[MM-20979] Add first implementation of the Bleve search engine (#14562)

* [MM-20979] Add first implementation of the Bleve search engine

* Fix i18n

* Migrate searchengine utils tests

* Fix linter

* Don't add allTermsQ if both termQueries and notTermQueries are empty

* Fix test that should work if user is system admin

* Modify naming according to review comments

* Abstract getIndexDir function

* Extracting bleve engine name as a constant

* Merge both Indexer interfaces into one

* Add worker stopped message

* Allow worker to be started/stopped with config change

* Use constants for index names

* Modify test order

* Fix linter

* Trying to unlock the CI

api4/api.go

@@ -86,6 +86,8 @@ type Routes struct {
 
 	Elasticsearch *mux.Router // 'api/v4/elasticsearch'
 
+	Bleve *mux.Router // 'api/v4/bleve'
+
 	DataRetention *mux.Router // 'api/v4/data_retention'
 
 	Brand *mux.Router // 'api/v4/brand'
@@ -198,6 +200,7 @@ func Init(configservice configservice.ConfigService, globalOptionsFunc app.AppOp
 	api.BaseRoutes.Reactions = api.BaseRoutes.ApiRoot.PathPrefix("/reactions").Subrouter()
 	api.BaseRoutes.Jobs = api.BaseRoutes.ApiRoot.PathPrefix("/jobs").Subrouter()
 	api.BaseRoutes.Elasticsearch = api.BaseRoutes.ApiRoot.PathPrefix("/elasticsearch").Subrouter()
+	api.BaseRoutes.Bleve = api.BaseRoutes.ApiRoot.PathPrefix("/bleve").Subrouter()
 	api.BaseRoutes.DataRetention = api.BaseRoutes.ApiRoot.PathPrefix("/data_retention").Subrouter()
 
 	api.BaseRoutes.Emojis = api.BaseRoutes.ApiRoot.PathPrefix("/emoji").Subrouter()
@@ -232,6 +235,7 @@ func Init(configservice configservice.ConfigService, globalOptionsFunc app.AppOp
 	api.InitCluster()
 	api.InitLdap()
 	api.InitElasticsearch()
+	api.InitBleve()
 	api.InitDataRetention()
 	api.InitBrand()
 	api.InitJob()

api4/bleve.go

@@ -0,0 +1,39 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package api4
+
+import (
+	"net/http"
+
+	"github.com/mattermost/mattermost-server/v5/audit"
+	"github.com/mattermost/mattermost-server/v5/model"
+)
+
+func (api *API) InitBleve() {
+	api.BaseRoutes.Bleve.Handle("/purge_indexes", api.ApiSessionRequired(purgeBleveIndexes)).Methods("POST")
+}
+
+func purgeBleveIndexes(c *Context, w http.ResponseWriter, r *http.Request) {
+	auditRec := c.MakeAuditRecord("purgeBleveIndexes", audit.Fail)
+	defer c.LogAuditRec(auditRec)
+
+	if !c.App.SessionHasPermissionTo(*c.App.Session(), model.PERMISSION_MANAGE_SYSTEM) {
+		c.SetPermissionError(model.PERMISSION_MANAGE_SYSTEM)
+		return
+	}
+
+	if *c.App.Config().ExperimentalSettings.RestrictSystemAdmin {
+		c.Err = model.NewAppError("purgeBleveIndexes", "api.restricted_system_admin", nil, "", http.StatusForbidden)
+		return
+	}
+
+	if err := c.App.PurgeBleveIndexes(); err != nil {
+		c.Err = err
+		return
+	}
+
+	auditRec.Success()
+
+	ReturnStatusOK(w)
+}

api4/bleve_test.go

@@ -0,0 +1,32 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package api4
+
+import (
+	"testing"
+
+	"github.com/mattermost/mattermost-server/v5/model"
+)
+
+func TestBlevePurgeIndexes(t *testing.T) {
+	th := Setup(t).InitBasic()
+	defer th.TearDown()
+
+	t.Run("as system user", func(t *testing.T) {
+		_, resp := th.Client.PurgeBleveIndexes()
+		CheckForbiddenStatus(t, resp)
+	})
+
+	t.Run("as system admin", func(t *testing.T) {
+		_, resp := th.SystemAdminClient.PurgeBleveIndexes()
+		CheckOKStatus(t, resp)
+	})
+
+	t.Run("as restricted system admin", func(t *testing.T) {
+		th.App.UpdateConfig(func(cfg *model.Config) { *cfg.ExperimentalSettings.RestrictSystemAdmin = true })
+
+		_, resp := th.SystemAdminClient.PurgeBleveIndexes()
+		CheckForbiddenStatus(t, resp)
+	})
+}