Alerting: Rule version history API (#99041)

* implement store method to read rule versions

* implement request handler

* declare a new endpoint

* fix fake to return correct response

* add tests

* add integration tests

* rename history to versions

* apply diff from swagger CI step

Signed-off-by: Yuri Tseretyan <yuriy.tseretyan@grafana.com>

---------

Signed-off-by: Yuri Tseretyan <yuriy.tseretyan@grafana.com>

pkg/services/ngalert/tests/fakes/rules.go

@@ -22,6 +22,7 @@ type RuleStore struct {
 	mtx sync.Mutex
 	// OrgID -> RuleGroup -> Namespace -> Rules
 	Rules       map[int64][]*models.AlertRule
+	History     map[models.AlertRuleKey][]*models.AlertRule
 	Hook        func(cmd any) error // use Hook if you need to intercept some query and return an error
 	RecordedOps []any
 	Folders     map[int64][]*folder.Folder
@@ -40,6 +41,7 @@ func NewRuleStore(t *testing.T) *RuleStore {
 			return nil
 		},
 		Folders: map[int64][]*folder.Folder{},
+		History: map[models.AlertRuleKey][]*models.AlertRule{},
 	}
 }
 
@@ -50,6 +52,8 @@ func (f *RuleStore) PutRule(_ context.Context, rules ...*models.AlertRule) {
 mainloop:
 	for _, r := range rules {
 		rgs := f.Rules[r.OrgID]
+		cp := models.CopyRule(r)
+		f.History[r.GetKey()] = append(f.History[r.GetKey()], cp)
 		for idx, rulePtr := range rgs {
 			if rulePtr.UID == r.UID {
 				rgs[idx] = r
@@ -131,11 +135,7 @@ func (f *RuleStore) GetAlertRuleByUID(_ context.Context, q *models.GetAlertRuleB
 	if err := f.Hook(*q); err != nil {
 		return nil, err
 	}
-	rules, ok := f.Rules[q.OrgID]
-	if !ok {
-		return nil, nil
-	}
-
+	rules := f.Rules[q.OrgID]
 	for _, rule := range rules {
 		if rule.UID == q.UID {
 			return rule, nil
@@ -372,3 +372,22 @@ func (f *RuleStore) GetNamespacesByRuleUID(ctx context.Context, orgID int64, uid
 
 	return namespacesMap, nil
 }
+
+func (f *RuleStore) GetAlertRuleVersions(_ context.Context, key models.AlertRuleKey) ([]*models.AlertRule, error) {
+	f.mtx.Lock()
+	defer f.mtx.Unlock()
+
+	q := GenericRecordedQuery{
+		Name:   "GetAlertRuleVersions",
+		Params: []any{key},
+	}
+	defer func() {
+		f.RecordedOps = append(f.RecordedOps, q)
+	}()
+
+	if err := f.Hook(key); err != nil {
+		return nil, err
+	}
+
+	return f.History[key], nil
+}