@@ -3,7 +3,6 @@ // the Telegram Bot API.
 package tgbotapi
 
 import (
-	"bytes"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -12,7 +11,6 @@ "io/ioutil"
 	"mime/multipart"
 	"net/http"
 	"net/url"
-	"os"
 	"strings"
 	"time"
 )
@@ -180,54 +178,37 @@ }
 		}
 
 		for _, file := range files {
-			switch f := file.File.(type) {
-			case string:
-				fileHandle, err := os.Open(f)
+			if file.Data.NeedsUpload() {
+				name, reader, err := file.Data.UploadData()
 				if err != nil {
 					w.CloseWithError(err)
 					return
 				}
-				defer fileHandle.Close()
 
-				part, err := m.CreateFormFile(file.Name, fileHandle.Name())
+				part, err := m.CreateFormFile(file.Name, name)
 				if err != nil {
 					w.CloseWithError(err)
 					return
 				}
 
-				io.Copy(part, fileHandle)
-			case FileBytes:
-				part, err := m.CreateFormFile(file.Name, f.Name)
-				if err != nil {
+				if _, err := io.Copy(part, reader); err != nil {
 					w.CloseWithError(err)
 					return
 				}
 
-				buf := bytes.NewBuffer(f.Bytes)
-				io.Copy(part, buf)
-			case FileReader:
-				part, err := m.CreateFormFile(file.Name, f.Name)
-				if err != nil {
-					w.CloseWithError(err)
-					return
+				if closer, ok := reader.(io.ReadCloser); ok {
+					if err = closer.Close(); err != nil {
+						w.CloseWithError(err)
+						return
+					}
 				}
+			} else {
+				value := file.Data.SendData()
 
-				io.Copy(part, f.Reader)
-			case FileURL:
-				val := string(f)
-				if err := m.WriteField(file.Name, val); err != nil {
+				if err := m.WriteField(file.Name, value); err != nil {
 					w.CloseWithError(err)
 					return
 				}
-			case FileID:
-				val := string(f)
-				if err := m.WriteField(file.Name, val); err != nil {
-					w.CloseWithError(err)
-					return
-				}
-			default:
-				w.CloseWithError(errors.New(ErrBadFileType))
-				return
 			}
 		}
 	}()
@@ -316,8 +297,7 @@ }
 
 func hasFilesNeedingUpload(files []RequestFile) bool {
 	for _, file := range files {
-		switch file.File.(type) {
-		case string, FileBytes, FileReader:
+		if file.Data.NeedsUpload() {
 			return true
 		}
 	}
@@ -344,20 +324,7 @@
 		// However, if there are no files to be uploaded, there's likely things
 		// that need to be turned into params instead.
 		for _, file := range files {
-			var s string
-
-			switch f := file.File.(type) {
-			case string:
-				s = f
-			case FileID:
-				s = string(f)
-			case FileURL:
-				s = string(f)
-			default:
-				return nil, errors.New(ErrBadFileType)
-			}
-
-			params[file.Name] = s
+			params[file.Name] = file.Data.SendData()
 		}
 	}
 

@@ -127,7 +127,7 @@
 func TestSendWithNewPhoto(t *testing.T) {
 	bot, _ := getBot(t)
 
-	msg := NewPhoto(ChatID, "tests/image.jpg")
+	msg := NewPhoto(ChatID, FilePath("tests/image.jpg"))
 	msg.Caption = "Test"
 	_, err := bot.Send(msg)
 
@@ -169,7 +169,7 @@
 func TestSendWithNewPhotoReply(t *testing.T) {
 	bot, _ := getBot(t)
 
-	msg := NewPhoto(ChatID, "tests/image.jpg")
+	msg := NewPhoto(ChatID, FilePath("tests/image.jpg"))
 	msg.ReplyToMessageID = ReplyToMessageID
 
 	_, err := bot.Send(msg)
@@ -182,7 +182,7 @@
 func TestSendNewPhotoToChannel(t *testing.T) {
 	bot, _ := getBot(t)
 
-	msg := NewPhotoToChannel(Channel, "tests/image.jpg")
+	msg := NewPhotoToChannel(Channel, FilePath("tests/image.jpg"))
 	msg.Caption = "Test"
 	_, err := bot.Send(msg)
 
@@ -239,7 +239,7 @@
 func TestSendWithNewDocument(t *testing.T) {
 	bot, _ := getBot(t)
 
-	msg := NewDocument(ChatID, "tests/image.jpg")
+	msg := NewDocument(ChatID, FilePath("tests/image.jpg"))
 	_, err := bot.Send(msg)
 
 	if err != nil {
@@ -250,8 +250,8 @@
 func TestSendWithNewDocumentAndThumb(t *testing.T) {
 	bot, _ := getBot(t)
 
-	msg := NewDocument(ChatID, "tests/voice.ogg")
-	msg.Thumb = "tests/image.jpg"
+	msg := NewDocument(ChatID, FilePath("tests/voice.ogg"))
+	msg.Thumb = FilePath("tests/image.jpg")
 	_, err := bot.Send(msg)
 
 	if err != nil {
@@ -273,7 +273,7 @@
 func TestSendWithNewAudio(t *testing.T) {
 	bot, _ := getBot(t)
 
-	msg := NewAudio(ChatID, "tests/audio.mp3")
+	msg := NewAudio(ChatID, FilePath("tests/audio.mp3"))
 	msg.Title = "TEST"
 	msg.Duration = 10
 	msg.Performer = "TEST"
@@ -302,7 +302,7 @@
 func TestSendWithNewVoice(t *testing.T) {
 	bot, _ := getBot(t)
 
-	msg := NewVoice(ChatID, "tests/voice.ogg")
+	msg := NewVoice(ChatID, FilePath("tests/voice.ogg"))
 	msg.Duration = 10
 	_, err := bot.Send(msg)
 
@@ -356,7 +356,7 @@
 func TestSendWithNewVideo(t *testing.T) {
 	bot, _ := getBot(t)
 
-	msg := NewVideo(ChatID, "tests/video.mp4")
+	msg := NewVideo(ChatID, FilePath("tests/video.mp4"))
 	msg.Duration = 10
 	msg.Caption = "TEST"
 
@@ -384,7 +384,7 @@
 func TestSendWithNewVideoNote(t *testing.T) {
 	bot, _ := getBot(t)
 
-	msg := NewVideoNote(ChatID, 240, "tests/videonote.mp4")
+	msg := NewVideoNote(ChatID, 240, FilePath("tests/videonote.mp4"))
 	msg.Duration = 10
 
 	_, err := bot.Send(msg)
@@ -410,7 +410,7 @@
 func TestSendWithNewSticker(t *testing.T) {
 	bot, _ := getBot(t)
 
-	msg := NewSticker(ChatID, "tests/image.jpg")
+	msg := NewSticker(ChatID, FilePath("tests/image.jpg"))
 
 	_, err := bot.Send(msg)
 
@@ -434,7 +434,7 @@
 func TestSendWithNewStickerAndKeyboardHide(t *testing.T) {
 	bot, _ := getBot(t)
 
-	msg := NewSticker(ChatID, "tests/image.jpg")
+	msg := NewSticker(ChatID, FilePath("tests/image.jpg"))
 	msg.ReplyMarkup = ReplyKeyboardRemove{
 		RemoveKeyboard: true,
 		Selective:      false,
@@ -550,7 +550,7 @@ time.Sleep(time.Second * 2)
 
 	bot.Request(DeleteWebhookConfig{})
 
-	wh, err := NewWebhookWithCert("https://example.com/tgbotapi-test/"+bot.Token, "tests/cert.pem")
+	wh, err := NewWebhookWithCert("https://example.com/tgbotapi-test/"+bot.Token, FilePath("tests/cert.pem"))
 
 	if err != nil {
 		t.Error(err)
@@ -609,8 +609,8 @@ bot, _ := getBot(t)
 
 	cfg := NewMediaGroup(ChatID, []interface{}{
 		NewInputMediaPhoto(FileURL("https://github.com/go-telegram-bot-api/telegram-bot-api/raw/0a3a1c8716c4cd8d26a262af9f12dcbab7f3f28c/tests/image.jpg")),
-		NewInputMediaPhoto("tests/image.jpg"),
-		NewInputMediaVideo("tests/video.mp4"),
+		NewInputMediaPhoto(FilePath("tests/image.jpg")),
+		NewInputMediaVideo(FilePath("tests/video.mp4")),
 	})
 
 	messages, err := bot.SendMediaGroup(cfg)
@@ -632,7 +632,7 @@ bot, _ := getBot(t)
 
 	cfg := NewMediaGroup(ChatID, []interface{}{
 		NewInputMediaDocument(FileURL("https://i.imgur.com/unQLJIb.jpg")),
-		NewInputMediaDocument("tests/image.jpg"),
+		NewInputMediaDocument(FilePath("tests/image.jpg")),
 	})
 
 	messages, err := bot.SendMediaGroup(cfg)
@@ -653,8 +653,8 @@ func TestSendWithMediaGroupAudio(t *testing.T) {
 	bot, _ := getBot(t)
 
 	cfg := NewMediaGroup(ChatID, []interface{}{
-		NewInputMediaAudio("tests/audio.mp3"),
-		NewInputMediaAudio("tests/audio.mp3"),
+		NewInputMediaAudio(FilePath("tests/audio.mp3")),
+		NewInputMediaAudio(FilePath("tests/audio.mp3")),
 	})
 
 	messages, err := bot.SendMediaGroup(cfg)
@@ -715,7 +715,7 @@ bot.Debug = true
 
 	log.Printf("Authorized on account %s", bot.Self.UserName)
 
-	wh, err := NewWebhookWithCert("https://www.google.com:8443/"+bot.Token, "cert.pem")
+	wh, err := NewWebhookWithCert("https://www.google.com:8443/"+bot.Token, FilePath("cert.pem"))
 
 	if err != nil {
 		panic(err)
@@ -755,7 +755,7 @@ bot.Debug = true
 
 	log.Printf("Authorized on account %s", bot.Self.UserName)
 
-	wh, err := NewWebhookWithCert("https://www.google.com:8443/"+bot.Token, "cert.pem")
+	wh, err := NewWebhookWithCert("https://www.google.com:8443/"+bot.Token, FilePath("cert.pem"))
 
 	if err != nil {
 		panic(err)
@@ -1004,7 +1004,7 @@
 func TestEditMessageMedia(t *testing.T) {
 	bot, _ := getBot(t)
 
-	msg := NewPhoto(ChatID, "tests/image.jpg")
+	msg := NewPhoto(ChatID, FilePath("tests/image.jpg"))
 	msg.Caption = "Test"
 	m, err := bot.Send(msg)
 
@@ -1017,7 +1017,7 @@ BaseEdit: BaseEdit{
 			ChatID:    ChatID,
 			MessageID: m.MessageID,
 		},
-		Media: NewInputMediaVideo("tests/video.mp4"),
+		Media: NewInputMediaVideo(FilePath("tests/video.mp4")),
 	}
 
 	_, err = bot.Request(edit)
@@ -1028,17 +1028,17 @@ }
 
 func TestPrepareInputMediaForParams(t *testing.T) {
 	media := []interface{}{
-		NewInputMediaPhoto("tests/image.jpg"),
+		NewInputMediaPhoto(FilePath("tests/image.jpg")),
 		NewInputMediaVideo(FileID("test")),
 	}
 
 	prepared := prepareInputMediaForParams(media)
 
-	if media[0].(InputMediaPhoto).Media != "tests/image.jpg" {
+	if media[0].(InputMediaPhoto).Media != FilePath("tests/image.jpg") {
 		t.Error("Original media was changed")
 	}
 
-	if prepared[0].(InputMediaPhoto).Media != "attach://file-0" {
+	if prepared[0].(InputMediaPhoto).Media != FileID("attach://file-0") {
 		t.Error("New media was not replaced")
 	}
 

@@ -1,9 +1,11 @@
 package tgbotapi
 
 import (
+	"bytes"
 	"fmt"
 	"io"
 	"net/url"
+	"os"
 	"strconv"
 )
 
@@ -97,9 +99,7 @@ )
 
 // Library errors
 const (
-	// ErrBadFileType happens when you pass an unknown type
-	ErrBadFileType = "bad file type"
-	ErrBadURL      = "bad or empty url"
+	ErrBadURL = "bad or empty url"
 )
 
 // Chattable is any config type that can be sent.
@@ -108,19 +108,134 @@ params() (Params, error)
 	method() string
 }
 
-// RequestFile represents a file associated with a request. May involve
-// uploading a file, or passing an existing ID.
+// Fileable is any config type that can be sent that includes a file.
+type Fileable interface {
+	Chattable
+	files() []RequestFile
+}
+
+// RequestFile represents a file associated with a field name.
 type RequestFile struct {
-	// The multipart upload field name.
+	// The file field name.
 	Name string
-	// The file to upload.
-	File interface{}
+	// The file data to include.
+	Data RequestFileData
+}
+
+// RequestFileData represents the data to be used for a file.
+type RequestFileData interface {
+	// If the file needs to be uploaded.
+	NeedsUpload() bool
+
+	// Get the file name and an `io.Reader` for the file to be uploaded. This
+	// must only be called when the file needs to be uploaded.
+	UploadData() (string, io.Reader, error)
+	// Get the file data to send when a file does not need to be uploaded. This
+	// must only be called when the file does not need to be uploaded.
+	SendData() string
+}
+
+// FileBytes contains information about a set of bytes to upload
+// as a File.
+type FileBytes struct {
+	Name  string
+	Bytes []byte
+}
+
+func (fb FileBytes) NeedsUpload() bool {
+	return true
+}
+
+func (fb FileBytes) UploadData() (string, io.Reader, error) {
+	return fb.Name, bytes.NewReader(fb.Bytes), nil
+}
+
+func (fb FileBytes) SendData() string {
+	panic("FileBytes must be uploaded")
+}
+
+// FileReader contains information about a reader to upload as a File.
+type FileReader struct {
+	Name   string
+	Reader io.Reader
+}
+
+func (fr FileReader) NeedsUpload() bool {
+	return true
+}
+
+func (fr FileReader) UploadData() (string, io.Reader, error) {
+	return fr.Name, fr.Reader, nil
+}
+
+func (fr FileReader) SendData() string {
+	panic("FileReader must be uploaded")
+}
+
+// FilePath is a path to a local file.
+type FilePath string
+
+func (fp FilePath) NeedsUpload() bool {
+	return true
+}
+
+func (fp FilePath) UploadData() (string, io.Reader, error) {
+	fileHandle, err := os.Open(string(fp))
+	if err != nil {
+		return "", nil, err
+	}
+
+	name := fileHandle.Name()
+	return name, fileHandle, err
 }
 
-// Fileable is any config type that can be sent that includes a file.
-type Fileable interface {
-	Chattable
-	files() []RequestFile
+func (fp FilePath) SendData() string {
+	panic("FilePath must be uploaded")
+}
+
+// FileURL is a URL to use as a file for a request.
+type FileURL string
+
+func (fu FileURL) NeedsUpload() bool {
+	return false
+}
+
+func (fu FileURL) UploadData() (string, io.Reader, error) {
+	panic("FileURL cannot be uploaded")
+}
+
+func (fu FileURL) SendData() string {
+	return string(fu)
+}
+
+// FileID is an ID of a file already uploaded to Telegram.
+type FileID string
+
+func (fi FileID) NeedsUpload() bool {
+	return false
+}
+
+func (fi FileID) UploadData() (string, io.Reader, error) {
+	panic("FileID cannot be uploaded")
+}
+
+func (fi FileID) SendData() string {
+	return string(fi)
+}
+
+// fileAttach is a internal file type used for processed media groups.
+type fileAttach string
+
+func (fa fileAttach) NeedsUpload() bool {
+	return false
+}
+
+func (fa fileAttach) UploadData() (string, io.Reader, error) {
+	panic("fileAttach cannot be uploaded")
+}
+
+func (fa fileAttach) SendData() string {
+	return string(fa)
 }
 
 // LogOutConfig is a request to log out of the cloud Bot API server.
@@ -176,7 +291,7 @@
 // BaseFile is a base type for all file config types.
 type BaseFile struct {
 	BaseChat
-	File interface{}
+	File RequestFileData
 }
 
 func (file BaseFile) params() (Params, error) {
@@ -291,7 +406,7 @@
 // PhotoConfig contains information about a SendPhoto request.
 type PhotoConfig struct {
 	BaseFile
-	Thumb           interface{}
+	Thumb           RequestFileData
 	Caption         string
 	ParseMode       string
 	CaptionEntities []MessageEntity
@@ -317,13 +432,13 @@
 func (config PhotoConfig) files() []RequestFile {
 	files := []RequestFile{{
 		Name: "photo",
-		File: config.File,
+		Data: config.File,
 	}}
 
 	if config.Thumb != nil {
 		files = append(files, RequestFile{
 			Name: "thumb",
-			File: config.Thumb,
+			Data: config.Thumb,
 		})
 	}
 
@@ -333,7 +448,7 @@
 // AudioConfig contains information about a SendAudio request.
 type AudioConfig struct {
 	BaseFile
-	Thumb           interface{}
+	Thumb           RequestFileData
 	Caption         string
 	ParseMode       string
 	CaptionEntities []MessageEntity
@@ -365,13 +480,13 @@
 func (config AudioConfig) files() []RequestFile {
 	files := []RequestFile{{
 		Name: "audio",
-		File: config.File,
+		Data: config.File,
 	}}
 
 	if config.Thumb != nil {
 		files = append(files, RequestFile{
 			Name: "thumb",
-			File: config.Thumb,
+			Data: config.Thumb,
 		})
 	}
 
@@ -381,7 +496,7 @@
 // DocumentConfig contains information about a SendDocument request.
 type DocumentConfig struct {
 	BaseFile
-	Thumb                       interface{}
+	Thumb                       RequestFileData
 	Caption                     string
 	ParseMode                   string
 	CaptionEntities             []MessageEntity
@@ -405,13 +520,13 @@
 func (config DocumentConfig) files() []RequestFile {
 	files := []RequestFile{{
 		Name: "document",
-		File: config.File,
+		Data: config.File,
 	}}
 
 	if config.Thumb != nil {
 		files = append(files, RequestFile{
 			Name: "thumb",
-			File: config.Thumb,
+			Data: config.Thumb,
 		})
 	}
 
@@ -434,14 +549,14 @@
 func (config StickerConfig) files() []RequestFile {
 	return []RequestFile{{
 		Name: "sticker",
-		File: config.File,
+		Data: config.File,
 	}}
 }
 
 // VideoConfig contains information about a SendVideo request.
 type VideoConfig struct {
 	BaseFile
-	Thumb             interface{}
+	Thumb             RequestFileData
 	Duration          int
 	Caption           string
 	ParseMode         string
@@ -471,13 +586,13 @@
 func (config VideoConfig) files() []RequestFile {
 	files := []RequestFile{{
 		Name: "video",
-		File: config.File,
+		Data: config.File,
 	}}
 
 	if config.Thumb != nil {
 		files = append(files, RequestFile{
 			Name: "thumb",
-			File: config.Thumb,
+			Data: config.Thumb,
 		})
 	}
 
@@ -488,7 +603,7 @@ // AnimationConfig contains information about a SendAnimation request.
 type AnimationConfig struct {
 	BaseFile
 	Duration        int
-	Thumb           interface{}
+	Thumb           RequestFileData
 	Caption         string
 	ParseMode       string
 	CaptionEntities []MessageEntity
@@ -515,13 +630,13 @@
 func (config AnimationConfig) files() []RequestFile {
 	files := []RequestFile{{
 		Name: "animation",
-		File: config.File,
+		Data: config.File,
 	}}
 
 	if config.Thumb != nil {
 		files = append(files, RequestFile{
 			Name: "thumb",
-			File: config.Thumb,
+			Data: config.Thumb,
 		})
 	}
 
@@ -531,7 +646,7 @@
 // VideoNoteConfig contains information about a SendVideoNote request.
 type VideoNoteConfig struct {
 	BaseFile
-	Thumb    interface{}
+	Thumb    RequestFileData
 	Duration int
 	Length   int
 }
@@ -552,13 +667,13 @@
 func (config VideoNoteConfig) files() []RequestFile {
 	files := []RequestFile{{
 		Name: "video_note",
-		File: config.File,
+		Data: config.File,
 	}}
 
 	if config.Thumb != nil {
 		files = append(files, RequestFile{
 			Name: "thumb",
-			File: config.Thumb,
+			Data: config.Thumb,
 		})
 	}
 
@@ -568,7 +683,7 @@
 // VoiceConfig contains information about a SendVoice request.
 type VoiceConfig struct {
 	BaseFile
-	Thumb           interface{}
+	Thumb           RequestFileData
 	Caption         string
 	ParseMode       string
 	CaptionEntities []MessageEntity
@@ -596,13 +711,13 @@
 func (config VoiceConfig) files() []RequestFile {
 	files := []RequestFile{{
 		Name: "voice",
-		File: config.File,
+		Data: config.File,
 	}}
 
 	if config.Thumb != nil {
 		files = append(files, RequestFile{
 			Name: "thumb",
-			File: config.Thumb,
+			Data: config.Thumb,
 		})
 	}
 
@@ -1045,7 +1160,7 @@
 // WebhookConfig contains information about a SetWebhook request.
 type WebhookConfig struct {
 	URL                *url.URL
-	Certificate        interface{}
+	Certificate        RequestFileData
 	IPAddress          string
 	MaxConnections     int
 	AllowedUpdates     []string
@@ -1075,7 +1190,7 @@ func (config WebhookConfig) files() []RequestFile {
 	if config.Certificate != nil {
 		return []RequestFile{{
 			Name: "certificate",
-			File: config.Certificate,
+			Data: config.Certificate,
 		}}
 	}
 
@@ -1099,25 +1214,6 @@
 	return params, nil
 }
 
-// FileBytes contains information about a set of bytes to upload
-// as a File.
-type FileBytes struct {
-	Name  string
-	Bytes []byte
-}
-
-// FileReader contains information about a reader to upload as a File.
-type FileReader struct {
-	Name   string
-	Reader io.Reader
-}
-
-// FileURL is a URL to use as a file for a request.
-type FileURL string
-
-// FileID is an ID of a file already uploaded to Telegram.
-type FileID string
-
 // InlineConfig contains information on making an InlineQuery response.
 type InlineConfig struct {
 	InlineQueryID     string        `json:"inline_query_id"`
@@ -1706,7 +1802,7 @@
 func (config SetChatPhotoConfig) files() []RequestFile {
 	return []RequestFile{{
 		Name: "photo",
-		File: config.File,
+		Data: config.File,
 	}}
 }
 
@@ -1790,7 +1886,7 @@
 // UploadStickerConfig allows you to upload a sticker for use in a set later.
 type UploadStickerConfig struct {
 	UserID     int64
-	PNGSticker interface{}
+	PNGSticker RequestFileData
 }
 
 func (config UploadStickerConfig) method() string {
@@ -1808,7 +1904,7 @@
 func (config UploadStickerConfig) files() []RequestFile {
 	return []RequestFile{{
 		Name: "png_sticker",
-		File: config.PNGSticker,
+		Data: config.PNGSticker,
 	}}
 }
 
@@ -1819,8 +1915,8 @@ type NewStickerSetConfig struct {
 	UserID        int64
 	Name          string
 	Title         string
-	PNGSticker    interface{}
-	TGSSticker    interface{}
+	PNGSticker    RequestFileData
+	TGSSticker    RequestFileData
 	Emojis        string
 	ContainsMasks bool
 	MaskPosition  *MaskPosition
@@ -1850,13 +1946,13 @@ func (config NewStickerSetConfig) files() []RequestFile {
 	if config.PNGSticker != nil {
 		return []RequestFile{{
 			Name: "png_sticker",
-			File: config.PNGSticker,
+			Data: config.PNGSticker,
 		}}
 	}
 
 	return []RequestFile{{
 		Name: "tgs_sticker",
-		File: config.TGSSticker,
+		Data: config.TGSSticker,
 	}}
 }
 
@@ -1864,8 +1960,8 @@ // AddStickerConfig allows you to add a sticker to a set.
 type AddStickerConfig struct {
 	UserID       int64
 	Name         string
-	PNGSticker   interface{}
-	TGSSticker   interface{}
+	PNGSticker   RequestFileData
+	TGSSticker   RequestFileData
 	Emojis       string
 	MaskPosition *MaskPosition
 }
@@ -1890,13 +1986,13 @@ func (config AddStickerConfig) files() []RequestFile {
 	if config.PNGSticker != nil {
 		return []RequestFile{{
 			Name: "png_sticker",
-			File: config.PNGSticker,
+			Data: config.PNGSticker,
 		}}
 	}
 
 	return []RequestFile{{
 		Name: "tgs_sticker",
-		File: config.TGSSticker,
+		Data: config.TGSSticker,
 	}}
 
 }
@@ -1941,7 +2037,7 @@ // SetStickerSetThumbConfig allows you to set the thumbnail for a sticker set.
 type SetStickerSetThumbConfig struct {
 	Name   string
 	UserID int64
-	Thumb  interface{}
+	Thumb  RequestFileData
 }
 
 func (config SetStickerSetThumbConfig) method() string {
@@ -1960,7 +2056,7 @@
 func (config SetStickerSetThumbConfig) files() []RequestFile {
 	return []RequestFile{{
 		Name: "thumb",
-		File: config.Thumb,
+		Data: config.Thumb,
 	}}
 }
 
@@ -2134,45 +2230,38 @@ // It is expected to be used in conjunction with prepareInputMediaFile.
 func prepareInputMediaParam(inputMedia interface{}, idx int) interface{} {
 	switch m := inputMedia.(type) {
 	case InputMediaPhoto:
-		switch m.Media.(type) {
-		case string, FileBytes, FileReader:
-			m.Media = fmt.Sprintf("attach://file-%d", idx)
+		if m.Media.NeedsUpload() {
+			m.Media = fileAttach(fmt.Sprintf("attach://file-%d", idx))
 		}
 
 		return m
 	case InputMediaVideo:
-		switch m.Media.(type) {
-		case string, FileBytes, FileReader:
-			m.Media = fmt.Sprintf("attach://file-%d", idx)
+		if m.Media.NeedsUpload() {
+			m.Media = fileAttach(fmt.Sprintf("attach://file-%d", idx))
 		}
 
-		switch m.Thumb.(type) {
-		case string, FileBytes, FileReader:
-			m.Thumb = fmt.Sprintf("attach://file-%d-thumb", idx)
+		if m.Thumb != nil && m.Thumb.NeedsUpload() {
+			m.Thumb = fileAttach(fmt.Sprintf("attach://file-%d-thumb", idx))
 		}
 
 		return m
 	case InputMediaAudio:
-		switch m.Media.(type) {
-		case string, FileBytes, FileReader:
-			m.Media = fmt.Sprintf("attach://file-%d", idx)
+		if m.Media.NeedsUpload() {
+			m.Media = fileAttach(fmt.Sprintf("attach://file-%d", idx))
 		}
 
-		switch m.Thumb.(type) {
-		case string, FileBytes, FileReader:
-			m.Thumb = fmt.Sprintf("attach://file-%d-thumb", idx)
+		if m.Thumb != nil && m.Thumb.NeedsUpload() {
+			m.Thumb = fileAttach(fmt.Sprintf("attach://file-%d-thumb", idx))
 		}
 
 		return m
 	case InputMediaDocument:
-		switch m.Media.(type) {
-		case string, FileBytes, FileReader:
-			m.Media = fmt.Sprintf("attach://file-%d", idx)
+		if m.Media.NeedsUpload() {
+			m.Media = fileAttach(fmt.Sprintf("attach://file-%d", idx))
 		}
 
-		switch m.Thumb.(type) {
-		case string, FileBytes, FileReader:
-			m.Thumb = fmt.Sprintf("attach://file-%d-thumb", idx)
+		if m.Thumb != nil && m.Thumb.NeedsUpload() {
+			m.Thumb = fileAttach(fmt.Sprintf("attach://file-%d-thumb", idx))
 		}
 
 		return m
@@ -2194,59 +2283,52 @@ files := []RequestFile{}
 
 	switch m := inputMedia.(type) {
 	case InputMediaPhoto:
-		switch f := m.Media.(type) {
-		case string, FileBytes, FileReader:
+		if m.Media.NeedsUpload() {
 			files = append(files, RequestFile{
 				Name: fmt.Sprintf("file-%d", idx),
-				File: f,
+				Data: m.Media,
 			})
 		}
 	case InputMediaVideo:
-		switch f := m.Media.(type) {
-		case string, FileBytes, FileReader:
+		if m.Media.NeedsUpload() {
 			files = append(files, RequestFile{
 				Name: fmt.Sprintf("file-%d", idx),
-				File: f,
+				Data: m.Media,
 			})
 		}
 
-		switch f := m.Thumb.(type) {
-		case string, FileBytes, FileReader:
+		if m.Thumb != nil && m.Thumb.NeedsUpload() {
 			files = append(files, RequestFile{
-				Name: fmt.Sprintf("file-%d-thumb", idx),
-				File: f,
+				Name: fmt.Sprintf("file-%d", idx),
+				Data: m.Thumb,
 			})
 		}
 	case InputMediaDocument:
-		switch f := m.Media.(type) {
-		case string, FileBytes, FileReader:
+		if m.Media.NeedsUpload() {
 			files = append(files, RequestFile{
 				Name: fmt.Sprintf("file-%d", idx),
-				File: f,
+				Data: m.Media,
 			})
 		}
 
-		switch f := m.Thumb.(type) {
-		case string, FileBytes, FileReader:
+		if m.Thumb != nil && m.Thumb.NeedsUpload() {
 			files = append(files, RequestFile{
 				Name: fmt.Sprintf("file-%d", idx),
-				File: f,
+				Data: m.Thumb,
 			})
 		}
 	case InputMediaAudio:
-		switch f := m.Media.(type) {
-		case string, FileBytes, FileReader:
+		if m.Media.NeedsUpload() {
 			files = append(files, RequestFile{
 				Name: fmt.Sprintf("file-%d", idx),
-				File: f,
+				Data: m.Media,
 			})
 		}
 
-		switch f := m.Thumb.(type) {
-		case string, FileBytes, FileReader:
+		if m.Thumb != nil && m.Thumb.NeedsUpload() {
 			files = append(files, RequestFile{
 				Name: fmt.Sprintf("file-%d", idx),
-				File: f,
+				Data: m.Thumb,
 			})
 		}
 	}

@@ -70,7 +70,7 @@ // chatID is where to send it, file is a string path to the file,
 // FileReader, or FileBytes.
 //
 // Note that you must send animated GIFs as a document.
-func NewPhoto(chatID int64, file interface{}) PhotoConfig {
+func NewPhoto(chatID int64, file RequestFileData) PhotoConfig {
 	return PhotoConfig{
 		BaseFile: BaseFile{
 			BaseChat: BaseChat{ChatID: chatID},
@@ -82,7 +82,7 @@
 // NewPhotoToChannel creates a new photo uploader to send a photo to a channel.
 //
 // Note that you must send animated GIFs as a document.
-func NewPhotoToChannel(username string, file interface{}) PhotoConfig {
+func NewPhotoToChannel(username string, file RequestFileData) PhotoConfig {
 	return PhotoConfig{
 		BaseFile: BaseFile{
 			BaseChat: BaseChat{
@@ -94,7 +94,7 @@ }
 }
 
 // NewAudio creates a new sendAudio request.
-func NewAudio(chatID int64, file interface{}) AudioConfig {
+func NewAudio(chatID int64, file RequestFileData) AudioConfig {
 	return AudioConfig{
 		BaseFile: BaseFile{
 			BaseChat: BaseChat{ChatID: chatID},
@@ -104,7 +104,7 @@ }
 }
 
 // NewDocument creates a new sendDocument request.
-func NewDocument(chatID int64, file interface{}) DocumentConfig {
+func NewDocument(chatID int64, file RequestFileData) DocumentConfig {
 	return DocumentConfig{
 		BaseFile: BaseFile{
 			BaseChat: BaseChat{ChatID: chatID},
@@ -114,7 +114,7 @@ }
 }
 
 // NewSticker creates a new sendSticker request.
-func NewSticker(chatID int64, file interface{}) StickerConfig {
+func NewSticker(chatID int64, file RequestFileData) StickerConfig {
 	return StickerConfig{
 		BaseFile: BaseFile{
 			BaseChat: BaseChat{ChatID: chatID},
@@ -124,7 +124,7 @@ }
 }
 
 // NewVideo creates a new sendVideo request.
-func NewVideo(chatID int64, file interface{}) VideoConfig {
+func NewVideo(chatID int64, file RequestFileData) VideoConfig {
 	return VideoConfig{
 		BaseFile: BaseFile{
 			BaseChat: BaseChat{ChatID: chatID},
@@ -134,7 +134,7 @@ }
 }
 
 // NewAnimation creates a new sendAnimation request.
-func NewAnimation(chatID int64, file interface{}) AnimationConfig {
+func NewAnimation(chatID int64, file RequestFileData) AnimationConfig {
 	return AnimationConfig{
 		BaseFile: BaseFile{
 			BaseChat: BaseChat{ChatID: chatID},
@@ -147,7 +147,7 @@ // NewVideoNote creates a new sendVideoNote request.
 //
 // chatID is where to send it, file is a string path to the file,
 // FileReader, or FileBytes.
-func NewVideoNote(chatID int64, length int, file interface{}) VideoNoteConfig {
+func NewVideoNote(chatID int64, length int, file RequestFileData) VideoNoteConfig {
 	return VideoNoteConfig{
 		BaseFile: BaseFile{
 			BaseChat: BaseChat{ChatID: chatID},
@@ -158,7 +158,7 @@ }
 }
 
 // NewVoice creates a new sendVoice request.
-func NewVoice(chatID int64, file interface{}) VoiceConfig {
+func NewVoice(chatID int64, file RequestFileData) VoiceConfig {
 	return VoiceConfig{
 		BaseFile: BaseFile{
 			BaseChat: BaseChat{ChatID: chatID},
@@ -177,7 +177,7 @@ }
 }
 
 // NewInputMediaPhoto creates a new InputMediaPhoto.
-func NewInputMediaPhoto(media interface{}) InputMediaPhoto {
+func NewInputMediaPhoto(media RequestFileData) InputMediaPhoto {
 	return InputMediaPhoto{
 		BaseInputMedia{
 			Type:  "photo",
@@ -187,7 +187,7 @@ }
 }
 
 // NewInputMediaVideo creates a new InputMediaVideo.
-func NewInputMediaVideo(media interface{}) InputMediaVideo {
+func NewInputMediaVideo(media RequestFileData) InputMediaVideo {
 	return InputMediaVideo{
 		BaseInputMedia: BaseInputMedia{
 			Type:  "video",
@@ -197,7 +197,7 @@ }
 }
 
 // NewInputMediaAnimation creates a new InputMediaAnimation.
-func NewInputMediaAnimation(media interface{}) InputMediaAnimation {
+func NewInputMediaAnimation(media RequestFileData) InputMediaAnimation {
 	return InputMediaAnimation{
 		BaseInputMedia: BaseInputMedia{
 			Type:  "animation",
@@ -207,7 +207,7 @@ }
 }
 
 // NewInputMediaAudio creates a new InputMediaAudio.
-func NewInputMediaAudio(media interface{}) InputMediaAudio {
+func NewInputMediaAudio(media RequestFileData) InputMediaAudio {
 	return InputMediaAudio{
 		BaseInputMedia: BaseInputMedia{
 			Type:  "audio",
@@ -217,7 +217,7 @@ }
 }
 
 // NewInputMediaDocument creates a new InputMediaDocument.
-func NewInputMediaDocument(media interface{}) InputMediaDocument {
+func NewInputMediaDocument(media RequestFileData) InputMediaDocument {
 	return InputMediaDocument{
 		BaseInputMedia: BaseInputMedia{
 			Type:  "document",
@@ -316,7 +316,7 @@ // NewWebhookWithCert creates a new webhook with a certificate.
 //
 // link is the url you wish to get webhooks,
 // file contains a string to a file, FileReader, or FileBytes.
-func NewWebhookWithCert(link string, file interface{}) (WebhookConfig, error) {
+func NewWebhookWithCert(link string, file RequestFileData) (WebhookConfig, error) {
 	u, err := url.Parse(link)
 
 	if err != nil {
@@ -769,7 +769,7 @@ }
 }
 
 // NewChatPhoto allows you to update the photo for a chat.
-func NewChatPhoto(chatID int64, photo interface{}) SetChatPhotoConfig {
+func NewChatPhoto(chatID int64, photo RequestFileData) SetChatPhotoConfig {
 	return SetChatPhotoConfig{
 		BaseFile: BaseFile{
 			BaseChat: BaseChat{
@@ -781,7 +781,7 @@ }
 }
 
 // NewDeleteChatPhoto allows you to delete the photo for a chat.
-func NewDeleteChatPhoto(chatID int64, photo interface{}) DeleteChatPhotoConfig {
+func NewDeleteChatPhoto(chatID int64) DeleteChatPhotoConfig {
 	return DeleteChatPhotoConfig{
 		ChatID: chatID,
 	}

@@ -17,7 +17,7 @@ }
 }
 
 func TestNewWebhookWithCert(t *testing.T) {
-	exampleFile := File{FileID: "123"}
+	exampleFile := FileID("123")
 	result, err := NewWebhookWithCert("https://example.com/token", exampleFile)
 
 	if err != nil ||

@@ -1685,7 +1685,7 @@ // that exists on the Telegram servers (recommended),
 	// pass an HTTP URL for Telegram to get a file from the Internet,
 	// or pass “attach://<file_attach_name>” to upload a new one
 	// using multipart/form-data under <file_attach_name> name.
-	Media interface{} `json:"media"`
+	Media RequestFileData `json:"media"`
 	// thumb intentionally missing as it is not currently compatible
 
 	// Caption of the video to be sent, 0-1024 characters after entities parsing.
@@ -1717,7 +1717,7 @@ // Thumbnail of the file sent; can be ignored if thumbnail generation for
 	// the file is supported server-side.
 	//
 	// optional
-	Thumb interface{} `json:"thumb,omitempty"`
+	Thumb RequestFileData `json:"thumb,omitempty"`
 	// Width video width
 	//
 	// optional
@@ -1743,7 +1743,7 @@ // Thumbnail of the file sent; can be ignored if thumbnail generation for
 	// the file is supported server-side.
 	//
 	// optional
-	Thumb interface{} `json:"thumb,omitempty"`
+	Thumb RequestFileData `json:"thumb,omitempty"`
 	// Width video width
 	//
 	// optional
@@ -1765,7 +1765,7 @@ // Thumbnail of the file sent; can be ignored if thumbnail generation for
 	// the file is supported server-side.
 	//
 	// optional
-	Thumb interface{} `json:"thumb,omitempty"`
+	Thumb RequestFileData `json:"thumb,omitempty"`
 	// Duration of the audio in seconds
 	//
 	// optional
@@ -1787,7 +1787,7 @@ // Thumbnail of the file sent; can be ignored if thumbnail generation for
 	// the file is supported server-side.
 	//
 	// optional
-	Thumb interface{} `json:"thumb,omitempty"`
+	Thumb RequestFileData `json:"thumb,omitempty"`
 	// DisableContentTypeDetection disables automatic server-side content type
 	// detection for files uploaded using multipart/form-data. Always true, if
 	// the document is sent as part of an album

@@ -361,3 +361,13 @@ _ Fileable = (*MediaGroupConfig)(nil)
 	_ Fileable = (*WebhookConfig)(nil)
 	_ Fileable = (*SetStickerSetThumbConfig)(nil)
 )
+
+// Ensure all RequestFileData types are correct.
+var (
+	_ RequestFileData = (*FilePath)(nil)
+	_ RequestFileData = (*FileBytes)(nil)
+	_ RequestFileData = (*FileReader)(nil)
+	_ RequestFileData = (*FileURL)(nil)
+	_ RequestFileData = (*FileID)(nil)
+	_ RequestFileData = (*fileAttach)(nil)
+)