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/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [https://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.neo4j.server.rest.repr;

import java.util.ArrayList;
import java.util.Collection;
import java.util.LinkedList;
import java.util.List;
import org.neo4j.graphdb.ConstraintViolationException;
import org.neo4j.internal.helpers.collection.IterableWrapper;
import org.neo4j.kernel.api.exceptions.Status;
import org.neo4j.server.rest.Neo4jError;

public class ExceptionRepresentation extends MappingRepresentation {
    private final List errors = new LinkedList<>();
    private boolean includeLegacyRepresentation;

    public ExceptionRepresentation(Throwable exception) {
        this(exception, true);
    }

    public ExceptionRepresentation(Throwable exception, boolean includeLegacyRepresentation) {
        super(RepresentationType.EXCEPTION);
        this.errors.add(new Neo4jError(statusCode(exception), exception));
        this.includeLegacyRepresentation = includeLegacyRepresentation;
    }

    @Override
    protected void serialize(MappingSerializer serializer) {
        // For legacy reasons, this actually serializes into two separate formats - the old format, which simply
        // serializes a single exception, and the new format which serializes multiple errors and provides simple
        // status codes.
        if (includeLegacyRepresentation) {
            renderWithLegacyFormat(errors.get(0).cause(), serializer);
        }

        renderWithStatusCodeFormat(serializer);
    }

    private void renderWithStatusCodeFormat(MappingSerializer serializer) {
        serializer.putList("errors", ErrorEntryRepresentation.list(errors));
    }

    private static void renderWithLegacyFormat(Throwable exception, MappingSerializer serializer) {
        String message = exception.getMessage();
        if (message != null) {
            serializer.putString("message", message);
        }
        serializer.putString("exception", exception.getClass().getSimpleName());
        serializer.putString("fullname", exception.getClass().getName());
        StackTraceElement[] trace = exception.getStackTrace();
        if (trace != null) {
            Collection lines = new ArrayList<>(trace.length);
            for (StackTraceElement element : trace) {
                if (element.toString().matches(".*(jetty|jersey|sun\\.reflect|mortbay|javax\\.servlet).*")) {
                    continue;
                }
                lines.add(element.toString());
            }
            serializer.putList("stackTrace", ListRepresentation.string(lines));
        }

        Throwable cause = exception.getCause();
        if (cause != null) {
            serializer.putMapping("cause", new ExceptionRepresentation(cause));
        }
    }

    private static class ErrorEntryRepresentation extends MappingRepresentation {
        private final Neo4jError error;

        ErrorEntryRepresentation(Neo4jError error) {
            super("error-entry");
            this.error = error;
        }

        @Override
        protected void serialize(MappingSerializer serializer) {
            serializer.putString("code", error.status().code().serialize());
            serializer.putString("message", error.getMessage());
        }

        public static ListRepresentation list(Collection errors) {
            return new ListRepresentation(
                    "error-list", new IterableWrapper(errors) {
                        @Override
                        protected ErrorEntryRepresentation underlyingObjectToObject(Neo4jError error) {
                            return new ErrorEntryRepresentation(error);
                        }
                    });
        }
    }

    private static Status statusCode(Throwable current) {
        while (current != null) {
            if (current instanceof Status.HasStatus) {
                return ((Status.HasStatus) current).status();
            }
            if (current instanceof ConstraintViolationException) {
                return Status.Schema.ConstraintValidationFailed;
            }
            current = current.getCause();
        }
        return Status.General.UnknownError;
    }
}