/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.sling.caconfig.resource;

import java.util.Collection;

import org.apache.sling.api.resource.Resource;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
import org.osgi.annotation.versioning.ProviderType;

/**
 * Getting context-aware configuration resources for a given resource context.
 * This is a low-level interface for supporting advanced use cases. If you just want to fetch
 * some configuration parameters {@link org.apache.sling.caconfig.ConfigurationResolver}
 * is the right place.
 */
@ProviderType
public interface ConfigurationResourceResolver {

    /**
     * Get a context-aware singleton configuration resource defined by the given configuration name.
     *
     * @param resource Context resource to fetch configuration for
     * @param bucketName Configuration "bucket" name. Each high-level configuration resolver should store 
     *     it's configuration data grouped in a child resource of the configuration resource. This is what
     *     we call a "bucket", and the resource name is specified with this parameter.
     * @param configName Configuration name or relative path.
     * @return Configuration resource or {@code null}.
     */
    @Nullable Resource getResource(@NotNull Resource resource, @NotNull String bucketName, @NotNull String configName);

    /**
     * Get a collection of context-aware configuration resources defined by the given configuration name.
     * @param resource Context resource to fetch configuration for
     * @param bucketName Configuration "bucket" name. Each high-level configuration resolver should store 
     *     it's configuration data grouped in a child resource of the configuration resource. This is what
     *     we call a "bucket", and the resource name is specified with this parameter.
     * @param configName Configuration name or relative path.
     * @return Collection of configuration resources, the collection might be empty.
     */
    @NotNull Collection<Resource> getResourceCollection(@NotNull Resource resource, @NotNull String bucketName, @NotNull String configName);

    /**
     * Get the inner-most context path (deepest path) returned by {@link #getAllContextPaths(Resource)}.
     * @param resource Context resource to fetch configuration for
     * @return Context path or null
     */
    String getContextPath(@NotNull Resource resource);

    /**
     * Get all context paths for which context-aware configurations could be defined.
     * The context paths are always ancestors of the resource path, or the resource path itself.
     * Which ancestors are allowed for context-aware configuration depends on configuration.
     * @param resource Context resource to fetch configuration for
     * @return List of context paths
     */
    @NotNull Collection<String> getAllContextPaths(@NotNull Resource resource);

}