/// <summary>
/// Builds a <see cref="CheckAvailabilityOp"/>.
/// </summary>
/// <param name="steps">The individual availability check steps.</param>
/// <param name="endMessageOp">OPTIONAL operation to execute to get the message that should be emitted when all <paramref name="steps"/> have been evaluated and none have stopped the availability check (we've reached the end of the chain). DEFAULT is to omit this message.</param>
/// <param name="endAvailability">OPTIONAL value that specifies the availability of the subject when all <paramref name="steps"/> have been evaluated and none have stopped the availability check (we've reached the end of the chain). DEFAULT is to determine that the subject is enabled.</param>
/// <returns>
/// The operation.
/// </returns>
public static CheckAvailabilityOp CheckAvailability(
this IReadOnlyList <AvailabilityCheckStep> steps,
IReturningOperation <string> endMessageOp = null,
Availability endAvailability = Availability.Enabled)
{
var availabilityCheckChain = new AvailabilityCheckChain(steps, endMessageOp, endAvailability);
var result = new CheckAvailabilityOp(availabilityCheckChain);
return(result);
}
/// <inheritdoc />
public async Task <AvailabilityCheckResult> ExecuteAsync(
CheckAvailabilityOp operation)
{
// NOTE: THIS CODE IS A NEAR DUPLICATE OF THE SYNC METHOD ABOVE; NO GOOD WAY TO D.R.Y. IT OUT
if (operation == null)
{
throw new ArgumentNullException(nameof(operation));
}
AvailabilityCheckResult result = null;
var availabilityCheckChain = operation.AvailabilityCheckChain;
foreach (var availabilityCheckStep in availabilityCheckChain.Steps)
{
var operationResult = await this.protocolFactory.GetProtocolAndExecuteViaReflectionAsync <bool>(availabilityCheckStep.Operation);
var availabilityCheckStepAction = operationResult
? availabilityCheckStep.TrueAction
: availabilityCheckStep.FalseAction;
if (availabilityCheckStepAction == AvailabilityCheckStepAction.NextStep)
{
continue;
}
var availability = GetAvailability(availabilityCheckStepAction);
result = new AvailabilityCheckResult(Op.Const(availability), availabilityCheckStep.StopMessageOp);
break;
}
if (result == null)
{
result = new AvailabilityCheckResult(Op.Const(availabilityCheckChain.EndAvailability), availabilityCheckChain.EndMessageOp);
}
return(result);
}