package org.eclipse.emf.edapt.cdo.migration;

import java.util.Collection;
import java.util.List;

import org.eclipse.emf.ecore.EAttribute;
import org.eclipse.emf.ecore.EClass;
import org.eclipse.emf.ecore.ENamedElement;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.ecore.EPackage;
import org.eclipse.emf.ecore.EReference;
import org.eclipse.emf.ecore.EStructuralFeature;
import org.eclipse.emf.ecore.EcorePackage;
import org.eclipse.emf.ecore.util.EcoreUtil;
import org.eclipse.emf.edapt.internal.migration.internal.ForwardConverter;
import org.eclipse.emf.edapt.spi.migration.Instance;
import org.eclipse.emf.edapt.spi.migration.ReferenceSlot;

public class StrategyForwardConverter extends ForwardConverter {

	Collection<EPackage> rootPackages;

	public StrategyForwardConverter(Collection<EPackage> ePackages) {
		rootPackages = ePackages;
	}

	@Override
	protected Instance newInstance(EObject eObject, boolean proxy) {

		// Lookup from the metamodel eClass so we have an EClass with
		// a ECoreFactory instead of CDOFactory for objecss.
		final EObject find = find(eObject.eClass());

		if (find instanceof EClass) {
			// EClass eClass = eObject.eClass();
			final Instance element = model.newInstance((EClass) find);
			mapping.put(eObject, element);
			if (proxy) {
				element.setUri(EcoreUtil.getURI(eObject));
			}
			return element;
		}
		return null;
	}

	@Override
	@SuppressWarnings({ "rawtypes", "unchecked" })
	protected void initInstance(EObject eObject) {
		final Instance element = resolve(eObject);
		final EClass c = eObject.eClass();
		for (final EAttribute attribute : c.getEAllAttributes()) {
			if (ignore(attribute)) {
				continue;
			}
			final EObject lookupAttribute = find(attribute);
			if (lookupAttribute instanceof EAttribute) {
				// Get the lookup attribute and set it.
				if (eObject.eIsSet(attribute)) {
					final Object value = eObject.eGet(attribute);
					element.set((EStructuralFeature) lookupAttribute, value);
				}
			}
		}

		for (final EReference reference : c.getEAllReferences()) {
			if (ignore(reference)) {
				continue;
			}

			// Get the lookup attribute and set it.
			final EObject lookupReference = find(reference);

			if (lookupReference instanceof EReference) {
				final Object value = eObject.eGet(reference);
				if (reference.isMany()) {
					final List<EObject> valueEObjects = (List<EObject>) value;
					int index = 0;
					for (final EObject valueEObject : valueEObjects) {
						final Instance valueInstance = resolve(valueEObject);
						if (reference.isUnique()
							&& ((List) element
								.get((EStructuralFeature) lookupReference))
									.contains(valueInstance)) {
							final ReferenceSlot referenceSlot = (ReferenceSlot) element
								.getSlot((EStructuralFeature) lookupReference);
							try {
								referenceSlot.getValues().move(index,
									valueInstance);
								index++;
							} catch (final IndexOutOfBoundsException e) {
								// ignore missing inverse link
							}
						} else {
							element.add((EStructuralFeature) lookupReference,
								index, valueInstance);
							index++;
						}
					}
				} else {
					if (value != null) {
						final EObject valueEObject = (EObject) value;
						final Instance valueInstance = resolve(valueEObject);
						element.set((EStructuralFeature) lookupReference,
							valueInstance);
					}
				}
			}
		}
	}

	/** Find an element in the metamodel created for migration. */
	@SuppressWarnings("unchecked")
	private EObject find(EObject sourceElement) {
		if (sourceElement == EcorePackage.eINSTANCE) {
			return sourceElement;
		}
		final EObject sourceParent = sourceElement.eContainer();
		if (sourceParent == null) {
			final EPackage sourcePackage = (EPackage) sourceElement;
			for (final EPackage targetPackage : rootPackages) {
				if (targetPackage.getNsURI().equals(sourcePackage.getNsURI())) {
					return targetPackage;
				}
			}
			return sourcePackage;
		}
		final EObject targetParent = find(sourceParent);
		if (targetParent == sourceParent) {
			return sourceElement;
		}
		final EReference reference = sourceElement.eContainmentFeature();
		if (reference.isMany()) {

			// CB Doesn't work for CDO! (Not with already loaded resources,
			// turned on the option to emulate Generated packages, but provides
			// Classifiers here in different order....

			final List<EObject> targetChildren = (List<EObject>) targetParent
				.eGet(reference);
			for (final EObject t : targetChildren) {
				if (t instanceof ENamedElement
					&& sourceElement instanceof ENamedElement) {
					if (((ENamedElement) t).getName().equals(
						((ENamedElement) sourceElement).getName())) {
						return t;
					}
				}

			}

			// Fallback to using index ..
			final List<EObject> sourceChildren = (List<EObject>) sourceParent
				.eGet(reference);
			final int index = sourceChildren.indexOf(sourceElement);
			final EObject targetElement = targetChildren.get(index);
			return targetElement;
		}
		final EObject targetElement = (EObject) targetParent.eGet(reference);
		return targetElement;
	}

}