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This module contains the Table/SQL API for writing table programs within the table ecosystem using the Java programming language.
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/*
 * 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.flink.table.operations;

import org.apache.flink.annotation.Internal;
import org.apache.flink.table.catalog.CatalogPartitionSpec;
import org.apache.flink.table.catalog.ResolvedSchema;
import org.apache.flink.table.utils.EncodingUtils;
import org.apache.flink.util.StringUtils;

import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.function.Function;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Collectors;

/** Helper methods for {@link Operation}s. */
@Internal
public class OperationUtils {

    private static final String OPERATION_INDENT = "    ";

    /**
     * Increases indentation for description of string of child {@link Operation}. The input can
     * already contain indentation. This will increase all the indentations by one level.
     *
     * @param item result of {@link Operation#asSummaryString()}
     * @return string with increased indentation
     */
    static String indent(String item) {

        // '([^']|'')*': Matches the escape sequence "'...'" where the content between "'"
        // characters can contain anything except "'" unless its doubled ('').
        //
        // Then each match is checked. If it starts with "'", it's left unchanged
        // (escaped sequence). Otherwise, it replaces newlines within the match with indent.

        Pattern pattern = Pattern.compile("('([^']|'')*')|\\n");
        Matcher matcher = pattern.matcher(item);
        StringBuffer output = new StringBuffer();

        while (matcher.find()) {
            final String group = matcher.group();
            if (group.startsWith("'")) {
                matcher.appendReplacement(output, Matcher.quoteReplacement(group));
            } else {
                String replaced = group.replaceAll("\n", "\n" + OPERATION_INDENT);
                matcher.appendReplacement(output, Matcher.quoteReplacement(replaced));
            }
        }
        matcher.appendTail(output);

        return "\n" + OPERATION_INDENT + output;
    }

    /**
     * Formats a Tree of {@link Operation} in a unified way. It prints all the parameters and adds
     * all children formatted and properly indented in the following lines.
     *
     * The format is
     *
     * 
{@code
     * : [(key1: [value1], key2: [v1, v2])]
     *     
     *          
     *     
     * }
     *
     * @param operationName The operation name.
     * @param parameters The operation's parameters.
     * @param children The operation's children.
     * @param childToString The function to convert child to String.
     * @param  The type of the child.
     * @return String representation of the given operation.
     */
    public static  String formatWithChildren(
            String operationName,
            Map parameters,
            List children,
            Function childToString) {
        String description =
                parameters.entrySet().stream()
                        .map(entry -> formatParameter(entry.getKey(), entry.getValue()))
                        .collect(Collectors.joining(", "));

        final StringBuilder stringBuilder = new StringBuilder();

        stringBuilder.append(operationName).append(":");

        if (!StringUtils.isNullOrWhitespaceOnly(description)) {
            stringBuilder.append(" (").append(description).append(")");
        }

        String childrenDescription =
                children.stream()
                        .map(child -> OperationUtils.indent(childToString.apply(child)))
                        .collect(Collectors.joining());

        return stringBuilder.append(childrenDescription).toString();
    }

    public static String formatSelectColumns(ResolvedSchema schema) {
        return schema.getColumnNames().stream()
                .map(EncodingUtils::escapeIdentifier)
                .collect(Collectors.joining(", "));
    }

    public static String formatParameter(String name, Object value) {
        final StringBuilder stringBuilder = new StringBuilder();
        stringBuilder.append(name);
        stringBuilder.append(": ");
        if (value.getClass().isArray()) {
            stringBuilder.append(Arrays.toString((Object[]) value));
        } else if (value instanceof Collection) {
            stringBuilder.append(value);
        } else {
            stringBuilder.append("[").append(value).append("]");
        }
        return stringBuilder.toString();
    }

    public static String formatProperties(Map properties) {
        return properties.entrySet().stream()
                .map(entry -> formatParameter(entry.getKey(), entry.getValue()))
                .collect(Collectors.joining(", "));
    }

    public static String formatPartitionSpec(CatalogPartitionSpec spec) {
        return formatPartitionSpec(spec.getPartitionSpec());
    }

    public static String formatPartitionSpec(Map spec) {
        return spec.entrySet().stream()
                .map(entry -> entry.getKey() + "=" + entry.getValue())
                .collect(Collectors.joining(", "));
    }

    private OperationUtils() {}
}