/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
 */

package org.apache.tinkerpop.gremlin.groovy.jsr223;

import groovy.json.StringEscapeUtils;
import org.apache.commons.configuration.ConfigurationConverter;
import org.apache.tinkerpop.gremlin.process.traversal.Bytecode;
import org.apache.tinkerpop.gremlin.process.traversal.P;
import org.apache.tinkerpop.gremlin.process.traversal.SackFunctions;
import org.apache.tinkerpop.gremlin.process.traversal.Translator;
import org.apache.tinkerpop.gremlin.process.traversal.Traversal;
import org.apache.tinkerpop.gremlin.process.traversal.TraversalSource;
import org.apache.tinkerpop.gremlin.process.traversal.TraversalStrategy;
import org.apache.tinkerpop.gremlin.process.traversal.step.TraversalOptionParent;
import org.apache.tinkerpop.gremlin.process.traversal.strategy.TraversalStrategyProxy;
import org.apache.tinkerpop.gremlin.process.traversal.util.ConnectiveP;
import org.apache.tinkerpop.gremlin.process.traversal.util.OrP;
import org.apache.tinkerpop.gremlin.structure.Edge;
import org.apache.tinkerpop.gremlin.structure.Element;
import org.apache.tinkerpop.gremlin.structure.Vertex;
import org.apache.tinkerpop.gremlin.structure.VertexProperty;
import org.apache.tinkerpop.gremlin.structure.util.StringFactory;
import org.apache.tinkerpop.gremlin.util.function.Lambda;

import java.sql.Timestamp;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import java.util.UUID;
import java.util.function.BinaryOperator;
import java.util.function.Supplier;
import java.util.function.UnaryOperator;

/**
 * Converts bytecode to a Groovy string of Gremlin.
 *
 * @author Marko A. Rodriguez (http://markorodriguez.com)
 * @author Stephen Mallette (http://stephen.genoprime.com)
 */
public final class GroovyTranslator implements Translator.ScriptTranslator {

    private final String traversalSource;
    private final TypeTranslator typeTranslator;

    private GroovyTranslator(final String traversalSource, final TypeTranslator typeTranslator) {
        this.traversalSource = traversalSource;
        this.typeTranslator = typeTranslator;
    }

    public static final GroovyTranslator of(final String traversalSource) {
        return of(traversalSource, TypeTranslator.identity());
    }

    public static final GroovyTranslator of(final String traversalSource, final TypeTranslator typeTranslator) {
        return new GroovyTranslator(traversalSource, Optional.ofNullable(typeTranslator).orElse(TypeTranslator.identity()));
    }

    ///////

    @Override
    public String translate(final Bytecode bytecode) {
        return this.internalTranslate(this.traversalSource, bytecode);
    }

    @Override
    public String getTargetLanguage() {
        return "gremlin-groovy";
    }

    @Override
    public String toString() {
        return StringFactory.translatorString(this);
    }

    @Override
    public String getTraversalSource() {
        return this.traversalSource;
    }

    ///////

    private String internalTranslate(final String start, final Bytecode bytecode) {
        final StringBuilder traversalScript = new StringBuilder(start);
        for (final Bytecode.Instruction instruction : bytecode.getInstructions()) {
            final String methodName = instruction.getOperator();
            if (0 == instruction.getArguments().length)
                traversalScript.append(".").append(methodName).append("()");
            else {
                traversalScript.append(".");
                String temp = methodName + "(";

                // have to special case withSack() for Groovy because UnaryOperator and BinaryOperator signatures
                // make it impossible for the interpreter to figure out which function to call. specifically we need
                // to discern between:
                //     withSack(A initialValue, UnaryOperator<A> splitOperator)
                //     withSack(A initialValue, BinaryOperator<A> splitOperator)
                // and:
                //     withSack(Supplier<A> initialValue, UnaryOperator<A> mergeOperator)
                //     withSack(Supplier<A> initialValue, BinaryOperator<A> mergeOperator)
                if (methodName.equals(TraversalSource.Symbols.withSack) &&
                        instruction.getArguments().length == 2 && instruction.getArguments()[1] instanceof Lambda) {
                    final String castFirstArgTo = instruction.getArguments()[0] instanceof Lambda ?
                            Supplier.class.getName() : "";
                    final Lambda secondArg = (Lambda) instruction.getArguments()[1];
                    final String castSecondArgTo = secondArg.getLambdaArguments() == 1 ? UnaryOperator.class.getName() :
                            BinaryOperator.class.getName();
                    if (!castFirstArgTo.isEmpty())
                        temp = temp + String.format("(%s) ", castFirstArgTo);
                    temp = temp + String.format("%s, (%s) %s,",
                            convertToString(instruction.getArguments()[0]), castSecondArgTo,
                                    convertToString(instruction.getArguments()[1]));
                } else {
                    for (final Object object : instruction.getArguments()) {
                        temp = temp + convertToString(object) + ",";
                    }
                }
                traversalScript.append(temp.substring(0, temp.length() - 1)).append(")");
            }
        }
        return traversalScript.toString();
    }

    private String convertToString(final Object o) {
        // a TypeTranslator that returns Handled means that the typetranslator figure out how to convert the
        // object to a string and it should be used as-is, otherwise it gets passed down the line through the normal
        // process
        final Object object = typeTranslator.apply(o);

        if (object instanceof Handled)
            return ((Handled) object).getTranslation();
        else if (object instanceof Bytecode.Binding)
            return ((Bytecode.Binding) object).variable();
        else if (object instanceof Bytecode)
            return this.internalTranslate("__", (Bytecode) object);
        else if (object instanceof Traversal)
            return convertToString(((Traversal) object).asAdmin().getBytecode());
        else if (object instanceof String) {
            return (((String) object).contains("\"") ? "\"\"\"" + StringEscapeUtils.escapeJava((String) object) + "\"\"\"" : "\"" + StringEscapeUtils.escapeJava((String) object) + "\"")
                    .replace("$", "\\$");
        } else if (object instanceof Set) {
            final Set<String> set = new HashSet<>(((Set) object).size());
            for (final Object item : (Set) object) {
                set.add(convertToString(item));
            }
            return set.toString() + " as Set";
        } else if (object instanceof List) {
            final List<String> list = new ArrayList<>(((List) object).size());
            for (final Object item : (List) object) {
                list.add(convertToString(item));
            }
            return list.toString();
        } else if (object instanceof Map) {
            final StringBuilder map = new StringBuilder("[");
            for (final Map.Entry<?, ?> entry : ((Map<?, ?>) object).entrySet()) {
                map.append("(").
                        append(convertToString(entry.getKey())).
                        append("):(").
                        append(convertToString(entry.getValue())).
                        append("),");
            }

            // only need to remove this last bit if entries were added
            if (!((Map<?, ?>) object).isEmpty())
                map.deleteCharAt(map.length() - 1);

            return map.append("]").toString();
        } else if (object instanceof Long)
            return object + "L";
        else if (object instanceof Double)
            return object + "d";
        else if (object instanceof Float)
            return object + "f";
        else if (object instanceof Integer)
            return "(int) " + object;
        else if (object instanceof Class)
            return ((Class) object).getCanonicalName();
        else if (object instanceof Timestamp)
            return "new java.sql.Timestamp(" + ((Timestamp) object).getTime() + ")";
        else if (object instanceof Date)
            return "new java.util.Date(" + ((Date) object).getTime() + ")";
        else if (object instanceof UUID)
            return "java.util.UUID.fromString('" + object.toString() + "')";
        else if (object instanceof P)
            return convertPToString((P) object, new StringBuilder()).toString();
        else if (object instanceof SackFunctions.Barrier)
            return "SackFunctions.Barrier." + object.toString();
        else if (object instanceof VertexProperty.Cardinality)
            return "VertexProperty.Cardinality." + object.toString();
        else if (object instanceof TraversalOptionParent.Pick)
            return "TraversalOptionParent.Pick." + object.toString();
        else if (object instanceof Enum)
            return ((Enum) object).getDeclaringClass().getSimpleName() + "." + object.toString();
        else if (object instanceof Element) {
            if (object instanceof Vertex) {
                final Vertex vertex = (Vertex) object;
                return "new org.apache.tinkerpop.gremlin.structure.util.detached.DetachedVertex(" +
                        convertToString(vertex.id()) + "," +
                        convertToString(vertex.label()) + ", Collections.emptyMap())";
            } else if (object instanceof Edge) {
                final Edge edge = (Edge) object;
                return "new org.apache.tinkerpop.gremlin.structure.util.detached.DetachedEdge(" +
                        convertToString(edge.id()) + "," +
                        convertToString(edge.label()) + "," +
                        "Collections.emptyMap()," +
                        convertToString(edge.outVertex().id()) + "," +
                        convertToString(edge.outVertex().label()) + "," +
                        convertToString(edge.inVertex().id()) + "," +
                        convertToString(edge.inVertex().label()) + ")";
            } else {// VertexProperty
                final VertexProperty vertexProperty = (VertexProperty) object;
                return "new org.apache.tinkerpop.gremlin.structure.util.detached.DetachedVertexProperty(" +
                        convertToString(vertexProperty.id()) + "," +
                        convertToString(vertexProperty.label()) + "," +
                        convertToString(vertexProperty.value()) + "," +
                        "Collections.emptyMap()," +
                        convertToString(vertexProperty.element()) + ")";
            }
        } else if (object instanceof Lambda) {
            final String lambdaString = ((Lambda) object).getLambdaScript().trim();
            return lambdaString.startsWith("{") ? lambdaString : "{" + lambdaString + "}";
        } else if (object instanceof TraversalStrategyProxy) {
            final TraversalStrategyProxy proxy = (TraversalStrategyProxy) object;
            if (proxy.getConfiguration().isEmpty())
                return proxy.getStrategyClass().getCanonicalName() + ".instance()";
            else
                return proxy.getStrategyClass().getCanonicalName() + ".create(new org.apache.commons.configuration.MapConfiguration(" + convertToString(ConfigurationConverter.getMap(proxy.getConfiguration())) + "))";
        } else if (object instanceof TraversalStrategy) {
            return convertToString(new TraversalStrategyProxy(((TraversalStrategy) object)));
        } else
            return null == object ? "null" : object.toString();
    }

    private StringBuilder convertPToString(final P p, final StringBuilder current) {
        if (p instanceof ConnectiveP) {
            final List<P<?>> list = ((ConnectiveP) p).getPredicates();
            for (int i = 0; i < list.size(); i++) {
                convertPToString(list.get(i), current);
                if (i < list.size() - 1)
                    current.append(p instanceof OrP ? ".or(" : ".and(");
            }
            current.append(")");
        } else
            current.append("P.").append(p.getBiPredicate().toString()).append("(").append(convertToString(p.getValue())).append(")");
        return current;
    }
}