Интерфейс для авторизации

api/api.go

@@ -83,6 +83,7 @@ type VK struct {
 	Version     string
 	Client      *http.Client
 	Limit       int
+	Auth        Authenticator
 	Handler     func(method string, params Params) (Response, error)
 
 	mux      sync.Mutex
@@ -125,6 +126,7 @@ type Response struct {
 func Init(token string) *VK {
 	var vk VK
 	vk.AccessToken = token
+	vk.Auth = TokenAuthenticator(token)
 	vk.Version = Version
 
 	vk.Handler = vk.defaultHandler
@@ -211,8 +213,9 @@ func (vk *VK) defaultHandler(method string, params Params) (response Response, e
 //
 // TODO: remove in v2
 func (vk *VK) Request(method string, params Params) ([]byte, error) {
-	if _, ok := params["access_token"]; !ok {
-		params["access_token"] = vk.AccessToken
+	err := vk.Auth.Authenticate(params)
+	if err != nil {
+		return nil, err
 	}
 
 	if _, ok := params["v"]; !ok {
@@ -238,12 +241,16 @@ func (vk *VK) RequestUnmarshal(method string, params Params, obj interface{}) er
 //
 // https://vk.com/dev/Execute
 func (vk *VK) Execute(code string, obj interface{}) error {
-	params := Params{
-		"code":         code,
-		"access_token": vk.AccessToken,
-		"v":            vk.Version,
+	params := Params{}
+
+	err := vk.Auth.Authenticate(params)
+	if err != nil {
+		return err
 	}
 
+	params["v"] = vk.Version
+	params["code"] = code
+
 	resp, err := vk.Handler("execute", params)
 
 	// Add execute errors

api/authenticator.go

@@ -0,0 +1,102 @@
+package api
+
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+
+	"github.com/SevereCloud/vksdk/api/errors"
+)
+
+// Authenticator interface
+type Authenticator interface {
+	Authenticate(params Params) error
+}
+
+// AuthenticatorFunc func
+type AuthenticatorFunc func(params Params) error
+
+// Authenticate method
+// Implements Authenticator for AuthenticatorFunc
+func (f AuthenticatorFunc) Authenticate(params Params) error {
+	return f(params)
+}
+
+// TokenAuthenticator func
+// Creates new Authenticator which sets given access_token
+func TokenAuthenticator(token string) Authenticator {
+	return AuthenticatorFunc(func(params Params) error {
+		if _, ok := params["access_token"]; !ok {
+			params["access_token"] = token
+		}
+
+		return nil
+	})
+}
+
+// AuthCodeFlowRequest struct
+type AuthCodeFlowRequest struct {
+	ClientID     int    `json:"client_id"`
+	ClientSecret string `json:"client_secret"`
+	RedirectURL  string `json:"redirect_url"`
+	Code         string `json:"code"`
+	Version      string `json:"v"`
+}
+
+// TokenResponse struct
+type TokenResponse struct {
+	AccessToken string `json:"access_token"`
+	ExpiresIn   int    `json:"expires_in"`
+	UserID      int    `json:"user_id"`
+}
+
+// gets token from given AuthCodeFlowRequest
+func authCodeFlow(auth AuthCodeFlowRequest) (token TokenResponse, err error) {
+	encoded, err := json.Marshal(auth)
+	if err != nil {
+		return
+	}
+
+	resp, err := http.Post(
+		"https://oauth.vk.com/access_token",
+		"application/json",
+		bytes.NewReader(encoded),
+	)
+	if err != nil {
+		return
+	}
+
+	if resp.Body != nil {
+		defer resp.Body.Close()
+	}
+
+	var response Response
+
+	err = json.NewDecoder(resp.Body).Decode(&response)
+	if err != nil {
+		return
+	}
+
+	err = errors.New(response.Error)
+	if err != nil {
+		return
+	}
+
+	err = json.Unmarshal(response.Response, &token)
+
+	return token, err
+}
+
+// CodeAuthenticator func
+// Authorization code flow implementation
+func CodeAuthenticator(auth AuthCodeFlowRequest) (Authenticator, error) {
+	r, err := authCodeFlow(auth)
+
+	return AuthenticatorFunc(func(params Params) error {
+		if _, ok := params["access_token"]; !ok {
+			params["access_token"] = r.AccessToken
+		}
+
+		return nil
+	}), err
+}