Add the API for search files (#15605)

* Adding search files api

* Fixing golangci-lint

* Adding bulk-indexing and improving a bit the name indexing for bleve and elasticsearch

* Add content extraction config migration

* Fixing a problem with document extraction

* Unapplying certain changes moved to other PR

* Fixing tests

* Making extract content app migration a private method

* Addressing PR review comments

* Addressing PR review comments

* Adding feature flag

* Removing debug string

* Fixing imports

* Fixing linting errors

* Do not migrate the config if the feature flag is not enabled

* Fix tests

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

app/upload.go

@@ -15,6 +15,7 @@ import (
 	"github.com/mattermost/mattermost-server/v5/mlog"
 	"github.com/mattermost/mattermost-server/v5/model"
 	"github.com/mattermost/mattermost-server/v5/plugin"
+	"github.com/mattermost/mattermost-server/v5/services/docextractor"
 	"github.com/mattermost/mattermost-server/v5/store"
 )
 
@@ -295,6 +296,22 @@ func (a *App) UploadData(us *model.UploadSession, rd io.Reader) (*model.FileInfo
 		}
 	}
 
+	if *a.Config().FileSettings.ExtractContent && a.Config().FeatureFlags.FilesSearch {
+		infoCopy := *info
+		a.Srv().Go(func() {
+			text, err := docextractor.Extract(infoCopy.Name, file, docextractor.ExtractSettings{
+				ArchiveRecursion: *a.Config().FileSettings.ArchiveRecursion,
+			})
+			if err != nil {
+				mlog.Error("Failed to extract file content", mlog.Err(err))
+				return
+			}
+			if storeErr := a.Srv().Store.FileInfo().SetContent(infoCopy.Id, text); storeErr != nil {
+				mlog.Error("Failed to save the extracted file content", mlog.Err(storeErr))
+			}
+		})
+	}
+
 	// delete upload session
 	if storeErr := a.Srv().Store.UploadSession().Delete(us.Id); storeErr != nil {
 		mlog.Warn("Failed to delete UploadSession", mlog.Err(storeErr))