server/public/ -- pre-requisite changes (#23278)

* invert depdendency: filestore -> model

* markdown: nolint:misspell

* inline jsonutils within model

* push model.GetInfoForBytes -> channels/app

* push channel/utils.CompileGo* -> plugin/utils

* push plugin/scheduler -> channels/jobs/plugins

* push utils.Copy(File|Dir) -> model

* oauthproiders/gitlab -> channels/app/oauthproviders/gitlab

* decouple plugin from einterfaces.MetricsInterface

* fix TestGetInfoForFile

* Revert "Run golangci in server CI (#23240)"

This reverts commit 349e5d4573.

* add model/utils

---------

Co-authored-by: Agniva De Sarker <agnivade@yahoo.co.in>

server/channels/app/file_info.go

@@ -0,0 +1,58 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package app
+
+import (
+	"image"
+	"io"
+	"mime"
+	"net/http"
+	"path/filepath"
+	"strings"
+
+	"github.com/mattermost/mattermost-server/server/v8/channels/utils/imgutils"
+	"github.com/mattermost/mattermost-server/server/v8/model"
+)
+
+func getInfoForBytes(name string, data io.ReadSeeker, size int) (*model.FileInfo, *model.AppError) {
+	info := &model.FileInfo{
+		Name: name,
+		Size: int64(size),
+	}
+	var err *model.AppError
+
+	extension := strings.ToLower(filepath.Ext(name))
+	info.MimeType = mime.TypeByExtension(extension)
+
+	if extension != "" {
+		// The client expects a file extension without the leading period
+		info.Extension = extension[1:]
+	} else {
+		info.Extension = extension
+	}
+
+	if info.IsImage() {
+		// Only set the width and height if it's actually an image that we can understand
+		if config, _, err := image.DecodeConfig(data); err == nil {
+			info.Width = config.Width
+			info.Height = config.Height
+
+			if info.MimeType == "image/gif" {
+				// Just show the gif itself instead of a preview image for animated gifs
+				data.Seek(0, io.SeekStart)
+				frameCount, err := imgutils.CountGIFFrames(data)
+				if err != nil {
+					// Still return the rest of the info even though it doesn't appear to be an actual gif
+					info.HasPreviewImage = true
+					return info, model.NewAppError("getInfoForBytes", "app.file_info.get.gif.app_error", nil, "", http.StatusBadRequest).Wrap(err)
+				}
+				info.HasPreviewImage = frameCount == 1
+			} else {
+				info.HasPreviewImage = true
+			}
+		}
+	}
+
+	return info, err
+}