Mono repo -> Master (#22553)

Combines the following repositories into one:

https://github.com/mattermost/mattermost-server
https://github.com/mattermost/mattermost-webapp
https://github.com/mattermost/focalboard
https://github.com/mattermost/mattermost-plugin-playbooks

server/platform/services/docextractor/docextractor.go

@@ -0,0 +1,46 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package docextractor
+
+import (
+	"io"
+)
+
+// ExtractSettings defines the features enabled/disable during the document text extraction.
+type ExtractSettings struct {
+	ArchiveRecursion bool
+	MMPreviewURL     string
+	MMPreviewSecret  string
+}
+
+// Extract extract the text from a document using the system default extractors
+func Extract(filename string, r io.ReadSeeker, settings ExtractSettings) (string, error) {
+	return ExtractWithExtraExtractors(filename, r, settings, []Extractor{})
+}
+
+// ExtractWithExtraExtractors extract the text from a document using the provided extractors beside the system default extractors.
+func ExtractWithExtraExtractors(filename string, r io.ReadSeeker, settings ExtractSettings, extraExtractors []Extractor) (string, error) {
+	enabledExtractors := &combineExtractor{}
+	for _, extraExtractor := range extraExtractors {
+		enabledExtractors.Add(extraExtractor)
+	}
+	enabledExtractors.Add(&documentExtractor{})
+	enabledExtractors.Add(&pdfExtractor{})
+
+	if settings.ArchiveRecursion {
+		enabledExtractors.Add(&archiveExtractor{SubExtractor: enabledExtractors})
+	} else {
+		enabledExtractors.Add(&archiveExtractor{})
+	}
+
+	if settings.MMPreviewURL != "" {
+		enabledExtractors.Add(newMMPreviewExtractor(settings.MMPreviewURL, settings.MMPreviewSecret, pdfExtractor{}))
+	}
+	enabledExtractors.Add(&plainExtractor{})
+
+	if enabledExtractors.Match(filename) {
+		return enabledExtractors.Extract(filename, r)
+	}
+	return "", nil
+}