net.roboconf.dm.templating.internal.helpers.AllHelper.java Source code

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Here is the source code for net.roboconf.dm.templating.internal.helpers.AllHelper.java

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/**
 * Copyright 2013-2017 Linagora, Universit Joseph Fourier, Floralis
 *
 * The present code is developed in the scope of the joint LINAGORA -
 * Universit Joseph Fourier - Floralis research program and is designated
 * as a "Result" pursuant to the terms and conditions of the LINAGORA
 * - Universit Joseph Fourier - Floralis research program. Each copyright
 * holder of Results enumerated here above fully & independently holds complete
 * ownership of the complete Intellectual Property rights applicable to the whole
 * of said Results, and may freely exploit it in any manner which does not infringe
 * the moral rights of the other copyright holders.
 *
 * Licensed 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 net.roboconf.dm.templating.internal.helpers;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.logging.Logger;

import net.roboconf.core.utils.Utils;
import net.roboconf.dm.templating.internal.contexts.ApplicationContextBean;
import net.roboconf.dm.templating.internal.contexts.InstanceContextBean;

import org.apache.commons.lang3.StringUtils;

import com.github.jknack.handlebars.Context;
import com.github.jknack.handlebars.Helper;
import com.github.jknack.handlebars.Options;

/**
 * Helper needed to select all the instances matching a given criterion.
 * @author Pierre Bourret - Universit Joseph Fourier
 */
public class AllHelper implements Helper<Object> {

    public static final String NAME = "all";
    private final Logger logger = Logger.getLogger(getClass().getName());

    /**
     * Selects instances according to a selection path.
     * <p>For example:</p>
     * <pre>
     * {{#all children path="/VM/Apache" installer="script"}}
     *   {{path}}
     * {{/all}}
     * </pre>
     */
    @Override
    public CharSequence apply(final Object computedContext, final Options options) throws IOException {

        // Get parameters
        Object context = options.context.model();
        String componentPath = null;
        if (computedContext instanceof String)
            componentPath = (String) computedContext;

        if (Utils.isEmptyOrWhitespaces(componentPath))
            componentPath = InstanceFilter.JOKER;

        // Process them
        CharSequence result = StringUtils.EMPTY;
        if (context instanceof ApplicationContextBean) {
            // Implicit: all instances of the application.
            result = safeApply(((ApplicationContextBean) context).getInstances(), options, componentPath);

        } else if (context instanceof InstanceContextBean) {
            // Implicit: all descendants of the instance.
            result = safeApply(descendantInstances((InstanceContextBean) context), options, componentPath);

        } else {
            this.logger.warning(
                    "An unexpected context was received: " + (context == null ? null : context.getClass()));
        }

        return result;
    }

    /**
     * Same as above, but with type-safe arguments.
     *
     * @param instances the instances to which this helper is applied.
     * @param options   the options of this helper invocation.
     * @return a string result.
     * @throws IOException if a template cannot be loaded.
     */
    private String safeApply(Collection<InstanceContextBean> instances, Options options, String componentPath)
            throws IOException {

        // Parse the filter.
        String installerName = (String) options.hash.get("installer");
        final InstanceFilter filter = InstanceFilter.createFilter(componentPath, installerName);

        // Apply the filter.
        final Collection<InstanceContextBean> selectedInstances = filter.apply(instances);

        // Apply the content template of the helper to each selected instance.
        final StringBuilder buffer = new StringBuilder();
        final Context parent = options.context;
        int index = 0;
        final int last = selectedInstances.size() - 1;

        for (final InstanceContextBean instance : selectedInstances) {
            final Context current = Context.newBuilder(parent, instance).combine("@index", index)
                    .combine("@first", index == 0 ? "first" : "").combine("@last", index == last ? "last" : "")
                    .combine("@odd", index % 2 == 0 ? "" : "odd").combine("@even", index % 2 == 0 ? "even" : "")
                    .build();

            index++;
            buffer.append(options.fn(current));
        }

        return buffer.toString();
    }

    /**
     * Returns all the descendant instances of the given instance.
     * @param instance the instance which descendants must be retrieved.
     * @return the descendants of the given instance.
     */
    private static Collection<InstanceContextBean> descendantInstances(final InstanceContextBean instance) {

        final Collection<InstanceContextBean> result = new ArrayList<InstanceContextBean>();
        for (final InstanceContextBean child : instance.getChildren()) {
            result.add(child);
            result.addAll(descendantInstances(child));
        }

        return result;
    }
}