/**
 * *******************************************************************************
 * Copyright (c) 2020, 2021 Robert Bosch GmbH.
 * 
 * This program and the accompanying materials are made
 * available under the terms of the Eclipse Public License 2.0
 * which is available at https://www.eclipse.org/legal/epl-2.0/
 * 
 * SPDX-License-Identifier: EPL-2.0
 * 
 * Contributors:
 *     Robert Bosch GmbH - initial API and implementation
 * *******************************************************************************
 */

package org.eclipse.app4mc.slg.config.util;

import java.io.File;
import java.io.IOException;

import org.eclipse.app4mc.slg.config.ConfigModel;
import org.eclipse.app4mc.slg.config.ConfigurationPackage;
import org.eclipse.emf.common.util.EList;
import org.eclipse.emf.common.util.URI;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.ecore.resource.Resource;
import org.eclipse.emf.ecore.resource.ResourceSet;
import org.eclipse.emf.ecore.resource.impl.ResourceSetImpl;
import org.eclipse.emf.ecore.xmi.impl.XMIResourceFactoryImpl;

public final class ConfigurationFileLoader {

	public static ConfigModel loadConfigurationFile(String filePath) {

		ResourceSet resourceSet = new ResourceSetImpl();
		resourceSet.getResourceFactoryRegistry().getExtensionToFactoryMap()
				.put(Resource.Factory.Registry.DEFAULT_EXTENSION, new XMIResourceFactoryImpl());

		resourceSet.getPackageRegistry().put(ConfigurationPackage.eNS_URI, ConfigurationPackage.eINSTANCE);

		File file = new File(filePath);

		try {
			String path = file.getCanonicalPath();
			URI uri = file.isFile() ? URI.createFileURI(path) : URI.createURI(path);
			Resource resource = resourceSet.getResource(uri, true);

			// Validate the contents of the loaded resource.
			//
			EList<EObject> contents = resource.getContents();

			if (! contents.isEmpty()) {
				EObject eObject = contents.get(0);
				if (eObject instanceof ConfigModel) {
					return (ConfigModel) eObject;
				}
			}
		} catch (RuntimeException | IOException exception) {
			throw new IllegalStateException("Error on loading configuration file", exception);
		}

		return null;
	}

}