How to send an email by clicking a reject reason with the reject reason?

I want to send an email ,I have  a reject button by clicking that need a wizard for typing the reason and send email with the reason.

I have done like this, below shows the code :

@api.one
def reject_leave_manager(self):
    if self.state == 'confirm':
        
context = {
    'user_id': self.id
}
form_view = self.env.ref('leave_management_ft.view_message_form_leave_request')
return {'name': _('Reject Reason'),
        'context': context,
        'type': 'ir.actions.act_window',
        'view_type': 'form',
        'view_mode': 'form',
        'res_model': 'mail.mail',
        # 'res_id': mail_id.id,
        'views': [(form_view.id, 'form'), ],
        'target': 'new'}

class MailToLeaveReject(models.Model):
    _inherit = 'mail.mail'

    body_msg = fields.Html()

    def mail_leave_reject_reason(self):
        context = self.env.context
        asset_id = context['user_id']
        asset_obj = self.env['hr.holidays'].browse(asset_id)
        mail_values_refuse = {
            # 'email_from': self.employee_id.work_email,
            'email_to': asset_obj.employee_id.work_email,
            'subject': 'Leave rejected ' ,
            'body_html': 'Dear '+asset_obj.employee_id.name+',<br><br>Your request for '+ asset_obj.holiday_status_id.name+' from '
                         +asset_obj.from_date+' to '
                         +asset_obj.to_date+' has been rejected  due to '
                        'the reason:'+self.body_msg+'<br> Regards',
            # 'notification': True,
        }
        mail = self.env['mail.mail'].create(mail_values_refuse)
        mail.send()



This is the code I have written for getting the solution,but there there only changes the state to rejected,