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/*
 * Copyright 2015 the original author or authors.
 *
 * 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.
 */

package ratpack.config.internal.source;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.ObjectNode;
import com.fasterxml.jackson.databind.node.TextNode;
import ratpack.config.ConfigSource;
import ratpack.file.FileSystemBinding;
import ratpack.func.Function;
import ratpack.func.Pair;

import java.util.Optional;
import java.util.Properties;
import java.util.stream.Stream;

public abstract class AbstractPropertiesConfigSource implements ConfigSource {
  private final Optional prefix;

  protected AbstractPropertiesConfigSource(Optional prefix) {
    this.prefix = prefix;
  }

  protected abstract Properties loadProperties() throws Exception;

  @Override
  public ObjectNode loadConfigData(ObjectMapper objectMapper, FileSystemBinding fileSystemBinding) throws Exception {
    ObjectNode rootNode = objectMapper.createObjectNode();
    Properties properties = loadProperties();
    Stream> pairs = properties.stringPropertyNames().stream().map(key -> Pair.of(key, properties.getProperty(key)));
    if (prefix.isPresent()) {
      pairs = pairs
        .filter(p -> p.left.startsWith(prefix.get()))
        .map(((Function, Pair>) p -> p.mapLeft(s -> s.substring(prefix.get().length()))).toFunction());
    }
    pairs.forEach(p -> populate(rootNode, p.left, p.right));
    return rootNode;
  }

  private void populate(ObjectNode node, String key, String value) {
    int nextDot = key.indexOf('.');
    int nextOpenBracket = key.indexOf('[');
    boolean hasDelimiter = nextDot != -1;
    boolean hasIndexing = nextOpenBracket != -1;
    if (hasDelimiter && (!hasIndexing || (nextDot < nextOpenBracket))) {
      String fieldName = key.substring(0, nextDot);
      String remainingKey = key.substring(nextDot + 1);
      ObjectNode childNode = (ObjectNode) node.get(fieldName);
      if (childNode == null) {
        childNode = node.putObject(fieldName);
      }
      populate(childNode, remainingKey, value);
    } else if (hasIndexing) {
      int nextCloseBracket = key.indexOf(']', nextOpenBracket + 1);
      if (nextCloseBracket == -1) {
        throw new IllegalArgumentException("Invalid remaining key: " + key);
      }
      String fieldName = key.substring(0, nextOpenBracket);
      int index = Integer.valueOf(key.substring(nextOpenBracket + 1, nextCloseBracket));
      String remainingKey = key.substring(nextCloseBracket + 1);
      ArrayNode arrayNode = (ArrayNode) node.get(fieldName);
      if (arrayNode == null) {
        arrayNode = node.putArray(fieldName);
      }
      padToLength(arrayNode, index + 1);
      if (remainingKey.isEmpty()) {
        arrayNode.set(index, TextNode.valueOf(value));
      } else if (remainingKey.startsWith(".")) {
        remainingKey = remainingKey.substring(1);
        ObjectNode childNode;
        if (arrayNode.hasNonNull(index)) {
          childNode = (ObjectNode) arrayNode.get(index);
        } else {
          childNode = arrayNode.objectNode();
          arrayNode.set(index, childNode);
        }
        populate(childNode, remainingKey, value);
      } else {
        throw new IllegalArgumentException("Unknown key format: " + key);
      }
    } else {
      node.set(key, TextNode.valueOf(value));
    }
  }

  private static void padToLength(ArrayNode arrayNode, int length) {
    while (arrayNode.size() < length) {
      arrayNode.addNull();
    }
  }
}