/*******************************************************************************
 * Copyright (c) 2014 École Polytechnique de Montréal
 *
 * All rights reserved. This program and the accompanying materials are
 * made available under the terms of the Eclipse Public License v1.0 which
 * accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *   Geneviève Bastien - Initial API and implementation
 *******************************************************************************/

package fr.inria.linuxtools.tmf.core.analysis;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.InvalidRegistryObjectException;
import org.eclipse.core.runtime.Platform;

import fr.inria.linuxtools.internal.tmf.core.Activator;

/**
 * Utility class for accessing TMF analysis module extensions from the
 * platform's extensions registry and returning the modules' outputs, wrapped as
 * new module listeners.
 *
 * @author Geneviève Bastien
 * @since 3.0
 */
public class TmfAnalysisModuleOutputs {

    /** Extension point ID */
    public static final String TMF_ANALYSIS_TYPE_ID = "fr.inria.linuxtools.tmf.core.analysis"; //$NON-NLS-1$

    /** Extension point element 'output' */
    public static final String OUTPUT_ELEM = "output"; //$NON-NLS-1$

    /** Extension point attribute 'outputClass' */
    public static final String CLASS_ATTR = "class"; //$NON-NLS-1$

    /** Extension point attribute 'id' */
    public static final String ID_ATTR = "id"; //$NON-NLS-1$

    /**
     * Extension point element 'analysisId' to associate the output to a single
     * analysis
     */
    public static final String ANALYSIS_ID_ELEM = "analysisId"; //$NON-NLS-1$

    /**
     * Extension point element 'analysisModuleClass' to associate the output
     * with an analysis module class
     */
    public static final String MODULE_CLASS_ELEM = "analysisModuleClass"; //$NON-NLS-1$

    private TmfAnalysisModuleOutputs() {

    }

    /**
     * Return the analysis module outputs, wrapped as new module listeners,
     * advertised in the extension point, in iterable format.
     *
     * @return List of {@link ITmfNewAnalysisModuleListener}
     */
    public static Iterable<ITmfNewAnalysisModuleListener> getOutputListeners() {
        List<ITmfNewAnalysisModuleListener> newModuleListeners = new ArrayList<>();
        // Get the sources element from the extension point
        IConfigurationElement[] config = Platform.getExtensionRegistry().getConfigurationElementsFor(TMF_ANALYSIS_TYPE_ID);
        for (IConfigurationElement ce : config) {
            String elementName = ce.getName();
            if (elementName.equals(OUTPUT_ELEM)) {
                try {
                    IAnalysisOutput output = (IAnalysisOutput) ce.createExecutableExtension(CLASS_ATTR);
                    ITmfNewAnalysisModuleListener listener = null;
                    for (IConfigurationElement childCe : ce.getChildren()) {
                        if (childCe.getName().equals(ANALYSIS_ID_ELEM)) {
                            listener = new TmfNewAnalysisOutputListener(output, childCe.getAttribute(ID_ATTR), null);
                        } else if (childCe.getName().equals(MODULE_CLASS_ELEM)) {
                            listener = new TmfNewAnalysisOutputListener(output, null, childCe.createExecutableExtension(CLASS_ATTR).getClass().asSubclass(IAnalysisModule.class));
                        }
                    }
                    if (listener != null) {
                        newModuleListeners.add(listener);
                    }
                } catch (InvalidRegistryObjectException | CoreException e) {
                    Activator.logError("Error creating module output listener", e); //$NON-NLS-1$
                }
            }
        }
        return newModuleListeners;
    }
}