PLT-3105 Files table migration (#4068)

* Implemented initial changes for files table

* Removed *_benchmark_test.go files

* Re-implemented GetPublicFile and added support for old path

* Localization for files table

* Moved file system code into utils package

* Finished server-side changes and added initial upgrade script

* Added getPostFiles api

* Re-add Extension and HasPreviewImage fields to FileInfo

* Removed unused translation

* Fixed merge conflicts left over after permissions changes

* Forced FileInfo.extension to be lower case

* Changed FileUploadResponse to contain the FileInfos instead of FileIds

* Fixed permissions on getFile* calls

* Fixed notifications for file uploads

* Added initial version of client code for files changes

* Permanently added FileIds field to Post object and removed Post.HasFiles

* Updated PostStore.Update to be usable in more circumstances

* Re-added Filenames field and switched file migration to be entirely lazy-loaded

* Increased max listener count for FileStore

* Removed unused fileInfoCache

* Moved file system code back into api

* Removed duplicate test case

* Fixed unit test running on ports other than 8065

* Renamed HasPermissionToPostContext to HasPermissionToChannelByPostContext

* Refactored handleImages to make it more easily understandable

* Renamed getPostFiles to getFileInfosForPost

* Re-added pre-FileIds posts to analytics

* Changed files to be saved as their ids as opposed to id/filename.ext

* Renamed FileInfo.UserId to FileInfo.CreatorId

* Fixed detection of language in CodePreview

* Fixed switching between threads in the RHS not loading new files

* Add serverside protection against a rare bug where the client sends the same file twice for a single post

* Refactored the important parts of uploadFile api call into a function that can be called without a web context

7 files changed, 363 insertions, 112 deletions

diff --git a/model/client.go b/model/client.go
index 1048239be..f9a56b86e 100644
--- a/model/client.go
+++ b/model/client.go
@@ -124,6 +124,10 @@ func (c *Client) GetGeneralRoute() string {
 	return "/general"
 }
 
+func (c *Client) GetFileRoute(fileId string) string {
+	return fmt.Sprintf("/files/%v", fileId)
+}
+
 func (c *Client) DoPost(url, data, contentType string) (*http.Response, *AppError) {
 	rq, _ := http.NewRequest("POST", c.Url+url, strings.NewReader(data))
 	rq.Header.Set("Content-Type", contentType)
@@ -1289,8 +1293,33 @@ func (c *Client) UploadProfileFile(data []byte, contentType string) (*Result, *A
 	return c.uploadFile(c.ApiUrl+"/users/newimage", data, contentType)
 }
 
-func (c *Client) UploadPostAttachment(data []byte, contentType string) (*Result, *AppError) {
-	return c.uploadFile(c.ApiUrl+c.GetTeamRoute()+"/files/upload", data, contentType)
+func (c *Client) UploadPostAttachment(data []byte, channelId string, filename string) (*FileUploadResponse, *AppError) {
+	c.clearExtraProperties()
+
+	body := &bytes.Buffer{}
+	writer := multipart.NewWriter(body)
+
+	if part, err := writer.CreateFormFile("files", filename); err != nil {
+		return nil, NewLocAppError("UploadPostAttachment", "model.client.upload_post_attachment.file.app_error", nil, err.Error())
+	} else if _, err = io.Copy(part, bytes.NewBuffer(data)); err != nil {
+		return nil, NewLocAppError("UploadPostAttachment", "model.client.upload_post_attachment.file.app_error", nil, err.Error())
+	}
+
+	if part, err := writer.CreateFormField("channel_id"); err != nil {
+		return nil, NewLocAppError("UploadPostAttachment", "model.client.upload_post_attachment.channel_id.app_error", nil, err.Error())
+	} else if _, err = io.Copy(part, strings.NewReader(channelId)); err != nil {
+		return nil, NewLocAppError("UploadPostAttachment", "model.client.upload_post_attachment.channel_id.app_error", nil, err.Error())
+	}
+
+	if err := writer.Close(); err != nil {
+		return nil, NewLocAppError("UploadPostAttachment", "model.client.upload_post_attachment.writer.app_error", nil, err.Error())
+	}
+
+	if result, err := c.uploadFile(c.ApiUrl+c.GetTeamRoute()+"/files/upload", body.Bytes(), writer.FormDataContentType()); err != nil {
+		return nil, err
+	} else {
+		return result.Data.(*FileUploadResponse), nil
+	}
 }
 
 func (c *Client) uploadFile(url string, data []byte, contentType string) (*Result, *AppError) {
@@ -1312,55 +1341,51 @@ func (c *Client) uploadFile(url string, data []byte, contentType string) (*Resul
 	}
 }
 
-func (c *Client) GetFile(url string, isFullUrl bool) (*Result, *AppError) {
-	var rq *http.Request
-	if isFullUrl {
-		rq, _ = http.NewRequest("GET", url, nil)
+func (c *Client) GetFile(fileId string) (io.ReadCloser, *AppError) {
+	if r, err := c.DoApiGet(c.GetFileRoute(fileId)+"/get", "", ""); err != nil {
+		return nil, err
 	} else {
-		rq, _ = http.NewRequest("GET", c.ApiUrl+c.GetTeamRoute()+"/files/get"+url, nil)
-	}
-
-	if len(c.AuthToken) > 0 {
-		rq.Header.Set(HEADER_AUTH, "BEARER "+c.AuthToken)
+		c.fillInExtraProperties(r)
+		return r.Body, nil
 	}
+}
 
-	if rp, err := c.HttpClient.Do(rq); err != nil {
-		return nil, NewLocAppError(url, "model.client.connecting.app_error", nil, err.Error())
-	} else if rp.StatusCode >= 300 {
-		return nil, AppErrorFromJson(rp.Body)
+func (c *Client) GetFileThumbnail(fileId string) (io.ReadCloser, *AppError) {
+	if r, err := c.DoApiGet(c.GetFileRoute(fileId)+"/get_thumbnail", "", ""); err != nil {
+		return nil, err
 	} else {
-		defer closeBody(rp)
-		return &Result{rp.Header.Get(HEADER_REQUEST_ID),
-			rp.Header.Get(HEADER_ETAG_SERVER), rp.Body}, nil
+		c.fillInExtraProperties(r)
+		return r.Body, nil
 	}
 }
 
-func (c *Client) GetFileInfo(url string) (*Result, *AppError) {
-	var rq *http.Request
-	rq, _ = http.NewRequest("GET", c.ApiUrl+c.GetTeamRoute()+"/files/get_info"+url, nil)
-
-	if len(c.AuthToken) > 0 {
-		rq.Header.Set(HEADER_AUTH, "BEARER "+c.AuthToken)
+func (c *Client) GetFilePreview(fileId string) (io.ReadCloser, *AppError) {
+	if r, err := c.DoApiGet(c.GetFileRoute(fileId)+"/get_preview", "", ""); err != nil {
+		return nil, err
+	} else {
+		defer closeBody(r)
+		c.fillInExtraProperties(r)
+		return r.Body, nil
 	}
+}
 
-	if rp, err := c.HttpClient.Do(rq); err != nil {
-		return nil, NewLocAppError(url, "model.client.connecting.app_error", nil, err.Error())
-	} else if rp.StatusCode >= 300 {
-		return nil, AppErrorFromJson(rp.Body)
+func (c *Client) GetFileInfo(fileId string) (*FileInfo, *AppError) {
+	if r, err := c.DoApiGet(c.GetFileRoute(fileId)+"/get_info", "", ""); err != nil {
+		return nil, err
 	} else {
-		defer closeBody(rp)
-		return &Result{rp.Header.Get(HEADER_REQUEST_ID),
-			rp.Header.Get(HEADER_ETAG_SERVER), FileInfoFromJson(rp.Body)}, nil
+		defer closeBody(r)
+		c.fillInExtraProperties(r)
+		return FileInfoFromJson(r.Body), nil
 	}
 }
 
-func (c *Client) GetPublicLink(filename string) (*Result, *AppError) {
-	if r, err := c.DoApiPost(c.GetTeamRoute()+"/files/get_public_link", MapToJson(map[string]string{"filename": filename})); err != nil {
-		return nil, err
+func (c *Client) GetPublicLink(fileId string) (string, *AppError) {
+	if r, err := c.DoApiGet(c.GetFileRoute(fileId)+"/get_public_link", "", ""); err != nil {
+		return "", err
 	} else {
 		defer closeBody(r)
-		return &Result{r.Header.Get(HEADER_REQUEST_ID),
-			r.Header.Get(HEADER_ETAG_SERVER), StringFromJson(r.Body)}, nil
+		c.fillInExtraProperties(r)
+		return StringFromJson(r.Body), nil
 	}
 }
 
@@ -1930,3 +1955,17 @@ func (c *Client) GetWebrtcToken() (map[string]string, *AppError) {
 		return MapFromJson(r.Body), nil
 	}
 }
+
+// GetFileInfosForPost returns a list of FileInfo objects for a given post id, if successful.
+// Otherwise, it returns an error.
+func (c *Client) GetFileInfosForPost(channelId string, postId string, etag string) ([]*FileInfo, *AppError) {
+	c.clearExtraProperties()
+
+	if r, err := c.DoApiGet(c.GetChannelRoute(channelId)+fmt.Sprintf("/posts/%v/get_file_infos", postId), "", etag); err != nil {
+		return nil, err
+	} else {
+		defer closeBody(r)
+		c.fillInExtraProperties(r)
+		return FileInfosFromJson(r.Body), nil
+	}
+}
diff --git a/model/compliance_post.go b/model/compliance_post.go
index ce26a3660..027e534b7 100644
--- a/model/compliance_post.go
+++ b/model/compliance_post.go
@@ -34,7 +34,7 @@ type CompliancePost struct {
 	PostType       string
 	PostProps      string
 	PostHashtags   string
-	PostFilenames  string
+	PostFileIds    string
 }
 
 func CompliancePostHeader() []string {
@@ -60,7 +60,7 @@ func CompliancePostHeader() []string {
 		"PostType",
 		"PostProps",
 		"PostHashtags",
-		"PostFilenames",
+		"PostFileIds",
 	}
 }
 
@@ -99,6 +99,6 @@ func (me *CompliancePost) Row() []string {
 		me.PostType,
 		me.PostProps,
 		me.PostHashtags,
-		me.PostFilenames,
+		me.PostFileIds,
 	}
 }
diff --git a/model/compliance_post_test.go b/model/compliance_post_test.go
index 28e20ba4b..49f41a121 100644
--- a/model/compliance_post_test.go
+++ b/model/compliance_post_test.go
@@ -14,7 +14,7 @@ func TestCompliancePostHeader(t *testing.T) {
 }
 
 func TestCompliancePost(t *testing.T) {
-	o := CompliancePost{TeamName: "test", PostFilenames: "files", PostCreateAt: GetMillis()}
+	o := CompliancePost{TeamName: "test", PostFileIds: "files", PostCreateAt: GetMillis()}
 	r := o.Row()
 
 	if r[0] != "test" {
diff --git a/model/file.go b/model/file.go
index fa98a3b3a..c218c4246 100644
--- a/model/file.go
+++ b/model/file.go
@@ -14,8 +14,8 @@ var (
 )
 
 type FileUploadResponse struct {
-	Filenames []string `json:"filenames"`
-	ClientIds []string `json:"client_ids"`
+	FileInfos []*FileInfo `json:"file_infos"`
+	ClientIds []string    `json:"client_ids"`
 }
 
 func FileUploadResponseFromJson(data io.Reader) *FileUploadResponse {
diff --git a/model/file_info.go b/model/file_info.go
index f785042b3..687473d4f 100644
--- a/model/file_info.go
+++ b/model/file_info.go
@@ -6,58 +6,55 @@ package model
 import (
 	"bytes"
 	"encoding/json"
+	"image"
 	"image/gif"
 	"io"
 	"mime"
 	"path/filepath"
+	"strings"
 )
 
 type FileInfo struct {
-	Filename        string `json:"filename"`
-	Size            int    `json:"size"`
+	Id              string `json:"id"`
+	CreatorId       string `json:"user_id"`
+	PostId          string `json:"post_id,omitempty"`
+	CreateAt        int64  `json:"create_at"`
+	UpdateAt        int64  `json:"update_at"`
+	DeleteAt        int64  `json:"delete_at"`
+	Path            string `json:"-"` // not sent back to the client
+	ThumbnailPath   string `json:"-"` // not sent back to the client
+	PreviewPath     string `json:"-"` // not sent back to the client
+	Name            string `json:"name"`
 	Extension       string `json:"extension"`
+	Size            int64  `json:"size"`
 	MimeType        string `json:"mime_type"`
-	HasPreviewImage bool   `json:"has_preview_image"`
+	Width           int    `json:"width,omitempty"`
+	Height          int    `json:"height,omitempty"`
+	HasPreviewImage bool   `json:"has_preview_image,omitempty"`
 }
 
-func GetInfoForBytes(filename string, data []byte) (*FileInfo, *AppError) {
-	size := len(data)
-
-	var mimeType string
-	extension := filepath.Ext(filename)
-	isImage := IsFileExtImage(extension)
-	if isImage {
-		mimeType = GetImageMimeType(extension)
+func (info *FileInfo) ToJson() string {
+	b, err := json.Marshal(info)
+	if err != nil {
+		return ""
 	} else {
-		mimeType = mime.TypeByExtension(extension)
+		return string(b)
 	}
+}
 
-	if extension != "" && extension[0] == '.' {
-		// the client expects a file extension without the leading period
-		extension = extension[1:]
-	}
+func FileInfoFromJson(data io.Reader) *FileInfo {
+	decoder := json.NewDecoder(data)
 
-	hasPreviewImage := isImage
-	if mimeType == "image/gif" {
-		// just show the gif itself instead of a preview image for animated gifs
-		if gifImage, err := gif.DecodeAll(bytes.NewReader(data)); err != nil {
-			return nil, NewLocAppError("GetInfoForBytes", "model.file_info.get.gif.app_error", nil, "filename="+filename)
-		} else {
-			hasPreviewImage = len(gifImage.Image) == 1
-		}
+	var info FileInfo
+	if err := decoder.Decode(&info); err != nil {
+		return nil
+	} else {
+		return &info
 	}
-
-	return &FileInfo{
-		Filename:        filename,
-		Size:            size,
-		Extension:       extension,
-		MimeType:        mimeType,
-		HasPreviewImage: hasPreviewImage,
-	}, nil
 }
 
-func (info *FileInfo) ToJson() string {
-	b, err := json.Marshal(info)
+func FileInfosToJson(infos []*FileInfo) string {
+	b, err := json.Marshal(infos)
 	if err != nil {
 		return ""
 	} else {
@@ -65,13 +62,113 @@ func (info *FileInfo) ToJson() string {
 	}
 }
 
-func FileInfoFromJson(data io.Reader) *FileInfo {
+func FileInfosFromJson(data io.Reader) []*FileInfo {
 	decoder := json.NewDecoder(data)
 
-	var info FileInfo
-	if err := decoder.Decode(&info); err != nil {
+	var infos []*FileInfo
+	if err := decoder.Decode(&infos); err != nil {
 		return nil
 	} else {
-		return &info
+		return infos
+	}
+}
+
+func (o *FileInfo) PreSave() {
+	if o.Id == "" {
+		o.Id = NewId()
+	}
+
+	if o.CreateAt == 0 {
+		o.CreateAt = GetMillis()
+		o.UpdateAt = o.CreateAt
+	}
+}
+
+func (o *FileInfo) IsValid() *AppError {
+	if len(o.Id) != 26 {
+		return NewLocAppError("FileInfo.IsValid", "model.file_info.is_valid.id.app_error", nil, "")
+	}
+
+	if len(o.CreatorId) != 26 {
+		return NewLocAppError("FileInfo.IsValid", "model.file_info.is_valid.user_id.app_error", nil, "id="+o.Id)
+	}
+
+	if len(o.PostId) != 0 && len(o.PostId) != 26 {
+		return NewLocAppError("FileInfo.IsValid", "model.file_info.is_valid.post_id.app_error", nil, "id="+o.Id)
+	}
+
+	if o.CreateAt == 0 {
+		return NewLocAppError("FileInfo.IsValid", "model.file_info.is_valid.create_at.app_error", nil, "id="+o.Id)
+	}
+
+	if o.UpdateAt == 0 {
+		return NewLocAppError("FileInfo.IsValid", "model.file_info.is_valid.update_at.app_error", nil, "id="+o.Id)
+	}
+
+	if o.Path == "" {
+		return NewLocAppError("FileInfo.IsValid", "model.file_info.is_valid.path.app_error", nil, "id="+o.Id)
 	}
+
+	return nil
+}
+
+func (o *FileInfo) IsImage() bool {
+	return strings.HasPrefix(o.MimeType, "image")
+}
+
+func GetInfoForBytes(name string, data []byte) (*FileInfo, *AppError) {
+	info := &FileInfo{
+		Name: name,
+		Size: int64(len(data)),
+	}
+	var err *AppError
+
+	extension := strings.ToLower(filepath.Ext(name))
+	info.MimeType = mime.TypeByExtension(extension)
+
+	if extension != "" && extension[0] == '.' {
+		// 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(bytes.NewReader(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
+				if gifConfig, err := gif.DecodeAll(bytes.NewReader(data)); err != nil {
+					// Still return the rest of the info even though it doesn't appear to be an actual gif
+					info.HasPreviewImage = true
+					err = NewLocAppError("GetInfoForBytes", "model.file_info.get.gif.app_error", nil, "name="+name)
+				} else {
+					info.HasPreviewImage = len(gifConfig.Image) == 1
+				}
+			} else {
+				info.HasPreviewImage = true
+			}
+		}
+	}
+
+	return info, err
+}
+
+func GetEtagForFileInfos(infos []*FileInfo) string {
+	if len(infos) == 0 {
+		return Etag()
+	}
+
+	var maxUpdateAt int64
+
+	for _, info := range infos {
+		if info.UpdateAt > maxUpdateAt {
+			maxUpdateAt = info.UpdateAt
+		}
+	}
+
+	return Etag(infos[0].PostId, maxUpdateAt)
 }
diff --git a/model/file_info_test.go b/model/file_info_test.go
index 90256aed7..d3671f252 100644
--- a/model/file_info_test.go
+++ b/model/file_info_test.go
@@ -5,56 +5,137 @@ package model
 
 import (
 	"encoding/base64"
+	_ "image/gif"
+	_ "image/png"
 	"io/ioutil"
 	"strings"
 	"testing"
 )
 
-func TestGetInfoForBytes(t *testing.T) {
+func TestFileInfoIsValid(t *testing.T) {
+	info := &FileInfo{
+		Id:        NewId(),
+		CreatorId: NewId(),
+		CreateAt:  1234,
+		UpdateAt:  1234,
+		PostId:    "",
+		Path:      "fake/path.png",
+	}
+
+	if err := info.IsValid(); err != nil {
+		t.Fatal(err)
+	}
+
+	info.Id = ""
+	if err := info.IsValid(); err == nil {
+		t.Fatal("empty Id isn't valid")
+	}
+
+	info.Id = NewId()
+	info.CreateAt = 0
+	if err := info.IsValid(); err == nil {
+		t.Fatal("empty CreateAt isn't valid")
+	}
+
+	info.CreateAt = 1234
+	info.UpdateAt = 0
+	if err := info.IsValid(); err == nil {
+		t.Fatal("empty UpdateAt isn't valid")
+	}
+
+	info.UpdateAt = 1234
+	info.PostId = NewId()
+	if err := info.IsValid(); err != nil {
+		t.Fatal(err)
+	}
+
+	info.Path = ""
+	if err := info.IsValid(); err == nil {
+		t.Fatal("empty Path isn't valid")
+	}
+
+	info.Path = "fake/path.png"
+	if err := info.IsValid(); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestFileInfoIsImage(t *testing.T) {
+	info := &FileInfo{
+		MimeType: "image/png",
+	}
+
+	if !info.IsImage() {
+		t.Fatal("file is an image")
+	}
+
+	info.MimeType = "text/plain"
+	if info.IsImage() {
+		t.Fatal("file is not an image")
+	}
+}
+
+func TestGetInfoForFile(t *testing.T) {
 	fakeFile := make([]byte, 1000)
 
 	if info, err := GetInfoForBytes("file.txt", fakeFile); err != nil {
 		t.Fatal(err)
-	} else if info.Filename != "file.txt" {
-		t.Fatalf("Got incorrect filename: %v", info.Filename)
+	} else if info.Name != "file.txt" {
+		t.Fatalf("Got incorrect filename: %v", info.Name)
+	} else if info.Extension != "txt" {
+		t.Fatalf("Got incorrect extension: %v", info.Extension)
 	} else if info.Size != 1000 {
 		t.Fatalf("Got incorrect size: %v", info.Size)
-	} else if info.Extension != "txt" {
-		t.Fatalf("Got incorrect file extension: %v", info.Extension)
 	} else if !strings.HasPrefix(info.MimeType, "text/plain") {
 		t.Fatalf("Got incorrect mime type: %v", info.MimeType)
+	} else if info.Width != 0 {
+		t.Fatalf("Got incorrect width: %v", info.Width)
+	} else if info.Height != 0 {
+		t.Fatalf("Got incorrect height: %v", info.Height)
 	} else if info.HasPreviewImage {
-		t.Fatalf("Got HasPreviewImage = true for non-image file")
+		t.Fatalf("Got incorrect has preview image: %v", info.HasPreviewImage)
 	}
 
-	if info, err := GetInfoForBytes("file.png", fakeFile); err != nil {
+	pngFile, err := ioutil.ReadFile("../tests/test.png")
+	if err != nil {
+		t.Fatalf("Failed to load test.png: %v", err.Error())
+	}
+	if info, err := GetInfoForBytes("test.png", pngFile); err != nil {
 		t.Fatal(err)
-	} else if info.Filename != "file.png" {
-		t.Fatalf("Got incorrect filename: %v", info.Filename)
-	} else if info.Size != 1000 {
-		t.Fatalf("Got incorrect size: %v", info.Size)
+	} else if info.Name != "test.png" {
+		t.Fatalf("Got incorrect filename: %v", info.Name)
 	} else if info.Extension != "png" {
-		t.Fatalf("Got incorrect file extension: %v", info.Extension)
+		t.Fatalf("Got incorrect extension: %v", info.Extension)
+	} else if info.Size != 279591 {
+		t.Fatalf("Got incorrect size: %v", info.Size)
 	} else if info.MimeType != "image/png" {
 		t.Fatalf("Got incorrect mime type: %v", info.MimeType)
+	} else if info.Width != 408 {
+		t.Fatalf("Got incorrect width: %v", info.Width)
+	} else if info.Height != 336 {
+		t.Fatalf("Got incorrect height: %v", info.Height)
 	} else if !info.HasPreviewImage {
-		t.Fatalf("Got HasPreviewImage = false for image")
+		t.Fatalf("Got incorrect has preview image: %v", info.HasPreviewImage)
 	}
 
 	// base 64 encoded version of handtinywhite.gif from http://probablyprogramming.com/2009/03/15/the-tiniest-gif-ever
 	gifFile, _ := base64.StdEncoding.DecodeString("R0lGODlhAQABAIABAP///wAAACwAAAAAAQABAAACAkQBADs=")
 	if info, err := GetInfoForBytes("handtinywhite.gif", gifFile); err != nil {
 		t.Fatal(err)
-	} else if info.Filename != "handtinywhite.gif" {
-		t.Fatalf("Got incorrect filename: %v", info.Filename)
+	} else if info.Name != "handtinywhite.gif" {
+		t.Fatalf("Got incorrect filename: %v", info.Name)
+	} else if info.Extension != "gif" {
+		t.Fatalf("Got incorrect extension: %v", info.Extension)
 	} else if info.Size != 35 {
 		t.Fatalf("Got incorrect size: %v", info.Size)
-	} else if info.Extension != "gif" {
-		t.Fatalf("Got incorrect file extension: %v", info.Extension)
 	} else if info.MimeType != "image/gif" {
 		t.Fatalf("Got incorrect mime type: %v", info.MimeType)
+	} else if info.Width != 1 {
+		t.Fatalf("Got incorrect width: %v", info.Width)
+	} else if info.Height != 1 {
+		t.Fatalf("Got incorrect height: %v", info.Height)
 	} else if !info.HasPreviewImage {
-		t.Fatalf("Got HasPreviewImage = false for static gif")
+		t.Fatalf("Got incorrect has preview image: %v", info.HasPreviewImage)
 	}
 
 	animatedGifFile, err := ioutil.ReadFile("../tests/testgif.gif")
@@ -63,29 +144,57 @@ func TestGetInfoForBytes(t *testing.T) {
 	}
 	if info, err := GetInfoForBytes("testgif.gif", animatedGifFile); err != nil {
 		t.Fatal(err)
-	} else if info.Filename != "testgif.gif" {
-		t.Fatalf("Got incorrect filename: %v", info.Filename)
+	} else if info.Name != "testgif.gif" {
+		t.Fatalf("Got incorrect filename: %v", info.Name)
+	} else if info.Extension != "gif" {
+		t.Fatalf("Got incorrect extension: %v", info.Extension)
 	} else if info.Size != 38689 {
 		t.Fatalf("Got incorrect size: %v", info.Size)
-	} else if info.Extension != "gif" {
-		t.Fatalf("Got incorrect file extension: %v", info.Extension)
 	} else if info.MimeType != "image/gif" {
 		t.Fatalf("Got incorrect mime type: %v", info.MimeType)
+	} else if info.Width != 118 {
+		t.Fatalf("Got incorrect width: %v", info.Width)
+	} else if info.Height != 118 {
+		t.Fatalf("Got incorrect height: %v", info.Height)
 	} else if info.HasPreviewImage {
-		t.Fatalf("Got HasPreviewImage = true for animated gif")
+		t.Fatalf("Got incorrect has preview image: %v", info.HasPreviewImage)
 	}
 
 	if info, err := GetInfoForBytes("filewithoutextension", fakeFile); err != nil {
 		t.Fatal(err)
-	} else if info.Filename != "filewithoutextension" {
-		t.Fatalf("Got incorrect filename: %v", info.Filename)
+	} else if info.Name != "filewithoutextension" {
+		t.Fatalf("Got incorrect filename: %v", info.Name)
+	} else if info.Extension != "" {
+		t.Fatalf("Got incorrect extension: %v", info.Extension)
 	} else if info.Size != 1000 {
 		t.Fatalf("Got incorrect size: %v", info.Size)
-	} else if info.Extension != "" {
-		t.Fatalf("Got incorrect file extension: %v", info.Extension)
 	} else if info.MimeType != "" {
 		t.Fatalf("Got incorrect mime type: %v", info.MimeType)
+	} else if info.Width != 0 {
+		t.Fatalf("Got incorrect width: %v", info.Width)
+	} else if info.Height != 0 {
+		t.Fatalf("Got incorrect height: %v", info.Height)
 	} else if info.HasPreviewImage {
-		t.Fatalf("Got HasPreviewImage = true for non-image file")
+		t.Fatalf("Got incorrect has preview image: %v", info.HasPreviewImage)
+	}
+
+	// Always make the extension lower case to make it easier to use in other places
+	if info, err := GetInfoForBytes("file.TXT", fakeFile); err != nil {
+		t.Fatal(err)
+	} else if info.Name != "file.TXT" {
+		t.Fatalf("Got incorrect filename: %v", info.Name)
+	} else if info.Extension != "txt" {
+		t.Fatalf("Got incorrect extension: %v", info.Extension)
+	}
+
+	// Don't error out for image formats we don't support
+	if info, err := GetInfoForBytes("file.tif", fakeFile); err != nil {
+		t.Fatal(err)
+	} else if info.Name != "file.tif" {
+		t.Fatalf("Got incorrect filename: %v", info.Name)
+	} else if info.Extension != "tif" {
+		t.Fatalf("Got incorrect extension: %v", info.Extension)
+	} else if info.MimeType != "image/tiff" && info.MimeType != "image/x-tiff" {
+		t.Fatalf("Got incorrect mime type: %v", info.MimeType)
 	}
 }
diff --git a/model/post.go b/model/post.go
index 33caeb9ea..da14b650f 100644
--- a/model/post.go
+++ b/model/post.go
@@ -35,7 +35,8 @@ type Post struct {
 	Type          string          `json:"type"`
 	Props         StringInterface `json:"props"`
 	Hashtags      string          `json:"hashtags"`
-	Filenames     StringArray     `json:"filenames"`
+	Filenames     StringArray     `json:"filenames,omitempty"` // Deprecated, do not use this field any more
+	FileIds       StringArray     `json:"file_ids,omitempty"`
 	PendingPostId string          `json:"pending_post_id" db:"-"`
 }
 
@@ -118,6 +119,10 @@ func (o *Post) IsValid() *AppError {
 		return NewLocAppError("Post.IsValid", "model.post.is_valid.filenames.app_error", nil, "id="+o.Id)
 	}
 
+	if utf8.RuneCountInString(ArrayToJson(o.FileIds)) > 150 {
+		return NewLocAppError("Post.IsValid", "model.post.is_valid.file_ids.app_error", nil, "id="+o.Id)
+	}
+
 	if utf8.RuneCountInString(StringInterfaceToJson(o.Props)) > 8000 {
 		return NewLocAppError("Post.IsValid", "model.post.is_valid.props.app_error", nil, "id="+o.Id)
 	}
@@ -145,15 +150,16 @@ func (o *Post) PreSave() {
 	if o.Filenames == nil {
 		o.Filenames = []string{}
 	}
+
+	if o.FileIds == nil {
+		o.FileIds = []string{}
+	}
 }
 
 func (o *Post) MakeNonNil() {
 	if o.Props == nil {
 		o.Props = make(map[string]interface{})
 	}
-	if o.Filenames == nil {
-		o.Filenames = []string{}
-	}
 }
 
 func (o *Post) AddProp(key string, value interface{}) {