Albums added, this commit resolves #103.

README.md

@@ -5,7 +5,7 @@
 [![Travis](https://travis-ci.org/tucnak/telebot.svg?branch=v2)](https://travis-ci.org/tucnak/telebot)
 
 ```bash
-go get gopkg.in/tucnak/telebot.v2
+go get -u gopkg.in/tucnak/telebot.v2
 ```
 
 Telebot is a bot framework for [Telegram](https://telegram.org) [Bot API](https://core.telegram.org/bots/api).

api.go

@@ -39,52 +39,59 @@ func (b *Bot) sendCommand(method string, payload interface{}) ([]byte, error) {
 	return json, nil
 }
 
-func (b *Bot) sendFile(method, name, path string, params map[string]string) ([]byte, error) {
-	file, err := os.Open(path)
-	if err != nil {
-		return []byte{}, wrapSystem(err)
-	}
-	defer file.Close()
-
+func (b *Bot) sendFiles(
+	method string,
+	files map[string]string,
+	params map[string]string) ([]byte, error) {
+	// ---
 	body := &bytes.Buffer{}
 	writer := multipart.NewWriter(body)
-	part, err := writer.CreateFormFile(name, filepath.Base(path))
-	if err != nil {
-		return []byte{}, wrapSystem(err)
-	}
 
-	if _, err = io.Copy(part, file); err != nil {
-		return []byte{}, wrapSystem(err)
+	for name, path := range files {
+		file, err := os.Open(path)
+		if err != nil {
+			return nil, wrapSystem(err)
+		}
+		defer file.Close()
+
+		part, err := writer.CreateFormFile(name, filepath.Base(path))
+		if err != nil {
+			return nil, wrapSystem(err)
+		}
+
+		if _, err = io.Copy(part, file); err != nil {
+			return nil, wrapSystem(err)
+		}
 	}
 
 	for field, value := range params {
 		writer.WriteField(field, value)
 	}
 
-	if err = writer.Close(); err != nil {
-		return []byte{}, wrapSystem(err)
+	if err := writer.Close(); err != nil {
+		return nil, wrapSystem(err)
 	}
 
 	url := fmt.Sprintf("https://api.telegram.org/bot%s/%s", b.Token, method)
 	req, err := http.NewRequest("POST", url, body)
 	if err != nil {
-		return []byte{}, wrapSystem(err)
+		return nil, wrapSystem(err)
 	}
 
 	req.Header.Add("Content-Type", writer.FormDataContentType())
 
 	resp, err := http.DefaultClient.Do(req)
 	if err != nil {
-		return []byte{}, errors.Wrap(err, "http.Post failed")
+		return nil, errors.Wrap(err, "http.Post failed")
 	}
 
 	if resp.StatusCode == http.StatusInternalServerError {
-		return []byte{}, errors.New("api error: internal server error")
+		return nil, errors.New("api error: internal server error")
 	}
 
 	json, err := ioutil.ReadAll(resp.Body)
 	if err != nil {
-		return []byte{}, wrapSystem(err)
+		return nil, wrapSystem(err)
 	}
 
 	return json, nil
@@ -103,11 +110,12 @@ func (b *Bot) sendObject(f *File, what string, params map[string]string) (*Messa
 	if f.InCloud() {
 		params[what] = f.FileID
 		respJSON, err = b.sendCommand(sendWhat, params)
-	} else if f.FileURL != nil {
-		params[what] = f.FileURL.String()
+	} else if f.FileURL != "" {
+		params[what] = f.FileURL
 		respJSON, err = b.sendCommand(sendWhat, params)
 	} else {
-		respJSON, err = b.sendFile(sendWhat, what, f.FileLocal, params)
+		respJSON, err = b.sendFiles(sendWhat,
+			map[string]string{what: f.FileLocal}, params)
 	}
 
 	if err != nil {

bot.go

@@ -276,8 +276,97 @@ func (b *Bot) Send(to Recipient, what interface{}, options ...interface{}) (*Mes
 	}
 }
 
-// Reply behaves just like Send() with an exception of "reply-to" indicator.
+// SendAlbum is used when sending multiple instances of media as a single
+// message (so-called album).
 //
+// From all existing options, it only supports telebot.Silent.
+func (b *Bot) SendAlbum(to Recipient, a Album, options ...interface{}) ([]Message, error) {
+	media := make([]string, len(a))
+	files := make(map[string]string)
+
+	for i, x := range a {
+		var (
+			f                    *File
+			caption              string
+			mediaRepr, mediaType string
+		)
+
+		switch y := x.(type) {
+		case *Photo:
+			f = &y.File
+			mediaType = "photo"
+			caption = y.Caption
+		case *Video:
+			f = &y.File
+			mediaType = "video"
+			caption = y.Caption
+		default:
+			return nil, errors.Errorf("telebot: album entry #%d is not valid", i)
+		}
+
+		if f.InCloud() {
+			mediaRepr = f.FileID
+		} else if f.FileURL != "" {
+			mediaRepr = f.FileURL
+		} else if f.OnDisk() {
+			mediaRepr = fmt.Sprintf("attach://%d", i)
+			files[strconv.Itoa(i)] = f.FileLocal
+		} else {
+			return nil, errors.Errorf(
+				"telebot: album entry #%d doesn't exist anywhere", i)
+		}
+
+		jsonRepr, _ := json.Marshal(map[string]string{
+			"type":    mediaType,
+			"media":   mediaRepr,
+			"caption": caption,
+		})
+
+		media[i] = string(jsonRepr)
+	}
+
+	params := map[string]string{
+		"chat_id": to.Recipient(),
+		"media":   "[" + strings.Join(media, ",") + "]",
+	}
+
+	sendOpts := extractOptions(options)
+	embedSendOptions(params, sendOpts)
+
+	respJSON, err := b.sendFiles("sendMediaGroup", files, params)
+
+	var resp struct {
+		Ok          bool
+		Result      []Message
+		Description string
+	}
+
+	err = json.Unmarshal(respJSON, &resp)
+	if err != nil {
+		return nil, errors.Wrap(err, "bad response json")
+	}
+
+	if !resp.Ok {
+		return nil, errors.Errorf("api error: %s", resp.Description)
+	}
+
+	for attachName, _ := range files {
+		i, _ := strconv.Atoi(attachName)
+
+		var newID string
+		if resp.Result[i].Photo != nil {
+			newID = resp.Result[i].Photo.FileID
+		} else {
+			newID = resp.Result[i].Video.FileID
+		}
+
+		a[i].MediaFile().FileID = newID
+	}
+
+	return resp.Result, nil
+}
+
+// Reply behaves just like Send() with an exception of "reply-to" indicator.
 func (b *Bot) Reply(to *Message, what interface{}, options ...interface{}) (*Message, error) {
 	// This function will panic upon unsupported payloads and options!
 	sendOpts := extractOptions(options)
@@ -302,9 +391,6 @@ func (b *Bot) Forward(to Recipient, what *Message, options ...interface{}) (*Mes
 	}
 
 	sendOpts := extractOptions(options)
-	if sendOpts == nil {
-		sendOpts = &SendOptions{}
-	}
 	embedSendOptions(params, sendOpts)
 
 	respJSON, err := b.sendCommand("forwardMessage", params)

file.go

@@ -1,7 +1,6 @@
 package telebot
 
 import (
-	"net/url"
 	"os"
 )
 
@@ -14,10 +13,10 @@ type File struct {
 	FilePath string `json:"file_path"`
 
 	// file on local file system.
-	FileLocal string
+	FileLocal string `json:"file_local"`
 
 	// file on the internet
-	FileURL *url.URL
+	FileURL string `json:"file_url"`
 }
 
 // FromDisk constructs a new local (on-disk) file object.
@@ -42,8 +41,8 @@ func FromDisk(filename string) File {
 //
 //     photo := &tb.Photo{File: tb.FromURL("https://site.com/picture.jpg")}
 //
-func FromURL(u *url.URL) File {
-	return File{FileURL: u}
+func FromURL(url string) File {
+	return File{FileURL: url}
 }
 
 func (f *File) stealRef(g *File) {
@@ -51,7 +50,7 @@ func (f *File) stealRef(g *File) {
 		f.FileLocal = g.FileLocal
 	}
 
-	if g.FileURL != nil {
+	if g.FileURL != "" {
 		f.FileURL = g.FileURL
 	}
 }

media.go

@@ -1,15 +1,21 @@
 package telebot
 
-import "encoding/json"
+import (
+	"encoding/json"
+)
 
-type photoSize struct {
-	File
-
-	Width  int `json:"width"`
-	Height int `json:"height"`
-
-	// (Optional)
-	Caption string `json:"caption,omitempty"`
+// Album lets you group multiple media (so-called InputMedia)
+// into a single messsage.
+//
+// On older clients albums look like N regular messages.
+type Album []InputMedia
+
+// InputMedia is a generic type for all kinds of media you
+// can put into an album.
+type InputMedia interface {
+	// As some files must be uploaded (instead of referencing)
+	// outer layers of Telebot require it.
+	MediaFile() *File
 }
 
 // Photo object represents a single photo file.
@@ -23,6 +29,18 @@ type Photo struct {
 	Caption string `json:"caption,omitempty"`
 }
 
+type photoSize struct {
+	File
+	Width   int    `json:"width"`
+	Height  int    `json:"height"`
+	Caption string `json:"caption,omitempty"`
+}
+
+// MediaFile returns &Photo.File
+func (p *Photo) MediaFile() *File {
+	return &p.File
+}
+
 // UnmarshalJSON is custom unmarshaller required to abstract
 // away the hassle of treating different thumbnail sizes.
 // Instead, Telebot chooses the hi-res one and just sticks to
@@ -58,7 +76,7 @@ type Audio struct {
 	File
 
 	// Duration of the recording in seconds as defined by sender.
-	Duration int `json:"duration"`
+	Duration int `json:"duration,omitempty"`
 
 	// (Optional)
 	Caption   string `json:"caption,omitempty"`
@@ -83,18 +101,24 @@ type Document struct {
 
 // Video object represents a video file.
 type Video struct {
-	Audio
+	File
 
 	Width  int `json:"width"`
 	Height int `json:"height"`
 
-	Duration int `json:"duration"`
+	Duration int `json:"duration,omitempty"`
 
 	// (Optional)
+	Caption   string `json:"caption,omitempty"`
 	Thumbnail *Photo `json:"thumb,omitempty"`
 	MIME      string `json:"mime_type,omitempty"`
 }
 
+// MediaFile returns &Video.File
+func (v *Video) MediaFile() *File {
+	return &v.File
+}
+
 // Voice object represents a voice note.
 type Voice struct {
 	File

message.go

@@ -108,7 +108,7 @@ type Message struct {
 	NewChatTitle string `json:"new_chat_title"`
 
 	// For a service message, represents all available
-	// thumbnails of new chat photo.
+	// thumbnails of the new chat photo.
 	//
 	// Sender would lead to a User, capable of change.
 	NewChatPhoto []Photo `json:"new_chat_photo"`