feat(channels): align email oauth authorization

internal/handler/api/v1/email_oauth_authorization.go

@@ -0,0 +1,54 @@
+package v1
+
+import (
+	"fmt"
+	"net/url"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/golang-jwt/jwt/v5"
+)
+
+type chatwootEmailOAuthAuthorizationConfig struct {
+	ClientIDEnv     string
+	ClientSecretEnv string
+	AuthorizeURL    string
+	RedirectPath    string
+	Scope           string
+	ExtraParams     map[string]string
+}
+
+func buildChatwootEmailOAuthAuthorizationURL(accountID uint, cfg chatwootEmailOAuthAuthorizationConfig) (string, error) {
+	clientID := strings.TrimSpace(os.Getenv(cfg.ClientIDEnv))
+	clientSecret := strings.TrimSpace(os.Getenv(cfg.ClientSecretEnv))
+	if clientID == "" || clientSecret == "" {
+		return "", fmt.Errorf("email OAuth is not configured")
+	}
+
+	state, err := signedChatwootOAuthState(accountID, clientSecret)
+	if err != nil {
+		return "", err
+	}
+
+	frontendURL := strings.TrimRight(envOrDefaultV1("FRONTEND_URL", "http://localhost:3000"), "/")
+	params := url.Values{}
+	params.Set("client_id", clientID)
+	params.Set("redirect_uri", frontendURL+cfg.RedirectPath)
+	params.Set("response_type", "code")
+	params.Set("scope", cfg.Scope)
+	params.Set("state", state)
+	for key, value := range cfg.ExtraParams {
+		params.Set(key, value)
+	}
+
+	return cfg.AuthorizeURL + "?" + params.Encode(), nil
+}
+
+func signedChatwootOAuthState(accountID uint, secret string) (string, error) {
+	token := jwt.NewWithClaims(jwt.SigningMethodHS256, jwt.MapClaims{
+		"sub": accountID,
+		"iat": time.Now().Unix(),
+	})
+	return token.SignedString([]byte(secret))
+}