curator-master/curator-x-async/src/main/java/org/apache/curator/x/async/modeled/details/ZPathImpl.java
/*
 * 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.curator.x.async.modeled.details;

import static org.apache.curator.utils.ZKPaths.PATH_SEPARATOR;
import com.google.common.base.Splitter;
import com.google.common.collect.ImmutableList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.function.UnaryOperator;
import java.util.regex.Pattern;
import java.util.stream.Collectors;
import org.apache.curator.x.async.modeled.NodeName;
import org.apache.curator.x.async.modeled.ZPath;
import org.apache.zookeeper.common.PathUtils;

public class ZPathImpl implements ZPath {
    public static final ZPath root = new ZPathImpl(Collections.singletonList(PATH_SEPARATOR), null);

    private final List<String> nodes;
    private final boolean isResolved;
    private volatile String fullPath = null;
    private volatile ZPath parent = null;
    private volatile Pattern schema = null;

    public static ZPath parse(String fullPath, UnaryOperator<String> nameFilter) {
        return parseInternal(fullPath, nameFilter);
    }

    private static ZPathImpl parseInternal(String fullPath, UnaryOperator<String> nameFilter) {
        List<String> nodes = ImmutableList.<String>builder()
                .add(PATH_SEPARATOR)
                .addAll(Splitter.on(PATH_SEPARATOR).omitEmptyStrings().splitToList(fullPath).stream()
                        .map(nameFilter)
                        .collect(Collectors.toList()))
                .build();
        nodes.forEach(ZPathImpl::validate);
        return new ZPathImpl(nodes, null);
    }

    public static ZPath from(String[] names) {
        return from(null, Arrays.asList(names));
    }

    public static ZPath from(List<String> names) {
        return from(null, names);
    }

    public static ZPath from(ZPath base, String[] names) {
        return from(base, Arrays.asList(names));
    }

    public static ZPath from(ZPath base, List<String> names) {
        names = Objects.requireNonNull(names, "names cannot be null");
        names.forEach(ZPathImpl::validate);
        ImmutableList.Builder<String> builder = ImmutableList.builder();
        if (base != null) {
            if (base instanceof ZPathImpl) {
                builder.addAll(((ZPathImpl) base).nodes);
            } else {
                builder.addAll(Splitter.on(PATH_SEPARATOR).omitEmptyStrings().splitToList(base.fullPath()));
            }
        } else {
            builder.add(PATH_SEPARATOR);
        }
        List<String> nodes = builder.addAll(names).build();
        return new ZPathImpl(nodes, null);
    }

    @Override
    public ZPath child(Object child) {
        return new ZPathImpl(nodes, NodeName.nameFrom(child));
    }

    @Override
    public ZPath parent() {
        checkRootAccess();
        if (parent == null) {
            parent = new ZPathImpl(nodes.subList(0, nodes.size() - 1), null);
        }
        return parent;
    }

    @Override
    public boolean isRoot() {
        return nodes.size() == 1;
    }

    @Override
    public boolean startsWith(ZPath path) {
        ZPathImpl rhs;
        if (path instanceof ZPathImpl) {
            rhs = (ZPathImpl) path;
        } else {
            rhs = parseInternal(path.fullPath(), s -> s);
        }
        return (nodes.size() >= rhs.nodes.size())
                && nodes.subList(0, rhs.nodes.size()).equals(rhs.nodes);
    }

    @Override
    public Pattern toSchemaPathPattern() {
        if (schema == null) {
            schema = Pattern.compile(buildFullPath(s -> isParameter(s) ? ".*" : s));
        }
        return schema;
    }

    @Override
    public String fullPath() {
        checkResolved();
        if (fullPath == null) {
            fullPath = buildFullPath(s -> s);
        }
        return fullPath;
    }

    @Override
    public String nodeName() {
        return nodes.get(nodes.size() - 1);
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }

        ZPathImpl zPaths = (ZPathImpl) o;

        return nodes.equals(zPaths.nodes);
    }

    @Override
    public int hashCode() {
        return nodes.hashCode();
    }

    @Override
    public String toString() {
        return nodes.subList(1, nodes.size()).stream()
                .map(name -> isParameter(name) ? name.substring(1) : name)
                .collect(Collectors.joining(PATH_SEPARATOR, PATH_SEPARATOR, ""));
    }

    @Override
    public ZPath resolved(List<Object> parameters) {
        Iterator<Object> iterator = parameters.iterator();
        List<String> nodeNames = nodes.stream()
                .map(name -> {
                    if (isParameter(name) && iterator.hasNext()) {
                        return NodeName.nameFrom(iterator.next());
                    }
                    return name;
                })
                .collect(Collectors.toList());
        return new ZPathImpl(nodeNames, null);
    }

    @Override
    public boolean isResolved() {
        return isResolved;
    }

    private static boolean isParameter(String name) {
        return (name.length() > 1) && name.startsWith(PATH_SEPARATOR);
    }

    private ZPathImpl(List<String> nodes, String child) {
        ImmutableList.Builder<String> builder = ImmutableList.<String>builder().addAll(nodes);
        if (child != null) {
            validate(child);
            builder.add(child);
        }
        this.nodes = builder.build();
        isResolved = this.nodes.stream().noneMatch(ZPathImpl::isParameter);
    }

    private void checkRootAccess() {
        if (isRoot()) {
            throw new NoSuchElementException("The root has no parent");
        }
    }

    private void checkResolved() {
        if (!isResolved) {
            throw new IllegalStateException("This ZPath has not been resolved: " + toString());
        }
    }

    private static void validate(String nodeName) {
        if (isParameter(Objects.requireNonNull(nodeName, "nodeName cannot be null"))) {
            return;
        }
        if (nodeName.equals(PATH_SEPARATOR)) {
            return;
        }
        PathUtils.validatePath(PATH_SEPARATOR + nodeName);
    }

    private String buildFullPath(UnaryOperator<String> filter) {
        boolean addSeparator = false;
        StringBuilder str = new StringBuilder();
        int size = nodes.size();
        int parameterIndex = 0;
        for (int i = 0; i < size; ++i) {
            if (i > 1) {
                str.append(PATH_SEPARATOR);
            }
            str.append(filter.apply(nodes.get(i)));
        }
        return str.toString();
    }
}
