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/*
 * Copyright 2008-present MongoDB, Inc.
 *
 * Licensed 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.
 */

// BasicBSONCallback.java

package org.bson;

import org.bson.types.BSONTimestamp;
import org.bson.types.BasicBSONList;
import org.bson.types.Binary;
import org.bson.types.Code;
import org.bson.types.CodeWScope;
import org.bson.types.Decimal128;
import org.bson.types.MaxKey;
import org.bson.types.MinKey;
import org.bson.types.ObjectId;

import java.util.Date;
import java.util.LinkedList;
import java.util.List;
import java.util.UUID;
import java.util.regex.Pattern;

/**
 * An implementation of {@code BsonCallback} that creates an instance of BSONObject.
 */
public class BasicBSONCallback implements BSONCallback {

    private Object root;
    private final LinkedList stack;
    private final LinkedList nameStack;

    /**
     * Creates a new instance.
     */
    public BasicBSONCallback() {
        stack = new LinkedList<>();
        nameStack = new LinkedList<>();
        reset();
    }

    @Override
    public Object get() {
        return root;
    }

    /**
     * Factory method for creating a new BSONObject.
     *
     * @return a new BasicBSONObject.
     */
    public BSONObject create() {
        return new BasicBSONObject();
    }

    /**
     * Factory method for creating a new BSON List.
     *
     * @return a new BasicBSONList.
     */
    protected BSONObject createList() {
        return new BasicBSONList();
    }

    @Override
    public BSONCallback createBSONCallback() {
        return new BasicBSONCallback();
    }

    /**
     * Helper method to create either a BSON Object or a BSON List depending upon whether the {@code array} parameter is true or not.
     *
     * @param array set to true to create a new BSON List, otherwise will create a new BSONObject
     * @param path  a list of field names to navigate to this field in the document
     * @return the new BSONObject
     */
    public BSONObject create(final boolean array, final List path) {
        return array ? createList() : create();
    }

    @Override
    public void objectStart() {
        if (stack.size() > 0) {
            throw new IllegalStateException("Illegal object beginning in current context.");
        }
        root = create(false, null);
        stack.add((BSONObject) root);
    }

    @Override
    public void objectStart(final String name) {
        nameStack.addLast(name);
        BSONObject o = create(false, nameStack);
        stack.getLast().put(name, o);
        stack.addLast(o);
    }

    @Override
    public Object objectDone() {
        BSONObject o = stack.removeLast();
        if (nameStack.size() > 0) {
            nameStack.removeLast();
        } else if (stack.size() > 0) {
            throw new IllegalStateException("Illegal object end in current context.");
        }

        return o;
    }

    @Override
    public void arrayStart() {
        root = create(true, null);
        stack.add((BSONObject) root);
    }

    @Override
    public void arrayStart(final String name) {
        nameStack.addLast(name);
        BSONObject o = create(true, nameStack);
        stack.getLast().put(name, o);
        stack.addLast(o);
    }

    @Override
    public Object arrayDone() {
        return objectDone();
    }

    @Override
    public void gotNull(final String name) {
        cur().put(name, null);
    }

    @Override
    public void gotUndefined(final String name) {
    }

    @Override
    public void gotMinKey(final String name) {
        cur().put(name, new MinKey());
    }

    @Override
    public void gotMaxKey(final String name) {
        cur().put(name, new MaxKey());
    }

    @Override
    public void gotBoolean(final String name, final boolean value) {
        _put(name, value);
    }

    @Override
    public void gotDouble(final String name, final double value) {
        _put(name, value);
    }

    @Override
    public void gotInt(final String name, final int value) {
        _put(name, value);
    }

    @Override
    public void gotLong(final String name, final long value) {
        _put(name, value);
    }

    @Override
    public void gotDecimal128(final String name, final Decimal128 value) {
        _put(name, value);
    }

    @Override
    public void gotDate(final String name, final long millis) {
        _put(name, new Date(millis));
    }

    @Override
    public void gotRegex(final String name, final String pattern, final String flags) {
        _put(name, Pattern.compile(pattern, BSON.regexFlags(flags)));
    }

    @Override
    public void gotString(final String name, final String value) {
        _put(name, value);
    }

    @Override
    public void gotSymbol(final String name, final String value) {
        _put(name, value);
    }

    @Override
    public void gotTimestamp(final String name, final int time, final int increment) {
        _put(name, new BSONTimestamp(time, increment));
    }

    @Override
    public void gotObjectId(final String name, final ObjectId id) {
        _put(name, id);
    }

    @Override
    public void gotDBRef(final String name, final String namespace, final ObjectId id) {
        _put(name, new BasicBSONObject("$ns", namespace).append("$id", id));
    }

    @Override
    public void gotBinary(final String name, final byte type, final byte[] data) {
        if (type == BSON.B_GENERAL || type == BSON.B_BINARY) {
            _put(name, data);
        } else {
            _put(name, new Binary(type, data));
        }
    }

    @Override
    public void gotUUID(final String name, final long part1, final long part2) {
        _put(name, new UUID(part1, part2));
    }

    @Override
    public void gotCode(final String name, final String code) {
        _put(name, new Code(code));
    }

    @Override
    public void gotCodeWScope(final String name, final String code, final Object scope) {
        _put(name, new CodeWScope(code, (BSONObject) scope));
    }

    /**
     * Puts a new value into the document.
     *
     * @param name  the name of the field
     * @param value the value
     */
    protected void _put(final String name, final Object value) {
        cur().put(name, value);
    }

    /**
     * Gets the current value
     *
     * @return the current value
     */
    protected BSONObject cur() {
        return stack.getLast();
    }

    /**
     * Gets the name of the current field
     *
     * @return the name of the current field.
     */
    protected String curName() {
        return nameStack.peekLast();
    }

    /**
     * Sets the root document for this position
     *
     * @param root the new root document
     */
    protected void setRoot(final Object root) {
        this.root = root;
    }

    /**
     * Returns whether this is the top level or not
     *
     * @return true if there's nothing on the stack, and this is the top level of the document.
     */
    protected boolean isStackEmpty() {
        return stack.size() < 1;
    }

    @Override
    public void reset() {
        root = null;
        stack.clear();
        nameStack.clear();
    }
}