/*=============================================================================#
 # Copyright (c) 2007, 2021 Stephan Wahlbrink and others.
 # 
 # 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, or the Apache License, Version 2.0
 # which is available at https://www.apache.org/licenses/LICENSE-2.0.
 # 
 # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
 # 
 # Contributors:
 #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
 #=============================================================================*/

package org.eclipse.statet.internal.ltk.core;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IExtensionRegistry;
import org.eclipse.core.runtime.Platform;
import org.eclipse.core.runtime.content.IContentType;
import org.eclipse.core.runtime.content.IContentTypeManager;

import org.eclipse.statet.jcommons.collections.ImCollections;
import org.eclipse.statet.jcommons.lang.Disposable;

import org.eclipse.statet.ltk.core.IExtContentTypeManager;


public class ExtContentTypeServices implements IExtContentTypeManager, Disposable {
	
	
	private static boolean matches(IContentType type, final String typeId) {
		while (type != null) {
			if (typeId.equals(type.getId())) {
				return true;
			}
			type= type.getBaseType();
		}
		return false;
	}
	
	private static boolean matches(final String[] ids, final String typeId) {
		for (int i= 0; i < ids.length; i++) {
			if (typeId.equals(ids[i])) {
				return true;
			}
		}
		return false;
	}
	
	private static void add(final Map<String, Set<String>> map, final String key, final String value) {
		Set<String> set= map.get(key);
		if (set == null) {
			set= new HashSet<>();
			map.put(key, set);
		}
		set.add(value);
	}
	
	private static Map<String, String[]> copy(final Map<String, Set<String>> from, final Map<String, String[]> to) {
		for (final Map.Entry<String, Set<String>> entry : from.entrySet()) {
			final Set<String> set= entry.getValue();
			to.put(entry.getKey(), set.toArray(new String[set.size()]));
		}
		return to;
	}
	
	
	private static final String CONFIG_CONTENTTYPEACTIVATION_EXTENSIONPOINT_ID= "org.eclipse.statet.ltk.ContentTypeActivation"; //$NON-NLS-1$
	private static final String CONFIG_CONTENTTYPE_ELEMENT_NAME= "contentType"; //$NON-NLS-1$
	private static final String CONFIG_ID_ATTRIBUTE_NAME= "id"; //$NON-NLS-1$
	private static final String CONFIG_CONTENTTYPE_ID_ATTRIBUTE_NAME= "contentTypeId"; //$NON-NLS-1$
	private static final String CONFIG_SECONDARY_ID_ATTRIBUTE_NAME= "secondaryId"; //$NON-NLS-1$
	private static final String CONFIG_MODELTYPE_ID_ATTRIBUTE_NAME= "modelTypeId"; //$NON-NLS-1$
	
	
	private static final String[] NO_TYPES= new String[0];
	
	
	private Map<String, String[]> primaryToSecondary;
	private Map<String, String[]> secondaryToPrimary;
	private Map<String, String> primaryToModel;
	private Map<String, ModelTypeDescriptorImpl> modelDescriptors;
	
	
	public ExtContentTypeServices() {
		load();
	}
	
	
	private void load() {
		final IExtensionRegistry extensionRegistry= Platform.getExtensionRegistry();
		
		final Map<String, ModelTypeDescriptorImpl> modelTypes= new HashMap<>();
		
		final Map<String, Set<String>> primaryToSecondary= new HashMap<>();
		final Map<String, Set<String>> secondaryToPrimary= new HashMap<>();
		final Map<String, String> primaryToModel= new HashMap<>();
		
		{	final IConfigurationElement[] elements= extensionRegistry
					.getConfigurationElementsFor(CONFIG_CONTENTTYPEACTIVATION_EXTENSIONPOINT_ID); 
			for (final IConfigurationElement element : elements) {
				if (element.getName().equals(CONFIG_CONTENTTYPE_ELEMENT_NAME)) { 
					String primary= element.getAttribute(CONFIG_ID_ATTRIBUTE_NAME); 
					String secondary= element.getAttribute(CONFIG_SECONDARY_ID_ATTRIBUTE_NAME); 
					if (primary != null && secondary != null
							&& primary.length() > 0 && secondary.length() > 0) {
						primary= primary.intern();
						secondary= secondary.intern();
						add(primaryToSecondary, primary, secondary);
						add(secondaryToPrimary, secondary, primary);
					}
				}
			}
		}
		{	final IConfigurationElement[] elements= extensionRegistry
					.getConfigurationElementsFor("org.eclipse.statet.ltk.ModelTypes"); //$NON-NLS-1$
			for (final IConfigurationElement element : elements) {
				if (element.getName().equals("modelType")) { //$NON-NLS-1$
					String id= element.getAttribute(CONFIG_ID_ATTRIBUTE_NAME); 
					if (id != null && !id.isEmpty()) {
						id= id.intern();
						ModelTypeDescriptorImpl descriptor= modelTypes.get(id);
						if (descriptor == null) {
							descriptor= new ModelTypeDescriptorImpl(id);
							modelTypes.put(id, descriptor);
						}
						final IConfigurationElement[] children= element.getChildren();
						for (final IConfigurationElement child : children) {
							if (child.getName().equals("secondaryType")) { //$NON-NLS-1$
								String secondaryId= child.getAttribute(CONFIG_MODELTYPE_ID_ATTRIBUTE_NAME);
								if (secondaryId != null && !secondaryId.isEmpty()) {
									secondaryId= secondaryId.intern();
									if (!descriptor.secondaryTypeIds.contains(secondaryId)) {
										descriptor.secondaryTypeIds.add(secondaryId);
									}
								}
							}
						}
					}
				}
				if (element.getName().equals(CONFIG_CONTENTTYPE_ELEMENT_NAME)) {
					String contentTypeId= element.getAttribute(CONFIG_CONTENTTYPE_ID_ATTRIBUTE_NAME); 
					String modelTypeId= element.getAttribute(CONFIG_MODELTYPE_ID_ATTRIBUTE_NAME); 
					if (contentTypeId != null && !contentTypeId.isEmpty()
							&& modelTypeId != null && !modelTypeId.isEmpty() ) {
						contentTypeId= contentTypeId.intern();
						modelTypeId= modelTypeId.intern();
						primaryToModel.put(contentTypeId, modelTypeId);
					}
				}
			}
		}
		
		checkModelTypes(modelTypes);
		
		this.primaryToSecondary= copy(primaryToSecondary, new HashMap<String, String[]>());
		this.secondaryToPrimary= copy(secondaryToPrimary, new HashMap<String, String[]>());
		this.primaryToModel= primaryToModel;
		this.modelDescriptors= modelTypes;
	}
	
	private static void checkModelTypes(final Map<String, ModelTypeDescriptorImpl> modelTypes) {
		final List<String> temp= new ArrayList<>();
		for (final ModelTypeDescriptorImpl descriptor : modelTypes.values()) {
			synchronized (descriptor) {
				temp.clear();
				for (final String sId : descriptor.secondaryTypeIds) {
					if (modelTypes.containsKey(sId)) {
						temp.add(sId);
					}
				}
				descriptor.checkedSecondaryTypeIds= ImCollections.toList(temp);
			}
		}
	}
	
	
	@Override
	public String[] getSecondaryContentTypes(final String primaryContentType) {
		final String[] types= this.primaryToSecondary.get(primaryContentType);
		return (types != null) ? types : ExtContentTypeServices.NO_TYPES;
	}
	
	@Override
	public String[] getPrimaryContentTypes(final String secondaryContentType) {
		final String[] types= this.secondaryToPrimary.get(secondaryContentType);
		return (types != null) ? types : ExtContentTypeServices.NO_TYPES;
	}
	
	@Override
	public boolean matchesActivatedContentType(final String primaryContentTypeId, final String activatedContentTypeId, final boolean self) {
		final IContentTypeManager manager= Platform.getContentTypeManager();
		final IContentType primaryContentType= manager.getContentType(primaryContentTypeId);
		IContentType primary= primaryContentType;
		if (self &&
				(primary.getId().equals(activatedContentTypeId)
				|| matches(primary, activatedContentTypeId))) {
			return true;
		}
		while (primary != null) {
			final String[] types= getSecondaryContentTypes(primary.getId());
			if (types != null && matches(types, activatedContentTypeId)) {
				return true;
			}
			primary= primary.getBaseType();
		}
		return false;
	}
	
	
	@Override
	public ModelTypeDescriptorImpl getModelType(final String modelTypeId) {
		return (modelTypeId != null) ? this.modelDescriptors.get(modelTypeId) : null;
	}
	
	@Override
	public ModelTypeDescriptorImpl getModelTypeForContentType(final String contentTypeId) {
		return getModelType(this.primaryToModel.get(contentTypeId));
	}
	
	
	@Override
	public void dispose() {
	}
	
}