/*
 * Copyright (c) 2013 Cisco Systems, Inc. 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.opendaylight.yangtools.yang.data.impl.schema;

import com.google.common.base.Function;
import com.google.common.base.Optional;
import com.google.common.base.Preconditions;
import com.google.common.collect.Collections2;
import com.google.common.collect.Maps;
import com.google.common.collect.Sets;
import java.util.Collections;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import javax.annotation.Nonnull;
import org.opendaylight.yangtools.yang.common.QName;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
import org.opendaylight.yangtools.yang.data.api.schema.AugmentationNode;
import org.opendaylight.yangtools.yang.data.api.schema.DataContainerChild;
import org.opendaylight.yangtools.yang.model.api.AugmentationSchema;
import org.opendaylight.yangtools.yang.model.api.AugmentationTarget;
import org.opendaylight.yangtools.yang.model.api.ChoiceCaseNode;
import org.opendaylight.yangtools.yang.model.api.ChoiceSchemaNode;
import org.opendaylight.yangtools.yang.model.api.DataNodeContainer;
import org.opendaylight.yangtools.yang.model.api.DataSchemaNode;

public final class SchemaUtils {

    private SchemaUtils() {
    }

    /**
     * @param qname - schema node to find
     * @param dataSchemaNode - iterable of schemaNodes to look through
     * @return - schema node with newest revision or absent if no schema node with matching qname is found
     */
    public static final Optional<DataSchemaNode> findFirstSchema(final QName qname, final Iterable<DataSchemaNode> dataSchemaNode) {
        DataSchemaNode sNode = null;
        if (dataSchemaNode != null && qname != null) {
            for (DataSchemaNode dsn : dataSchemaNode) {
                if (qname.isEqualWithoutRevision(dsn.getQName())) {
                    if (sNode == null || sNode.getQName().compareTo(dsn.getQName()) < 0) {
                        sNode = dsn;
                    }
                } else if (dsn instanceof ChoiceSchemaNode) {
                    for (ChoiceCaseNode choiceCase : ((ChoiceSchemaNode) dsn).getCases()) {
                        Optional<DataSchemaNode> foundDsn = findFirstSchema(qname, choiceCase.getChildNodes());
                        if (foundDsn != null && foundDsn.isPresent()) {
                            return foundDsn;
                        }
                    }
                }
            }
        }
        return Optional.fromNullable(sNode);
    }

    public static DataSchemaNode findSchemaForChild(final DataNodeContainer schema, final QName qname) {
        return findSchemaForChild(schema, qname, schema.getChildNodes());
    }

    public static DataSchemaNode findSchemaForChild(final DataNodeContainer schema, final QName qname, final Iterable<DataSchemaNode> childNodes) {
        Optional<DataSchemaNode> childSchema = findFirstSchema(qname, childNodes);
        Preconditions.checkState(childSchema.isPresent(),
                "Unknown child(ren) node(s) detected, identified by: %s, in: %s", qname, schema);
        return childSchema.get();
    }

    public static AugmentationSchema findSchemaForAugment(final AugmentationTarget schema, final Set<QName> qNames) {
        Optional<AugmentationSchema> schemaForAugment = findAugment(schema, qNames);
        Preconditions.checkState(schemaForAugment.isPresent(), "Unknown augmentation node detected, identified by: %s, in: %s",
                qNames, schema);
        return schemaForAugment.get();
    }

    public static AugmentationSchema findSchemaForAugment(final ChoiceSchemaNode schema, final Set<QName> qNames) {
        Optional<AugmentationSchema> schemaForAugment = Optional.absent();

        for (ChoiceCaseNode choiceCaseNode : schema.getCases()) {
            schemaForAugment = findAugment(choiceCaseNode, qNames);
            if(schemaForAugment.isPresent()) {
                break;
            }
        }

        Preconditions.checkState(schemaForAugment.isPresent(), "Unknown augmentation node detected, identified by: %s, in: %s",
                qNames, schema);
        return schemaForAugment.get();
    }

    private static Optional<AugmentationSchema> findAugment(final AugmentationTarget schema, final Set<QName> qNames) {
        for (AugmentationSchema augment : schema.getAvailableAugmentations()) {

            HashSet<QName> qNamesFromAugment = Sets.newHashSet(Collections2.transform(augment.getChildNodes(), new Function<DataSchemaNode, QName>() {
                @Override
                public QName apply(final @Nonnull DataSchemaNode input) {
                    Preconditions.checkNotNull(input);
                    return input.getQName();
                }
            }));

            if(qNamesFromAugment.equals(qNames)) {
                return Optional.of(augment);
            }
        }

        return Optional.absent();
    }

    public static DataSchemaNode findSchemaForChild(final ChoiceSchemaNode schema, final QName childPartialQName) {
        for (ChoiceCaseNode choiceCaseNode : schema.getCases()) {
            Optional<DataSchemaNode> childSchema = findFirstSchema(childPartialQName, choiceCaseNode.getChildNodes());
            if (childSchema.isPresent()) {
                return childSchema.get();
            }
        }


        throw new IllegalStateException(String.format("Unknown child(ren) node(s) detected, identified by: %s, in: %s",
                childPartialQName, schema));
    }

    /**
     * Recursively find all child nodes that come from choices.
     *
     * @return Map with all child nodes, to their most top augmentation
     */
    public static Map<QName, ChoiceSchemaNode> mapChildElementsFromChoices(final DataNodeContainer schema) {
        return mapChildElementsFromChoices(schema, schema.getChildNodes());
    }

    private static Map<QName, ChoiceSchemaNode> mapChildElementsFromChoices(final DataNodeContainer schema, final Iterable<DataSchemaNode> childNodes) {
        Map<QName, ChoiceSchemaNode> mappedChoices = Maps.newLinkedHashMap();

        for (final DataSchemaNode childSchema : childNodes) {
            if (childSchema instanceof ChoiceSchemaNode) {

                if (isFromAugment(schema, childSchema)) {
                    continue;
                }

                for (ChoiceCaseNode choiceCaseNode : ((ChoiceSchemaNode) childSchema).getCases()) {

                    for (QName qName : getChildNodesRecursive(choiceCaseNode)) {
                        mappedChoices.put(qName, (ChoiceSchemaNode) childSchema);
                    }
                }
            }
        }

        return mappedChoices;
    }

    private static boolean isFromAugment(final DataNodeContainer schema, final DataSchemaNode childSchema) {
        if (!(schema instanceof AugmentationTarget)) {
            return false;
        }

        for (AugmentationSchema augmentationSchema : ((AugmentationTarget) schema).getAvailableAugmentations()) {
            if(augmentationSchema.getDataChildByName(childSchema.getQName()) != null) {
                return true;
            }
        }

        return false;
    }

    /**
     * Recursively find all child nodes that come from augmentations.
     *
     * @return Map with all child nodes, to their most top augmentation
     */
    public static Map<QName, AugmentationSchema> mapChildElementsFromAugments(final AugmentationTarget schema) {

        Map<QName, AugmentationSchema> childNodesToAugmentation = Maps.newLinkedHashMap();

        // Find QNames of augmented child nodes
        Map<QName, AugmentationSchema> augments = Maps.newHashMap();
        for (final AugmentationSchema augmentationSchema : schema.getAvailableAugmentations()) {
            for (DataSchemaNode dataSchemaNode : augmentationSchema.getChildNodes()) {
                augments.put(dataSchemaNode.getQName(), augmentationSchema);
            }
        }

        // Augmented nodes have to be looked up directly in augmentationTarget
        // because nodes from augment do not contain nodes from other augmentations
        if (schema instanceof DataNodeContainer) {

            for (DataSchemaNode child : ((DataNodeContainer) schema).getChildNodes()) {
                // If is not augmented child, continue
                if (!(augments.containsKey(child.getQName()))) {
                    continue;
                }

                AugmentationSchema mostTopAugmentation = augments.get(child.getQName());

                // recursively add all child nodes in case of augment, case and choice
                if (child instanceof AugmentationSchema || child instanceof ChoiceCaseNode) {
                    for (QName qName : getChildNodesRecursive((DataNodeContainer) child)) {
                        childNodesToAugmentation.put(qName, mostTopAugmentation);
                    }
                } else if (child instanceof ChoiceSchemaNode) {
                    for (ChoiceCaseNode choiceCaseNode : ((ChoiceSchemaNode) child).getCases()) {
                        for (QName qName : getChildNodesRecursive(choiceCaseNode)) {
                            childNodesToAugmentation.put(qName, mostTopAugmentation);
                        }
                    }
                } else {
                    childNodesToAugmentation.put(child.getQName(), mostTopAugmentation);
                }
            }
        }

        // Choice Node has to map child nodes from all its cases
        if (schema instanceof ChoiceSchemaNode) {
            for (ChoiceCaseNode choiceCaseNode : ((ChoiceSchemaNode) schema).getCases()) {
                if (!(augments.containsKey(choiceCaseNode.getQName()))) {
                    continue;
                }

                for (QName qName : getChildNodesRecursive(choiceCaseNode)) {
                    childNodesToAugmentation.put(qName, augments.get(choiceCaseNode.getQName()));
                }
            }
        }

        return childNodesToAugmentation;
    }

    /**
     * Recursively list all child nodes.
     *
     * In case of choice, augment and cases, step in.
     */
    public static Set<QName> getChildNodesRecursive(final DataNodeContainer nodeContainer) {
        Set<QName> allChildNodes = Sets.newHashSet();

        for (DataSchemaNode childSchema : nodeContainer.getChildNodes()) {
            if(childSchema instanceof ChoiceSchemaNode) {
                for (ChoiceCaseNode choiceCaseNode : ((ChoiceSchemaNode) childSchema).getCases()) {
                    allChildNodes.addAll(getChildNodesRecursive(choiceCaseNode));
                }
            } else if(childSchema instanceof AugmentationSchema || childSchema instanceof ChoiceCaseNode) {
                allChildNodes.addAll(getChildNodesRecursive((DataNodeContainer) childSchema));
            }
            else {
                allChildNodes.add(childSchema.getQName());
            }
        }

        return allChildNodes;
    }

    /**
     * Retrieves real schemas for augmented child node.
     *
     * Schema of the same child node from augment, and directly from target is not the same.
     * Schema of child node from augment is incomplete, therefore its useless for XML/NormalizedNode translation.
     *
     */
    public static Set<DataSchemaNode> getRealSchemasForAugment(final AugmentationTarget targetSchema, final AugmentationSchema augmentSchema) {
        if (!(targetSchema.getAvailableAugmentations().contains(augmentSchema))) {
            return Collections.emptySet();
        }

        Set<DataSchemaNode> realChildNodes = Sets.newHashSet();

        if(targetSchema instanceof DataNodeContainer) {
            realChildNodes = getRealSchemasForAugment((DataNodeContainer)targetSchema, augmentSchema);
        } else if(targetSchema instanceof ChoiceSchemaNode) {
            for (DataSchemaNode dataSchemaNode : augmentSchema.getChildNodes()) {
                for (ChoiceCaseNode choiceCaseNode : ((ChoiceSchemaNode) targetSchema).getCases()) {
                    if(getChildNodesRecursive(choiceCaseNode).contains(dataSchemaNode.getQName())) {
                        realChildNodes.add(choiceCaseNode.getDataChildByName(dataSchemaNode.getQName()));
                    }
                }
            }
        }

        return realChildNodes;
    }

    public static Set<DataSchemaNode> getRealSchemasForAugment(final DataNodeContainer targetSchema,
            final AugmentationSchema augmentSchema) {
        Set<DataSchemaNode> realChildNodes = Sets.newHashSet();
        for (DataSchemaNode dataSchemaNode : augmentSchema.getChildNodes()) {
            DataSchemaNode realChild = targetSchema.getDataChildByName(dataSchemaNode.getQName());
            realChildNodes.add(realChild);
        }
        return realChildNodes;
    }

    public static Optional<ChoiceCaseNode> detectCase(final ChoiceSchemaNode schema, final DataContainerChild<?, ?> child) {
        for (ChoiceCaseNode choiceCaseNode : schema.getCases()) {
            if (child instanceof AugmentationNode
                    && belongsToCaseAugment(choiceCaseNode,
                            (YangInstanceIdentifier.AugmentationIdentifier) child.getIdentifier())) {
                return Optional.of(choiceCaseNode);
            } else if (choiceCaseNode.getDataChildByName(child.getNodeType()) != null) {
                return Optional.of(choiceCaseNode);
            }
        }

        return Optional.absent();
    }

    public static boolean belongsToCaseAugment(final ChoiceCaseNode caseNode, final YangInstanceIdentifier.AugmentationIdentifier childToProcess) {
        for (AugmentationSchema augmentationSchema : caseNode.getAvailableAugmentations()) {

            Set<QName> currentAugmentChildNodes = Sets.newHashSet();
            for (DataSchemaNode dataSchemaNode : augmentationSchema.getChildNodes()) {
                currentAugmentChildNodes.add(dataSchemaNode.getQName());
            }

            if(childToProcess.getPossibleChildNames().equals(currentAugmentChildNodes)){
                return true;
            }
        }

        return false;
    }

    public static YangInstanceIdentifier.AugmentationIdentifier getNodeIdentifierForAugmentation(final AugmentationSchema schema) {
        return new YangInstanceIdentifier.AugmentationIdentifier(getChildQNames(schema));
    }

    public static Set<QName> getChildQNames(final AugmentationSchema schema) {
        Set<QName> qnames = Sets.newHashSet();

        for (DataSchemaNode dataSchemaNode : schema.getChildNodes()) {
            qnames.add(dataSchemaNode.getQName());
        }

        return qnames;
    }
}