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/**
 * Copyright 2012-2019 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 java.util.Optional;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * URI Template Expression.
 */
abstract class Expression implements TemplateChunk {

	private String name;
	private Pattern pattern;

	/**
	 * Create a new Expression.
	 *
	 * @param name
	 *            of the variable
	 * @param pattern
	 *            the resolved variable must adhere to, optional.
	 */
	Expression(String name, String pattern) {
		this.name = name;
		Optional.ofNullable(pattern).ifPresent(s -> this.pattern = Pattern.compile(s));
	}

	abstract String expand(Object variable, boolean encode);

	public String getName() {
		return this.name;
	}

	Pattern getPattern() {
		return pattern;
	}

	/**
	 * Checks if the provided value matches the variable pattern, if one is defined.
	 * Always true if no pattern is defined.
	 *
	 * @param value
	 *            to check.
	 * @return true if it matches.
	 */
	boolean matches(String value) {
		if (pattern == null) {
			return true;
		}
		return pattern.matcher(value).matches();
	}

	@Override
	public String getValue() {
		if (this.pattern != null) {
			return "{" + this.name + ":" + this.pattern + "}";
		}
		return "{" + this.name + "}";
	}

	@Override
	public String toString() {
		return this.getValue();
	}
}