/**

* Copyright 2012-2020 The Feign 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 feign.template;

import feign.Util;

import java.nio.charset.Charset;

import java.util.Collection;

import java.util.Collections;

import java.util.Iterator;

import java.util.LinkedHashSet;

import java.util.List;

import java.util.Map;

import java.util.concurrent.CopyOnWriteArrayList;

import java.util.stream.Collectors;

import java.util.stream.StreamSupport;

/**

* Template for HTTP Headers. Variables that are unresolved are ignored and Literals are not

* encoded.

*/

public final class HeaderTemplate extends Template {

/* cache a copy of the variables for lookup later */

private LinkedHashSet<String> values;

private String name;

public static HeaderTemplate from(String name, List<TemplateChunk> chunks) {

if (name == null || name.isEmpty()) {

throw new IllegalArgumentException("name is required.");

}

if (chunks == null) {

throw new IllegalArgumentException("chunks are required.");

}

return new HeaderTemplate(name, Util.UTF_8, chunks);

}

public static HeaderTemplate create(String name, Iterable<String> values) {

if (name == null || name.isEmpty()) {

throw new IllegalArgumentException("name is required.");

}

if (values == null) {

throw new IllegalArgumentException("values are required");

}

/* construct a uri template from the name and values */

StringBuilder template = new StringBuilder();

template.append(name)

.append(" ");

/* create a comma separated template for the header values */

Iterator<String> iterator = values.iterator();

while (iterator.hasNext()) {

template.append(iterator.next());

if (iterator.hasNext()) {

template.append(",");

}

}

return new HeaderTemplate(template.toString(), name, values, Util.UTF_8);

}

/**

* Append values to a Header Template.

*

* @param headerTemplate to append to.

* @param values to append.

* @return a new Header Template with the values added.

*/

public static HeaderTemplate append(HeaderTemplate headerTemplate, Iterable<String> values) {

LinkedHashSet<String> headerValues = new LinkedHashSet<>(headerTemplate.getValues());

headerValues.addAll(StreamSupport.stream(values.spliterator(), false)

.filter(Util::isNotBlank)

.collect(Collectors.toCollection(LinkedHashSet::new)));

return create(headerTemplate.getName(), headerValues);

}

/**

* Append {@link TemplateChunk} to a Header Template.

*

* @param headerTemplate to append to.

* @param chunks to append.

* @return a new HeaderTemplate with the values added.

*/

public static HeaderTemplate appendFrom(HeaderTemplate headerTemplate,

List<TemplateChunk> chunks) {

List<TemplateChunk> existing = new CopyOnWriteArrayList<>(headerTemplate.getTemplateChunks());

existing.addAll(chunks);

return from(headerTemplate.getName(), existing);

}

/**

* Creates a new Header Template.

*

* @param template to parse.

*/

private HeaderTemplate(String template, String name, Iterable<String> values, Charset charset) {

super(template, ExpansionOptions.REQUIRED, EncodingOptions.NOT_REQUIRED, false, charset);

this.values = StreamSupport.stream(values.spliterator(), false)

.filter(Util::isNotBlank)

.collect(Collectors.toCollection(LinkedHashSet::new));

this.name = name;

}

/**

* Creates a new Header Template from a set of TemplateChunks.

*

* @param name of the header.

* @param charset to encode the expanded values in.

* @param chunks for the template.

*/

private HeaderTemplate(String name, Charset charset, List<TemplateChunk> chunks) {

super(ExpansionOptions.REQUIRED, EncodingOptions.NOT_REQUIRED, false, charset,

chunks);

this.values = chunks.stream()

.map(TemplateChunk::getValue)

.collect(Collectors.toCollection(LinkedHashSet::new));

this.name = name;

}

public Collection<String> getValues() {

return Collections.unmodifiableCollection(values);

}

public String getName() {

return name;

}

@Override

public String expand(Map<String, ?> variables) {

String result = super.expand(variables);

/* remove any trailing commas */

while (result.endsWith(",")) {

result = result.replaceAll(",$", "");

}

/* space all the commas now */

result = result.replaceAll(",", ", ");

return result;

}

}