/// <summary>
/// Branches the request pipeline based on the result of the given predicate.
/// </summary>
/// <param name="app"></param>
/// <param name="predicate">Invoked with the request environment to determine if the branch should be taken</param>
/// <param name="configuration">Configures a branch to take</param>
/// <returns></returns>
public static IMiddlewareBuilder <TContext> MapWhen <TContext>(this IMiddlewareBuilder <TContext> app, Predicate <TContext> predicate, Action <IMiddlewareBuilder <TContext> > configuration)
where TContext : ContextBase
{
if (app == null)
{
throw new ArgumentNullException(nameof(app));
}
if (predicate == null)
{
throw new ArgumentNullException(nameof(predicate));
}
if (configuration == null)
{
throw new ArgumentNullException(nameof(configuration));
}
// create branch
var branchBuilder = app.New();
configuration(branchBuilder);
var branch = branchBuilder.Build();
// put middleware in pipeline
var options = new MapWhenOptions <TContext>
{
Predicate = predicate,
Branch = branch,
};
return(app.Use(next => new MapWhenMiddleware <TContext>(next, options).Invoke));
}
private static MiddlewareBranch <TContext>[] BuildMiddlewareBranches <TContext>(IMiddlewareBuilder <TContext> parentBuilder, Route <TContext>[] routes) where TContext : Context
{
if (parentBuilder == null)
{
throw new ArgumentNullException(nameof(parentBuilder));
}
if (routes == null)
{
throw new ArgumentNullException(nameof(routes));
}
return(routes.Select(route =>
{
// setup builder and invoke configuration pipeline
var branchBuilder = parentBuilder.New();
// register route context with relevant features (TODO: abstraction layering)
foreach (var property in parentBuilder.Properties.Where(x => x.Value is IRouteContextAware <TContext>))
{
branchBuilder.Properties.Add(property);
var routeContextAware = property.Value as IRouteContextAware <TContext>;
routeContextAware.PushRouteContext(route);
}
route.MiddlewareBuilderForRoute(branchBuilder);
// build the stack
var branchStack = branchBuilder.Build();
// unregister route context with relevant features
foreach (var property in parentBuilder.Properties.Where(x => x.Value is IRouteContextAware <TContext>))
{
var routeContextAware = property.Value as IRouteContextAware <TContext>;
routeContextAware.PopRouteContext();
}
return new MiddlewareBranch <TContext>(route.IsApplicable, branchStack);
}).ToArray());
}