/**
 *                                                                            
 * Copyright (c) 2011, 2016 - Loetz GmbH&Co.KG (69115 Heidelberg, Germany)
 *                                                                            
 * 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:   
 * Christophe Loetz (Loetz GmbH&Co.KG) - initial implementation 
 */
 package org.eclipse.osbp.infogrid.services;

import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import org.eclipse.emf.common.util.URI;
import org.eclipse.emf.ecore.EPackage;
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.util.EcoreUtil;
import org.eclipse.emf.ecore.xmi.impl.XMIResourceFactoryImpl;
import org.eclipse.osbp.infogrid.api.IGridSourceCache;
import org.eclipse.osbp.infogrid.model.gridsource.CxGridSource;
import org.eclipse.osbp.infogrid.model.gridsource.CxGridSourceInput;
import org.eclipse.osbp.infogrid.model.gridsource.CxGridSourcePackage;
import org.osgi.service.component.ComponentContext;
import org.osgi.service.component.annotations.Activate;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.Deactivate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Component(immediate = true)
public class GridSourceCache implements IGridSourceCache {

	private static final Logger LOGGER = LoggerFactory
			.getLogger(GridSourceCache.class);

	private ResourceSet resourceSet;
	private static final String URI_PATTERN = "local://%s";

	@Activate
	protected void activate(ComponentContext context) {
		resourceSet = new ResourceSetImpl();

		// do EMF registration
		EPackage.Registry.INSTANCE.put(
				CxGridSourcePackage.eINSTANCE.getNsURI(),
				CxGridSourcePackage.eINSTANCE);
		if (!Resource.Factory.Registry.INSTANCE.getExtensionToFactoryMap()
				.containsKey("gridsource_xmi")) {
			Resource.Factory.Registry.INSTANCE.getExtensionToFactoryMap().put(
					"gridsource_xmi", new XMIResourceFactoryImpl());
		}

	}

	@Deactivate
	protected void deactivate(ComponentContext context) {
		resourceSet.getResources().clear();
		resourceSet = null;
	}

	@Override
	public List<CxGridSource> getAllSources() {
		List<CxGridSource> result = new ArrayList<>();
		for (Resource resource : new ArrayList<>(resourceSet.getResources())) {
			if (resource.getContents().isEmpty()) {
				continue;
			}
			CxGridSource source = (CxGridSource) resource.getContents().get(0);
			if (source == null) {
				continue;
			}

			result.add(EcoreUtil.copy(source));
		}
		return result;
	}

	@Override
	public CxGridSource getSource(String id) {
		if (id == null) {
			return null;
		}
		CxGridSource cxSource = resourceSet.getResources().stream()
				.filter(r -> r.getContents().size() > 0)
				.map(r -> (CxGridSource) r.getContents().get(0)).filter(g -> {
					return id.equals(g.getId());
				}).findFirst().orElse(null);

		return cxSource != null ? EcoreUtil.copy(cxSource) : null;
	}

	@Override
	public List<CxGridSource> getSources(Class<?> inputType) {
		if (inputType == null) {
			return Collections.emptyList();
		}

		List<CxGridSource> result = new ArrayList<>();
		for (Resource resource : new ArrayList<>(resourceSet.getResources())) {
			if (resource.getContents().isEmpty()) {
				continue;
			}
			CxGridSource source = (CxGridSource) resource.getContents().get(0);
			if (source == null) {
				continue;
			}

			if (isFor(source, inputType)) {
				result.add(EcoreUtil.copy(source));
			}
		}

		return result;
	}

	private boolean isFor(CxGridSource source, Class<?> inputType) {
		for (CxGridSourceInput input : source.getInputs()) {
			if (input.getInputTypeFQN() != null
					&& inputType.getCanonicalName().equals(
							input.getInputTypeFQN())) {
				return true;
			}
		}
		return false;
	}

	@Override
	public void registerSources(List<URL> urls) {
		registerModels(urls);
	}

	@Override
	public void unregisterSources(List<URL> urls) {
		unregisterModels(urls);
	}

	@Override
	public void registerSource(CxGridSource source) {
		if (source == null) {
			return;
		}

		if (source.getId() == null) {
			LOGGER.warn("CxGridSource does not contain id. Is skipped!");
			return;
		}

		Resource resource = resourceSet.getResource(
				URI.createURI(createLocalURI(source)), false);
		if (resource == null) {
			resource = resourceSet.createResource(URI
					.createURI(createLocalURI(source)));
			resource.getContents().add(source);
		}
	}

	@Override
	public void unregisterSource(CxGridSource source) {
		if (source == null) {
			return;
		}

		if (source.getId() == null) {
			LOGGER.warn("CxGridSource does not contain id. Is skipped!");
			return;
		}

		Resource resource = resourceSet.getResource(
				URI.createURI(createLocalURI(source)), false);
		if (resource != null) {
			resourceSet.getResources().remove(resource);
		}
	}

	private static String createLocalURI(CxGridSource source) {
		return String.format(URI_PATTERN, source.getId());
	}

	private void registerModels(List<URL> urls) {
		for (URL url : urls) {
			Resource resource = resourceSet.getResource(
					URI.createURI(url.toString()), true);
			try {
				resource.load(null);
			} catch (IOException e) {
				LOGGER.error("{}", e);
			}
		}
	}

	private void unregisterModels(List<URL> urls) {
		for (URL url : urls) {
			Resource resource = resourceSet.getResource(
					URI.createURI(url.toString()), false);
			if (resource != null) {
				resource.unload();
				resourceSet.getResources().remove(resource);
			}
		}
	}
}