/*******************************************************************************
 * Copyright (c) 2013, 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 2.0 which
 * accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *   Geneviève Bastien - Initial API and implementation
 *******************************************************************************/

package org.eclipse.tracecompass.internal.tmf.core.analysis;

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

import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.Platform;
import org.eclipse.jdt.annotation.NonNull;
import org.eclipse.tracecompass.tmf.core.analysis.IAnalysisModuleHelper;
import org.eclipse.tracecompass.tmf.core.analysis.IAnalysisModuleSource;
import org.eclipse.tracecompass.tmf.core.analysis.TmfAnalysisModuleHelperConfigElement;

/**
 * Utility class for accessing TMF analysis module extensions from the
 * platform's extensions registry.
 *
 * @author Geneviève Bastien
 */
public final class TmfAnalysisModuleSourceConfigElement implements IAnalysisModuleSource {

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

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

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

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

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

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

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

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

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

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

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

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

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

    /**
     * The mapping of available analysis ID to their corresponding helper
     */
    private final List<IAnalysisModuleHelper> fAnalysisHelpers = new ArrayList<>();

    /**
     * Retrieves all configuration elements from the platform extension registry
     * for the analysis module extension.
     *
     * @return an array of analysis module configuration elements
     */
    public static IConfigurationElement[] getTypeElements() {
        IConfigurationElement[] elements =
                Platform.getExtensionRegistry().getConfigurationElementsFor(TMF_ANALYSIS_TYPE_ID);
        List<IConfigurationElement> typeElements = new LinkedList<>();
        for (IConfigurationElement element : elements) {
            if (element.getName().equals(MODULE_ELEM)) {
                typeElements.add(element);
            }
        }
        return typeElements.toArray(new @NonNull IConfigurationElement[typeElements.size()]);
    }

    /**
     * Constructor
     */
    public TmfAnalysisModuleSourceConfigElement() {
        populateAnalysisList();
    }

    @Override
    public Iterable<IAnalysisModuleHelper> getAnalysisModules() {
        return fAnalysisHelpers;
    }

    private void populateAnalysisList() {
        if (fAnalysisHelpers.isEmpty()) {
            // Populate the analysis module list
            IConfigurationElement[] config = Platform.getExtensionRegistry().getConfigurationElementsFor(TMF_ANALYSIS_TYPE_ID);
            for (IConfigurationElement ce : config) {
                String elementName = ce.getName();
                if (elementName.equals(TmfAnalysisModuleSourceConfigElement.MODULE_ELEM)) {
                    fAnalysisHelpers.add(new TmfAnalysisModuleHelperConfigElement(ce));
                }
            }
        }
    }

}