backend code

server/twitch/auth.go

@@ -0,0 +1,75 @@
+package twitch
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+	"time"
+)
+
+const authURL = "https://id.twitch.tv/oauth2/token"
+
+type AuthResponse struct {
+	AccessToken string `json:"access_token"`
+	ExpiresIn   int    `json:"expires_in"`
+	TokenType   string `json:"token_type"`
+}
+
+type AccessToken struct {
+	Token  string
+	Expiry time.Time
+}
+
+type AuthenticationManager struct {
+	clientId     string
+	clientSecret string
+	accesToken   *AccessToken
+}
+
+func NewAuthenticationManager(clientId, clientSecret string) *AuthenticationManager {
+	return &AuthenticationManager{
+		clientId:     clientId,
+		clientSecret: clientSecret,
+		accesToken:   &AccessToken{},
+	}
+}
+
+func (a *AuthenticationManager) GetAccessToken() (*AccessToken, error) {
+	if a.accesToken != nil && a.accesToken.Expiry.After(time.Now()) {
+		return a.accesToken, nil
+	}
+
+	data := url.Values{}
+	data.Set("client_id", a.clientId)
+	data.Set("client_secret", a.clientSecret)
+	data.Set("grant_type", "client_credentials")
+
+	resp, err := http.PostForm(authURL, data)
+	if err != nil {
+		return nil, fmt.Errorf("errore richiesta token: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("status non OK: %s", resp.Status)
+	}
+
+	var auth AuthResponse
+	if err := json.NewDecoder(resp.Body).Decode(&auth); err != nil {
+		return nil, fmt.Errorf("errore decoding JSON: %w", err)
+	}
+
+	token := &AccessToken{
+		Token:  auth.AccessToken,
+		Expiry: time.Now().Add(time.Duration(auth.ExpiresIn) * time.Second),
+	}
+
+	a.accesToken = token
+
+	return token, nil
+}
+
+func (a *AuthenticationManager) GetClientId() string {
+	return a.clientId
+}