/**
 * Copyright (c) 2014 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.controller.sal.restconf.impl;

import com.google.common.base.Function;
import com.google.common.base.Objects;
import com.google.common.base.Preconditions;
import com.google.common.base.Predicate;
import com.google.common.base.Splitter;
import com.google.common.base.Strings;
import com.google.common.collect.BiMap;
import com.google.common.collect.HashBiMap;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Iterables;

import java.io.UnsupportedEncodingException;
import java.net.URI;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.atomic.AtomicReference;

import javax.ws.rs.core.Response.Status;

import org.opendaylight.controller.sal.core.api.mount.MountInstance;
import org.opendaylight.controller.sal.core.api.mount.MountService;
import org.opendaylight.controller.sal.rest.api.Draft02;
import org.opendaylight.controller.sal.rest.impl.RestUtil;
import org.opendaylight.controller.sal.restconf.impl.RestconfError.ErrorTag;
import org.opendaylight.controller.sal.restconf.impl.RestconfError.ErrorType;
import org.opendaylight.yangtools.concepts.Codec;
import org.opendaylight.yangtools.yang.common.QName;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.InstanceIdentifierBuilder;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.NodeIdentifier;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.NodeIdentifierWithPredicates;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.PathArgument;
import org.opendaylight.yangtools.yang.model.api.AnyXmlSchemaNode;
import org.opendaylight.yangtools.yang.model.api.ChoiceCaseNode;
import org.opendaylight.yangtools.yang.model.api.ChoiceNode;
import org.opendaylight.yangtools.yang.model.api.ContainerSchemaNode;
import org.opendaylight.yangtools.yang.model.api.DataNodeContainer;
import org.opendaylight.yangtools.yang.model.api.DataSchemaNode;
import org.opendaylight.yangtools.yang.model.api.GroupingDefinition;
import org.opendaylight.yangtools.yang.model.api.LeafListSchemaNode;
import org.opendaylight.yangtools.yang.model.api.LeafSchemaNode;
import org.opendaylight.yangtools.yang.model.api.ListSchemaNode;
import org.opendaylight.yangtools.yang.model.api.Module;
import org.opendaylight.yangtools.yang.model.api.RpcDefinition;
import org.opendaylight.yangtools.yang.model.api.SchemaContext;
import org.opendaylight.yangtools.yang.model.api.SchemaContextListener;
import org.opendaylight.yangtools.yang.model.api.TypeDefinition;
import org.opendaylight.yangtools.yang.model.api.type.IdentityrefTypeDefinition;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class ControllerContext implements SchemaContextListener {
    private final static Logger LOG = LoggerFactory.getLogger(ControllerContext.class);

    private final static ControllerContext INSTANCE = new ControllerContext();

    private final static String NULL_VALUE = "null";

    private final static String MOUNT_MODULE = "yang-ext";

    private final static String MOUNT_NODE = "mount";

    public final static String MOUNT = "yang-ext:mount";

    private final static String URI_ENCODING_CHAR_SET = "ISO-8859-1";

    private static final Splitter SLASH_SPLITTER = Splitter.on('/');

    private final BiMap<URI, String> uriToModuleName = HashBiMap.<URI, String> create();

    private final Map<String, URI> moduleNameToUri = uriToModuleName.inverse();

    private final AtomicReference<Map<QName, RpcDefinition>> qnameToRpc =
            new AtomicReference<>(Collections.<QName, RpcDefinition>emptyMap());

    private volatile SchemaContext globalSchema;
    private volatile MountService mountService;

    public void setGlobalSchema(final SchemaContext globalSchema) {
        this.globalSchema = globalSchema;
    }

    public void setMountService(final MountService mountService) {
        this.mountService = mountService;
    }

    private ControllerContext() {
    }

    public static ControllerContext getInstance() {
        return ControllerContext.INSTANCE;
    }

    private void checkPreconditions() {
        if (globalSchema == null) {
            throw new RestconfDocumentedException(Status.SERVICE_UNAVAILABLE);
        }
    }

    public void setSchemas(final SchemaContext schemas) {
        this.onGlobalContextUpdated(schemas);
    }

    public InstanceIdWithSchemaNode toInstanceIdentifier(final String restconfInstance) {
        return this.toIdentifier(restconfInstance, false);
    }

    public InstanceIdWithSchemaNode toMountPointIdentifier(final String restconfInstance) {
        return this.toIdentifier(restconfInstance, true);
    }

    private InstanceIdWithSchemaNode toIdentifier(final String restconfInstance, final boolean toMountPointIdentifier) {
        this.checkPreconditions();

        final List<String> pathArgs = urlPathArgsDecode(SLASH_SPLITTER.split(restconfInstance));
        omitFirstAndLastEmptyString(pathArgs);
        if (pathArgs.isEmpty()) {
            return null;
        }

        String first = pathArgs.iterator().next();
        final String startModule = ControllerContext.toModuleName(first);
        if (startModule == null) {
            throw new RestconfDocumentedException("First node in URI has to be in format \"moduleName:nodeName\"",
                    ErrorType.PROTOCOL, ErrorTag.INVALID_VALUE);
        }

        InstanceIdentifierBuilder builder = YangInstanceIdentifier.builder();
        Module latestModule = this.getLatestModule(globalSchema, startModule);
        InstanceIdWithSchemaNode iiWithSchemaNode = this.collectPathArguments(builder, pathArgs, latestModule, null,
                toMountPointIdentifier);

        if (iiWithSchemaNode == null) {
            throw new RestconfDocumentedException("URI has bad format", ErrorType.PROTOCOL, ErrorTag.INVALID_VALUE);
        }

        return iiWithSchemaNode;
    }

    private static List<String> omitFirstAndLastEmptyString(final List<String> list) {
        if (list.isEmpty()) {
            return list;
        }

        String head = list.iterator().next();
        if (head.isEmpty()) {
            list.remove(0);
        }

        if (list.isEmpty()) {
            return list;
        }

        String last = list.get(list.size() - 1);
        if (last.isEmpty()) {
            list.remove(list.size() - 1);
        }

        return list;
    }

    private Module getLatestModule(final SchemaContext schema, final String moduleName) {
        Preconditions.checkArgument(schema != null);
        Preconditions.checkArgument(moduleName != null && !moduleName.isEmpty());

        Predicate<Module> filter = new Predicate<Module>() {
            @Override
            public boolean apply(final Module m) {
                return Objects.equal(m.getName(), moduleName);
            }
        };

        Iterable<Module> modules = Iterables.filter(schema.getModules(), filter);
        return this.filterLatestModule(modules);
    }

    private Module filterLatestModule(final Iterable<Module> modules) {
        Module latestModule = modules.iterator().hasNext() ? modules.iterator().next() : null;
        for (final Module module : modules) {
            if (module.getRevision().after(latestModule.getRevision())) {
                latestModule = module;
            }
        }
        return latestModule;
    }

    public Module findModuleByName(final String moduleName) {
        this.checkPreconditions();
        Preconditions.checkArgument(moduleName != null && !moduleName.isEmpty());
        return this.getLatestModule(globalSchema, moduleName);
    }

    public Module findModuleByName(final MountInstance mountPoint, final String moduleName) {
        Preconditions.checkArgument(moduleName != null && mountPoint != null);

        final SchemaContext mountPointSchema = mountPoint.getSchemaContext();
        return mountPointSchema == null ? null : this.getLatestModule(mountPointSchema, moduleName);
    }

    public Module findModuleByNamespace(final URI namespace) {
        this.checkPreconditions();
        Preconditions.checkArgument(namespace != null);

        final Set<Module> moduleSchemas = globalSchema.findModuleByNamespace(namespace);
        return moduleSchemas == null ? null : this.filterLatestModule(moduleSchemas);
    }

    public Module findModuleByNamespace(final MountInstance mountPoint, final URI namespace) {
        Preconditions.checkArgument(namespace != null && mountPoint != null);

        final SchemaContext mountPointSchema = mountPoint.getSchemaContext();
        Set<Module> moduleSchemas = mountPointSchema == null ? null : mountPointSchema.findModuleByNamespace(namespace);
        return moduleSchemas == null ? null : this.filterLatestModule(moduleSchemas);
    }

    public Module findModuleByNameAndRevision(final QName module) {
        this.checkPreconditions();
        Preconditions.checkArgument(module != null && module.getLocalName() != null && module.getRevision() != null);

        return globalSchema.findModuleByName(module.getLocalName(), module.getRevision());
    }

    public Module findModuleByNameAndRevision(final MountInstance mountPoint, final QName module) {
        this.checkPreconditions();
        Preconditions.checkArgument(module != null && module.getLocalName() != null && module.getRevision() != null
                && mountPoint != null);

        SchemaContext schemaContext = mountPoint.getSchemaContext();
        return schemaContext == null ? null : schemaContext.findModuleByName(module.getLocalName(),
                module.getRevision());
    }

    public DataNodeContainer getDataNodeContainerFor(final YangInstanceIdentifier path) {
        this.checkPreconditions();

        final Iterable<PathArgument> elements = path.getPathArguments();
        PathArgument head = elements.iterator().next();
        final QName startQName = head.getNodeType();
        final Module initialModule = globalSchema.findModuleByNamespaceAndRevision(startQName.getNamespace(),
                startQName.getRevision());
        DataNodeContainer node = initialModule;
        for (final PathArgument element : elements) {
            QName _nodeType = element.getNodeType();
            final DataSchemaNode potentialNode = ControllerContext.childByQName(node, _nodeType);
            if (potentialNode == null || !ControllerContext.isListOrContainer(potentialNode)) {
                return null;
            }
            node = (DataNodeContainer) potentialNode;
        }

        return node;
    }

    public String toFullRestconfIdentifier(final YangInstanceIdentifier path) {
        this.checkPreconditions();

        final Iterable<PathArgument> elements = path.getPathArguments();
        final StringBuilder builder = new StringBuilder();
        PathArgument head = elements.iterator().next();
        final QName startQName = head.getNodeType();
        final Module initialModule = globalSchema.findModuleByNamespaceAndRevision(startQName.getNamespace(),
                startQName.getRevision());
        DataNodeContainer node = initialModule;
        for (final PathArgument element : elements) {
            QName _nodeType = element.getNodeType();
            final DataSchemaNode potentialNode = ControllerContext.childByQName(node, _nodeType);
            if (!ControllerContext.isListOrContainer(potentialNode)) {
                return null;
            }
            node = ((DataNodeContainer) potentialNode);
            builder.append(this.convertToRestconfIdentifier(element, node));
        }

        return builder.toString();
    }

    public String findModuleNameByNamespace(final URI namespace) {
        this.checkPreconditions();

        String moduleName = this.uriToModuleName.get(namespace);
        if (moduleName == null) {
            final Module module = this.findModuleByNamespace(namespace);
            if (module != null) {
                moduleName = module.getName();
                this.uriToModuleName.put(namespace, moduleName);
            }
        }

        return moduleName;
    }

    public String findModuleNameByNamespace(final MountInstance mountPoint, final URI namespace) {
        final Module module = this.findModuleByNamespace(mountPoint, namespace);
        return module == null ? null : module.getName();
    }

    public URI findNamespaceByModuleName(final String moduleName) {
        URI namespace = this.moduleNameToUri.get(moduleName);
        if (namespace == null) {
            Module module = this.findModuleByName(moduleName);
            if (module != null) {
                URI _namespace = module.getNamespace();
                namespace = _namespace;
                this.uriToModuleName.put(namespace, moduleName);
            }
        }
        return namespace;
    }

    public URI findNamespaceByModuleName(final MountInstance mountPoint, final String moduleName) {
        final Module module = this.findModuleByName(mountPoint, moduleName);
        return module == null ? null : module.getNamespace();
    }

    public Set<Module> getAllModules(final MountInstance mountPoint) {
        this.checkPreconditions();

        SchemaContext schemaContext = mountPoint == null ? null : mountPoint.getSchemaContext();
        return schemaContext == null ? null : schemaContext.getModules();
    }

    public Set<Module> getAllModules() {
        this.checkPreconditions();
        return globalSchema.getModules();
    }

    public CharSequence toRestconfIdentifier(final QName qname) {
        this.checkPreconditions();

        String module = this.uriToModuleName.get(qname.getNamespace());
        if (module == null) {
            final Module moduleSchema = globalSchema.findModuleByNamespaceAndRevision(qname.getNamespace(),
                    qname.getRevision());
            if (moduleSchema == null) {
                return null;
            }

            this.uriToModuleName.put(qname.getNamespace(), moduleSchema.getName());
            module = moduleSchema.getName();
        }

        StringBuilder builder = new StringBuilder();
        builder.append(module);
        builder.append(":");
        builder.append(qname.getLocalName());
        return builder.toString();
    }

    public CharSequence toRestconfIdentifier(final MountInstance mountPoint, final QName qname) {
        if (mountPoint == null) {
            return null;
        }

        SchemaContext schemaContext = mountPoint.getSchemaContext();

        final Module moduleSchema = schemaContext.findModuleByNamespaceAndRevision(qname.getNamespace(),
                qname.getRevision());
        if (moduleSchema == null) {
            return null;
        }

        StringBuilder builder = new StringBuilder();
        builder.append(moduleSchema.getName());
        builder.append(":");
        builder.append(qname.getLocalName());
        return builder.toString();
    }

    public Module getRestconfModule() {
        return findModuleByNameAndRevision(Draft02.RestConfModule.IETF_RESTCONF_QNAME);
    }

    public DataSchemaNode getRestconfModuleErrorsSchemaNode() {
        Module restconfModule = getRestconfModule();
        if (restconfModule == null) {
            return null;
        }

        Set<GroupingDefinition> groupings = restconfModule.getGroupings();

        final Predicate<GroupingDefinition> filter = new Predicate<GroupingDefinition>() {
            @Override
            public boolean apply(final GroupingDefinition g) {
                return Objects.equal(g.getQName().getLocalName(), Draft02.RestConfModule.ERRORS_GROUPING_SCHEMA_NODE);
            }
        };

        Iterable<GroupingDefinition> filteredGroups = Iterables.filter(groupings, filter);

        final GroupingDefinition restconfGrouping = Iterables.getFirst(filteredGroups, null);

        List<DataSchemaNode> instanceDataChildrenByName = this.findInstanceDataChildrenByName(restconfGrouping,
                Draft02.RestConfModule.ERRORS_CONTAINER_SCHEMA_NODE);
        return Iterables.getFirst(instanceDataChildrenByName, null);
    }

    public DataSchemaNode getRestconfModuleRestConfSchemaNode(final Module inRestconfModule, final String schemaNodeName) {
        Module restconfModule = inRestconfModule;
        if (restconfModule == null) {
            restconfModule = getRestconfModule();
        }

        if (restconfModule == null) {
            return null;
        }

        Set<GroupingDefinition> groupings = restconfModule.getGroupings();

        final Predicate<GroupingDefinition> filter = new Predicate<GroupingDefinition>() {
            @Override
            public boolean apply(final GroupingDefinition g) {
                return Objects.equal(g.getQName().getLocalName(), Draft02.RestConfModule.RESTCONF_GROUPING_SCHEMA_NODE);
            }
        };

        Iterable<GroupingDefinition> filteredGroups = Iterables.filter(groupings, filter);

        final GroupingDefinition restconfGrouping = Iterables.getFirst(filteredGroups, null);

        List<DataSchemaNode> instanceDataChildrenByName = this.findInstanceDataChildrenByName(restconfGrouping,
                Draft02.RestConfModule.RESTCONF_CONTAINER_SCHEMA_NODE);
        final DataSchemaNode restconfContainer = Iterables.getFirst(instanceDataChildrenByName, null);

        if (Objects.equal(schemaNodeName, Draft02.RestConfModule.OPERATIONS_CONTAINER_SCHEMA_NODE)) {
            List<DataSchemaNode> instances = this.findInstanceDataChildrenByName(
                    ((DataNodeContainer) restconfContainer), Draft02.RestConfModule.OPERATIONS_CONTAINER_SCHEMA_NODE);
            return Iterables.getFirst(instances, null);
        } else if (Objects.equal(schemaNodeName, Draft02.RestConfModule.STREAMS_CONTAINER_SCHEMA_NODE)) {
            List<DataSchemaNode> instances = this.findInstanceDataChildrenByName(
                    ((DataNodeContainer) restconfContainer), Draft02.RestConfModule.STREAMS_CONTAINER_SCHEMA_NODE);
            return Iterables.getFirst(instances, null);
        } else if (Objects.equal(schemaNodeName, Draft02.RestConfModule.STREAM_LIST_SCHEMA_NODE)) {
            List<DataSchemaNode> instances = this.findInstanceDataChildrenByName(
                    ((DataNodeContainer) restconfContainer), Draft02.RestConfModule.STREAMS_CONTAINER_SCHEMA_NODE);
            final DataSchemaNode modules = Iterables.getFirst(instances, null);
            instances = this.findInstanceDataChildrenByName(((DataNodeContainer) modules),
                    Draft02.RestConfModule.STREAM_LIST_SCHEMA_NODE);
            return Iterables.getFirst(instances, null);
        } else if (Objects.equal(schemaNodeName, Draft02.RestConfModule.MODULES_CONTAINER_SCHEMA_NODE)) {
            List<DataSchemaNode> instances = this.findInstanceDataChildrenByName(
                    ((DataNodeContainer) restconfContainer), Draft02.RestConfModule.MODULES_CONTAINER_SCHEMA_NODE);
            return Iterables.getFirst(instances, null);
        } else if (Objects.equal(schemaNodeName, Draft02.RestConfModule.MODULE_LIST_SCHEMA_NODE)) {
            List<DataSchemaNode> instances = this.findInstanceDataChildrenByName(
                    ((DataNodeContainer) restconfContainer), Draft02.RestConfModule.MODULES_CONTAINER_SCHEMA_NODE);
            final DataSchemaNode modules = Iterables.getFirst(instances, null);
            instances = this.findInstanceDataChildrenByName(((DataNodeContainer) modules),
                    Draft02.RestConfModule.MODULE_LIST_SCHEMA_NODE);
            return Iterables.getFirst(instances, null);
        } else if (Objects.equal(schemaNodeName, Draft02.RestConfModule.STREAMS_CONTAINER_SCHEMA_NODE)) {
            List<DataSchemaNode> instances = this.findInstanceDataChildrenByName(
                    ((DataNodeContainer) restconfContainer), Draft02.RestConfModule.STREAMS_CONTAINER_SCHEMA_NODE);
            return Iterables.getFirst(instances, null);
        }

        return null;
    }

    private static DataSchemaNode childByQName(final ChoiceNode container, final QName name) {
        for (final ChoiceCaseNode caze : container.getCases()) {
            final DataSchemaNode ret = ControllerContext.childByQName(caze, name);
            if (ret != null) {
                return ret;
            }
        }

        return null;
    }

    private static DataSchemaNode childByQName(final ChoiceCaseNode container, final QName name) {
        return container.getDataChildByName(name);
    }

    private static DataSchemaNode childByQName(final ContainerSchemaNode container, final QName name) {
        return ControllerContext.dataNodeChildByQName(container, name);
    }

    private static DataSchemaNode childByQName(final ListSchemaNode container, final QName name) {
        return ControllerContext.dataNodeChildByQName(container, name);
    }

    private static DataSchemaNode childByQName(final Module container, final QName name) {
        return ControllerContext.dataNodeChildByQName(container, name);
    }

    private static DataSchemaNode childByQName(final DataSchemaNode container, final QName name) {
        return null;
    }

    private static DataSchemaNode dataNodeChildByQName(final DataNodeContainer container, final QName name) {
        DataSchemaNode ret = container.getDataChildByName(name);
        if (ret == null) {
            for (final DataSchemaNode node : container.getChildNodes()) {
                if ((node instanceof ChoiceCaseNode)) {
                    final ChoiceCaseNode caseNode = ((ChoiceCaseNode) node);
                    DataSchemaNode childByQName = ControllerContext.childByQName(caseNode, name);
                    if (childByQName != null) {
                        return childByQName;
                    }
                }
            }
        }
        return ret;
    }

    private String toUriString(final Object object) throws UnsupportedEncodingException {
        return object == null ? "" : URLEncoder.encode(object.toString(), ControllerContext.URI_ENCODING_CHAR_SET);
    }

    private InstanceIdWithSchemaNode collectPathArguments(final InstanceIdentifierBuilder builder,
            final List<String> strings, final DataNodeContainer parentNode, final MountInstance mountPoint,
            final boolean returnJustMountPoint) {
        Preconditions.<List<String>> checkNotNull(strings);

        if (parentNode == null) {
            return null;
        }

        if (strings.isEmpty()) {
            return new InstanceIdWithSchemaNode(builder.toInstance(), ((DataSchemaNode) parentNode), mountPoint);
        }

        String head = strings.iterator().next();
        final String nodeName = toNodeName(head);
        final String moduleName = ControllerContext.toModuleName(head);

        DataSchemaNode targetNode = null;
        if (!Strings.isNullOrEmpty(moduleName)) {
            if (Objects.equal(moduleName, ControllerContext.MOUNT_MODULE)
                    && Objects.equal(nodeName, ControllerContext.MOUNT_NODE)) {
                if (mountPoint != null) {
                    throw new RestconfDocumentedException("Restconf supports just one mount point in URI.",
                            ErrorType.APPLICATION, ErrorTag.OPERATION_NOT_SUPPORTED);
                }

                if (mountService == null) {
                    throw new RestconfDocumentedException(
                            "MountService was not found. Finding behind mount points does not work.",
                            ErrorType.APPLICATION, ErrorTag.OPERATION_NOT_SUPPORTED);
                }

                final YangInstanceIdentifier partialPath = builder.toInstance();
                final MountInstance mount = mountService.getMountPoint(partialPath);
                if (mount == null) {
                    LOG.debug("Instance identifier to missing mount point: {}", partialPath);
                    throw new RestconfDocumentedException("Mount point does not exist.", ErrorType.PROTOCOL,
                            ErrorTag.UNKNOWN_ELEMENT);
                }

                final SchemaContext mountPointSchema = mount.getSchemaContext();
                if (mountPointSchema == null) {
                    throw new RestconfDocumentedException("Mount point does not contain any schema with modules.",
                            ErrorType.APPLICATION, ErrorTag.UNKNOWN_ELEMENT);
                }

                if (returnJustMountPoint) {
                    YangInstanceIdentifier instance = YangInstanceIdentifier.builder().toInstance();
                    return new InstanceIdWithSchemaNode(instance, mountPointSchema, mount);
                }

                if (strings.size() == 1) {
                    YangInstanceIdentifier instance = YangInstanceIdentifier.builder().toInstance();
                    return new InstanceIdWithSchemaNode(instance, mountPointSchema, mount);
                }

                final String moduleNameBehindMountPoint = toModuleName(strings.get(1));
                if (moduleNameBehindMountPoint == null) {
                    throw new RestconfDocumentedException(
                            "First node after mount point in URI has to be in format \"moduleName:nodeName\"",
                            ErrorType.PROTOCOL, ErrorTag.INVALID_VALUE);
                }

                final Module moduleBehindMountPoint = this
                        .getLatestModule(mountPointSchema, moduleNameBehindMountPoint);
                if (moduleBehindMountPoint == null) {
                    throw new RestconfDocumentedException("\"" + moduleName
                            + "\" module does not exist in mount point.", ErrorType.PROTOCOL, ErrorTag.UNKNOWN_ELEMENT);
                }

                List<String> subList = strings.subList(1, strings.size());
                return this.collectPathArguments(YangInstanceIdentifier.builder(), subList, moduleBehindMountPoint, mount,
                        returnJustMountPoint);
            }

            Module module = null;
            if (mountPoint == null) {
                module = this.getLatestModule(globalSchema, moduleName);
                if (module == null) {
                    throw new RestconfDocumentedException("\"" + moduleName + "\" module does not exist.",
                            ErrorType.PROTOCOL, ErrorTag.UNKNOWN_ELEMENT);
                }
            } else {
                SchemaContext schemaContext = mountPoint.getSchemaContext();
                module = schemaContext == null ? null : this.getLatestModule(schemaContext, moduleName);
                if (module == null) {
                    throw new RestconfDocumentedException("\"" + moduleName
                            + "\" module does not exist in mount point.", ErrorType.PROTOCOL, ErrorTag.UNKNOWN_ELEMENT);
                }
            }

            targetNode = this.findInstanceDataChildByNameAndNamespace(parentNode, nodeName, module.getNamespace());
            if (targetNode == null) {
                throw new RestconfDocumentedException("URI has bad format. Possible reasons:\n" + " 1. \"" + head
                        + "\" was not found in parent data node.\n" + " 2. \"" + head
                        + "\" is behind mount point. Then it should be in format \"/" + MOUNT + "/" + head + "\".",
                        ErrorType.PROTOCOL, ErrorTag.INVALID_VALUE);
            }
        } else {
            final List<DataSchemaNode> potentialSchemaNodes = this.findInstanceDataChildrenByName(parentNode, nodeName);
            if (potentialSchemaNodes.size() > 1) {
                final StringBuilder strBuilder = new StringBuilder();
                for (final DataSchemaNode potentialNodeSchema : potentialSchemaNodes) {
                    strBuilder.append("   ").append(potentialNodeSchema.getQName().getNamespace()).append("\n");
                }

                throw new RestconfDocumentedException(
                        "URI has bad format. Node \""
                                + nodeName
                                + "\" is added as augment from more than one module. "
                                + "Therefore the node must have module name and it has to be in format \"moduleName:nodeName\"."
                                + "\nThe node is added as augment from modules with namespaces:\n"
                                + strBuilder.toString(), ErrorType.PROTOCOL, ErrorTag.INVALID_VALUE);
            }

            if (potentialSchemaNodes.isEmpty()) {
                throw new RestconfDocumentedException("\"" + nodeName + "\" in URI was not found in parent data node",
                        ErrorType.PROTOCOL, ErrorTag.UNKNOWN_ELEMENT);
            }

            targetNode = potentialSchemaNodes.iterator().next();
        }

        if (!ControllerContext.isListOrContainer(targetNode)) {
            throw new RestconfDocumentedException("URI has bad format. Node \"" + head
                    + "\" must be Container or List yang type.", ErrorType.PROTOCOL, ErrorTag.INVALID_VALUE);
        }

        int consumed = 1;
        if ((targetNode instanceof ListSchemaNode)) {
            final ListSchemaNode listNode = ((ListSchemaNode) targetNode);
            final int keysSize = listNode.getKeyDefinition().size();
            if ((strings.size() - consumed) < keysSize) {
                throw new RestconfDocumentedException("Missing key for list \"" + listNode.getQName().getLocalName()
                        + "\".", ErrorType.PROTOCOL, ErrorTag.DATA_MISSING);
            }

            final List<String> uriKeyValues = strings.subList(consumed, consumed + keysSize);
            final HashMap<QName, Object> keyValues = new HashMap<QName, Object>();
            int i = 0;
            for (final QName key : listNode.getKeyDefinition()) {
                {
                    final String uriKeyValue = uriKeyValues.get(i);
                    if (uriKeyValue.equals(NULL_VALUE)) {
                        throw new RestconfDocumentedException("URI has bad format. List \""
                                + listNode.getQName().getLocalName() + "\" cannot contain \"null\" value as a key.",
                                ErrorType.PROTOCOL, ErrorTag.INVALID_VALUE);
                    }

                    this.addKeyValue(keyValues, listNode.getDataChildByName(key), uriKeyValue, mountPoint);
                    i++;
                }
            }

            consumed = consumed + i;
            builder.nodeWithKey(targetNode.getQName(), keyValues);
        } else {
            builder.node(targetNode.getQName());
        }

        if ((targetNode instanceof DataNodeContainer)) {
            final List<String> remaining = strings.subList(consumed, strings.size());
            return this.collectPathArguments(builder, remaining, ((DataNodeContainer) targetNode), mountPoint,
                    returnJustMountPoint);
        }

        return new InstanceIdWithSchemaNode(builder.toInstance(), targetNode, mountPoint);
    }

    public DataSchemaNode findInstanceDataChildByNameAndNamespace(final DataNodeContainer container, final String name,
            final URI namespace) {
        Preconditions.<URI> checkNotNull(namespace);

        final List<DataSchemaNode> potentialSchemaNodes = this.findInstanceDataChildrenByName(container, name);

        Predicate<DataSchemaNode> filter = new Predicate<DataSchemaNode>() {
            @Override
            public boolean apply(final DataSchemaNode node) {
                return Objects.equal(node.getQName().getNamespace(), namespace);
            }
        };

        Iterable<DataSchemaNode> result = Iterables.filter(potentialSchemaNodes, filter);
        return Iterables.getFirst(result, null);
    }

    public List<DataSchemaNode> findInstanceDataChildrenByName(final DataNodeContainer container, final String name) {
        Preconditions.<DataNodeContainer> checkNotNull(container);
        Preconditions.<String> checkNotNull(name);

        List<DataSchemaNode> instantiatedDataNodeContainers = new ArrayList<DataSchemaNode>();
        this.collectInstanceDataNodeContainers(instantiatedDataNodeContainers, container, name);
        return instantiatedDataNodeContainers;
    }

    private void collectInstanceDataNodeContainers(final List<DataSchemaNode> potentialSchemaNodes,
            final DataNodeContainer container, final String name) {

        Predicate<DataSchemaNode> filter = new Predicate<DataSchemaNode>() {
            @Override
            public boolean apply(final DataSchemaNode node) {
                return Objects.equal(node.getQName().getLocalName(), name);
            }
        };

        Iterable<DataSchemaNode> nodes = Iterables.filter(container.getChildNodes(), filter);

        // Can't combine this loop with the filter above because the filter is
        // lazily-applied by Iterables.filter.
        for (final DataSchemaNode potentialNode : nodes) {
            if (this.isInstantiatedDataSchema(potentialNode)) {
                potentialSchemaNodes.add(potentialNode);
            }
        }

        Iterable<ChoiceNode> choiceNodes = Iterables.<ChoiceNode> filter(container.getChildNodes(), ChoiceNode.class);

        final Function<ChoiceNode, Set<ChoiceCaseNode>> choiceFunction = new Function<ChoiceNode, Set<ChoiceCaseNode>>() {
            @Override
            public Set<ChoiceCaseNode> apply(final ChoiceNode node) {
                return node.getCases();
            }
        };

        Iterable<Set<ChoiceCaseNode>> map = Iterables.<ChoiceNode, Set<ChoiceCaseNode>> transform(choiceNodes,
                choiceFunction);

        final Iterable<ChoiceCaseNode> allCases = Iterables.<ChoiceCaseNode> concat(map);
        for (final ChoiceCaseNode caze : allCases) {
            this.collectInstanceDataNodeContainers(potentialSchemaNodes, caze, name);
        }
    }

    public boolean isInstantiatedDataSchema(final DataSchemaNode node) {
        return node instanceof LeafSchemaNode || node instanceof LeafListSchemaNode
                || node instanceof ContainerSchemaNode || node instanceof ListSchemaNode
                || node instanceof AnyXmlSchemaNode;
    }

    private void addKeyValue(final HashMap<QName, Object> map, final DataSchemaNode node, final String uriValue,
            final MountInstance mountPoint) {
        Preconditions.<String> checkNotNull(uriValue);
        Preconditions.checkArgument((node instanceof LeafSchemaNode));

        final String urlDecoded = urlPathArgDecode(uriValue);
        final TypeDefinition<? extends Object> typedef = ((LeafSchemaNode) node).getType();
        Codec<Object, Object> codec = RestCodec.from(typedef, mountPoint);

        Object decoded = codec == null ? null : codec.deserialize(urlDecoded);
        String additionalInfo = "";
        if (decoded == null) {
            TypeDefinition<? extends Object> baseType = RestUtil.resolveBaseTypeFrom(typedef);
            if ((baseType instanceof IdentityrefTypeDefinition)) {
                decoded = this.toQName(urlDecoded);
                additionalInfo = "For key which is of type identityref it should be in format module_name:identity_name.";
            }
        }

        if (decoded == null) {
            throw new RestconfDocumentedException(uriValue + " from URI can't be resolved. " + additionalInfo,
                    ErrorType.PROTOCOL, ErrorTag.INVALID_VALUE);
        }

        map.put(node.getQName(), decoded);
    }

    private static String toModuleName(final String str) {
        final int idx = str.indexOf(':');
        if (idx == -1) {
            return null;
        }

        // Make sure there is only one occurrence
        if (str.indexOf(':', idx + 1) != -1) {
            return null;
        }

        return str.substring(0, idx);
    }

    private static String toNodeName(final String str) {
        final int idx = str.indexOf(':');
        if (idx == -1) {
            return str;
        }

        // Make sure there is only one occurrence
        if (str.indexOf(':', idx + 1) != -1) {
            return str;
        }

        return str.substring(idx + 1);
    }

    private QName toQName(final String name) {
        final String module = toModuleName(name);
        final String node = toNodeName(name);
        final Module m = globalSchema.findModuleByName(module, null);
        return m == null ? null : QName.create(m.getQNameModule(), node);
    }

    private static boolean isListOrContainer(final DataSchemaNode node) {
        return node instanceof ListSchemaNode || node instanceof ContainerSchemaNode;
    }

    public RpcDefinition getRpcDefinition(final String name) {
        final QName validName = this.toQName(name);
        return validName == null ? null : this.qnameToRpc.get().get(validName);
    }

    @Override
    public void onGlobalContextUpdated(final SchemaContext context) {
        if (context != null) {
            final Collection<RpcDefinition> defs = context.getOperations();
            final Map<QName, RpcDefinition> newMap = new HashMap<>(defs.size());

            for (final RpcDefinition operation : defs) {
                newMap.put(operation.getQName(), operation);
            }

            // FIXME: still not completely atomic
            this.qnameToRpc.set(ImmutableMap.copyOf(newMap));
            this.setGlobalSchema(context);
        }
    }

    public static List<String> urlPathArgsDecode(final Iterable<String> strings) {
        try {
            List<String> decodedPathArgs = new ArrayList<String>();
            for (final String pathArg : strings) {
                String _decode = URLDecoder.decode(pathArg, URI_ENCODING_CHAR_SET);
                decodedPathArgs.add(_decode);
            }
            return decodedPathArgs;
        } catch (UnsupportedEncodingException e) {
            throw new RestconfDocumentedException("Invalid URL path '" + strings + "': " + e.getMessage(),
                    ErrorType.PROTOCOL, ErrorTag.INVALID_VALUE);
        }
    }

    public String urlPathArgDecode(final String pathArg) {
        if (pathArg != null) {
            try {
                return URLDecoder.decode(pathArg, URI_ENCODING_CHAR_SET);
            } catch (UnsupportedEncodingException e) {
                throw new RestconfDocumentedException("Invalid URL path arg '" + pathArg + "': " + e.getMessage(),
                        ErrorType.PROTOCOL, ErrorTag.INVALID_VALUE);
            }
        }

        return null;
    }

    private CharSequence convertToRestconfIdentifier(final PathArgument argument, final DataNodeContainer node) {
        if (argument instanceof NodeIdentifier && node instanceof ContainerSchemaNode) {
            return convertToRestconfIdentifier((NodeIdentifier) argument, (ContainerSchemaNode) node);
        } else if (argument instanceof NodeIdentifierWithPredicates && node instanceof ListSchemaNode) {
            return convertToRestconfIdentifier((NodeIdentifierWithPredicates) argument, (ListSchemaNode) node);
        } else if (argument != null && node != null) {
            throw new IllegalArgumentException("Conversion of generic path argument is not supported");
        } else {
            throw new IllegalArgumentException("Unhandled parameter types: "
                    + Arrays.<Object> asList(argument, node).toString());
        }
    }

    private CharSequence convertToRestconfIdentifier(final NodeIdentifier argument, final ContainerSchemaNode node) {
        StringBuilder builder = new StringBuilder();
        builder.append("/");
        QName nodeType = argument.getNodeType();
        builder.append(this.toRestconfIdentifier(nodeType));
        return builder.toString();
    }

    private CharSequence convertToRestconfIdentifier(final NodeIdentifierWithPredicates argument,
            final ListSchemaNode node) {
        QName nodeType = argument.getNodeType();
        final CharSequence nodeIdentifier = this.toRestconfIdentifier(nodeType);
        final Map<QName, Object> keyValues = argument.getKeyValues();

        StringBuilder builder = new StringBuilder();
        builder.append("/");
        builder.append(nodeIdentifier);
        builder.append("/");

        List<QName> keyDefinition = node.getKeyDefinition();
        boolean hasElements = false;
        for (final QName key : keyDefinition) {
            if (!hasElements) {
                hasElements = true;
            } else {
                builder.append("/");
            }

            try {
                builder.append(this.toUriString(keyValues.get(key)));
            } catch (UnsupportedEncodingException e) {
                LOG.error("Error parsing URI: {}", keyValues.get(key), e);
                return null;
            }
        }

        return builder.toString();
    }

    private static DataSchemaNode childByQName(final Object container, final QName name) {
        if (container instanceof ChoiceCaseNode) {
            return childByQName((ChoiceCaseNode) container, name);
        } else if (container instanceof ChoiceNode) {
            return childByQName((ChoiceNode) container, name);
        } else if (container instanceof ContainerSchemaNode) {
            return childByQName((ContainerSchemaNode) container, name);
        } else if (container instanceof ListSchemaNode) {
            return childByQName((ListSchemaNode) container, name);
        } else if (container instanceof DataSchemaNode) {
            return childByQName((DataSchemaNode) container, name);
        } else if (container instanceof Module) {
            return childByQName((Module) container, name);
        } else {
            throw new IllegalArgumentException("Unhandled parameter types: "
                    + Arrays.<Object> asList(container, name).toString());
        }
    }
}