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/*
* Copyright (c) 2020 Oracle and/or its affiliates.
*
* 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 io.helidon.config;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.util.Optional;
import java.util.function.Function;
import io.helidon.config.spi.ConfigNode;
import io.helidon.config.spi.ConfigNode.ObjectNode;
import io.helidon.config.spi.ConfigParser;
import io.helidon.config.spi.ConfigSource;
/**
* A base implementation for config sources, that combines configuration from any type of a config source.
* This class does not directly implement the interfaces - this is left to the implementer of the config source.
* This class provides configuration methods as {@code protected}, so you can make them public in your implementation, to only
* expose methods that must be implemented.
*
* Other methods of the config source interfaces must be implemented by each source as they are data specific,
* such as {@link io.helidon.config.spi.PollableSource#isModified(Object)}.
*
* All other methods return reasonable defaults.
* Config framework analyzes the config source based on interfaces it implements.
*
* @see io.helidon.config.spi.ConfigSource
* @see io.helidon.config.spi.WatchableSource
* @see io.helidon.config.spi.PollableSource
* @see io.helidon.config.spi.ParsableSource
*/
public abstract class AbstractConfigSource extends AbstractSource implements ConfigSource {
private final Optional mediaType;
private final Optional parser;
private final Optional>> mediaTypeMapping;
private final Optional>> parserMapping;
private final boolean mediaMappingSupported;
/**
* Use common data from the builder to setup media type, parser, media type mapping, and
* parser mapping on this instance. Additional common data is handled by
* {@link io.helidon.config.AbstractSource#AbstractSource(AbstractSourceBuilder)}.
*
* @param builder builder used to set up this config source
*/
protected AbstractConfigSource(AbstractConfigSourceBuilder builder) {
super(builder);
this.mediaType = builder.mediaType();
this.parser = builder.parser();
this.mediaTypeMapping = builder.mediaTypeMapping();
this.parserMapping = builder.parserMapping();
this.mediaMappingSupported = mediaTypeMapping.isPresent() || parserMapping.isPresent();
}
/**
* Media type if on eis configured for parsing content of {@link io.helidon.config.spi.ParsableSource}.
* If there is none configured (default), a parser is chosen based on
* {@link io.helidon.config.spi.ConfigParser.Content#mediaType()} - media type detected during load of data.
*
* @return configured media type or empty if none configured
*/
protected Optional mediaType() {
return mediaType;
}
/**
* Config parser if one is configured to use for parsing content of {@link io.helidon.config.spi.ParsableSource}.
* If one is not configured on a source (default), a parser is chosen based on {@link #mediaType()}.
*
* @return a configured parser, or empty if one should be chosen from media type (or if this is not a parsable source)
*/
protected Optional parser() {
return parser;
}
@Override
public String toString() {
return description();
}
ObjectNode processNodeMapping(Function> mediaToParser,
ConfigKeyImpl configKey,
ObjectNode loaded) {
if (!mediaMappingSupported) {
return loaded;
}
return processObject(mediaToParser, configKey, loaded);
}
private ObjectNode processObject(Function> mediaToParser,
ConfigKeyImpl key,
ObjectNode objectNode) {
ObjectNode.Builder builder = ObjectNode.builder();
objectNode.forEach((name, node) -> builder.addNode(name, processNode(mediaToParser, key.child(name), node)));
return builder.build();
}
private ConfigNode processNode(Function> mediaToParser,
ConfigKeyImpl key,
ConfigNode node) {
switch (node.nodeType()) {
case OBJECT:
return processObject(mediaToParser, key, (ObjectNode) node);
case LIST:
return processList(mediaToParser, key, (ConfigNode.ListNode) node);
case VALUE:
return processValue(mediaToParser, key, (ConfigNode.ValueNode) node);
default:
throw new IllegalArgumentException("Unsupported node type: " + node.getClass().getName());
}
}
private ConfigNode.ListNode processList(Function> mediaToParser,
ConfigKeyImpl key,
ConfigNode.ListNode listNode) {
ListNodeBuilderImpl builder = (ListNodeBuilderImpl) ConfigNode.ListNode.builder();
for (int i = 0; i < listNode.size(); i++) {
builder.addNode(processNode(mediaToParser, key.child(Integer.toString(i)), listNode.get(i)));
}
return builder.build();
}
private ConfigNode processValue(Function> mediaToParser,
Config.Key key,
ConfigNode.ValueNode valueNode) {
Optional parser = findParserForKey(mediaToParser, key);
if (parser.isEmpty()) {
return valueNode;
}
ConfigParser found = parser.get();
return found.parse(ConfigParser.Content.builder()
// value node must have a value
.data(toStream(valueNode.get()))
.charset(StandardCharsets.UTF_8)
.build());
}
private InputStream toStream(String string) {
return new ByteArrayInputStream(string.getBytes(StandardCharsets.UTF_8));
}
private Optional findParserForKey(Function> mediaToParser,
Config.Key key) {
// try to find it in parser mapping (explicit parser for a key)
Optional parser = parserMapping.flatMap(it -> it.apply(key));
if (parser.isPresent()) {
return parser;
}
// now based on media type
Optional maybeMedia = mediaTypeMapping.flatMap(it -> it.apply(key));
if (maybeMedia.isEmpty()) {
// no media type configured, return empty
return Optional.empty();
}
String mediaType = maybeMedia.get();
// if media is explicit, parser is required
return Optional.of(mediaToParser.apply(mediaType)
.orElseThrow(() -> new ConfigException("Cannot find parser for media type "
+ mediaType
+ " for key "
+ key
+ " in config source "
+ description())));
}
}