camel-k-runtime-knative/src/main/java/org/apache/camel/k/loader/knative/KnativeSourceLoaderInterceptor.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
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package org.apache.camel.k.loader.knative;

import java.util.List;
import java.util.Optional;

import org.apache.camel.CamelContext;
import org.apache.camel.RoutesBuilder;
import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.k.Source;
import org.apache.camel.k.SourceLoader;
import org.apache.camel.k.annotation.LoaderInterceptor;
import org.apache.camel.k.support.SourcesSupport;
import org.apache.camel.model.RouteDefinition;
import org.apache.camel.model.ToDefinition;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@LoaderInterceptor("knative-source")
public class KnativeSourceLoaderInterceptor implements SourceLoader.Interceptor {
    private static final Logger LOGGER = LoggerFactory.getLogger(KnativeSourceLoaderInterceptor.class);

    @Override
    public void beforeLoad(SourceLoader loader, Source source) {
        // no-op
    }

    @Override
    public SourceLoader.Result afterLoad(SourceLoader loader, Source source, SourceLoader.Result result) {
        return new SourceLoader.Result() {
            @Override
            public Optional<RoutesBuilder> builder() {
                return result.builder().map(
                    bulider -> SourcesSupport.afterConfigure(bulider, KnativeSourceLoaderInterceptor::afterConfigure)
                );
            }

            @Override
            public Optional<Object> configuration() {
                return result.configuration();
            }
        };
    }

    private static void afterConfigure(RouteBuilder builder) {
        final CamelContext camelContext = builder.getContext();
        final List<RouteDefinition> definitions = builder.getRouteCollection().getRoutes();

        if (definitions.size() == 1) {
            final String sinkName = camelContext.resolvePropertyPlaceholders("{{knative.sink:sink}}");
            final String sinkUri = String.format("knative://endpoint/%s", sinkName);
            final RouteDefinition definition = definitions.get(0);

            LOGGER.info("Add sink:{} to route:{}", sinkUri, definition.getId());

            // assuming that route is linear like there's no content based routing
            // or ant other EIP that would branch the flow
            definition.getOutputs().add(new ToDefinition(sinkUri));
        } else {
            LOGGER.warn("Cannot determine route to enrich. the knative enpoint need to explicitly be defined");
        }
    }

}