/*
 * 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.node;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.function.Supplier;
import java.util.function.Function;

import org.opensearch.Version;
import org.opensearch.cluster.ClusterName;
import org.opensearch.common.settings.Settings;
import org.opensearch.common.settings.SettingsException;
import org.opensearch.env.Environment;

/**
 * Prepares internal settings
 *
 * @opensearch.internal
 */
public class InternalSettingsPreparer {

    private static final String SECRET_PROMPT_VALUE = "${prompt.secret}";
    private static final String TEXT_PROMPT_VALUE = "${prompt.text}";

    /**
     * TODO: Refactor this as transport client is removed and this used to prepare settings for the transport client by
     * gathering all opensearch system properties and setting defaults.
     */
    public static Settings prepareSettings(Settings input) {
        Settings.Builder output = Settings.builder();
        initializeSettings(output, input, Collections.emptyMap());
        finalizeSettings(output, () -> null);
        return output.build();
    }

    /**
     * Prepares the settings by gathering all opensearch system properties, optionally loading the configuration settings.
     *
     * @param input      the custom settings to use; these are not overwritten by settings in the configuration file
     * @param properties map of properties key/value pairs (usually from the command-line)
     * @param configPath path to config directory; (use null to indicate the default)
     * @param defaultNodeName supplier for the default node.name if the setting isn't defined
     * @return the {@link Environment}
     */
    public static Environment prepareEnvironment(
        Settings input,
        Map<String, String> properties,
        Path configPath,
        Supplier<String> defaultNodeName
    ) {
        // just create enough settings to build the environment, to get the config dir
        Settings.Builder output = Settings.builder();
        initializeSettings(output, input, properties);
        Environment environment = new Environment(output.build(), configPath);

        output = Settings.builder(); // start with a fresh output
        Path path = environment.configDir().resolve("opensearch.yml");
        if (Files.exists(path)) {
            try {
                output.loadFromPath(path);
            } catch (IOException e) {
                throw new SettingsException("Failed to load settings from " + path.toString(), e);
            }
        }

        // re-initialize settings now that the config file has been loaded
        initializeSettings(output, input, properties);
        checkSettingsForTerminalDeprecation(output);
        finalizeSettings(output, defaultNodeName);

        return new Environment(output.build(), configPath);
    }

    /**
     * Initializes the builder with the given input settings, and applies settings from the specified map (these settings typically come
     * from the command line).
     *
     * @param output the settings builder to apply the input and default settings to
     * @param input the input settings
     * @param esSettings a map from which to apply settings
     */
    static void initializeSettings(final Settings.Builder output, final Settings input, final Map<String, String> esSettings) {
        output.put(input);
        output.putProperties(esSettings, Function.identity());
        output.replacePropertyPlaceholders();
    }

    /**
     * Checks all settings values to make sure they do not have the old prompt settings. These were deprecated in 6.0.0.
     * This check should be removed in 8.0.0.
     */
    private static void checkSettingsForTerminalDeprecation(final Settings.Builder output) throws SettingsException {
        // This method to be removed in 8.0.0, as it was deprecated in 6.0 and removed in 7.0
        assert Version.CURRENT.major != 8 : "Logic pertaining to config driven prompting should be removed";
        for (String setting : output.keys()) {
            final String value = output.get(setting);
            if (value != null) {
                switch (value) {
                    case SECRET_PROMPT_VALUE:
                        throw new SettingsException(
                            "Config driven secret prompting was deprecated in 6.0.0. Use the keystore" + " for secure settings."
                        );
                    case TEXT_PROMPT_VALUE:
                        throw new SettingsException(
                            "Config driven text prompting was deprecated in 6.0.0. Use the keystore" + " for secure settings."
                        );
                }
            }
        }
    }

    /**
     * Finish preparing settings by replacing forced settings and any defaults that need to be added.
     */
    private static void finalizeSettings(Settings.Builder output, Supplier<String> defaultNodeName) {
        // allow to force set properties based on configuration of the settings provided
        List<String> forcedSettings = new ArrayList<>();
        for (String setting : output.keys()) {
            if (setting.startsWith("force.")) {
                forcedSettings.add(setting);
            }
        }
        for (String forcedSetting : forcedSettings) {
            String value = output.remove(forcedSetting);
            output.put(forcedSetting.substring("force.".length()), value);
        }
        output.replacePropertyPlaceholders();

        // put the cluster and node name if they aren't set
        if (output.get(ClusterName.CLUSTER_NAME_SETTING.getKey()) == null) {
            output.put(ClusterName.CLUSTER_NAME_SETTING.getKey(), ClusterName.CLUSTER_NAME_SETTING.getDefault(Settings.EMPTY).value());
        }
        if (output.get(Node.NODE_NAME_SETTING.getKey()) == null) {
            output.put(Node.NODE_NAME_SETTING.getKey(), defaultNodeName.get());
        }
    }
}