minimum interval is now dynamic

Xero.php

     //
     //sync users to wordpress system
     //does not work for too many users or employees
-    public function sync_users(){
+    public function sync_users($mininterval){
+        $this->usage();
+        $this->minimum_sync_interval_in_seconds = $mininterval;
+        $msg="Sync users with minimum interval set to $mininterval  \n";
+        $this->logConsole($msg);
+        
         try{
             $this->sync_clients();
             $this->sync_employees();
             echo $str;
         }
     }  
+    
+    private function usage(){
+        $msg = "_____________________________________________\n";
+        $msg .= "run this command at public_html/, where wp-config.php exist \n"; 
+        $msg .= "wp sync_users --mininterval=6000 \n";
+        $msg .= "6000 means those users synced within 6000 seconds will be bypassed \n";
+        $msg .= "to sync everything \n";
+        $msg .= "wp sync_users --mininterval=0 \n";
+        $msg .= "but it may hit XERO rate limit, 60call/sec, 5000/day \n";
+        $msg .= "---------------------------------------------\n";
+        $this->logConsole($msg);
+    }
 }

ts.php

         $a=1;
         return;
     }
+    
+    // Usage: `wp sync_users --mininterval=123 
     public function sync_user_cli($args = array(), $assoc_args = array()){
-        $this->cli = true;
-        echo "running sync user from command line;\n";
-        $this->xero->sync_users();
+        $arguments = wp_parse_args( $assoc_args, array(
+            'mininterval'    => 600,
+        ) );
+        $this->xero->sync_users($arguments['mininterval']);
         return;
     }
 }