/*
 * Copyright 2012-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *  http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. This file 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 com.amazonaws.services.s3.model;

import java.util.Map;

/**
 * Simple implementation of EncryptionMaterialsProvider that just wraps static
 * EncryptionMaterials.
 */
public class StaticEncryptionMaterialsProvider implements EncryptionMaterialsProvider {

    private final EncryptionMaterials materials;

    public StaticEncryptionMaterialsProvider(EncryptionMaterials materials) {
        this.materials = materials;
    }

    @Override
    public EncryptionMaterials getEncryptionMaterials() {
        return materials;
    }

    @Override
    public void refresh() {
    }

    @Override
    public EncryptionMaterials getEncryptionMaterials(
            final Map<String, String> materialDescIn) {
        final Map<String, String> materialDesc =
                materials.getMaterialsDescription();
        if (materialDescIn != null
                && materialDescIn.equals(materialDesc)) {
            return materials; // matching description
        }
        EncryptionMaterialsAccessor accessor = materials.getAccessor();
        if (accessor != null) {
            EncryptionMaterials accessorMaterials =
                    accessor.getEncryptionMaterials(materialDescIn);
            if (accessorMaterials != null)
                return accessorMaterials; // accessor decided materials
        }
        // The condition that there are
        // 1) no input materials description (typically from S3); and
        // 2) no materials description for the current client-side materials;
        // and
        // 3) the client's material accessor has no corresponding materials
        // for null or empty materials description;
        // implies that the only sensible materials is
        // the current client-side materials (which has no description).
        boolean noMaterialDescIn = materialDescIn == null || materialDescIn.size() == 0;
        boolean noMaterialDesc = materialDesc == null || materialDesc.size() == 0;
        return noMaterialDescIn && noMaterialDesc ? materials : null;
    }
}