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/api/api_ruler.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"net/http"
 	"slices"
+	"sort"
 	"strings"
 	"time"
 
@@ -330,6 +331,30 @@ func (srv RulerSrv) RouteGetRuleByUID(c *contextmodel.ReqContext, ruleUID string
 	return response.JSON(http.StatusOK, result)
 }
 
+func (srv RulerSrv) RouteGetRuleVersionsByUID(c *contextmodel.ReqContext, ruleUID string) response.Response {
+	ctx := c.Req.Context()
+	// make sure the user has access to the current version of the rule. Also, check if it exists
+	_, err := srv.getAuthorizedRuleByUid(ctx, c, ruleUID)
+	if err != nil {
+		if errors.Is(err, ngmodels.ErrAlertRuleNotFound) {
+			return response.Empty(http.StatusNotFound)
+		}
+		return response.ErrOrFallback(http.StatusInternalServerError, "failed to get rule by UID", err)
+	}
+
+	rules, err := srv.store.GetAlertRuleVersions(ctx, ngmodels.AlertRuleKey{OrgID: c.OrgID, UID: ruleUID})
+	if err != nil {
+		return response.ErrOrFallback(http.StatusInternalServerError, "failed to get rule history", err)
+	}
+	sort.Slice(rules, func(i, j int) bool { return rules[i].ID > rules[j].ID })
+	result := make(apimodels.GettableRuleVersions, 0, len(rules))
+	for _, rule := range rules {
+		// do not provide provenance status because we do not have historical changes for it
+		result = append(result, toGettableExtendedRuleNode(*rule, map[string]ngmodels.Provenance{}, srv.resolveUserIdToNameFn(ctx)))
+	}
+	return response.JSON(http.StatusOK, result)
+}
+
 func (srv RulerSrv) RoutePostNameRulesConfig(c *contextmodel.ReqContext, ruleGroupConfig apimodels.PostableRuleGroupConfig, namespaceUID string) response.Response {
 	namespace, err := srv.store.GetNamespaceByUID(c.Req.Context(), namespaceUID, c.SignedInUser.GetOrgID(), c.SignedInUser)
 	if err != nil {