/// <summary>
/// handle implicit token request
/// </summary>
protected virtual async Task ImplicitTokenRequestHandler(HttpContext context, IClient client, string scopesStr, string redirectURI, string state)
{
var token = await _tokenGenerator.GenerateAccessTokenAsync(
context : context
, grantType : GrantType.Implicit
, client : client
, scopes : scopesStr.Split(OAuth2Consts.Seperator_Scope)
, username : context.User.Identity.Name
);
context.Response.Redirect($"{redirectURI}?{OAuth2Consts.Form_AccessToken}={Uri.EscapeDataString(token)}&{OAuth2Consts.Form_TokenType}=Bearer&{OAuth2Consts.Form_ExpiresIn}={client.AccessTokenExpireSeconds}&{OAuth2Consts.Form_Scope}={Uri.EscapeDataString(scopesStr)}&{OAuth2Consts.Form_State}={Uri.EscapeDataString(state)}");
}