Sending photos, API improvements

api.go

@@ -1,15 +1,20 @@
 package telebot
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
+	"io"
 	"io/ioutil"
+	"mime/multipart"
 	"net/http"
 	"net/url"
+	"os"
+	"path/filepath"
 	"strconv"
 )
 
-func performApiCall(method string, token string, params url.Values) ([]byte, error) {
+func api_GET(method string, token string, params url.Values) ([]byte, error) {
 	url := fmt.Sprintf("https://api.telegram.org/bot%s/%s?%s",
 		token, method, params.Encode())
 
@@ -27,8 +32,58 @@ func performApiCall(method string, token string, params url.Values) ([]byte, err
 	return json, nil
 }
 
+func api_POST(method, token, name, path string, params url.Values) ([]byte, error) {
+	file, err := os.Open(path)
+	if err != nil {
+		return []byte{}, err
+	}
+	defer file.Close()
+
+	body := &bytes.Buffer{}
+	writer := multipart.NewWriter(body)
+	part, err := writer.CreateFormFile(name, filepath.Base(path))
+	if err != nil {
+		return []byte{}, err
+	}
+
+	if _, err = io.Copy(part, file); err != nil {
+		return []byte{}, err
+	}
+
+	for field, values := range params {
+		if len(values) > 0 {
+			writer.WriteField(field, values[0])
+		}
+	}
+
+	if err = writer.Close(); err != nil {
+		return []byte{}, err
+	}
+
+	url := fmt.Sprintf("https://api.telegram.org/bot%s/%s", token, method)
+	req, err := http.NewRequest("POST", url, body)
+	if err != nil {
+		return []byte{}, err
+	}
+
+	req.Header.Add("Content-Type", writer.FormDataContentType())
+
+	client := &http.Client{}
+	resp, err := client.Do(req)
+	if err != nil {
+		return []byte{}, err
+	}
+
+	json, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return []byte{}, err
+	}
+
+	return json, nil
+}
+
 func api_getMe(token string) (User, error) {
-	me_json, err := performApiCall("getMe", token, url.Values{})
+	me_json, err := api_GET("getMe", token, url.Values{})
 	if err != nil {
 		return User{}, err
 	}
@@ -53,8 +108,8 @@ func api_getMe(token string) (User, error) {
 
 func api_getUpdates(token string, offset int, updates chan<- Update) error {
 	params := url.Values{}
-	params.Set("offset", strconv.FormatInt(int64(offset), 10))
-	updates_json, err := performApiCall("getUpdates", token, params)
+	params.Set("offset", strconv.Itoa(offset))
+	updates_json, err := api_GET("getUpdates", token, params)
 	if err != nil {
 		return err
 	}
@@ -83,9 +138,9 @@ func api_getUpdates(token string, offset int, updates chan<- Update) error {
 
 func api_sendMessage(token string, recipient User, text string) error {
 	params := url.Values{}
-	params.Set("chat_id", strconv.FormatInt(int64(recipient.Id), 10))
+	params.Set("chat_id", strconv.Itoa(recipient.Id))
 	params.Set("text", text)
-	response_json, err := performApiCall("sendMessage", token, params)
+	response_json, err := api_GET("sendMessage", token, params)
 	if err != nil {
 		return err
 	}
@@ -109,18 +164,55 @@ func api_sendMessage(token string, recipient User, text string) error {
 
 func api_forwardMessage(token string, recipient User, message Message) error {
 	params := url.Values{}
-	params.Set("chat_id", strconv.FormatInt(int64(recipient.Id), 10))
-	params.Set("from_chat_id",
-		strconv.FormatInt(int64(message.Origin().Id), 10))
-	params.Set("message_id", strconv.FormatInt(int64(message.Id), 10))
+	params.Set("chat_id", strconv.Itoa(recipient.Id))
+	params.Set("from_chat_id", strconv.Itoa(message.Origin().Id))
+	params.Set("message_id", strconv.Itoa(message.Id))
+
+	response_json, err := api_GET("forwardMessage", token, params)
+	if err != nil {
+		return err
+	}
+
+	var response_recieved struct {
+		Ok          bool
+		Description string
+	}
+
+	err = json.Unmarshal(response_json, &response_recieved)
+	if err != nil {
+		return err
+	}
+
+	if !response_recieved.Ok {
+		return SendError{response_recieved.Description}
+	}
+
+	return nil
+}
+
+func api_sendPhoto(token string, recipient User, photo *Photo) error {
+	params := url.Values{}
+	params.Set("chat_id", strconv.Itoa(recipient.Id))
+	params.Set("caption", photo.Caption)
+
+	var response_json []byte
+	var err error
+
+	if photo.Exists() {
+		params.Set("photo", photo.FileId)
+		response_json, err = api_GET("sendPhoto", token, params)
+	} else {
+		response_json, err = api_POST("sendPhoto", token, "photo",
+			photo.filename, params)
+	}
 
-	response_json, err := performApiCall("forwardMessage", token, params)
 	if err != nil {
 		return err
 	}
 
 	var response_recieved struct {
 		Ok          bool
+		Result      Message
 		Description string
 	}
 
@@ -133,5 +225,8 @@ func api_forwardMessage(token string, recipient User, message Message) error {
 		return SendError{response_recieved.Description}
 	}
 
+	thumbnails := &response_recieved.Result.Photo
+	photo.File = (*thumbnails)[len(*thumbnails)-1].File
+
 	return nil
 }

bot.go

@@ -47,3 +47,8 @@ func (b *Bot) SendMessage(recipient User, message string) error {
 func (b *Bot) ForwardMessage(recipient User, message Message) error {
 	return api_forwardMessage(b.Token, recipient, message)
 }
+
+// SendPhoto sends a photo object to recipient.
+func (b *Bot) SendPhoto(recipient User, photo *Photo) error {
+	return api_sendPhoto(b.Token, recipient, photo)
+}

errors.go

@@ -17,6 +17,10 @@ type SendError struct {
 	Payload string
 }
 
+type FileError struct {
+	Payload string
+}
+
 func (e AuthError) Error() string {
 	return "AuthError: " + e.Payload
 }
@@ -28,3 +32,7 @@ func (e FetchError) Error() string {
 func (e SendError) Error() string {
 	return "SendError: " + e.Payload
 }
+
+func (e FileError) Error() string {
+	return "FileError: " + e.Payload
+}

telebot.go

@@ -27,6 +27,11 @@
 //
 package telebot
 
+import (
+	"fmt"
+	"os"
+)
+
 // Create does try to build a Bot with token `token`, which
 // is a secret API key assigned to particular bot.
 func Create(token string) (Bot, error) {
@@ -40,3 +45,18 @@ func Create(token string) (Bot, error) {
 		Identity: user,
 	}, nil
 }
+
+// NewFile attempts to create a File object, leading to a real
+// file on the file system, that could be uploaded later.
+//
+// Notice that NewFile doesn't upload file, but only creates
+// a descriptor for it.
+func NewFile(path string) (File, error) {
+	if _, err := os.Stat(path); os.IsNotExist(err) {
+		return File{}, FileError{
+			fmt.Sprintf("'%s' does not exist!", path),
+		}
+	}
+
+	return File{filename: path}, nil
+}

types.go

@@ -17,12 +17,23 @@ type Update struct {
 	Payload Message `json:"message"`
 }
 
-// File object represents any sort of file. Since you would
-// only deal with specific files in the wild, this structure
-// doesn't make any sense in specific application.
+// File object represents any sort of file.
 type File struct {
 	FileId   string `json:"file_id"`
 	FileSize int    `json:"file_size"`
+
+	// Local absolute path to file on file system. Valid only for
+	// new files, meant to be uploaded soon.
+	filename string
+}
+
+// Exists says whether file presents on Telegram servers or not.
+func (f File) Exists() bool {
+	if f.filename == "" {
+		return true
+	}
+
+	return false
 }
 
 // Thumbnail object represents a image/sticker of particular size.
@@ -33,6 +44,13 @@ type Thumbnail struct {
 	Height int `json:"height"`
 }
 
+// Photo object represents a photo with caption.
+type Photo struct {
+	Thumbnail
+
+	Caption string
+}
+
 // Audio object represents an audio file (voice note).
 type Audio struct {
 	File