/*
 * Copyright 2012-2016 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 org.springframework.security.access.hierarchicalroles;

import org.springframework.util.Assert;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.List;
import java.util.Map;

/**
 * Utility methods for {@link RoleHierarchy}.
 *
 * @author Thomas Darimont
 * @since 4.2.0
 */
public final class RoleHierarchyUtils {

	private RoleHierarchyUtils() {
	}

	/**
	 * Converts the supplied {@link Map} of role name to implied role name(s) to a string
	 * representation understood by {@link RoleHierarchyImpl#setHierarchy(String)}.
	 * The map key is the role name and the map value is a {@link List} of implied role name(s).
	 *
	 * @param roleHierarchyMap the mapping(s) of role name to implied role name(s)
	 * @return a string representation of a role hierarchy
	 * @throws IllegalArgumentException if roleHierarchyMap is null or empty or if a role name is null or
	 * empty or if an implied role name(s) is null or empty
	 *
	 */
	public static String roleHierarchyFromMap(Map<String, List<String>> roleHierarchyMap) {
		Assert.notEmpty(roleHierarchyMap, "roleHierarchyMap cannot be empty");

		StringWriter roleHierarchyBuffer = new StringWriter();
		PrintWriter roleHierarchyWriter = new PrintWriter(roleHierarchyBuffer);

		for (Map.Entry<String, List<String>> roleHierarchyEntry : roleHierarchyMap.entrySet()) {
			String role = roleHierarchyEntry.getKey();
			List<String> impliedRoles = roleHierarchyEntry.getValue();

			Assert.hasLength(role, "role name must be supplied");
			Assert.notEmpty(impliedRoles, "implied role name(s) cannot be empty");

			for (String impliedRole : impliedRoles) {
				String roleMapping = role + " > " + impliedRole;
				roleHierarchyWriter.println(roleMapping);
			}
		}

		return roleHierarchyBuffer.toString();
	}

}
