/********************************************************************************
 * Copyright (c) 2015-2019 Contributors to the Eclipse Foundation
 *
 * See the NOTICE file(s) distributed with this work for additional
 * information regarding copyright ownership.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 ********************************************************************************/

package org.eclipse.mdm.api.odsadapter.query;

import static org.eclipse.mdm.api.dflt.model.CatalogAttribute.VATTR_ENUMERATION_NAME;
import static org.eclipse.mdm.api.dflt.model.CatalogAttribute.VATTR_SCALAR_TYPE;
import static org.eclipse.mdm.api.dflt.model.CatalogAttribute.VATTR_SEQUENCE;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.HashSet;
import java.util.Optional;
import java.util.Set;

import org.eclipse.mdm.api.base.adapter.ChildrenStore;
import org.eclipse.mdm.api.base.adapter.Core;
import org.eclipse.mdm.api.base.adapter.DefaultCore;
import org.eclipse.mdm.api.base.adapter.EntityStore;
import org.eclipse.mdm.api.base.model.AxisType;
import org.eclipse.mdm.api.base.model.BaseEntity;
import org.eclipse.mdm.api.base.model.ContextType;
import org.eclipse.mdm.api.base.model.Entity;
import org.eclipse.mdm.api.base.model.EnumRegistry;
import org.eclipse.mdm.api.base.model.Enumeration;
import org.eclipse.mdm.api.base.model.EnumerationValue;
import org.eclipse.mdm.api.base.model.Interpolation;
import org.eclipse.mdm.api.base.model.ScalarType;
import org.eclipse.mdm.api.base.model.SequenceRepresentation;
import org.eclipse.mdm.api.base.model.TypeSpecification;
import org.eclipse.mdm.api.base.model.User;
import org.eclipse.mdm.api.base.model.ValueType;
import org.eclipse.mdm.api.base.model.VersionState;
import org.eclipse.mdm.api.dflt.model.CatalogAttribute;
import org.eclipse.mdm.api.dflt.model.EntityFactory;
import org.eclipse.mdm.api.odsadapter.lookup.config.EntityConfig;
import org.eclipse.mdm.api.odsadapter.lookup.config.EntityConfig.Key;

/**
 * ODS implementation of the {@link EntityFactory}.
 *
 * @since 1.0.0
 * @author Viktor Stoehr, Gigatronik Ingolstadt GmbH
 */
public final class ODSEntityFactory extends EntityFactory {

	// ======================================================================
	// Class variables
	// ======================================================================

	private static final Set<Class<? extends EnumerationValue>> ENUM_CLASSES = new HashSet<>();

	static {
		ENUM_CLASSES.add(ScalarType.class);
		ENUM_CLASSES.add(VersionState.class);
		ENUM_CLASSES.add(Interpolation.class);
		ENUM_CLASSES.add(AxisType.class);
		ENUM_CLASSES.add(SequenceRepresentation.class);
		ENUM_CLASSES.add(TypeSpecification.class);
	}

	// ======================================================================
	// Instance variables
	// ======================================================================

	private final ODSModelManager modelManager;
	private final Optional<User> loggedInUser;

	// ======================================================================
	// Constructors
	// ======================================================================

	/**
	 * Constructor.
	 *
	 * @param modelManager Used to create {@link Core}s.
	 * @param loggedInUser The logged in {@link User}.
	 */
	public ODSEntityFactory(ODSModelManager modelManager, Optional<User> loggedInUser) {
		this.modelManager = modelManager;
		this.loggedInUser = loggedInUser;
	}

	// ======================================================================
	// Public methods
	// ======================================================================

	/**
	 * Extracts the {@link Core} from an {@link Entity} instance. This method
	 * effectively makes access to the Core of a BaseEntity publicly available (by
	 * calling the corresponding protected method of BaseEntityFactory, which is
	 * this class's superclass) to users of ODSEntityFactory.
	 * 
	 * @param entity The {@link Entity} from which to extract the {@link Core}.
	 * @return The entity's {@link Core}.
	 */
	public static Core extract(Entity entity) {
		if (entity instanceof BaseEntity) {
			return getCore((BaseEntity) entity);
		} else {
			throw new IllegalArgumentException("Entity of type '" + entity.getClass().getSimpleName()
					+ "' does not extend '" + BaseEntity.class.getName() + "'");
		}
	}

	/**
	 * Create an instance of a class implementing the {@link Entity} interface with
	 * core as the instance's {@link Core}. This method effectively makes the
	 * protected BaseEntity constructor publicly available (by calling the
	 * corresponding protected method of BaseEntityFactory, which is this class's
	 * superclass) to users of ODSEntityFactory.
	 * 
	 * @param clazz The class to instantiate, must implement the {@link Entity}
	 *              interface.
	 * @param core  The {@link Core} to use for the newly created instance.
	 * @return The newly created instance.
	 */
	@SuppressWarnings("unchecked")
	public <T extends Entity> T createEntity(Class<T> clazz, Core core) {
		if (BaseEntity.class.isAssignableFrom(clazz)) {
			return (T) createBaseEntity(clazz.asSubclass(BaseEntity.class), core);
		} else {
			throw new IllegalArgumentException(
					"Class '" + clazz.getSimpleName() + "' does not extend '" + BaseEntity.class.getName() + "'");
		}

	}

	// ======================================================================
	// Protected methods
	// ======================================================================

	/**
	 * {@inheritDoc}
	 */
	@Override
	protected Optional<User> getLoggedInUser() {
		return loggedInUser;
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	protected <T extends Entity> Core createCore(Class<T> entityClass) {
		return createCore(new Key<>(entityClass));
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	protected <T extends Entity> Core createCore(Class<T> entityClass, ContextType contextType) {
		return createCore(new Key<>(entityClass, contextType));
	}

	/**
	 * {@inheritDoc}
	 */
	public static final EntityStore getMutableStore(BaseEntity entity) {
		return EntityFactory.getMutableStore(entity);
	}

	/**
	 * {@inheritDoc}
	 */
	public static final EntityStore getPermanentStore(BaseEntity entity) {
		return EntityFactory.getPermanentStore(entity);
	}

	/**
	 * {@inheritDoc}
	 */
	public static final ChildrenStore getChildrenStore(BaseEntity entity) {
		return EntityFactory.getChildrenStore(entity);
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	protected <T extends Entity> Core createCore(String name, Class<T> entityClass) {
		EntityConfig<?> entityConfig = modelManager.getEntityConfig(modelManager.getEntityType(name));
		if (!entityClass.equals(entityConfig.getEntityClass())) {
			throw new IllegalArgumentException("Incompatible entity class expected '" + entityClass.getName()
					+ "' but got '" + entityConfig.getEntityClass().getName() + "'");
		}
		Core core = new DefaultCore(entityConfig.getEntityType());
		core.getValues().get(Entity.ATTR_MIMETYPE).set(entityConfig.getMimeType());

		return core;
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	protected void validateEnum(Enumeration<?> enumerationObj) {
		EnumRegistry er = EnumRegistry.getInstance();
		// check if enum is properly registered
		if (er.get(enumerationObj.getName()) == null) {
			throw new IllegalArgumentException("Given enum class '" + enumerationObj.getName() + "' is not supported.");
		}
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	protected <T extends BaseEntity> T createBaseEntity(Class<T> clazz, Core core) {
		try {
			Constructor<T> constructor = clazz.getDeclaredConstructor(Core.class);
			try {
				return constructor.newInstance(core);
			} catch (IllegalAccessException exc) {
				return super.createBaseEntity(clazz, core);
			}
		} catch (NoSuchMethodException | InvocationTargetException | InstantiationException exc) {
			throw new IllegalStateException(exc.getMessage(), exc);
		}
	}

	// ======================================================================
	// Private methods
	// ======================================================================

	/**
	 * Creates a configured {@link Core} for given {@link Key}.
	 *
	 * @param <T> The entity type.
	 * @param key Used as identifier to resolve the {@link EntityConfig}.
	 * @return The created {@code Core} is returned.
	 */
	private <T extends Entity> Core createCore(Key<T> key) {
		EntityConfig<T> entityConfig = modelManager.findEntityConfig(key);
		Core core = new DefaultCore(entityConfig.getEntityType());
		core.getValues().get(Entity.ATTR_MIMETYPE).set(entityConfig.getMimeType());

		if (CatalogAttribute.class.equals(entityConfig.getEntityClass())) {
			core.getValues().put(VATTR_ENUMERATION_NAME, ValueType.STRING.create(VATTR_ENUMERATION_NAME));
			core.getValues().put(VATTR_SCALAR_TYPE,
					ValueType.ENUMERATION.create(EnumRegistry.getInstance().get("ScalarType"), VATTR_SCALAR_TYPE));
			core.getValues().put(VATTR_SEQUENCE, ValueType.BOOLEAN.create(VATTR_SEQUENCE));
		}

		return core;
	}
}