/*
 * 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.mdsal.binding.dom.codec.impl;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkState;
import static com.google.common.base.Verify.verify;
import static java.util.Objects.requireNonNull;

import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.collect.ImmutableMap;
import java.io.IOException;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.AbstractMap.SimpleEntry;
import java.util.Collection;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Optional;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import javassist.CannotCompileException;
import javassist.NotFoundException;
import org.eclipse.jdt.annotation.NonNull;
import org.eclipse.jdt.annotation.Nullable;
import org.opendaylight.mdsal.binding.dom.codec.api.BindingCodecTree;
import org.opendaylight.mdsal.binding.dom.codec.api.BindingCodecTreeNode;
import org.opendaylight.mdsal.binding.dom.codec.api.BindingDataObjectCodecTreeNode;
import org.opendaylight.mdsal.binding.dom.codec.impl.NodeCodecContext.CodecContextFactory;
import org.opendaylight.mdsal.binding.dom.codec.loader.CodecClassLoader;
import org.opendaylight.mdsal.binding.dom.codec.loader.StaticClassPool;
import org.opendaylight.mdsal.binding.dom.codec.util.BindingSchemaMapping;
import org.opendaylight.mdsal.binding.generator.util.BindingRuntimeContext;
import org.opendaylight.mdsal.binding.model.api.GeneratedType;
import org.opendaylight.mdsal.binding.spec.reflect.BindingReflections;
import org.opendaylight.yangtools.concepts.Codec;
import org.opendaylight.yangtools.concepts.Delegator;
import org.opendaylight.yangtools.concepts.Immutable;
import org.opendaylight.yangtools.util.ClassLoaderUtils;
import org.opendaylight.yangtools.yang.binding.Action;
import org.opendaylight.yangtools.yang.binding.BindingStreamEventWriter;
import org.opendaylight.yangtools.yang.binding.DataContainer;
import org.opendaylight.yangtools.yang.binding.DataObject;
import org.opendaylight.yangtools.yang.binding.DataObjectSerializer;
import org.opendaylight.yangtools.yang.binding.DataObjectSerializerRegistry;
import org.opendaylight.yangtools.yang.binding.Identifiable;
import org.opendaylight.yangtools.yang.binding.Identifier;
import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
import org.opendaylight.yangtools.yang.binding.Notification;
import org.opendaylight.yangtools.yang.binding.OpaqueObject;
import org.opendaylight.yangtools.yang.common.QName;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
import org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeStreamWriter;
import org.opendaylight.yangtools.yang.model.api.AnyXmlSchemaNode;
import org.opendaylight.yangtools.yang.model.api.DataNodeContainer;
import org.opendaylight.yangtools.yang.model.api.DataSchemaNode;
import org.opendaylight.yangtools.yang.model.api.DocumentedNode.WithStatus;
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.SchemaPath;
import org.opendaylight.yangtools.yang.model.api.TypeDefinition;
import org.opendaylight.yangtools.yang.model.api.TypedDataSchemaNode;
import org.opendaylight.yangtools.yang.model.api.type.IdentityrefTypeDefinition;
import org.opendaylight.yangtools.yang.model.api.type.InstanceIdentifierTypeDefinition;
import org.opendaylight.yangtools.yang.model.api.type.LeafrefTypeDefinition;
import org.opendaylight.yangtools.yang.model.api.type.UnionTypeDefinition;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

final class BindingCodecContext implements CodecContextFactory, BindingCodecTree, DataObjectSerializerRegistry,
        Immutable {
    private final class DataObjectSerializerProxy implements DataObjectSerializer, Delegator<DataObjectStreamer<?>> {
        private final @NonNull DataObjectStreamer<?> delegate;

        DataObjectSerializerProxy(final DataObjectStreamer<?> delegate) {
            this.delegate = requireNonNull(delegate);
        }

        @Override
        public DataObjectStreamer<?> getDelegate() {
            return delegate;
        }

        @Override
        public void serialize(final DataObject obj, final BindingStreamEventWriter stream) throws IOException {
            delegate.serialize(BindingCodecContext.this, obj, stream);
        }
    }

    private static final Logger LOG = LoggerFactory.getLogger(BindingCodecContext.class);

    private final LoadingCache<Class<?>, DataObjectStreamer<?>> streamers = CacheBuilder.newBuilder().build(
        new CacheLoader<Class<?>, DataObjectStreamer<?>>() {
            @Override
            public DataObjectStreamer<?> load(final Class<?> key) throws CannotCompileException, IOException,
                    NotFoundException, ReflectiveOperationException {
                final Class<?> streamer = loader.generateSubclass(DataObjectStreamerCustomizer.CT_DOS, key, "streamer",
                    DataObjectStreamerCustomizer.create(BindingCodecContext.this, key));

                final Field instance = streamer.getDeclaredField(DataObjectStreamerCustomizer.INSTANCE_FIELD);
                return (DataObjectStreamer<?>) instance.get(null);
            }
        });
    private final LoadingCache<Class<?>, DataObjectSerializer> serializers = CacheBuilder.newBuilder().build(
        new CacheLoader<Class<?>, DataObjectSerializer>() {
            @Override
            public DataObjectSerializer load(final Class<?> key) throws ExecutionException {
                return new DataObjectSerializerProxy(streamers.get(key));
            }
        });

    private final @NonNull CodecClassLoader loader = StaticClassPool.createLoader();
    private final InstanceIdentifierCodec instanceIdentifierCodec;
    private final IdentityCodec identityCodec;
    private final BindingNormalizedNodeCodecRegistry registry;
    private final BindingRuntimeContext context;
    private final SchemaRootCodecContext<?> root;

    BindingCodecContext(final BindingRuntimeContext context, final BindingNormalizedNodeCodecRegistry registry) {
        this.context = requireNonNull(context, "Binding Runtime Context is required.");
        this.root = SchemaRootCodecContext.create(this);
        this.identityCodec = new IdentityCodec(context);
        this.instanceIdentifierCodec = new InstanceIdentifierCodec(this);
        this.registry = requireNonNull(registry);
    }

    @Override
    public BindingRuntimeContext getRuntimeContext() {
        return context;
    }

    @Override
    public CodecClassLoader getLoader() {
        return loader;
    }

    InstanceIdentifierCodec getInstanceIdentifierCodec() {
        return instanceIdentifierCodec;
    }

    IdentityCodec getIdentityCodec() {
        return identityCodec;
    }

    @SuppressWarnings({"rawtypes", "unchecked"})
    @Override
    public DataObjectSerializer getEventStreamSerializer(final Class<?> type) {
        return registry.getSerializer((Class) type);
    }

    @Override
    public DataObjectStreamer<?> getDataObjectSerializer(final Class<?> type) {
        return streamers.getUnchecked(type);
    }

    @Override
    public DataObjectSerializer getSerializer(final Class<? extends DataObject> type) {
        return serializers.getUnchecked(type);
    }

    public Entry<YangInstanceIdentifier, BindingStreamEventWriter> newWriter(final InstanceIdentifier<?> path,
            final NormalizedNodeStreamWriter domWriter) {
        final List<YangInstanceIdentifier.PathArgument> yangArgs = new LinkedList<>();
        final DataContainerCodecContext<?,?> codecContext = getCodecContextNode(path, yangArgs);
        return new SimpleEntry<>(YangInstanceIdentifier.create(yangArgs), codecContext.createWriter(domWriter));
    }

    public BindingStreamEventWriter newWriterWithoutIdentifier(final InstanceIdentifier<?> path,
            final NormalizedNodeStreamWriter domWriter) {
        return getCodecContextNode(path, null).createWriter(domWriter);
    }

    BindingStreamEventWriter newRpcWriter(final Class<? extends DataContainer> rpcInputOrOutput,
            final NormalizedNodeStreamWriter domWriter) {
        return root.getRpc(rpcInputOrOutput).createWriter(domWriter);
    }

    BindingStreamEventWriter newNotificationWriter(final Class<? extends Notification> notification,
            final NormalizedNodeStreamWriter domWriter) {
        return root.getNotification(notification).createWriter(domWriter);
    }

    public DataContainerCodecContext<?,?> getCodecContextNode(final InstanceIdentifier<?> binding,
            final List<YangInstanceIdentifier.PathArgument> builder) {
        DataContainerCodecContext<?,?> currentNode = root;
        for (final InstanceIdentifier.PathArgument bindingArg : binding.getPathArguments()) {
            currentNode = currentNode.bindingPathArgumentChild(bindingArg, builder);
            checkArgument(currentNode != null, "Supplied Instance Identifier %s is not valid.", binding);
        }
        return currentNode;
    }

    /**
     * Multi-purpose utility function. Traverse the codec tree, looking for
     * the appropriate codec for the specified {@link YangInstanceIdentifier}.
     * As a side-effect, gather all traversed binding {@link InstanceIdentifier.PathArgument}s
     * into the supplied collection.
     *
     * @param dom {@link YangInstanceIdentifier} which is to be translated
     * @param bindingArguments Collection for traversed path arguments
     * @return Codec for target node, or @null if the node does not have a
     *         binding representation (choice, case, leaf).
     *
     */
    @Nullable BindingDataObjectCodecTreeNode<?> getCodecContextNode(final @NonNull YangInstanceIdentifier dom,
            final @Nullable Collection<InstanceIdentifier.PathArgument> bindingArguments) {
        NodeCodecContext currentNode = root;
        ListNodeCodecContext<?> currentList = null;

        for (final YangInstanceIdentifier.PathArgument domArg : dom.getPathArguments()) {
            checkArgument(currentNode instanceof DataContainerCodecContext,
                "Unexpected child of non-container node %s", currentNode);
            final DataContainerCodecContext<?,?> previous = (DataContainerCodecContext<?, ?>) currentNode;
            final NodeCodecContext nextNode = previous.yangPathArgumentChild(domArg);

            /*
             * List representation in YANG Instance Identifier consists of two
             * arguments: first is list as a whole, second is list as an item so
             * if it is /list it means list as whole, if it is /list/list - it
             * is wildcarded and if it is /list/list[key] it is concrete item,
             * all this variations are expressed in Binding Aware Instance
             * Identifier as Item or IdentifiableItem
             */
            if (currentList != null) {
                checkArgument(currentList == nextNode,
                        "List should be referenced two times in YANG Instance Identifier %s", dom);

                // We entered list, so now we have all information to emit
                // list path using second list argument.
                if (bindingArguments != null) {
                    bindingArguments.add(currentList.getBindingPathArgument(domArg));
                }
                currentList = null;
                currentNode = nextNode;
            } else if (nextNode instanceof ListNodeCodecContext) {
                // We enter list, we do not update current Node yet,
                // since we need to verify
                currentList = (ListNodeCodecContext<?>) nextNode;
            } else if (nextNode instanceof ChoiceNodeCodecContext) {
                // We do not add path argument for choice, since
                // it is not supported by binding instance identifier.
                currentNode = nextNode;
            } else if (nextNode instanceof DataContainerCodecContext) {
                if (bindingArguments != null) {
                    bindingArguments.add(((DataContainerCodecContext<?, ?>) nextNode).getBindingPathArgument(domArg));
                }
                currentNode = nextNode;
            } else if (nextNode instanceof ValueNodeCodecContext) {
                LOG.debug("Instance identifier referencing a leaf is not representable ({})", dom);
                return null;
            }
        }

        // Algorithm ended in list as whole representation
        // we sill need to emit identifier for list
        if (currentNode instanceof ChoiceNodeCodecContext) {
            LOG.debug("Instance identifier targeting a choice is not representable ({})", dom);
            return null;
        }
        if (currentNode instanceof CaseNodeCodecContext) {
            LOG.debug("Instance identifier targeting a case is not representable ({})", dom);
            return null;
        }

        if (currentList != null) {
            if (bindingArguments != null) {
                bindingArguments.add(currentList.getBindingPathArgument(null));
            }
            return currentList;
        }
        if (currentNode != null) {
            verify(currentNode instanceof BindingDataObjectCodecTreeNode, "Illegal return node %s for identifier %s",
                currentNode, dom);
            return (BindingDataObjectCodecTreeNode<?>) currentNode;
        }
        return null;
    }

    NotificationCodecContext<?> getNotificationContext(final SchemaPath notification) {
        return root.getNotification(notification);
    }

    RpcInputCodec<?> getRpcInputCodec(final SchemaPath path) {
        return root.getRpc(path);
    }

    ActionCodecContext getActionCodec(final Class<? extends Action<?, ?, ?>> action) {
        return root.getAction(action);
    }

    @Override
    public ImmutableMap<String, ValueNodeCodecContext> getLeafNodes(final Class<?> parentClass,
            final DataNodeContainer childSchema) {
        final Map<String, DataSchemaNode> getterToLeafSchema = new HashMap<>();
        for (final DataSchemaNode leaf : childSchema.getChildNodes()) {
            // FIXME: support AnyDataSchemaNode, too
            if (leaf instanceof TypedDataSchemaNode || leaf instanceof AnyXmlSchemaNode) {
                getterToLeafSchema.put(BindingSchemaMapping.getGetterMethodName(leaf), leaf);
            }
        }
        return getLeafNodesUsingReflection(parentClass, getterToLeafSchema);
    }

    private ImmutableMap<String, ValueNodeCodecContext> getLeafNodesUsingReflection(final Class<?> parentClass,
            final Map<String, DataSchemaNode> getterToLeafSchema) {
        final Map<String, ValueNodeCodecContext> leaves = new HashMap<>();
        for (final Method method : parentClass.getMethods()) {
            if (method.getParameterCount() == 0) {
                final DataSchemaNode schema = getterToLeafSchema.get(method.getName());

                final ValueNodeCodecContext valueNode;
                if (schema instanceof LeafSchemaNode) {
                    final LeafSchemaNode leafSchema = (LeafSchemaNode) schema;

                    final Class<?> valueType = method.getReturnType();
                    final Codec<Object, Object> codec = getCodec(valueType, leafSchema.getType());
                    valueNode = LeafNodeCodecContext.of(leafSchema, codec, method, valueType,
                        context.getSchemaContext());
                } else if (schema instanceof LeafListSchemaNode) {
                    final Optional<Type> optType = ClassLoaderUtils.getFirstGenericParameter(
                        method.getGenericReturnType());
                    checkState(optType.isPresent(), "Failed to find return type for %s", method);

                    final Class<?> valueType;
                    final Type genericType = optType.get();
                    if (genericType instanceof Class<?>) {
                        valueType = (Class<?>) genericType;
                    } else if (genericType instanceof ParameterizedType) {
                        valueType = (Class<?>) ((ParameterizedType) genericType).getRawType();
                    } else {
                        throw new IllegalStateException("Unexpected return type " + genericType);
                    }

                    final LeafListSchemaNode leafListSchema = (LeafListSchemaNode) schema;
                    final Codec<Object, Object> codec = getCodec(valueType, leafListSchema.getType());
                    valueNode = new LeafSetNodeCodecContext(leafListSchema, codec, method);
                } else if (schema instanceof AnyXmlSchemaNode) {
                    final Class<?> valueType = method.getReturnType();
                    verify(OpaqueObject.class.isAssignableFrom(valueType), "Illegal value type %s", valueType);
                    valueNode = new OpaqueNodeCodecContext.AnyXml<>((AnyXmlSchemaNode) schema, method,
                            valueType.asSubclass(OpaqueObject.class), loader);
                } else {
                    verify(schema == null, "Unhandled schema %s for method %s", schema, method);
                    // We do not have schema for leaf, so we will ignore it (e.g. getClass).
                    continue;
                }

                leaves.put(schema.getQName().getLocalName(), valueNode);
            }
        }
        return ImmutableMap.copyOf(leaves);
    }

    Codec<Object, Object> getCodec(final Class<?> valueType, final TypeDefinition<?> instantiatedType) {
        if (Class.class.equals(valueType)) {
            @SuppressWarnings({ "unchecked", "rawtypes" })
            final Codec<Object, Object> casted = (Codec) identityCodec;
            return casted;
        } else if (InstanceIdentifier.class.equals(valueType)) {
            @SuppressWarnings({ "unchecked", "rawtypes" })
            final Codec<Object, Object> casted = (Codec) instanceIdentifierCodec;
            return casted;
        } else if (BindingReflections.isBindingClass(valueType)) {
            return getCodecForBindingClass(valueType, instantiatedType);
        }
        return ValueTypeCodec.NOOP_CODEC;
    }

    @SuppressWarnings("checkstyle:illegalCatch")
    private Codec<Object, Object> getCodecForBindingClass(final Class<?> valueType, final TypeDefinition<?> typeDef) {
        if (typeDef instanceof IdentityrefTypeDefinition) {
            return ValueTypeCodec.encapsulatedValueCodecFor(valueType, typeDef, identityCodec);
        } else if (typeDef instanceof InstanceIdentifierTypeDefinition) {
            return ValueTypeCodec.encapsulatedValueCodecFor(valueType, typeDef, instanceIdentifierCodec);
        } else if (typeDef instanceof UnionTypeDefinition) {
            final Callable<UnionTypeCodec> unionLoader = UnionTypeCodec.loader(valueType, (UnionTypeDefinition) typeDef,
                this);
            try {
                return unionLoader.call();
            } catch (final Exception e) {
                throw new IllegalStateException("Unable to load codec for " + valueType, e);
            }
        } else if (typeDef instanceof LeafrefTypeDefinition) {
            final Entry<GeneratedType, WithStatus> typeWithSchema = context.getTypeWithSchema(valueType);
            final WithStatus schema = typeWithSchema.getValue();
            checkState(schema instanceof TypeDefinition);
            return getCodec(valueType, (TypeDefinition<?>) schema);
        }
        return ValueTypeCodec.getCodecFor(valueType, typeDef);
    }

    @Override
    public IdentifiableItemCodec getPathArgumentCodec(final Class<?> listClz, final ListSchemaNode schema) {
        final Optional<Class<Identifier<?>>> optIdentifier = ClassLoaderUtils.findFirstGenericArgument(listClz,
                Identifiable.class);
        checkState(optIdentifier.isPresent(), "Failed to find identifier for %s", listClz);

        final Class<Identifier<?>> identifier = optIdentifier.get();
        final Map<QName, ValueContext> valueCtx = new HashMap<>();
        for (final ValueNodeCodecContext leaf : getLeafNodes(identifier, schema).values()) {
            final QName name = leaf.getDomPathArgument().getNodeType();
            valueCtx.put(name, new ValueContext(identifier, leaf));
        }
        return IdentifiableItemCodec.of(schema, identifier, listClz, valueCtx);
    }

    @SuppressWarnings("unchecked")
    @Override
    public <T extends DataObject> BindingDataObjectCodecTreeNode<T> getSubtreeCodec(final InstanceIdentifier<T> path) {
        // TODO Do we need defensive check here?
        return (BindingDataObjectCodecTreeNode<T>) getCodecContextNode(path, null);
    }

    @Override
    public BindingCodecTreeNode getSubtreeCodec(final YangInstanceIdentifier path) {
        return getCodecContextNode(path, null);
    }

    @Override
    public BindingCodecTreeNode getSubtreeCodec(final SchemaPath path) {
        throw new UnsupportedOperationException("Not implemented yet.");
    }
}