/*******************************************************************************
 * Copyright (c) 2005, 2017 IBM Corporation and others.
 * 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
 *
 *******************************************************************************/
package org.eclipse.dltk.internal.core.builder;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.IdentityHashMap;
import java.util.List;
import java.util.Map;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.dltk.core.DLTKCore;
import org.eclipse.dltk.core.builder.IScriptBuilder;
import org.eclipse.dltk.utils.NatureExtensionManager;

public class ScriptBuilderManager
		extends NatureExtensionManager<IScriptBuilder> {

	private ScriptBuilderManager() {
		super(LANGUAGE_EXTPOINT, IScriptBuilder.class, "#"); //$NON-NLS-1$
	}

	private final static String LANGUAGE_EXTPOINT = DLTKCore.PLUGIN_ID
			+ ".builder"; //$NON-NLS-1$

	private static ScriptBuilderManager manager = null;

	private synchronized static ScriptBuilderManager getManager() {
		if (manager == null) {
			manager = new ScriptBuilderManager();
		}
		return manager;
	}

	@Override
	protected void registerConfigurationElements(
			IConfigurationElement[] elements, String categoryAttr) {
		super.registerConfigurationElements(elements, categoryAttr);
		for (IConfigurationElement element : elements) {
			if ("disable".equals(element.getName())) { //$NON-NLS-1$
				final String natureId = element.getAttribute(categoryAttr);
				if (natureId != null && natureId.length() != 0) {
					final String className = element.getAttribute("className"); //$NON-NLS-1$
					if (className != null && className.length() != 0) {
						List<String> disable = disabled.get(natureId);
						if (disable == null) {
							disable = new ArrayList<>();
							disabled.put(natureId, disable);
						}
						if (!disable.contains(className)) {
							disable.add(className);
						}
					}
				}
			}
		}
	}

	private Map<String, List<String>> disabled = new HashMap<>();

	@Override
	protected boolean isValidElement(IConfigurationElement element) {
		return "builder".equals(element.getName()); //$NON-NLS-1$
	}

	static int priorityOf(IConfigurationElement element) {
		final String priority = element.getAttribute("priority");
		if (priority != null) {
			try {
				return Integer.parseInt(priority);
			} catch (NumberFormatException e) {
				// ignore & fall thru
			}
		}
		return 0;
	}

	@Override
	protected void initializeDescriptors(List<Object> descriptors) {
		Collections.sort(descriptors, (o1, o2) -> {
			final IConfigurationElement e1 = (IConfigurationElement) o1;
			final IConfigurationElement e2 = (IConfigurationElement) o2;
			return priorityOf(e2) - priorityOf(e1);
		});
	}

	@Override
	protected IScriptBuilder[] filter(IScriptBuilder[] objects,
			String natureId) {
		if (objects != null) {
			final List<String> disable = disabled.get(natureId);
			if (disable != null) {
				final List<IScriptBuilder> output = new ArrayList<>();
				for (IScriptBuilder object : objects) {
					if (!disable.contains(object.getClass().getName())) {
						output.add(object);
					}
				}
				if (!output.isEmpty()) {
					return output.toArray(createArray(output.size()));
				} else {
					return null;
				}
			}
		}
		return objects;
	}

	protected final Map<Object, Integer> priorities = new IdentityHashMap<>();

	@Override
	protected Object createInstanceByDescriptor(Object descriptor)
			throws CoreException {
		final Object instance = super.createInstanceByDescriptor(descriptor);
		priorities.put(instance,
				priorityOf((IConfigurationElement) descriptor));
		return instance;
	}

	@Override
	protected IScriptBuilder[] merge(IScriptBuilder[] all,
			IScriptBuilder[] nature) {
		final IScriptBuilder[] result = super.merge(all, nature);
		Arrays.sort(result, new Comparator<IScriptBuilder>() {
			int priority(IScriptBuilder builder) {
				Integer value = priorities.get(builder);
				return value != null ? value.intValue() : 0;
			}

			@Override
			public int compare(IScriptBuilder o1, IScriptBuilder o2) {
				return priority(o2) - priority(o1);
			}
		});
		return result;
	}

	/**
	 * Return merged with all elements with nature #
	 *
	 * @param natureId
	 * @return
	 * @throws CoreException
	 */
	public static IScriptBuilder[] getScriptBuilders(String natureId) {
		return getManager().getInstances(natureId);
	}

	public static IScriptBuilder[] getAllScriptBuilders() {
		return getManager().getAllInstances();
	}

}