/// <summary>
/// Looks up a source element at a given location, identifies the source value, and verifies whether the element is
/// available, enabled, or set to true.
/// </summary>
/// <param name="element">The target <see cref="SourceElement"/>.</param>
/// <param name="evaluateValue">Boolean indicator noting whether to use the Value to determine enabled status.</param>
/// <returns>
/// Boolean value representing whether or not the source is available, enabled or set to true.
/// </returns>
public static bool IsEnabled(SourceElement element, bool evaluateValue)
{
if (element == null) {
return false;
}
if (!element.Enabled) {
return false;
}
else if (!evaluateValue || element.Location == null) {
return true;
}
string value = GetValue(element);
if (String.IsNullOrEmpty(value)) return false;
return Convert.ToBoolean(value, CultureInfo.InvariantCulture);
}
/// <summary>
/// Determines whether the specified element is trusted via its availability.
/// </summary>
/// <param name="element">The <see cref="SourceElement"/> object.</param>
/// <returns>
/// Boolean value representing whether the specified element is available.
/// </returns>
public static bool IsTrusted(SourceElement element)
{
return (element == null)? false : element.Trusted;
}
/// <summary>
/// Gets the value for the specified element, assuming it's enabled, and based on the type of specified element's source,
/// looks up its value.
/// </summary>
/// <param name="element">The configuration element.</param>
/// <returns>The target value, or null if one is not found.</returns>
public static string GetValue(SourceElement element)
{
/*------------------------------------------------------------------------------------------------------------------------
| Validate input
\-----------------------------------------------------------------------------------------------------------------------*/
Contract.Requires<ArgumentNullException>(HttpContext.Current != null, "Assumes the current HTTP context is available.");
/*------------------------------------------------------------------------------------------------------------------------
| Return null if the element is disabled or missing
\-----------------------------------------------------------------------------------------------------------------------*/
if (element == null || !element.Enabled) return null;
/*------------------------------------------------------------------------------------------------------------------------
| Pull value from support source
\-----------------------------------------------------------------------------------------------------------------------*/
string value = null;
switch (element.Source?.ToUpperInvariant()?? "") {
case("QUERYSTRING") :
value = HttpContext.Current.Request.QueryString[element.Location];
break;
case("FORM") :
value = HttpContext.Current.Request.Form[element.Location];
break;
case("APPLICATION") :
value = (string)HttpContext.Current.Application?[element.Location];
break;
case("SESSION") :
value = (string)HttpContext.Current.Session?[element.Location];
break;
case("COOKIE") :
value = HttpContext.Current.Request.Cookies[element.Location]?.Value;
break;
case("ROLE") :
value = Roles.IsUserInRole(element.Location).ToString();
break;
case("HOSTNAME") :
value = element.Location;
break;
case("URL") :
if (Int32.Parse(element.Location, CultureInfo.InvariantCulture) >= 0) {
value = HttpContext.Current.Request.Path.Split('/')[Int32.Parse(element.Location, CultureInfo.InvariantCulture)];
}
break;
default :
throw new ConfigurationErrorsException("The source '" + element.Source + "' in the web.config is invalid.");
}
return value;
}
