/*
 * SPDX-License-Identifier: Apache-2.0
 *
 * The OpenSearch Contributors require contributions made to
 * this file be licensed under the Apache-2.0 license or a
 * compatible open source license.
 */

/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch 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.
 */

/*
 * Modifications Copyright OpenSearch Contributors. See
 * GitHub history for details.
 */

package org.opensearch.common.ssl;

import javax.net.ssl.X509ExtendedTrustManager;

import java.nio.file.Path;
import java.security.GeneralSecurityException;
import java.security.KeyStore;
import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;

/**
 * A {@link SslTrustConfig} that builds a Trust Manager from a keystore file.
 */
final class StoreTrustConfig implements SslTrustConfig {
    private final Path path;
    private final char[] password;
    private final String type;
    private final String algorithm;

    /**
     * @param path      The path to the keystore file
     * @param password  The password for the keystore
     * @param type      The {@link KeyStore#getType() type} of the keystore (typically "PKCS12" or "jks").
     *                  See {@link KeyStoreUtil#inferStoreType(String)}.
     * @param algorithm The algorithm to use for the Trust Manager (see {@link javax.net.ssl.TrustManagerFactory#getAlgorithm()}).
     */
    StoreTrustConfig(Path path, char[] password, String type, String algorithm) {
        this.path = path;
        this.type = type;
        this.algorithm = algorithm;
        this.password = password;
    }

    @Override
    public Collection<Path> getDependentFiles() {
        return Collections.singleton(path);
    }

    @Override
    public X509ExtendedTrustManager createTrustManager() {
        try {
            final KeyStore store = KeyStoreUtil.readKeyStore(path, type, password);
            checkTrustStore(store);
            return KeyStoreUtil.createTrustManager(store, algorithm);
        } catch (GeneralSecurityException e) {
            throw new SslConfigException(
                "cannot create trust manager for path=["
                    + (path == null ? null : path.toAbsolutePath())
                    + "] type=["
                    + type
                    + "] password=["
                    + (password.length == 0 ? "<empty>" : "<non-empty>")
                    + "]",
                e
            );
        }
    }

    /**
     * Verifies that the keystore contains at least 1 trusted certificate entry.
     */
    private void checkTrustStore(KeyStore store) throws GeneralSecurityException {
        Enumeration<String> aliases = store.aliases();
        while (aliases.hasMoreElements()) {
            String alias = aliases.nextElement();
            if (store.isCertificateEntry(alias)) {
                return;
            }
        }
        final String message;
        if (path != null) {
            message = "the truststore [" + path + "] does not contain any trusted certificate entries";
        } else {
            message = "the configured PKCS#11 token does not contain any trusted certificate entries";
        }
        throw new SslConfigException(message);
    }

}
