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Camel Jolt Support
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/**
 * 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.
 */
package org.apache.camel.component.jolt;

import java.io.InputStream;

import com.bazaarvoice.jolt.Chainr;
import com.bazaarvoice.jolt.Defaultr;
import com.bazaarvoice.jolt.JsonUtils;
import com.bazaarvoice.jolt.Removr;
import com.bazaarvoice.jolt.Shiftr;
import com.bazaarvoice.jolt.Sortr;
import com.bazaarvoice.jolt.Transform;

import org.apache.camel.Exchange;
import org.apache.camel.ExchangePattern;
import org.apache.camel.Message;
import org.apache.camel.component.ResourceEndpoint;
import org.apache.camel.spi.UriEndpoint;
import org.apache.camel.spi.UriParam;
import org.apache.camel.util.ObjectHelper;

/**
 * The jolt component allows you to process a JSON messages using an JOLT specification (such as JSON-JSON transformation).
 */
@UriEndpoint(scheme = "jolt", title = "JOLT", syntax = "jolt:resourceUri", producerOnly = true, label = "transformation")
public class JoltEndpoint extends ResourceEndpoint {
    
    private Transform transform;
    
    @UriParam(defaultValue = "Hydrated")
    private JoltInputOutputType outputType;
    
    @UriParam(defaultValue = "Hydrated")
    private JoltInputOutputType inputType;
    
    @UriParam(defaultValue = "Chainr")
    private JoltTransformType transformDsl = JoltTransformType.Chainr;
    
    public JoltEndpoint() {
    }

    public JoltEndpoint(String uri, JoltComponent component, String resourceUri) {
        super(uri, component, resourceUri);
    }

    @Override
    public boolean isSingleton() {
        return true;
    }

    @Override
    public ExchangePattern getExchangePattern() {
        return ExchangePattern.InOut;
    }

    @Override
    protected String createEndpointUri() {
        return "jolt:" + getResourceUri();
    }

    private synchronized Transform getTransform() throws Exception {
        if (transform == null) {
            if (log.isDebugEnabled()) {
                String path = getResourceUri();
                log.debug("Jolt content read from resource {} with resourceUri: {} for endpoint {}", new Object[]{getResourceUri(), path, getEndpointUri()});
            }

            // Sortr does not require a spec
            if (this.transformDsl == JoltTransformType.Sortr) {
                this.transform = new Sortr();
            } else {
                // getResourceAsInputStream also considers the content cache
                Object spec = JsonUtils.jsonToObject(getResourceAsInputStream());
                switch(this.transformDsl) {
                case Shiftr:
                    this.transform = new Shiftr(spec);
                    break;
                case Defaultr:
                    this.transform = new Defaultr(spec);
                    break;
                case Removr:
                    this.transform = new Removr(spec);
                    break;
                case Chainr:
                default:
                    this.transform = Chainr.fromSpec(spec);
                    break;
                }
            }
            
        }
        return transform;
    }

    /**
     * Sets the Transform to use. If not set a Transform specified by the transformDsl will be created
     */
    public void setTransform(Transform transform) {
        this.transform = transform;
    }
    
    public JoltInputOutputType getOutputType() {
        return outputType;
    }
    
    /**
     * Specifies if the output should be hydrated JSON or a JSON String.
     */
    public void setOutputType(JoltInputOutputType outputType) {
        this.outputType = outputType;
    }
    
    public JoltInputOutputType getInputType() {
        return inputType;
    }
    
    /**
     * Specifies if the input is hydrated JSON or a JSON String.
     */
    public void setInputType(JoltInputOutputType inputType) {
        this.inputType = inputType;
    }
    
    public JoltTransformType getTransformDsl() {
        return transformDsl;
    }
    
    /**
     * Specifies the Transform DSL of the endpoint resource. If none is specified Chainr will be used.
     */
    public void setTransformDsl(JoltTransformType transformType) {
        this.transformDsl = transformType;
    }
    
    public JoltEndpoint findOrCreateEndpoint(String uri, String newResourceUri) {
        String newUri = uri.replace(getResourceUri(), newResourceUri);
        log.debug("Getting endpoint with URI: {}", newUri);
        return getCamelContext().getEndpoint(newUri, JoltEndpoint.class);
    }

    @Override
    protected void onExchange(Exchange exchange) throws Exception {
        String path = getResourceUri();
        ObjectHelper.notNull(path, "resourceUri");

        String newResourceUri = exchange.getIn().getHeader(JoltConstants.JOLT_RESOURCE_URI, String.class);
        if (newResourceUri != null) {
            exchange.getIn().removeHeader(JoltConstants.JOLT_RESOURCE_URI);

            log.debug("{} set to {} creating new endpoint to handle exchange", JoltConstants.JOLT_RESOURCE_URI, newResourceUri);
            JoltEndpoint newEndpoint = findOrCreateEndpoint(getEndpointUri(), newResourceUri);
            newEndpoint.onExchange(exchange);
            return;
        }
        Object input;
        if (getInputType() == JoltInputOutputType.JsonString) {
            input = JsonUtils.jsonToObject(exchange.getIn().getBody(InputStream.class));
        } else {
            input = exchange.getIn().getBody();
        }
        Object output = getTransform().transform(input);
                
        // now lets output the results to the exchange
        Message out = exchange.getOut();
        if (getOutputType() == JoltInputOutputType.JsonString) {
            out.setBody(JsonUtils.toJsonString(output));
        } else {
            out.setBody(output);
        }
        out.setHeaders(exchange.getIn().getHeaders());
        out.setAttachments(exchange.getIn().getAttachments());
    }
}