+	// Filtering is weird but firing, pending, and normal filters also need to be
+	// applied to the rule. Others such as nodata and error should have no effect.
+	// This is to match the current behavior in the UI.
+	filteredRules := make([]apimodels.AlertingRule, 0, len(ruleGroup.Rules))
+	for _, rule := range ruleGroup.Rules {
+		var state *eval.State
+		switch rule.State {
+		case "normal", "inactive":
+			state = util.Pointer(eval.Normal)
+		case "alerting", "firing":
+			state = util.Pointer(eval.Alerting)
+		case "pending":
+			state = util.Pointer(eval.Pending)
+		}
+		if state != nil {
+			if _, ok := withStatesFast[*state]; ok {
+				filteredRules = append(filteredRules, rule)
+			}
+		}
+	}
+	ruleGroup.Rules = filteredRules
+}
+
 // This is the same as matchers.Matches but avoids the need to create a LabelSet
 func matchersMatch(matchers []*labels.Matcher, labels map[string]string) bool {
 	for _, m := range matchers {