feat(zarinhub): automate access token refresh

backend/cmd/api/config.go

@@ -8,12 +8,14 @@ import (
 )
 
 type config struct {
-	ServerAddr       string
-	FrontendOrigin   string
-	ZarinHubEndpoint string
-	ZarinHubToken    string
-	ZarinHubTimeout  time.Duration
-	DatabasePath     string
+	ServerAddr           string
+	FrontendOrigin       string
+	ZarinHubEndpoint     string
+	ZarinHubAuthEndpoint string
+	ZarinHubUsername     string
+	ZarinHubPassword     string
+	ZarinHubTimeout      time.Duration
+	DatabasePath         string
 }
 
 func loadConfig() (config, error) {
@@ -21,9 +23,14 @@ func loadConfig() (config, error) {
 }
 
 func readConfig(getenv func(string) string) (config, error) {
-	token := strings.TrimSpace(getenv("ZARINHUB_ACCESS_TOKEN"))
-	if token == "" {
-		return config{}, fmt.Errorf("ZARINHUB_ACCESS_TOKEN is required")
+	username := strings.TrimSpace(getenv("ZARINHUB_API_USERNAME"))
+	if username == "" {
+		return config{}, fmt.Errorf("ZARINHUB_API_USERNAME is required")
+	}
+
+	password := strings.TrimSpace(getenv("ZARINHUB_API_PASSWORD"))
+	if password == "" {
+		return config{}, fmt.Errorf("ZARINHUB_API_PASSWORD is required")
 	}
 
 	timeoutText := valueOrDefault(
@@ -50,8 +57,13 @@ func readConfig(getenv func(string) string) (config, error) {
 			getenv("ZARINHUB_ENDPOINT"),
 			"https://zarin-hub.com/api/v5/KYC/CardToIban",
 		),
-		ZarinHubToken:   token,
-		ZarinHubTimeout: timeout,
+		ZarinHubAuthEndpoint: valueOrDefault(
+			getenv("ZARINHUB_AUTH_ENDPOINT"),
+			"https://zarin-hub.com/api/v5/Authentication/GetToken",
+		),
+		ZarinHubUsername: username,
+		ZarinHubPassword: password,
+		ZarinHubTimeout:  timeout,
 		DatabasePath: valueOrDefault(
 			getenv("DATABASE_PATH"),
 			"./card-to-iban.db",